register interest

Professor Helen McShane

Research Area: Immunology
Scientific Themes: Immunology & Infectious Disease
Keywords: Tuberculosis, Vaccine, Immunisation and Clinical Trial
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Vaccinating an infant in The Gambia

Vaccinating an infant in The Gambia

Meeting Queen Sophia of Spain, May 2014

Meeting Queen Sophia of Spain, May 2014

The HIV epidemic and the emergence of multi and extensively drug-resistant strains of Mycobacterium tuberculosis (M.tb) mean that global control of tuberculosis (TB), particularly adult pulmonary TB, remains inadequate. There is an urgent need for better control measures, and the most cost effective way to control any infectious disease epidemic is with effective vaccination. The current vaccine, BCG confers protection against disseminated disease in childhood, but does not reliably protect against pulmonary disease. A strong cell mediated immune response is essential for protective immunity. It is known that Class II-restricted CD4+ T cells are essential for protective immunity and that class I-restricted CD8+ T lymphocytes may play a role in maintaining the latent state. Other cell types, including gamma delta cells and Th17 cells may also play a role. Antibodies may have some role, particularly in prevention of infection.

Since 2002, my group has conducted a series of clinical trials in the UK, The Gambia, South Africa, Senegal and Uganda, to investigate the safety, immunogenicity and efficacy of candidate TB vaccines, including MVA85A (recombinant modified vaccinia Ankara expressing antigen 85A) and ChAdOx1 85A (chimp adenovirus expressing antigen 85A) (both developed at the Jenner), and a number of industry partners’ vaccines. MVA85A and ChAdOx1 85A are used as boost vaccines for BCG-primed subjects; heterologous prime-boost vaccination regimens provide an effective way to induce high levels of cellular immunity, while the inclusion of BCG in a new regimen allows the retention of the protective effects of BCG in childhood against severe disease. Both vaccines have been shown to be safe and immunogenic in healthy adult volunteers. MVA85A has been further studied in M.tb latently infected individuals, and HIV-infected individuals, and the vaccine is safe and immunogenic in these groups. Successful healthy adult clinical trials were followed by age de-escalation studies that demonstrated safety in children and infants.

MVA85A was the first new TB candidate vaccine to be evaluated in an efficacy trial since BCG was last tested in infants in the 1960s. The first efficacy trial, conducted from 2009-2012 in collaboration with the South African TB Vaccine Initiative (SATVI) and supported by Aeras and the Wellcome Trust, enrolled 2797 South African infants who were randomised to receive BCG alone at birth or BCG followed by MVA85A boost at 4-6 months of age. MVA85A vaccination was safe but did not improve upon BCG-induced protection.

 A second randomised, double-blind, placebo-controlled, efficacy trial has taken place in South Africa and Senegal in HIV-infected adults, with the collaboration of the University of Cape Town and CHU Le Dantec and support from Aeras and EDCTP. This trial started in 2011 and the 650 adults completed follow up in late 2014. Results are expected shortly.

A current area of interest to our group is whether delivering a TB vaccine via the aerosol route (through nebulisation directly into the lungs) is a more effective method of vaccination. In the last few years we have started clinical trials investigating aerosol delivery of MVA85A and have shown this route to be both safe and immunogenic. Other current projects within my group include the development of a BCG challenge model in humans, evaluating the effect of helminth infection on vaccine induced immune responses, and the evaluation of the protective efficacy of new antigens in viral vectors.

Name Department Institution Country
Dr Henry Bettinson Respiratory Medicine Churchill Hospital United Kingdom
Prof Keith Channon FMedSci FRCP (RDM) Cardiovascular Medicine Oxford University, John Radcliffe Hospital United Kingdom
Professor Hazel Dockrell London School of Hygeine and Tropical Medicine United Kingdom
Prof Alexander (Hal) Drakesmith (RDM) Investigative Medicine Division Oxford University, Weatherall Institute of Molecular Medicine United Kingdom
Professor Alison Elliott MRC Laboratories, Entebbe Uganda
Dr Tom Evans Aeras United States
Dr Helen A Fletcher University of Oxford United Kingdom
Professor Mark Hatherill South African TB Vaccine Initiative (SATVI), Cape Town South Africa
Professor Glyn Hewinson Animal and Plant Health Agency United Kingdom
Professor Adrian VS Hill Jenner Institute Oxford University, Old Road Campus Research Building United Kingdom
Dr Kris Huygen Belgian Scientific Institute for Public Health Belgium
Professor David Lewinsohn University of Oregon United States
Professor Souleymane MBoup University of Dakar Senegal
Professor Paul Moss University of Birmingham United Kingdom
Professor Tom Ottenhoff Department of Infectious Diseases Leiden University Netherlands
Dr Ann Rawkins Public Health England, Porton Down United Kingdom
Dr Sally Sharpe Public Health England, Porton Down United Kingdom
Dr Martin Vordermeier Jenner Institute University of Oxford United Kingdom
Professor Robert Wilkinson University of Cape Town South Africa
Ginsberg AM, Ruhwald M, Mearns H, McShane H. 2016. TB vaccines in clinical development. Tuberculosis (Edinb), 99 Suppl 1 pp. S16-S20. | Show Abstract | Read more

The 4th Global Forum on TB Vaccines, convened in Shanghai, China, from 21 - 24 April 2015, brought together a wide and diverse community involved in tuberculosis vaccine research and development to discuss the current status of, and future directions for this critical effort. This paper summarizes the sessions on TB Vaccines in Clinical Development, and Clinical Research: Data and Findings. Summaries of all sessions from the 4th Global Forum are compiled in a special supplement of Tuberculosis. [August 2016, Vol 99, Supp S1, S1-S30].

Davenne T, McShane H. 2016. Why don't we have an effective tuberculosis vaccine yet? Expert Rev Vaccines, 15 (8), pp. 1009-1013. | Show Abstract | Read more

Mycobacterium tuberculosis (M.tb) has co-evolved with humans for thousands of years, to cause tuberculosis (TB). The success of M.tb as a pathogen is in part because of the ways in which M.tb evades and exploits different cell subsets, to persist and cause disease. M.tb expresses numerous molecules to prevent its recognition and destruction by immune cells. The only licensed vaccine against TB, Bacillle Calmette-Guerin (BCG), is effective at preventing disseminated disease in infants but confers highly variable efficacy against pulmonary TB in adults, particularly in the developing world. A greater understanding of the reasons for this variability, together with a better understanding of the early, innate, and non-antigen specific mechanisms of protection would facilitate the design and development of more effective vaccines.

Minhinnick A, Satti I, Harris S, Wilkie M, Sheehan S, Stockdale L, Manjaly Thomas ZR, Lopez-Ramon R et al. 2016. A first-in-human phase 1 trial to evaluate the safety and immunogenicity of the candidate tuberculosis vaccine MVA85A-IMX313, administered to BCG-vaccinated adults. Vaccine, 34 (11), pp. 1412-1421. | Show Abstract | Read more

INTRODUCTION: There is an urgent need for a new and effective tuberculosis vaccine because BCG does not sufficiently prevent pulmonary disease. IMX313 is a novel carrier protein designed to improve cellular and humoral immunity. MVA85A-IMX313 is a novel vaccine candidate designed to boost immunity primed by bacillus Calmette-Guérin (BCG) that has been immunogenic in pre-clinical studies. This is the first evaluation of IMX313 delivered as MVA85A-IMX313 in humans. METHODS: In this phase 1, open-label first-in-human trial, 30 healthy previously BCG-vaccinated adults were enrolled into three treatment groups and vaccinated with low dose MVA85A-IMX313 (group A), standard dose MVA85A-IMX313 (group B), or MVA85A (group C). Volunteers were followed up for 6 months for safety and immunogenicity assessment. RESULTS: The majority of adverse events were mild and there were no vaccine-related serious AEs. Both MVA85A-IMX313 and MVA85A induced a significant increase in IFN-γ ELISpot responses. There were no significant differences between the Ag85A ELISpot and intracellular cytokine responses between the two study groups B (MVA85A-IMX313) and C (MVA85A) at any time point post-vaccination. CONCLUSION: MVA85A-IMX313 was well tolerated and immunogenic. There was no significant difference in the number of vaccine-related, local or systemic adverse reactions between MVA85A and MVA85A-IMX313 groups. The mycobacteria-specific cellular immune responses induced by MVA85A-IMX313 were not significantly different to those detected in the MVA85A group. In light of this encouraging safety data, further work to improve the potency of molecular adjuvants like IMX313 is merited. This trial was registered on clinicatrials.gov ref. NCT01879163.

O'Shea MK, McShane H. 2016. A review of clinical models for the evaluation of human TB vaccines. Hum Vaccin Immunother, 12 (5), pp. 1177-1187. | Show Abstract | Read more

While much progress has been made in the fight against the scourge of tuberculosis (TB), we are still some way from reaching the ambitious targets of eliminating it as a global public health problem by the mid twenty-first century. A new and effective vaccine that protects against pulmonary TB disease will be an essential element of any control strategy. Over a dozen vaccines are currently in development, but recent efficacy trial data from one of the most advanced candidates have been disappointing. Limitations of current preclinical animal models exist, together with a lack of a complete understanding of host immunity to TB or robust correlates of disease risk and protection. Therefore, in the context of such obstacles, we discuss the lessons identified from recent efficacy trials, current concepts of biomarkers and correlates of protection, the potential of innovative clinical models such as human challenge and conducting trials in high-incidence settings to evaluate TB vaccines in humans, and the use of systems vaccinology and novel technologies including transcriptomics and metabolomics, that may facilitate their utility.

McShane H. 2016. From AIDS to TB vaccines--A career in infectious diseases and translational vaccinology. Hum Vaccin Immunother, 12 (1), pp. 5-7. | Read more

Fletcher HA, Snowden MA, Landry B, Rida W, Satti I, Harris SA, Matsumiya M, Tanner R et al. 2016. Corrigendum: T-cell activation is an immune correlate of risk in BCG vaccinated infants. Nat Commun, 7 pp. 11633. | Read more

Stylianou E, Griffiths KL, Poyntz HC, Harrington-Kandt R, Dicks MD, Stockdale L, Betts G, McShane H. 2015. Improvement of BCG protective efficacy with a novel chimpanzee adenovirus and a modified vaccinia Ankara virus both expressing Ag85A. Vaccine, 33 (48), pp. 6800-6808. | Show Abstract | Read more

A replication-deficient chimpanzee adenovirus expressing Ag85A (ChAdOx1.85A) was assessed, both alone and in combination with modified vaccinia Ankara also expressing Ag85A (MVA85A), for its immunogenicity and protective efficacy against a Mycobacterium tuberculosis (M.tb) challenge in mice. Naïve and BCG-primed mice were vaccinated or boosted with ChAdOx1.85A and MVA85A in different combinations. Although intranasally administered ChAdOx1.85A induced strong immune responses in the lungs, it failed to consistently protect against aerosol M.tb challenge. In contrast, ChAdOx1.85A followed by MVA85A administered either mucosally or systemically, induced strong immune responses and was able to improve the protective efficacy of BCG. This vaccination regime has consistently shown superior protection over BCG alone and should be evaluated further.

Bunyasi EW, Tameris M, Geldenhuys H, Schmidt BM, Luabeya AK, Mulenga H, Scriba TJ, Hanekom WA, Mahomed H, McShane H, Hatherill M. 2015. Evaluation of Xpert® MTB/RIF Assay in Induced Sputum and Gastric Lavage Samples from Young Children with Suspected Tuberculosis from the MVA85A TB Vaccine Trial. PLoS One, 10 (11), pp. e0141623. | Show Abstract | Read more

OBJECTIVE: Diagnosis of childhood tuberculosis is limited by the paucibacillary respiratory samples obtained from young children with pulmonary disease. We aimed to compare accuracy of the Xpert® MTB/RIF assay, an automated nucleic acid amplification test, between induced sputum and gastric lavage samples from young children in a tuberculosis endemic setting. METHODS: We analyzed standardized diagnostic data from HIV negative children younger than four years of age who were investigated for tuberculosis disease near Cape Town, South Africa [2009-2012]. Two paired, consecutive induced sputa and early morning gastric lavage samples were obtained from children with suspected tuberculosis. Samples underwent Mycobacterial Growth Indicator Tube [MGIT] culture and Xpert MTB/RIF assay. We compared diagnostic yield across samples using the two-sample test of proportions and McNemar's χ2 test; and Wilson's score method to calculate sensitivity and specificity. RESULTS: 1,020 children were evaluated for tuberculosis during 1,214 admission episodes. Not all children had 4 samples collected. 57 of 4,463[1.3%] and 26 of 4,606[0.6%] samples tested positive for Mycobacterium tuberculosis on MGIT culture and Xpert MTB/RIF assay respectively. 27 of 2,198[1.2%] and 40 of 2,183[1.8%] samples tested positive [on either Xpert MTB/RIF assay or MGIT culture] on induced sputum and gastric lavage samples, respectively. 19/1,028[1.8%] and 33/1,017[3.2%] admission episodes yielded a positive MGIT culture or Xpert MTB/RIF assay from induced sputum and gastric lavage, respectively. Sensitivity of Xpert MTB/RIF assay was 8/30[26.7%; 95% CI: 14.2-44.4] for two induced sputum samples and 7/31[22.6%; 11.4-39.8] [p = 0.711] for two gastric lavage samples. Corresponding specificity was 893/893[100%;99.6-100] and 885/890[99.4%;98.7-99.8] respectively [p = 0.025]. CONCLUSION: Sensitivity of Xpert MTB/RIF assay was low, compared to MGIT culture, but diagnostic performance of Xpert MTB/RIF did not differ sufficiently between induced sputum and gastric lavage to justify selection of one sampling method over the other, in young children with suspected pulmonary TB. TRIAL REGISTRATION: ClinicalTrials.gov NCT00953927.

Sheehan S, Harris SA, Satti I, Hokey DA, Dheenadhayalan V, Stockdale L, Manjaly Thomas ZR, Minhinnick A et al. 2015. A Phase I, Open-Label Trial, Evaluating the Safety and Immunogenicity of Candidate Tuberculosis Vaccines AERAS-402 and MVA85A, Administered by Prime-Boost Regime in BCG-Vaccinated Healthy Adults. PLoS One, 10 (11), pp. e0141687. | Show Abstract | Read more

BACKGROUND: MVA85A and AERAS-402 are two clinically advanced viral vectored TB vaccine candidates expressing Mycobacterium tuberculosis antigens designed to boost BCG-induced immunity. Clinical trials with candidate malaria vaccines have demonstrated that adenoviral vector based priming immunisation, followed by MVA vector boost, induced high levels of immunity. We present the safety and immunogenicity results of the first clinical trial to evaluate this immunisation strategy in TB. METHODS: In this phase 1, open-label trial, 40 healthy previously BCG-vaccinated participants were enrolled into three treatment groups and vaccinated with 1 or 2 doses of AERAS-402 followed by MVA85A; or 3 doses of AERAS-402. RESULTS: Most related adverse events (AEs) were mild and there were no vaccine related serious AEs. Boosting AERAS-402 with MVA85A significantly increased Ag85A-specific T-cell responses from day of vaccination. Two priming doses of AERAS-402 followed by MVA85A boost, resulted in a significantly higher AUC post-peak Ag85A response compared to three doses of AERAS-402 and historical data with MVA85A vaccination alone. The frequency of CD8+ T-cells producing IFN-γ, TNF-α and IL-2 was highest in the group receiving two priming doses of AERAS-402 followed by MVA85A. CONCLUSIONS: Vaccination with AERAS-402 followed by MVA85A was safe and increased the durability of antigen specific T-cell responses and the frequency and polyfunctionality of CD8+ T-cells, which may be important in protection against TB. Further clinical trials with adenoviral prime-MVA85A boost regimens are merited to optimise vaccination intervals, dose and route of immunisation and to evaluate this strategy in the target population in TB high burden countries. TRIAL REGISTRATION: ClinicalTrials.gov NCT01683773.

Minhinnick A, Harris S, Wilkie M, Peter J, Stockdale L, Manjaly-Thomas ZR, Vermaak S, Satti I, Moss P, McShane H. 2016. Optimization of a Human Bacille Calmette-Guérin Challenge Model: A Tool to Evaluate Antimycobacterial Immunity. J Infect Dis, 213 (5), pp. 824-830. | Show Abstract | Read more

BACKGROUND: There is an urgent need for an improved tuberculosis vaccine. The lack of a validated correlate of protection slows progress in achieving this goal. A human mycobacterial challenge model, using bacille Calmette-Guérin (BCG) as a surrogate for a Mycobacterium tuberculosis challenge, would facilitate vaccine selection for field efficacy testing. Optimization of this model is required. METHODS: Healthy BCG-naive adults were assigned to receive intradermal standard-dose BCG SSI (group A), standard-dose BCG TICE (group B), high-dose BCG SSI (group C), and high-dose BCG TICE (group D). Two weeks after BCG challenge, skin biopsy of the challenge site was performed. BCG mycobacterial load was quantified by solid culture and quantitative polymerase chain reaction. RESULTS: BCG was well tolerated, and reactogenicity was similar between groups, regardless of strain and dose. There was significantly greater recovery of BCG from the high-dose challenge groups, compared with standard-dose challenge. BCG strain did not significantly affect BCG recovery. CONCLUSIONS: BCG challenge dose affects sensitivity of this model. We have selected high-dose BCG SSI to take forward in future challenge studies. Assessment of candidate tuberculosis vaccine effectiveness with this optimized model could contribute to vaccine selection for efficacy trials. CLINICAL TRIALS REGISTRATION: NCT02088892.

Smith SG, Smits K, Joosten SA, van Meijgaarden KE, Satti I, Fletcher HA, Caccamo N, Dieli F et al. 2015. Intracellular Cytokine Staining and Flow Cytometry: Considerations for Application in Clinical Trials of Novel Tuberculosis Vaccines. PLoS One, 10 (9), pp. e0138042. | Show Abstract | Read more

Intracellular cytokine staining combined with flow cytometry is one of a number of assays designed to assess T-cell immune responses. It has the specific advantage of enabling the simultaneous assessment of multiple phenotypic, differentiation and functional parameters pertaining to responding T-cells, most notably, the expression of multiple effector cytokines. These attributes make the technique particularly suitable for the assessment of T-cell immune responses induced by novel tuberculosis vaccines in clinical trials. However, depending upon the particular nature of a given vaccine and trial setting, there are approaches that may be taken at different stages of the assay that are more suitable than other alternatives. In this paper, the Tuberculosis Vaccine Initiative (TBVI) TB Biomarker Working group reports on efforts to assess the conditions that will determine when particular assay approaches should be employed. We have found that choices relating to the use of fresh whole blood or peripheral blood mononuclear cells (PBMC) and frozen PBMC; use of serum-containing or serum-free medium; length of stimulation period and use of co-stimulatory antibodies can all affect the sensitivity of intracellular cytokine assays. In the case of sample material, frozen PBMC, despite some loss of sensitivity, may be more advantageous for batch analysis. We also recommend that for multi-site studies, common antibody panels, gating strategies and analysis approaches should be employed for better comparability.

Mulenga H, Tameris MD, Luabeya KK, Geldenhuys H, Scriba TJ, Hussey GD, Mahomed H, Landry BS, Hanekom WA, McShane H, Hatherill M. 2015. The Role of Clinical Symptoms in the Diagnosis of Intrathoracic Tuberculosis in Young Children. Pediatr Infect Dis J, 34 (11), pp. 1157-1162. | Show Abstract | Read more

BACKGROUND: Childhood tuberculosis (TB) is usually Mycobacterium tuberculosis (MTB) culture negative. Furthermore, clinical presentation may be altered by active case finding, isoniazid prophylaxis and early treatment. We aimed to establish the value of presenting symptoms for intrathoracic TB case diagnosis among young children. METHODS: Healthy, HIV-uninfected, South African infants in an efficacy trial of a novel TB vaccine (MVA85A) were followed for 2 years for suspected TB. When suspected, investigation followed a standardized algorithm comprising symptom history, QuantiFERON Gold-in-Tube, chest radiography (CXR), MTB culture and Xpert MTB/RIF from paired gastric lavage and induced sputa. Adjusted odds ratios and 95% confidence intervals describe the associations between symptoms and positive MTB culture or Xpert MTB/RIF, and CXR compatible with intrathoracic TB. RESULTS: Persistent cough was present in 172/1017 (16.9%) of the children investigated for TB. MTB culture/Xpert MTB/RIF was positive in 38/1017 children (3.7%); and CXR was positive, that is, compatible with intrathoracic TB, in 131/1017 children (12.9%). Children with persistent cough had more than triple the odds of a positive MTB culture/Xpert MTB/RIF (adjusted odds ratios: 3.3, 95% confidence interval: 1.5-7.0) and positive CXR (adjusted odds ratios: 3.5, 95% confidence interval: 2.2-5.5). Persistent cough was the only symptom that differentiated children with severe (56.5%) from nonsevere intrathoracic TB disease (28.2%; P = 0.001). CONCLUSION: Persistent cough was the cardinal diagnostic symptom associated with microbiologic and radiologic evidence, and disease severity, of intrathoracic TB. Symptom-based definitions of TB disease for diagnostic, preventive and therapeutic studies should prioritize persistent cough above other symptoms compatible with childhood TB.

Naranbhai V, Fletcher HA, Tanner R, O'Shea MK, McShane H, Fairfax BP, Knight JC, Hill AV. 2015. Distinct Transcriptional and Anti-Mycobacterial Profiles of Peripheral Blood Monocytes Dependent on the Ratio of Monocytes: Lymphocytes. EBioMedicine, 2 (11), pp. 1619-1626. | Show Abstract | Read more

The ratio of monocytes and lymphocytes (ML ratio) in peripheral blood is associated with tuberculosis and malaria disease risk and cancer and cardiovascular disease outcomes. We studied anti-mycobacterial function and the transcriptome of monocytes in relation to the ML ratio. Mycobacterial growth inhibition assays of whole or sorted blood were performed and mycobacteria were enumerated by liquid culture. Transcriptomes of unstimulated CD14 + monocytes isolated by magnetic bead sorting were characterised by microarray. Transcript expression was tested for association with ML ratio calculated from leucocyte differential counts by linear regression. The ML ratio was associated with mycobacterial growth in vitro (β = 2.23, SE 0.91, p = 0.02). Using sorted monocytes and lymphocytes, in vivo ML ratio (% variance explained R(2) = 11%, p = 0.02) dominated over in vitro ratios (R(2) = 5%, p = 0.10) in explaining mycobacterial growth. Expression of 906 genes was associated with the ML ratio and 53 with monocyte count alone. ML-ratio associated genes were enriched for type-I and -II interferon signalling (p = 1.2 × 10(− 8)), and for genes under transcriptional control of IRF1, IRF2, RUNX1, RELA and ESRRB. The ML-ratio-associated gene set was enriched in TB disease (3.11-fold, 95% CI: 2.28-4.19, p = 5.7 × 10(− 12)) and other inflammatory diseases including atopy, HIV, IBD and SLE. The ML ratio is associated with distinct transcriptional and anti-mycobacterial profiles of monocytes that may explain the disease associations of the ML ratio.

Cliff JM, Kaufmann SH, McShane H, van Helden P, O'Garra A. 2015. The human immune response to tuberculosis and its treatment: a view from the blood. Immunol Rev, 264 (1), pp. 88-102. | Show Abstract | Read more

The immune response upon infection with the pathogen Mycobacterium tuberculosis is poorly understood, hampering the discovery of new treatments and the improvements in diagnosis. In the last years, a blood transcriptional signature in tuberculosis has provided knowledge on the immune response occurring during active tuberculosis disease. This signature was absent in the majority of asymptomatic individuals who are latently infected with M. tuberculosis (referred to as latent). Using modular and pathway analyses of the complex data has shown, now in multiple studies, that the signature of active tuberculosis is dominated by overexpression of interferon-inducible genes (consisting of both type I and type II interferon signaling), myeloid genes, and inflammatory genes. There is also downregulation of genes encoding B and T-cell function. The blood signature of tuberculosis correlates with the extent of radiographic disease and is diminished upon effective treatment suggesting the possibility of new improved strategies to support diagnostic assays and methods for drug treatment monitoring. The signature suggested a previously under-appreciated role for type I interferons in development of active tuberculosis disease, and numerous mechanisms have now been uncovered to explain how type I interferon impedes the protective response to M. tuberculosis infection.

Manjaly Thomas ZR, McShane H. 2015. Aerosol immunisation for TB: matching route of vaccination to route of infection. Trans R Soc Trop Med Hyg, 109 (3), pp. 175-181. | Show Abstract | Read more

TB remains a very significant global health burden. There is an urgent need for better tools for TB control, which include an effective vaccine. Bacillus Calmette-Guérin (BCG), the currently licensed vaccine, confers highly variable protection against pulmonary TB, the main source of TB transmission. Replacing BCG completely or boosting BCG with another vaccine are the two current strategies for TB vaccine development. Delivering a vaccine by aerosol represents a way to match the route of vaccination to the route of infection. This route of immunisation offers not only the scientific advantage of delivering the vaccine directly to the respiratory mucosa, but also practical and logistical advantages. This review summarises the state of current TB vaccine candidates in the pipeline, reviews current progress in aerosol administration of vaccines in general and evaluates the potential for TB vaccine candidates to be administered by the aerosol route.

Luabeya KK, Tameris MD, Geldenhuys HD, Mulenga H, Van Schalkwyk A, Hughes EJ, Toefey A, Scriba TJ et al. 2015. Risk of Disease After Isoniazid Preventive Therapy for Mycobacterium tuberculosis Exposure in Young HIV-uninfected Children. Pediatr Infect Dis J, 34 (11), pp. 1218-1222. | Show Abstract | Read more

BACKGROUND: The risk of developing tuberculosis (TB) disease in HIV-uninfected children after isoniazid preventive therapy (IPT) for a positive QuantiFERON-TB Gold In-Tube test (QFT-GIT) is unknown. The aim of this study was to evaluate risk of TB disease after IPT in young HIV-uninfected children with a positive QFT-GIT result, or household TB contact. METHODS: HIV-uninfected South African infants aged 4-6 months were screened for enrolment in a TB vaccine trial. Baseline household TB contact and positive QFT-GIT result were exclusion criteria, and these infants were referred for IPT. Outcome data are reported for 36 months after IPT referral. RESULTS: Four thousand seven hundred forty-nine infants were screened. Household TB contact was reported in 131 (2.8%) infants; 279 (6.0%) were QFT-GIT positive, and 138 of these 410 infants (34.0%) started IPT. Forty-four cases of TB disease (11.0%) were recorded within 991 child years of observation. TB disease incidence was 4.8 versus 3.6 per 100 child years in household exposed versus QFT-GIT-positive children [incidence rate ratio: 1.35; 95% confidence interval (CI): 0.67-2.88] and 2.4 versus 5.5 per 100 child years in children who received versus did not receive IPT, respectively (incidence rate ratio: 0.44; 95% CI: 0.17-0.96). Adjusted hazard ratio (Cox regression) for TB disease was 0.48 (95% CI: 0.21-1.05) for those who received IPT. CONCLUSION: In young HIV-uninfected children, the effect of IPT on risk of TB disease is similar, whether TB exposure was defined by household contact history or by positive QFT-GIT result. International IPT guidelines for HIV-uninfected children with a positive QFT-GIT result should be updated.

Ndiaye BP, Thienemann F, Ota M, Landry BS, Camara M, Dièye S, Dieye TN, Esmail H et al. 2015. Safety, immunogenicity, and efficacy of the candidate tuberculosis vaccine MVA85A in healthy adults infected with HIV-1: a randomised, placebo-controlled, phase 2 trial. Lancet Respir Med, 3 (3), pp. 190-200. | Show Abstract | Read more

BACKGROUND: HIV-1 infection is associated with increased risk of tuberculosis and a safe and effective vaccine would assist control measures. We assessed the safety, immunogenicity, and efficacy of a candidate tuberculosis vaccine, modified vaccinia virus Ankara expressing antigen 85A (MVA85A), in adults infected with HIV-1. METHODS: We did a randomised, double-blind, placebo-controlled, phase 2 trial of MVA85A in adults infected with HIV-1, at two clinical sites, in Cape Town, South Africa and Dakar, Senegal. Eligible participants were aged 18-50 years, had no evidence of active tuberculosis, and had baseline CD4 counts greater than 350 cells per μL if they had never received antiretroviral therapy or greater than 300 cells per μL (and with undetectable viral load before randomisation) if they were receiving antiretroviral therapy; participants with latent tuberculosis infection were eligible if they had completed at least 5 months of isoniazid preventive therapy, unless they had completed treatment for tuberculosis disease within 3 years before randomisation. Participants were randomly assigned (1:1) in blocks of four by randomly generated sequence to receive two intradermal injections of either MVA85A or placebo. Randomisation was stratified by antiretroviral therapy status and study site. Participants, nurses, investigators, and laboratory staff were masked to group allocation. The second (booster) injection of MVA85A or placebo was given 6-12 months after the first vaccination. The primary study outcome was safety in all vaccinated participants (the safety analysis population). Safety was assessed throughout the trial as defined in the protocol. Secondary outcomes were immunogenicity and vaccine efficacy against Mycobacterium tuberculosis infection and disease, assessed in the per-protocol population. Immunogenicity was assessed in a subset of participants at day 7 and day 28 after the first and second vaccination, and M tuberculosis infection and disease were assessed at the end of the study. The trial is registered with ClinicalTrials.gov, number NCT01151189. FINDINGS: Between Aug 4, 2011, and April 24, 2013, 650 participants were enrolled and randomly assigned; 649 were included in the safety analysis (324 in the MVA85A group and 325 in the placebo group) and 645 in the per-protocol analysis (320 and 325). 513 (71%) participants had CD4 counts greater than 300 cells per μL and were receiving antiretroviral therapy; 136 (21%) had CD4 counts above 350 cells per μL and had never received antiretroviral therapy. 277 (43%) had received isoniazid prophylaxis before enrolment. Solicited adverse events were more frequent in participants who received MVA85A (288 [89%]) than in those given placebo (235 [72%]). 34 serious adverse events were reported, 17 (5%) in each group. MVA85A induced a significant increase in antigen 85A-specific T-cell response, which peaked 7 days after both vaccinations and was primarily monofunctional. The number of participants with negative QuantiFERON-TB Gold In-Tube findings at baseline who converted to positive by the end of the study was 38 (20%) of 186 in the MVA85A group and 40 (23%) of 173 in the placebo group, for a vaccine efficacy of 11·7% (95% CI -41·3 to 44·9). In the per-protocol population, six (2%) cases of tuberculosis disease occurred in the MVA85A group and nine (3%) occurred in the placebo group, for a vaccine efficacy of 32·8% (95% CI -111·5 to 80·3). INTERPRETATION: MVA85A was well tolerated and immunogenic in adults infected with HIV-1. However, we detected no efficacy against M tuberculosis infection or disease, although the study was underpowered to detect an effect against disease. Potential reasons for the absence of detectable efficacy in this trial include insufficient induction of a vaccine-induced immune response or the wrong type of vaccine-induced immune response, or both. FUNDING: European & Developing Countries Clinical Trials Partnership (IP.2007.32080.002), Aeras, Bill & Melinda Gates Foundation, Wellcome Trust, and Oxford-Emergent Tuberculosis Consortium.

Tanner R, Kakalacheva K, Miller E, Pathan AA, Chalk R, Sander CR, Scriba T, Tameris M et al. 2014. Serum indoleamine 2,3-dioxygenase activity is associated with reduced immunogenicity following vaccination with MVA85A. BMC Infect Dis, 14 (1), pp. 660. | Show Abstract | Read more

BACKGROUND: There is an urgent need for improved vaccines to protect against tuberculosis. The currently available vaccine Bacille Calmette-Guerin (BCG) has varying immunogenicity and efficacy across different populations for reasons not clearly understood. MVA85A is a modified vaccinia virus expressing antigen 85A from Mycobacterium tuberculosis which has been in clinical development since 2002 as a candidate vaccine to boost BCG-induced protection. A recent efficacy trial in South African infants failed to demonstrate enhancement of protection over BCG alone. The immunogenicity was lower than that seen in UK trials. The enzyme Indoleamine 2,3-dioxygenase (IDO) catalyses the first and rate-limiting step in the breakdown of the essential amino acid tryptophan. T cells are dependent on tryptophan and IDO activity suppresses T-cell proliferation and function. METHODS: Using samples collected during phase I trials with MVA85A across the UK and South Africa we have investigated the relationship between vaccine immunogenicity and IDO using IFN-γ ELISPOT, qPCR and liquid chromatography mass spectrometry. RESULTS: We demonstrate an IFN-γ dependent increase in IDO mRNA expression in peripheral blood mononuclear cells (PBMC) following MVA85A vaccination in UK subjects. IDO mRNA correlates positively with the IFN-γ ELISPOT response indicating that vaccine specific induction of IDO in PBMC is unlikely to limit the development of vaccine specific immunity. IDO activity in the serum of volunteers from the UK and South Africa was also assessed. There was no change in serum IDO activity following MVA85A vaccination. However, we observed higher baseline IDO activity in South African volunteers when compared to UK volunteers. In both UK and South African serum samples, baseline IDO activity negatively correlated with vaccine-specific IFN-γ responses, suggesting that IDO activity may impair the generation of a CD4+ T cell memory response. CONCLUSIONS: Baseline IDO activity was higher in South African volunteers when compared to UK volunteers, which may represent a potential mechanism for the observed variation in vaccine immunogenicity in South African and UK populations and may have important implications for future vaccination strategies. TRIAL REGISTRATION: Trials are registered at ClinicalTrials.gov; UK cohort NCT00427830, UK LTBI cohort NCT00456183, South African cohort NCT00460590, South African LTBI cohort NCT00480558.

Wilkie ME, McShane H. 2015. TB vaccine development: where are we and why is it so difficult? Thorax, 70 (3), pp. 299-301. | Show Abstract | Read more

The development of an effective TB vaccine remains paramount to achieving the goal of global eradication of TB by 2050. The only licensed vaccine, BCG, has variable efficacy and is poorly effective in high burden countries. The development of promising candidate vaccines to either 'boost' a BCG primed immune system or replace BCG altogether is a key area for innovative research. Here, we discuss some of the issues encountered in the development of potential candidate vaccines and the future challenges.

Matsumiya M, Satti I, Chomka A, Harris SA, Stockdale L, Meyer J, Fletcher HA, McShane H. 2015. Gene expression and cytokine profile correlate with mycobacterial growth in a human BCG challenge model. J Infect Dis, 211 (9), pp. 1499-1509. | Show Abstract | Read more

BACKGROUND: Bacillus Calmette-Guerin (BCG) vaccine is the most widely administered vaccine in the world, yet its mechanism of action remains unclear. We hypothesize that certain immune pathways are associated with reduced mycobacterial growth following BCG challenge in human volunteers. METHODS: We used samples from a mycobacterial challenge in which previously BCG-vaccinated or BCG-naive adults in the United Kingdom were challenged intradermally with a standard dose of BCG. Any remaining BCG was quantified in a skin biopsy specimen obtained 2 weeks after challenge and used as a measure of BCG growth and functional antimycobacterial immunity. We measured the immune response over the 2-week challenge, using DNA microarrays and flow cytometry, and correlated this with mycobacterial growth. RESULTS: The magnitude of the immune response to BCG is greater in previously vaccinated volunteers, and this correlates with reduced mycobacterial growth but increased scarring at the vaccination site. In particular, the interferon γ and interleukin 17 pathways are strongly induced in previously vaccinated volunteers and correlate with reduced mycobacterial growth in this population. CONCLUSION: This study identifies pathways associated with control of mycobacterial growth in vivo in human volunteers and supports the use of BCG challenge as a tool for evaluating vaccine efficacy and identifying mechanisms of antimycobacterial immunity.

Satti I, Meyer J, Harris SA, Manjaly Thomas ZR, Griffiths K, Antrobus RD, Rowland R, Ramon RL et al. 2014. Safety and immunogenicity of a candidate tuberculosis vaccine MVA85A delivered by aerosol in BCG-vaccinated healthy adults: a phase 1, double-blind, randomised controlled trial. Lancet Infect Dis, 14 (10), pp. 939-946. | Show Abstract | Read more

BACKGROUND: Intradermal MVA85A, a candidate vaccine against tuberculosis, induces high amounts of Ag85A-specific CD4 T cells in adults who have already received the BCG vaccine, but aerosol delivery of this vaccine might offer immunological and logistical advantages. We did a phase 1 double-blind trial to compare the safety and immunogenicity of aerosol-administered and intradermally administered MVA85A METHODS: In this phase 1, double-blind, proof-of-concept trial, 24 eligible BCG-vaccinated healthy UK adults were randomly allocated (1:1) by sequentially numbered, sealed, opaque envelopes into two groups: aerosol MVA85A and intradermal saline placebo or intradermal MVA85A and aerosol saline placebo. Participants, the bronchoscopist, and immunologists were masked to treatment assignment. The primary outcome was safety, assessed by the frequency and severity of vaccine-related local and systemic adverse events. The secondary outcome was immunogenicity assessed with laboratory markers of cell-mediated immunity in blood and bronchoalveolar lavage samples. Safety and immunogenicity were assessed for 24 weeks after vaccination. Immunogenicity to both insert Ag85A and vector modified vaccinia virus Ankara (MVA) was assessed by ex-vivo interferon-γ ELISpot and serum ELISAs. Since all participants were randomised and vaccinated according to protocol, our analyses were per protocol. This trial is registered with ClinicalTrials.gov, number NCT01497769. FINDINGS: Both administration routes were well tolerated and immunogenic. Respiratory adverse events were rare and mild. Intradermal MVA85A was associated with expected mild local injection-site reactions. Systemic adverse events did not differ significantly between the two groups. Three participants in each group had no vaccine-related systemic adverse events; fatigue (11/24 [46%]) and headache (10/24 [42%]) were the most frequently reported symptoms. Ag85A-specific systemic responses were similar across groups. Ag85A-specific CD4 T cells were detected in bronchoalveolar lavage cells from both groups and responses were higher in the aerosol group than in the intradermal group. MVA-specific cellular responses were detected in both groups, whereas serum antibodies to MVA were only detectable after intradermal administration of the vaccine. INTERPRETATION: Further clinical trials assessing the aerosol route of vaccine delivery are merited for tuberculosis and other respiratory pathogens. FUNDING: The Wellcome Trust and Oxford Radcliffe Hospitals Biomedical Research Centre.

Villarreal-Ramos B, Berg S, Chamberlain L, McShane H, Hewinson RG, Clifford D, Vordermeier M. 2014. Development of a BCG challenge model for the testing of vaccine candidates against tuberculosis in cattle. Vaccine, 32 (43), pp. 5645-5649. | Show Abstract | Read more

Vaccination is being considered as part of a sustainable strategy for the control of bovine tuberculosis (BTB) in the UK. The live attenuated Mycobacterium bovis bacillus Calmette-Guerin (BCG) has been used experimentally to vaccinate cattle against BTB. However, BCG confers partial protection against BTB and therefore, there is a need to develop improved vaccines. BTB vaccine efficacy experiments require the use of biosafety level 3 facilities which are expensive to maintain, generally oversubscribed and represent a bottle neck for the testing of vaccine candidates. One indicator of the induction of protective responses would be the ability of the host's immune response to control/kill mycobacteria. In this work we have evaluated an intranodal BCG challenge for the selection of vaccine candidates at biosafety level 2 which are capable of inducing mycobactericidal responses. To our knowledge, this is the first such report. Whilst BCG only confers partial protection, it is still the standard against which other vaccines are judged. Therefore we tested the BCG intranodal challenge in BCG (Danish strain) vaccinated cattle and showed that vaccinated cattle had lower BCG cfu counts than naïve cattle at 14 and 21 days after intranodal challenge with BCG (Tokyo strain). This model could help prioritize competing TB vaccine candidates and exploration of primary and secondary immune responses to mycobacteria.

Naranbhai V, Moodley D, Chipato T, Stranix-Chibanda L, Nakabaiito C, Kamateeka M, Musoke P, Manji K et al. 2014. The association between the ratio of monocytes: lymphocytes and risk of tuberculosis among HIV-infected postpartum women. J Acquir Immune Defic Syndr, 67 (5), pp. 573-575. | Show Abstract | Read more

Recent human studies support historical animal studies that suggested an association between peripheral blood monocyte:lymphocyte (ML) ratio and tuberculosis (TB) disease. To evaluate generalizability of this finding, we modeled the association between peripartum ML ratio and incident TB disease within 18 months postpartum among 1202 HIV-infected women in South Africa, Tanzania, Uganda, and Zimbabwe. The ML ratio was associated with increased risk of TB disease independently to combination antiretroviral therapy, World Health Organization stage, or CD4 count (adjusted hazard ratio = 1.22, 95% confidence interval: 1.07 to 1.4, P = 0.003 per 0.1 unit increase in ML ratio).

Naranbhai V, Kim S, Fletcher H, Cotton MF, Violari A, Mitchell C, Nachman S, McSherry G, McShane H, Hill AV, Madhi SA. 2014. The association between the ratio of monocytes:lymphocytes at age 3 months and risk of tuberculosis (TB) in the first two years of life. BMC Med, 12 (1), pp. 120. | Show Abstract | Read more

BACKGROUND: Recent transcriptomic studies revived a hypothesis suggested by historical studies in rabbits that the ratio of peripheral blood monocytes to lymphocytes (ML) is associated with risk of tuberculosis (TB) disease. Recent data confirmed the hypothesis in cattle and in adults infected with HIV. METHODS: We tested this hypothesis in 1,336 infants (540 HIV-infected, 796 HIV-exposed, uninfected (HEU)) prospectively followed in a randomized controlled trial of isoniazid prophylaxis in Southern Africa, the IMPAACT P1041 study. We modeled the relationship between ML ratio at enrollment (91 to 120 days after birth) and TB disease or death in HIV-infected children and latent Mycobacterium tuberculosis (MTB) infection, TB disease or death in HEU children within 96 weeks (with 12 week window) of randomization. Infants were followed-up prospectively and routinely assessed for MTB exposure and outcomes. Cox proportional hazards models allowing for non-linear associations were used; in all cases linear models were the most parsimonious. RESULTS: Increasing ML ratio at baseline was significantly associated with TB disease/death within two years (adjusted hazard ratio (HR) 1.17 per unit increase in ML ratio; 95% confidence interval (CI) 1.01 to 1.34; P = 0.03). Neither monocyte count nor lymphocyte counts alone were associated with TB disease. The association was not statistically dissimilar between HIV infected and HEU children. Baseline ML ratio was associated with composite endpoints of TB disease and death and/or TB infection. It was strongest when restricted to probable and definite TB disease (HR 1.50; 95% CI 1.19 to 1.89; P = 0.006). Therefore, per 0.1 unit increase in the ML ratio at three to four months of age, the hazard of probable or definite TB disease before two years was increased by roughly 4% (95% CI 1.7% to 6.6%). CONCLUSION: Elevated ML ratio at three- to four-months old is associated with increased hazards of TB disease before two years among children in Southern Africa. While significant, the modest effect size suggests that the ML ratio plays a modest role in predicting TB disease-free survival; its utility may, therefore, be limited to combination with existing tools to stratify TB risk, or to inform underlying pathophysiologic determinants of TB disease.

Iqbal AJ, McNeill E, Kapellos TS, Regan-Komito D, Norman S, Burd S, Smart N, Machemer DE et al. 2014. Human CD68 promoter GFP transgenic mice allow analysis of monocyte to macrophage differentiation in vivo. Blood, 124 (15), pp. e33-e44. | Show Abstract | Read more

The recruitment of monocytes and their differentiation into macrophages at sites of inflammation are key events in determining the outcome of the inflammatory response and initiating the return to tissue homeostasis. To study monocyte trafficking and macrophage differentiation in vivo, we have generated a novel transgenic reporter mouse expressing a green fluorescent protein (GFP) under the control of the human CD68 promoter. CD68-GFP mice express high levels of GFP in both monocyte and embryo-derived tissue resident macrophages in adult animals. The human CD68 promoter drives GFP expression in all CD115(+) monocytes of adult blood, spleen, and bone marrow; we took advantage of this to directly compare the trafficking of bone marrow-derived CD68-GFP monocytes to that of CX3CR1(GFP) monocytes in vivo using a sterile zymosan peritonitis model. Unlike CX3CR1(GFP) monocytes, which downregulate GFP expression on differentiation into macrophages in this model, CD68-GFP monocytes retain high-level GFP expression for 72 hours after differentiation into macrophages, allowing continued cell tracking during resolution of inflammation. In summary, this novel CD68-GFP transgenic reporter mouse line represents a powerful resource for analyzing monocyte mobilization and monocyte trafficking as well as studying the fate of recruited monocytes in models of acute and chronic inflammation.

Harris SA, Satti I, Matsumiya M, Stockdale L, Chomka A, Tanner R, O'Shea MK, Manjaly Thomas ZR et al. 2014. Process of assay selection and optimization for the study of case and control samples from a phase IIb efficacy trial of a candidate tuberculosis vaccine, MVA85A. Clin Vaccine Immunol, 21 (7), pp. 1005-1011. | Show Abstract | Read more

The first phase IIb safety and efficacy trial of a new tuberculosis vaccine since that for BCG was completed in October 2012. BCG-vaccinated South African infants were randomized to receive modified vaccinia virus Ankara, expressing the Mycobacterium tuberculosis antigen 85A (MVA85A), or placebo. MVA85A did not significantly boost the protective effect of BCG. Cryopreserved samples provide a unique opportunity for investigating the correlates of the risk of tuberculosis disease in this population. Due to the limited amount of sample available from each infant, preliminary work was necessary to determine which assays and conditions give the most useful information. Peripheral blood mononuclear cells (PBMC) were stimulated with antigen 85A (Ag85A) and purified protein derivative from M. tuberculosis in an ex vivo gamma interferon (IFN-γ) enzyme-linked immunosorbent spot assay (ELISpot) and a Ki67 proliferation assay. The effects of a 2-h or overnight rest of thawed PBMC on ELISpot responses and cell populations were determined. Both the ELISpot and Ki67 assays detected differences between the MVA85A and placebo groups, and the results correlated well. The cell numbers and ELISpot responses decreased significantly after an overnight rest, and surface flow cytometry showed a significant loss of CD4(+) and CD8(+) T cells. Of the infants tested, 50% had a positive ELISpot response to a single pool of flu, Epstein-Barr virus (EBV), and cytomegalovirus (CMV) (FEC) peptides. This pilot work has been essential in determining the assays and conditions to be used in the correlate study. Moving forward, PBMC will be rested for 2 h before assay setup. The ELISpot assay, performed in duplicate, will be selected over the Ki67 assay, and further work is needed to evaluate the effect of high FEC responses on vaccine-induced immunity and susceptibility to tuberculosis disease.

Thomas Z-RM, Meyer J, Harris S, Satti I, Sheehan S, Bettinson H, McShane H. 2014. Evaluating aerosol administration of a candidate TB vaccine MVA85A HUMAN GENE THERAPY, 25 (5), pp. A7-A7.

Dean G, Clifford D, Gilbert S, McShane H, Hewinson RG, Vordermeier HM, Villarreal-Ramos B. 2014. Effect of dose and route of immunisation on the immune response induced in cattle by heterologous Bacille Calmette-Guerin priming and recombinant adenoviral vector boosting Veterinary Immunology and Immunopathology, 158 (3-4), pp. 208-213. | Show Abstract | Read more

BCG is used experimentally as a vaccine against tuberculosis (TB), induced by Mycobacterium bovis, in cattle (bTB). However, the efficacy of BCG is variable in humans, cattle and guinea pigs. An adenoviral vector expressing Antigen 85A (Ad5Ag85A) has enhanced protection against TB in mice when used in combination with BCG for prime-boost experiments. However, the route of immunisation affects the degree of protection seen. This work examines the immunogenicity of a new vectored vaccine (Ad5-TBF) that expresses Ag85A, Rv0287, Rv0288 and Rv0251c to explore the effects of dose of adenoviral boost and route of inoculation on immunogenicity. We found that 2×109 infectious units (iu) delivered intradermally conferred the most consistent and strongest responses of the different regimes tested. © 2014 .

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Dean G, Whelan A, Clifford D, Salguero FJ, Xing Z, Gilbert S, McShane H, Hewinson RG, Vordermeier M, Villarreal-Ramos B. 2014. Comparison of the immunogenicity and protection against bovine tuberculosis following immunization by BCG-riming and boosting with adenovirus or protein based vaccines Vaccine, 32 (11), pp. 1304-1310. | Show Abstract | Read more

There is a requirement for vaccines or vaccination strategies that confer better protection against TB than the current live attenuated Mycobacterium bovis Bacillus Calmette-Guerin (BCG) vaccine for use in cattle. Boosting with recombinant viral vectors expressing mycobacterial proteins, such as Ag85A, has shown a degree of promise as a strategy for improving on the protection afforded by BCG. Experiments in small animal models have indicated that broadening the immune response to include mycobacterial antigens other than Ag85A, such as Rv0288, induced by boosting with Ad5 constructs has a direct effect on the protection afforded against TB. Here, we compared the immunogenicity and protection against challenge with M. bovis afforded by boosting BCG-vaccinated cattle with a human type 5 (Ad5)-based vaccine expressing the mycobacterial antigens Ag85A (Ad5-85A); or Ag85A, Rv0251, Rv0287 and Rv0288 (Ad5-TBF); or with protein TBF emulsified in adjuvant (Adj-TBF). Boosting with TBF broaden the immune response. The kinetics of Ad5-TBF and Adj-TBF were shown to be different, with effector T cell responses from the latter developing more slowly but being more durable than those induced by Ad5-TBF. No increase in protection compared to BCG alone was afforded by Ad5-TBF or Adj-TBF by gross pathology or bacteriology. Using histopathology, as a novel parameter of protection, we show that boosting BCG vaccinated cattle with Ad5-85A induced significantly better protection than BCG alone. © 2013.

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McShane H, Williams A. 2014. A review of preclinical animal models utilised for TB vaccine evaluation in the context of recent human efficacy data Tuberculosis, 94 (2), pp. 105-110. | Show Abstract | Read more

Summary There is an urgent need for an improved TB vaccine. Vaccine development is hindered by the lack of immune correlates and uncertain predictive value of preclinical animal models. As data become available from human efficacy trials, there is an opportunity to evaluate the predictive value of the criteria used to select candidate vaccines. Here we review the efficacy in animal models of the MVA85A candidate vaccine in light of recent human efficacy data and propose refinements to the preclinical models with the aim of increasing their predictive value for human efficacy. © 2013 Elsevier Ltd. All rights reserved.

Naranbhai V, Moodley D, Chipato T, Stranix-Chibanda L, Nakabaiito C, Kamateeka M, Musoke P, Manji K et al. 2014. The association between the ratio of monocytes: Lymphocytes and risk of tuberculosis among HIV-infected postpartum women Journal of Acquired Immune Deficiency Syndromes, 67 (5), pp. 573-575. | Show Abstract

Copyright © 2014 by Lippincott Williams & Wilkins.Recent human studies support historical animal studies that suggested an association between peripheral blood monocyte: lymphocyte (ML) ratio and tuberculosis (TB) disease. To evaluate generalizability of this finding, we modeled the association between peripartum ML ratio and incident TB disease within 18 months postpartum among 1202 HIV-infected women in South Africa, Tanzania, Uganda, and Zimbabwe. The ML ratio was associated with increased risk of TB disease independently to combination antiretroviral therapy, World Health Organization stage, or CD4 count (adjusted hazard ratio = 1.22, 95% confidence interval: 1.07 to 1.4, P = 0.003 per 0.1 unit increase in ML ratio).

Minhinnick A, Wilkie M, McShane H. 2014. Vaccines Side Effects of Drugs Annual, 36 pp. 465-482. | Show Abstract | Read more

© 2014 Elsevier B.V.The Side Effects of Drugs Annuals forms a series of volumes in which the adverse effects of drugs and adverse reactions to them are surveyed. The series supplements the contents of Meyler's Side Effects of Drugs: the International Encyclopedia of Adverse Drug Reactions and Interactions. This review of the January 2012 to June 2013 publications on vaccines covers Bacille Calmette-Guérin vaccine, diphtheria-pertussis vaccines, human papilloma virus vaccine, influenza vaccine, Japanese encephalitis vaccine, measles vaccine, measles-mumps-rubella vaccine, mumps vaccine, rubella vaccine, rotavirus vaccine, smallpox vaccine, varicella vaccine and yellow fever vaccine.

O'Shea MK, Fletcher TE, Beeching NJ, Dedicoat M, Spence D, McShane H, Cunningham AF, Wilson D. 2014. Tuberculin skin testing and treatment modulates interferon-gamma release assay results for latent tuberculosis in migrants. PLoS One, 9 (5), pp. e97366. | Show Abstract | Read more

BACKGROUND: Identifying latent tuberculosis infection (LTBI) in people migrating from TB endemic regions to low incidence countries is an important control measure. However, no prospective longitudinal comparisons between diagnostic tests used in such migrant populations are available. OBJECTIVES: To compare commercial interferon (IFN)-gamma release assays (IGRAs) and the tuberculin skin test (TST) for diagnosing LTBI in a migrant population, and the influence of antecedent TST and LTBI treatment on IGRA performance. MATERIALS AND METHODS: This cohort study, performed from February to September 2012, assessed longitudinal IGRA and TST responses in Nepalese military recruits recently arrived in the UK. Concomitant T-SPOT.TB, QFT-GIT and TST were performed on day 0, with IGRAs repeated 7 and 200 days later, following treatment for LTBI if necessary. RESULTS: 166 Nepalese recruits were prospectively assessed. At entry, 21 individuals were positive by T-SPOT.TB and 8 individuals by QFT-GIT. There was substantial agreement between TST and T-SPOT.TB positives at baseline (71.4% agreement; κ = 0.62; 95% CI:0.44-0.79), but only moderate concordance between positive IGRAs (38.1% agreement; κ = 0.46; 95% CI:0.25-0.67). When reassessed 7 days following TST, numbers of IGRA-positive individuals changed from 8 to 23 for QFT-GIT (p = 0.0074) and from 21 to 23 for T-SPOT.TB (p = 0.87). This resulted in an increase in IGRA concordance to substantial (64.3% agreement; κ = 0.73; 95% CI:0.58-0.88). Thus, in total on day 0 and day 7 after testing, 29 out of 166 participants (17.5%) provided a positive IGRA and of these 13 were TST negative. Two hundred days after the study commenced and three months after treatment for LTBI was completed by those who were given chemoprophylaxis, 23 and 21 participants were positive by T-SPOT.TB or QFT-GIT respectively. When individual responses were examined longitudinally within this population 35% of the day 7 QFT-GIT-positive, and 19% T-SPOT.TB-positive individuals, were negative by IGRA. When the change in the levels of secreted IFN-γ was examined after chemoprophylaxis the median levels were found to have fallen dramatically by 77.3% from a pre-treatment median concentration of IFN-γ 2.73 IU/ml to a post-treatment median concentration IFN-γ 0.62 (p = 0.0002). CONCLUSIONS: This study suggests differences in the capacity of commercially available IGRAs to identify LTBI in the absence of antecedent TST and that IGRAs, in the time periods examined, may not be the optimal tests to determine the success of chemoprophylaxis for LTBI.

McShane H. 2014. Understanding BCG is the key to improving it. Clin Infect Dis, 58 (4), pp. 481-482. | Read more

Harris SA, Meyer J, Satti I, Marsay L, Poulton ID, Tanner R, Minassian AM, Fletcher HA, McShane H. 2014. Evaluation of a human BCG challenge model to assess antimycobacterial immunity induced by BCG and a candidate tuberculosis vaccine, MVA85A, alone and in combination. J Infect Dis, 209 (8), pp. 1259-1268. | Show Abstract | Read more

BACKGROUND: A new vaccine is urgently needed to combat tuberculosis. However, without a correlate of protection, selection of the vaccines to take forward into large-scale efficacy trials is difficult. Use of bacille Calmette-Guérin (BCG) as a surrogate for human Mycobacterium tuberculosis challenge is a novel model that could aid selection. METHODS: Healthy adults were assigned to groups A and B (BCG-naive) or groups C and D (BCG-vaccinated). Groups B and D received candidate tuberculosis vaccine MVA85A. Participants were challenged with intradermal BCG 4 weeks after those who received MVA85A. Skin biopsies of the challenge site were taken 2 weeks post challenge and BCG load quantified by culture and quantitative polymerase chain reaction (qPCR). RESULTS: Volunteers with a history of BCG showed some degree of protective immunity to challenge, having lower BCG loads compared with volunteers without prior BCG, regardless of MVA85A status. There was a significant inverse correlation between antimycobacterial immunity at peak response after MVA85A and BCG load detected by qPCR. CONCLUSION: Our results support previous findings that this BCG challenge model is able to detect differences in antimycobacterial immunity induced by vaccination and could aid in the selection of candidate tuberculosis vaccines for field efficacy testing.

Griffiths KL, Stylianou E, Poyntz HC, Betts GJ, Fletcher HA, McShane H. 2013. Cholera toxin enhances vaccine-induced protection against Mycobacterium tuberculosis challenge in mice. PLoS One, 8 (10), pp. e78312. | Show Abstract | Read more

Interleukin (IL)-17 is emerging as an important cytokine in vaccine-induced protection against tuberculosis disease in animal models. Here we show that compared to parenteral delivery, BCG delivered mucosally enhances cytokine production, including interferon gamma and IL-17, in the lungs. Furthermore, we find that cholera toxin, delivered mucosally along with BCG, further enhances IL-17 production by CD4(+) T cells over mucosal BCG alone both in the lungs and systemically. This boosting effect of CT is also observed using a vaccine regimen of BCG followed by the candidate vaccine MVA85A. Using a murine Mycobacterium tuberculosis (M.tb) aerosol challenge model, we demonstrate the ability of cholera toxin delivered at the time of a priming BCG vaccination to improve protection against tuberculosis disease in a manner at least partially dependent on the observed increase in IL-17. This observed increase in IL-17 in the lungs has no adverse effect on lung pathology following M.tb challenge, indicating that IL-17 can safely be boosted in murine lungs in a vaccine/M.tb challenge setting.

Naranbhai V, Hill AV, Abdool Karim SS, Naidoo K, Abdool Karim Q, Warimwe GM, McShane H, Fletcher H. 2014. Ratio of monocytes to lymphocytes in peripheral blood identifies adults at risk of incident tuberculosis among HIV-infected adults initiating antiretroviral therapy. J Infect Dis, 209 (4), pp. 500-509. | Show Abstract | Read more

BACKGROUND: Eight decades ago, the ratio of monocytes to lymphocytes (hereafter, the "ML ratio") was noted to affect outcomes of mycobacterial infection in rabbits. Recent transcriptomic studies support a role for relative proportions of myeloid and lymphoid transcripts in tuberculosis outcomes. The ML ratio in peripheral blood is known to be governed by hematopoietic stem cells with distinct biases. METHODS: The predictive value of the baseline ML ratio was modeled in 2 prospective cohorts of HIV-infected adults starting cART in South Africa (primary cohort, 1862 participants; replication cohort, 345 participants). Incident tuberculosis was diagnosed with clinical, radiographic, and microbiologic methods per contemporary guidelines. Kaplan-Meier survival analyses and Cox proportional hazards modeling were conducted. RESULTS: The incidence rate of tuberculosis differed significantly by baseline ML ratio: 32.61 (95% confidence interval [CI], 15.38-61.54), 16.36 (95% CI, 12.39-21.23), and 51.80 (95% CI, 23.10-101.71) per 1000 patient-years for ML ratios of less than the 5th percentile, between the 5th and 95th percentiles, and greater than the 95th percentile, respectively (P = .007). Neither monocyte counts nor lymphocyte counts alone were associated with tuberculosis. After adjustment for sex, World Health Organization human immunodeficiency virus disease stage, CD4(+) T-cell counts, and previous history of tuberculosis, hazards of disease were significantly higher for patients with ML ratios of less than the 5th percentile or greater than the 95th percentile (adjusted hazard ratio, 2.47; 95% CI, 1.39-4.40; P = .002). CONCLUSIONS: The ML ratio may be a useful, readily available tool to stratify the risk of tuberculosis and suggests involvement of hematopoietic stem cell bias in tuberculosis pathogenesis.

Dintwe OB, Day CL, Smit E, Nemes E, Gray C, Tameris M, McShane H, Mahomed H, Hanekom WA, Scriba TJ. 2013. Heterologous vaccination against human tuberculosis modulates antigen-specific CD4+ T-cell function. Eur J Immunol, 43 (9), pp. 2409-2420. | Show Abstract | Read more

Heterologous prime-boost strategies hold promise for vaccination against tuberculosis. However, the T-cell characteristics required for protection are not known. We proposed that boost vaccines should induce long-lived functional and phenotypic changes to T cells primed by Bacille Calmette Guerin (BCG) and/or natural exposure to mycobacteria. We characterized changes among specific CD4(+) T cells after vaccination with the MVA85A vaccine in adults, adolescents, and children. CD4(+) T cells identified with Ag85A peptide-bearing HLA class II tetramers were characterized by flow cytometry. We also measured proliferative potential and cytokine expression of Ag85A-specific CD4(+) T cells. During the effector phase, MVA85A-induced specific CD4(+) T cells coexpressed IFN-γ and IL-2, skin homing integrins, and the activation marker CD38. This was followed by contraction and a transition to predominantly IL-2-expressing, CD45RA(-) CCR7(+) CD27(+) or CD45RA(+) CCR7(+) CD27(+) specific CD4(+) T cells. These surface phenotypes were similar to Ag85A-specific T cells prior to MVA85A. However, functional differences were observed postvaccination: specific proliferative capacity was markedly higher after 6-12 months than before vaccination. Our data suggest that MVA85A vaccination may modulate Ag85A-specific CD4(+) T-cell function, resulting in greater recall potential. Importantly, surface phenotypes commonly used as proxies for memory T-cell function did not associate with functional effects of vaccination.

Fletcher HA, Tanner R, Wallis RS, Meyer J, Manjaly ZR, Harris S, Satti I, Silver RF et al. 2013. Inhibition of mycobacterial growth in vitro following primary but not secondary vaccination with Mycobacterium bovis BCG. Clin Vaccine Immunol, 20 (11), pp. 1683-1689. | Show Abstract | Read more

Despite the widespread use of the Mycobacterium bovis BCG vaccine, there are more than 9 million new cases of tuberculosis (TB) every year, and there is an urgent need for better TB vaccines. TB vaccine candidates are selected for evaluation based in part on the detection of an antigen-specific gamma interferon (IFN-γ) response. The measurement of mycobacterial growth in blood specimens obtained from subjects immunized with investigational TB vaccines may be a better in vitro correlate of in vivo vaccine efficacy. We performed a clinical study with 30 United Kingdom adults who were followed for 6 months to evaluate the abilities of both a whole-blood- and a novel peripheral blood mononuclear cell (PBMC)-based mycobacterial growth inhibition assay to measure a response to primary vaccination and revaccination with BCG. Using cryopreserved PBMCs, we observed a significant improvement in mycobacterial growth inhibition following primary vaccination but no improvement in growth inhibition following revaccination with BCG (P < 0.05). Mycobacterial growth inhibition following primary BCG vaccination was not correlated with purified protein derivative (PPD) antigen-specific IFN-γ enzyme-linked immunospot (ELISPOT) responses. We demonstrate that a mycobacterial growth inhibition assay can detect improved capacity to control growth following primary immunization, but not revaccination, with BCG. This is the first study to demonstrate that an in vitro growth inhibition assay can identify a difference in vaccine responses by comparing both primary and secondary BCG vaccinations, suggesting that in vitro growth inhibition assays may serve as better surrogates of clinical efficacy than the assays currently used for the assessment of candidate TB vaccines.

Dieye TN, Ndiaye BP, Dieng AB, Fall M, Brittain N, Vermaak S, Camara M, Diop-Ndiaye H et al. 2013. Two doses of candidate TB vaccine MVA85A in antiretroviral therapy (ART) naïve subjects gives comparable immunogenicity to one dose in ART+ subjects. PLoS One, 8 (6), pp. e67177. | Show Abstract | Read more

Tuberculosis (TB) is a global public health problem exacerbated by the HIV epidemic. Here we evaluate a candidate TB vaccine, MVA85A, in a Phase I study in HIV-infected adults in Senegal. 24 patients were enrolled: Group 1∶12, antiretroviral therapy (ART) naïve, adults, with CD4 counts >300 and HIV RNA load <100,000 copies/ml. Group 2∶12 adults, stable on ART, with CD4 counts >300, and an undetectable HIV RNA load. Safety was evaluated by occurrence of local and systemic adverse events (AEs) and by monitoring of CD4 count, HIV RNA load, haematology and biochemistry. Immunogenicity was evaluated by ex-vivo interferon-gamma ELISpot assay. 87.7% of AEs were mild; 11.6% were moderate; and 0.7% were severe. 29.2% of AEs were systemic; 70.8% were expected local AEs. There were no vaccine-related Serious Adverse Events (SAEs) or clinically significant effects on HIV RNA load or CD4 count. In ART naive subjects, the first MVA85A immunisation induced a significant immune response at 1 and 4 weeks post-immunisation, which contracted to baseline by 12 weeks. Durability of immunogenicity in subjects on ART persisted out to 24 weeks post-vaccination. A second dose of MVA85A at 12 months enhanced immunogenicity in ART naïve subjects. Subjects on ART had higher responses after the first vaccination compared with ART naïve subjects; responses were comparable after 2 immunisations. In conclusion, MVA85A is well-tolerated and immunogenic in HIV-infected subjects in Senegal. A two dose regimen in ART naïve subjects is comparable in immunogenicity to a single dose in subjects on ART. Clinicaltrials.gov trial identifier NCT00731471.

Rowland R, O'Hara GA, Hamill M, Poulton ID, Donaldson H, Dinsmore L, James T, Barnes E et al. 2013. Determining the validity of hospital laboratory reference intervals for healthy young adults participating in early clinical trials of candidate vaccines. Hum Vaccin Immunother, 9 (8), pp. 1741-1751. | Show Abstract | Read more

This was a retrospective study to determine the validity of institutional reference intervals for interpreting biochemistry and hematology results in healthy adults in the context of clinical trials of preventive vaccines. An example population of 974 healthy adults participating in clinical trials at the Jenner Institute, Oxford, UK, between 1999 and 2009 was studied. Methods for calculating the central 95% ranges and determining the coefficients of within person variation were demonstrated. Recommendations have been made as to how these data can be usefully applied to the interpretation of blood results in healthy adult subjects for the purposes of clinical trial inclusion decisions and post-vaccination safety monitoring.

McShane H. 2013. Vaccines for tuberculosis pp. 243-260.

Meyer J, McShane H. 2013. The next 10 years for tuberculosis vaccines: do we have the right plans in place? Expert Rev Vaccines, 12 (4), pp. 443-451. | Show Abstract | Read more

The control of TB is a global health priority. Over the last decade, considerable progress has been made in the field of TB vaccines with numerous vaccine candidates entering the clinic and two candidates now in Phase IIb efficacy trials. Nevertheless, the lack of predictive animal models and biomarkers of TB vaccine efficacy prevents rational vaccine down-selection and necessitates prolonged and expensive clinical efficacy trials in target populations. Advances in molecular technology and progress in the development of human as well as animal mycobacterial challenge models make the identification of one or more immune correlates of protection a genuine prospect over the next decade. Moreover, the increasing pace, extent and coordination of global research efforts in TB promises to broaden understanding and inform the next generation of vaccine candidates against TB as well as related globally important pathogens.

White AD, Sibley L, Dennis MJ, Gooch K, Betts G, Edwards N, Reyes-Sandoval A, Carroll MW et al. 2013. Evaluation of the safety and immunogenicity of a candidate tuberculosis vaccine, MVA85A, delivered by aerosol to the lungs of macaques. Clin Vaccine Immunol, 20 (5), pp. 663-672. | Show Abstract | Read more

Tuberculosis (TB) is a reemerging disease. The only available vaccine, Mycobacterium bovis BCG, is delivered intradermally and confers highly variable efficacy against pulmonary disease. There is an urgent need for improved vaccination strategies. Murine studies suggest that immunizations delivered directly to the respiratory mucosa might be a more effective route of vaccination. This study compared the immunogenicity of a leading candidate tuberculosis (TB) vaccine, modified vaccinia virus Ankara expressing antigen 85A (MVA85A), in rhesus macaques, delivered either as an aerosol or as an intradermal boost immunization 12 weeks after an intradermal BCG prime vaccine. Aerosol vaccination was well tolerated. MVA85A delivered by aerosol or by intradermal injection induced antigen-specific immune responses in the periphery and the lung, with a trend toward the highest response when the compartment and route of delivery were matched. The ability of poxvirus-vectored vaccines delivered by the systemic route to induce responses in the mucosal immune compartment in macaques is in contrast to the independent compartmentalization of mucosal and systemic immune systems described in mice. Unlike intradermal vaccination, aerosol vaccination did not induce a detectable serum anti-vector antibody response. The delivery of vaccines to the lungs might provide an immunization strategy that limits the induction of systemic anti-vector immunity, which would be extremely useful in the development of improved vaccine strategies. This is the first study to show a recombinant MVA-vectored vaccine to be highly immunogenic when delivered by the aerosol route to nonhuman primates. These results provide important safety and proof-of-concept data for further evaluation of this route of immunization for use in human clinical trials.

Matsumiya M, Stylianou E, Griffiths K, Lang Z, Meyer J, Harris SA, Rowland R, Minassian AM, Pathan AA, Fletcher H, McShane H. 2013. Roles for Treg expansion and HMGB1 signaling through the TLR1-2-6 axis in determining the magnitude of the antigen-specific immune response to MVA85A. PLoS One, 8 (7), pp. e67922. | Show Abstract | Read more

A better understanding of the relationships between vaccine, immunogenicity and protection from disease would greatly facilitate vaccine development. Modified vaccinia virus Ankara expressing antigen 85A (MVA85A) is a novel tuberculosis vaccine candidate designed to enhance responses induced by BCG. Antigen-specific interferon-γ (IFN-γ) production is greatly enhanced by MVA85A, however the variability between healthy individuals is extensive. In this study we have sought to characterize the early changes in gene expression in humans following vaccination with MVA85A and relate these to long-term immunogenicity. Two days post-vaccination, MVA85A induces a strong interferon and inflammatory response. Separating volunteers into high and low responders on the basis of T cell responses to 85A peptides measured during the trial, an expansion of circulating CD4+ CD25+ Foxp3+ cells is seen in low but not high responders. Additionally, high levels of Toll-like Receptor (TLR) 1 on day of vaccination are associated with an increased response to antigen 85A. In a classification model, combined expression levels of TLR1, TICAM2 and CD14 on day of vaccination and CTLA4 and IL2Rα two days post-vaccination can classify high and low responders with over 80% accuracy. Furthermore, administering MVA85A in mice with anti-TLR2 antibodies may abrogate high responses, and neutralising antibodies to TLRs 1, 2 or 6 or HMGB1 decrease CXCL2 production during in vitro stimulation with MVA85A. HMGB1 is released into the supernatant following atimulation with MVA85A and we propose this signal may be the trigger activating the TLR pathway. This study suggests an important role for an endogenous ligand in innate sensing of MVA and demonstrates the importance of pattern recognition receptors and regulatory T cell responses in determining the magnitude of the antigen specific immune response to vaccination with MVA85A in humans.

Cited:

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Scopus

Pitt JM, Blankley S, McShane H, O'Garra A. 2013. Vaccination against tuberculosis: How can we better BCG? Microbial Pathogenesis, 58 pp. 2-16. | Show Abstract | Read more

Tuberculosis remains one of the most significant human diseases of the developing world, accounting for 3800 worldwide deaths per day. Although we currently have a vaccine for tuberculosis, BCG, this is insufficient at protecting from adult pulmonary tuberculosis in the parts of the world where a good vaccine is most needed. This has prompted the search for new vaccination strategies that can protect better than BCG, or can boost BCG-induced immunity. We discuss these subjects in line with what is known of the immune responses to BCG and Mycobacterium tuberculosis - the etiological agent of the disease, as well as the particular difficulties facing development of new vaccines against tuberculosis. A greater understanding of the factors constituting optimal protection against Mycobacterium tuberculosis infection, as well as which pathogenic factors facilitate active disease, will accelerate the delivery of safe vaccines able to restrict active tuberculosis and thus impede contagion. © 2013 .

Meyer J, Harris SA, Satti I, Poulton ID, Poyntz HC, Tanner R, Rowland R, Griffiths KL, Fletcher HA, McShane H. 2013. Comparing the safety and immunogenicity of a candidate TB vaccine MVA85A administered by intramuscular and intradermal delivery. Vaccine, 31 (7), pp. 1026-1033. | Show Abstract | Read more

BACKGROUND: New vaccines to prevent tuberculosis are urgently needed. MVA85A is a novel viral vector TB vaccine candidate designed to boost BCG-induced immunity when delivered intradermally. To date, intramuscular delivery has not been evaluated. Skin and muscle have distinct anatomical and immunological properties which could impact upon vaccine-mediated cellular immunity. METHODS: We conducted a randomised phase I trial comparing the safety and immunogenicity of 1×10(8)pfu MVA85A delivered intramuscularly or intradermally to 24 healthy BCG-vaccinated adults. RESULTS: Intramuscular and intradermal MVA85A were well tolerated. Intradermally-vaccinated subjects experienced significantly more local adverse events than intramuscularly-vaccinated subjects, with no difference in systemic adverse events. Both routes generated strong and sustained Ag85A-specific IFNγ T cell responses and induced multifunctional CD4+ T cells. The frequencies of CD4+ T cells expressing chemokine receptors CCR4, CCR6, CCR7 and CXCR3 induced by vaccination was similar between routes. CONCLUSIONS: In this phase I trial the intramuscular delivery of MVA85A was well tolerated and induced strong, durable cellular immune responses in healthy BCG vaccinated adults, comparable to intradermal delivery. These findings are important for TB vaccine development and are of relevance to HIV, malaria, influenza and other intracellular pathogens for which T cell-inducing MVA-based vaccine platforms are being evaluated.

Rowland R, Pathan AA, Satti I, Poulton ID, Matsumiya MM, Whittaker M, Minassian AM, O'Hara GA et al. 2013. Safety and immunogenicity of an FP9-vectored candidate tuberculosis vaccine (FP85A), alone and with candidate vaccine MVA85A in BCG-vaccinated healthy adults: a phase I clinical trial. Hum Vaccin Immunother, 9 (1), pp. 50-62. | Show Abstract | Read more

The safety and immunogenicity of a new candidate tuberculosis (TB) vaccine, FP85A was evaluated alone and in heterologous prime-boost regimes with another candidate TB vaccine, MVA85A. This was an open label, non-controlled, non-randomized Phase I clinical trial. Healthy previously BCG-vaccinated adult subjects were enrolled sequentially into three groups and vaccinated with FP85A alone, or both FP85A and MVA85A, with a four week interval between vaccinations. Passive and active data on adverse events were collected. Immunogenicity was evaluated by Enzyme Linked Immunospot (ELISpot), flow cytometry and Enzyme Linked Immunosorbent assay (ELISA). Most adverse events were mild and there were no vaccine-related serious adverse events. FP85A vaccination did not enhance antigen 85A-specific cellular immunity. When MVA85A vaccination was preceded by FP85A vaccination, cellular immune responses were lower compared with when MVA85A vaccination was the first immunisation. MVA85A vaccination, but not FP85A vaccination, induced anti-MVA IgG antibodies. Both MVA85A and FP85A vaccinations induced anti-FP9 IgG antibodies. In conclusion, FP85A vaccination was well tolerated but did not induce antigen-specific cellular immune responses. We hypothesize that FP85A induced anti-FP9 IgG antibodies with cross-reactivity for MVA85A, which may have mediated inhibition of the immune response to subsequent MVA85A. ClinicalTrials.gov identification number: NCT00653770.

K. Owiafe P. 2012. Differential Cytokine Levels in Adults Induced by a Novel Candidate TB Boost Vaccine, MVA85A-According to Previous BCG Vaccination Status Journal of Vaccines & Vaccination, 03 (07), | Show Abstract | Read more

MVA85A is a candidate boost vaccine for TB. A previously reported study showed no differences in response to MVA85A in 10 BCG vaccinated (BCG+) and 11 BCG naive (BCG-) adult Gambians. Here we evaluated the effect of pre-existing plasma cytokines in both groups before and after MVA85A vaccination on the vaccine-induced immune response. Pre-vaccination levels of IL-8 were higher in BCG+ subjects, whilst MCP-1 levels were lower compared to BCG-. Following MVA85A vaccination, concentrations of IL-8, IL-18, IL-12(p70) and MCP-1 were differentially induced between BCG+ and BCG- groups. The implications of these findings depend on their role in TB pathogenesis. © 2012 Owiafe PK, et al.

Scriba TJ, Tameris M, Smit E, van der Merwe L, Hughes EJ, Kadira B, Mauff K, Moyo S et al. 2012. A phase IIa trial of the new tuberculosis vaccine, MVA85A, in HIV- and/or Mycobacterium tuberculosis-infected adults. Am J Respir Crit Care Med, 185 (7), pp. 769-778. | Show Abstract | Read more

RATIONALE: Novel tuberculosis (TB) vaccines should be safe and effective in populations infected with Mycobacterium tuberculosis (M.tb) and/or HIV for effective TB control. OBJECTIVE: To determine the safety and immunogenicity of MVA85A, a novel TB vaccine, among M.tb- and/or HIV-infected persons in a setting where TB and HIV are endemic. METHODS: An open-label, phase IIa trial was conducted in 48 adults with M.tb and/or HIV infection. Safety and immunogenicity were analyzed up to 52 weeks after intradermal vaccination with 5 × 10(7) plaque-forming units of MVA85A. Specific T-cell responses were characterized by IFN-γ enzyme-linked immunospot and whole blood intracellular cytokine staining assays. MEASUREMENTS AND MAIN RESULTS: MVA85A was well tolerated and no vaccine-related serious adverse events were recorded. MVA85A induced robust and durable response of mostly polyfunctional CD4(+) T cells, coexpressing IFN-γ, tumor necrosis factor-α, and IL-2. Magnitudes of pre- and postvaccination T-cell responses were lower in HIV-infected, compared with HIV-uninfected, vaccinees. No significant effect of antiretroviral therapy on immunogenicity of MVA85A was observed. CONCLUSIONS: MVA85A was safe and immunogenic in persons with HIV and/or M.tb infection. These results support further evaluation of safety and efficacy of this vaccine for prevention of TB in these target populations.

Rowland R, Brittain N, Poulton ID, Minassian AM, Sander C, Porter DW, Williams N, Satti I, Pathan AA, Lawrie AM, McShane H. 2012. A review of the tolerability of the candidate TB vaccine, MVA85A compared with BCG and Yellow Fever vaccines, and correlation between MVA85A vaccine reactogenicity and cellular immunogenicity Trials in Vaccinology, 1 pp. 27-35. | Show Abstract | Read more

Background: The development of a new, more effective vaccine against tuberculosis (TB) for use in healthy and HIV-infected adults, children and infants, remains a global health priority. MVA85A is a candidate tuberculosis vaccine designed to enhance immunity to the existing vaccine, Bacillus Calmette-Guerin (BCG). MVA85A entered clinical trials in 2002 and has now progressed to Phase IIb proof-of-concept efficacy trials in infants and HIV-infected adults in Africa. Methods: A detailed analysis was conducted of the cumulative safety data of intradermal delivery of MVA85A in 112 healthy adult subjects in a series of open label, single arm, non-controlled, Phase I safety and immunogenicity clinical trials in the UK. The trials differed with respect to previous mycobacterial exposure, vaccine regime and dose. Objective safety measures (local reaction size and body temperature) were evaluated for correlations with adaptive antigen-specific immune responses. Results: All subjects in the combined mid-dose group developed a local reaction, of which 92% were mild, 8% were moderate and no reactions were severe. Around 90% of subjects in each group reported at least one systemic adverse event, most commonly headache, myalgia, malaise, feeling feverish, fatigue and arthralgia. Of all systemic adverse events in the combined mid-dose group, 96% were mild, 3% were moderate and 1% were severe (but none of these were judged to be vaccine-related). Pre-vaccination mycobacterial exposure did not affect the adverse event profile. The size of local reaction and frequency of systemic adverse events increased with MVA85A vaccine dose. There were no documented fevers in the low-dose group, whilst 3% of subjects in the combined mid-dose group and 21% in the high-dose group had documented fevers. Peak local reactions were larger after a second poxvirus vaccination, but other local and systemic adverse events were comparable to a single MVA85A vaccination. No severe systemic AEs or serious adverse events in any group were judged to be vaccine-related. Local AEs compared favourably to BCG vaccine-induced local AE and systemic AEs after MVA85A vaccination were comparable to those after the live viral Yellow Fever vaccine in similar populations. There were no correlations found between local reaction size or body temperature and adaptive immune responses (measured by ex vivo interferon gamma Enzyme Linked Immunospot). Conclusions: The candidate TB vaccine, MVA85A has been safely administered to over 100 healthy adults in the UK. Intradermal vaccination with MVA85A induced a transient, superficial reaction local to the injection site and mild short-lived viral symptoms. The local and systemic AE profile of MVA85A vaccination was comparable to published data of other intradermal vaccines and live viral vaccines respectively. Local reaction sizes and body temperature measurements did not correlate with the adaptive cellular immune response to MVA85A. © 2012 Elsevier Ltd.

Betts G, Poyntz H, Stylianou E, Reyes-Sandoval A, Cottingham M, Hill A, McShane H. 2012. Optimising immunogenicity with viral vectors: mixing MVA and HAdV-5 expressing the mycobacterial antigen Ag85A in a single injection. PLoS One, 7 (12), pp. e50447. | Show Abstract | Read more

The Bacillus Calmette - Guerin (BCG) vaccine provides a critical but limited defense against Mycobacterium tuberculosis (M.tb). More than 60 years after the widespread introduction of BCG, there is an urgent need for a better vaccine. A large body of pre-clinical research continues to support ongoing clinical trials to assess whether viral vectors expressing M.tb antigens that are shared by BCG and M.tb, can be used alongside BCG to enhance protection. A major focus involves using multiple unique viral vectors to limit anti-vector immunity and thereby enhance responses to the insert antigen delivered. The successful introduction of viral vector vaccines to target M.tb and other pathogens will be reliant on reducing the costs when using multiple vectors and inhibiting the development of unwanted anti-vector responses that interfere with the response to insert antigen. This study examines methods to reduce the logistical costs of vaccination by mixing different viral vectors that share the same insert antigen in one vaccine; and whether combining different viral vectors reduces anti-vector immunity to improve immunogenicity to the insert antigen. Here we show that a homologous prime-boost regimen with a mixture of MVA (Modified Vaccinia virus Ankara) and Ad5 (human adenovirus type 5) vectors both expressing Ag85A in a single vaccine preparation is able to reduce anti-vector immunity, compared with a homologous prime-boost regimen with either vector alone. However, the level of immunogenicity induced by the homologous mixture remained comparable to that induced with single viral vectors and was less immunogenic than a heterologous Ad5 prime-MVA-boost regimen. These findings advance the understanding of how anti-vector immunity maybe reduced in viral vector vaccination regimens. Furthermore, an insight is provided to the impact on vaccine immunogenicity from altering vaccination methods to reduce the logistical demands of using separate vaccine preparations in the field.

Checkley AM, McShane H. 2011. Tuberculosis vaccines: progress and challenges. Trends Pharmacol Sci, 32 (10), pp. 601-606. | Show Abstract | Read more

An effective tuberculosis (TB) vaccine could have a significant impact on the current TB pandemic. The past decade has seen sustained global investment into reaching this goal; currently there are several promising vaccines in clinical trials. Current strategies include the development of an improved bacille Calmette-Guerin (BCG) vaccine to be given at birth and a booster vaccine to be administered after BCG. Here, we describe the current vaccination strategy and review the main issues in novel TB vaccine development. Potential vaccine candidates are evaluated in pre-clinical animal models, and the most promising go into clinical testing; a vaccine candidate is evaluated in at least one model before progressing to early clinical trials. The main challenge in early trials is the lack of a defined correlate of vaccine-induced immune protection. Following this, large efficacy trials are undertaken, which face the daunting challenges of cost, logistics and trial site capacity.

Scriba TJ, Tameris M, Mansoor N, Smit E, van der Merwe L, Mauff K, Hughes EJ, Moyo S et al. 2011. Dose-finding study of the novel tuberculosis vaccine, MVA85A, in healthy BCG-vaccinated infants. J Infect Dis, 203 (12), pp. 1832-1843. | Show Abstract | Read more

BACKGROUND: BCG, the only licensed tuberculosis vaccine, affords poor protection against lung tuberculosis in infants and children. A new tuberculosis vaccine, which may enhance the BCG-induced immune response, is urgently needed. We assessed the safety of and characterized the T cell response induced by 3 doses of the candidate vaccine, MVA85A, in BCG-vaccinated infants from a setting where tuberculosis is endemic. METHODS:  Infants aged 5-12 months were vaccinated intradermally with either 2.5 × 10(7), 5 × 10(7), or 10 × 10(7) plaque-forming units of MVA85A, or placebo. Adverse events were documented, and T-cell responses were assessed by interferon γ (IFN-γ) enzyme-linked immunospot assay and intracellular cytokine staining. RESULTS: The 3 MVA85A doses were well tolerated, and no vaccine-related serious adverse events were recorded. MVA85A induced potent, durable T-cell responses, which exceeded prevaccination responses up to 168 d after vaccination. No dose-related differences in response magnitude were observed. Multiple CD4 T cell subsets were induced; polyfunctional CD4 T cells co-expressing T-helper cell 1 cytokines with or without granulocyte-macrophage colony-stimulating factor predominated. IFN-γ-expressing CD8 T cells, which peaked later than CD4 T cells, were also detectable. CONCLUSIONS: MVA85A was safe and induced robust, polyfunctional, durable CD4 and CD8 T-cell responses in infants. These data support efficacy evaluation of MVA85A to prevent tuberculosis in infancy. Clinical Trials Registration. NCT00679159.

Rowland R, McShane H. 2011. Tuberculosis vaccines in clinical trials. Expert Rev Vaccines, 10 (5), pp. 645-658. | Show Abstract | Read more

Effective prophylactic and/or therapeutic vaccination is a key strategy for controlling the global TB epidemic. The partial effectiveness of the existing TB vaccine, bacille Calmette-Guérin (BCG), suggests effective vaccination is possible and highlights the need for an improved vaccination strategy. Clinical trials are evaluating both modifications to the existing BCG immunization methods and also novel TB vaccines, designed to replace or boost BCG. Candidate vaccines in clinical development include live mycobacterial vaccines designed to replace BCG, subunit vaccines designed to boost BCG and therapeutic vaccines designed as an adjunct to chemotherapy. There is a great need for validated animal models, identification of immunological biomarkers of protection and field sites with the capacity for large-scale efficacy testing in order to develop and license a novel TB vaccine or regimen.

Minassian AM, Rowland R, Beveridge NE, Poulton ID, Satti I, Harris S, Poyntz H, Hamill M et al. 2011. A Phase I study evaluating the safety and immunogenicity of MVA85A, a candidate TB vaccine, in HIV-infected adults. BMJ Open, 1 (2), pp. e000223. | Show Abstract | Read more

Objectives Control of the tuberculosis (TB) epidemic is a global health priority and one that is likely to be achieved only through vaccination. The critical overlap with the HIV epidemic requires any effective TB vaccine regimen to be safe in individuals who are infected with HIV. The objectives of this clinical trial were to evaluate the safety and immunogenicity of a leading candidate TB vaccine, MVA85A, in healthy, HIV-infected adults. Design This was an open-label Phase I trial, performed in 20 healthy HIV-infected, antiretroviral-naïve subjects. Two different doses of MVA85A were each evaluated as a single immunisation in 10 subjects, with 24 weeks of follow-up. The safety of MVA85A was assessed by clinical and laboratory markers, including regular CD4 counts and HIV RNA load measurements. Vaccine immunogenicity was assessed by ex vivo interferon γ (IFN-γ) ELISpot assays and flow-cytometric analysis. Results MVA85A was safe in subjects with HIV infection, with an adverse-event profile comparable with historical data from previous trials in HIV-uninfected subjects. There were no clinically significant vaccine-related changes in CD4 count or HIV RNA load in any subjects, and no evidence from qPCR analyses to indicate that MVA85A vaccination leads to widespread preferential infection of vaccine-induced CD4 T cell populations. Both doses of MVA85A induced an antigen-specific IFN-γ response that was durable for 24 weeks, although of a lesser magnitude compared with historical data from HIV-uninfected subjects. The functional quality of the vaccine-induced T cell response in HIV-infected subjects was remarkably comparable with that observed in healthy HIV-uninfected controls, but less durable. Conclusion MVA85A is safe and immunogenic in healthy adults infected with HIV. Further safety and efficacy evaluation of this candidate vaccine in TB- and HIV-endemic areas is merited.

Hopkins R, Bridgeman A, Joseph J, Gilbert SC, McShane H, Hanke T. 2011. Dual neonate vaccine platform against HIV-1 and M. tuberculosis. PLoS One, 6 (5), pp. e20067. | Show Abstract | Read more

Acquired immunodeficiency syndrome and tuberculosis (TB) are two of the world's most devastating diseases. The first vaccine the majority of infants born in Africa receive is Mycobacterium bovis bacillus Calmette-Guérin (BCG) as a prevention against TB. BCG protects against disseminated disease in the first 10 years of life, but provides a variable protection against pulmonary TB and enhancing boost delivered by recombinant modified vaccinia virus Ankara (rMVA) expressing antigen 85A (Ag85A) of M. tuberculosis is currently in phase IIb evaluation in African neonates. If the newborn's mother is positive for human immunodeficiency virus type 1 (HIV-1), the baby is at high risk of acquiring HIV-1 through breastfeeding. We suggested that a vaccination consisting of recombinant BCG expressing HIV-1 immunogen administered at birth followed by a boost with rMVA sharing the same immunogen could serve as a strategy for prevention of mother-to-child transmission of HIV-1 and rMVA expressing an African HIV-1-derived immunogen HIVA is currently in phase I trials in African neonates. Here, we aim to develop a dual neonate vaccine platform against HIV-1 and TB consisting of BCG.HIVA administered at birth followed by a boost with MVA.HIVA.85A. Thus, mMVA.HIVA.85A and sMVA.HIVA.85A vaccines were constructed, in which the transgene transcription is driven by either modified H5 or short synthetic promoters, respectively, and tested for immunogenicity alone and in combination with BCG.HIVA(222). mMVA.HIVA.85A was produced markerless and thus suitable for clinical manufacture. While sMVA.HIVA.85A expressed higher levels of the immunogens, it was less immunogenic than mMVA.HIVA.85A in BALB/c mice. A BCG.HIVA(222)-mMVA.HIVA.85A prime-boost regimen induced robust T cell responses to both HIV-1 and M. tuberculosis. Therefore, proof-of-principle for a dual anti-HIV-1/M. tuberculosis infant vaccine platform is established. Induction of immune responses against these pathogens soon after birth is highly desirable and may provide a basis for lifetime protection maintained by boosts later in life.

Checkley AM, Wyllie DH, Scriba TJ, Golubchik T, Hill AV, Hanekom WA, McShane H. 2011. Identification of antigens specific to non-tuberculous mycobacteria: the Mce family of proteins as a target of T cell immune responses. PLoS One, 6 (10), pp. e26434. | Show Abstract | Read more

The lack of an effective TB vaccine hinders current efforts in combating the TB pandemic. One theory as to why BCG is less protective in tropical countries is that exposure to non-tuberculous mycobacteria (NTM) reduces BCG efficacy. There are currently several new TB vaccines in clinical trials, and NTM exposure may also be relevant in this context. NTM exposure cannot be accurately evaluated in the absence of specific antigens; those which are known to be present in NTM and absent from M. tuberculosis and BCG. We therefore used a bioinformatic pipeline to define proteins which are present in common NTM and absent from the M. tuberculosis complex, using protein BLAST, TBLASTN and a short sequence protein BLAST to ensure the specificity of this process. We then assessed immune responses to these proteins, in healthy South Africans and in patients from the United Kingdom and United States with documented exposure to NTM. Low level responses were detected to a cluster of proteins from the mammalian cell entry family, and to a cluster of hypothetical proteins, using ex vivo ELISpot and a 6 day proliferation assay. These early findings may provide a basis for characterising exposure to NTM at a population level, which has applications in the field of TB vaccine design as well as in the development of diagnostic tests.

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Ota MOC, Odutola AA, Owiafe PK, Donkor S, Owolabi OA, Brittain NJ, Williams N, Rowland-Jones S, Hill AVS, Adegbola RA, McShane H. 2011. Immunogenicity of the Tuberculosis Vaccine MVA85A Is Reduced by Coadministration with EPI Vaccines in a Randomized Controlled Trial in Gambian Infants SCIENCE TRANSLATIONAL MEDICINE, 3 (88), pp. 88ra56-88ra56. | Show Abstract | Read more

New tuberculosis vaccines are urgently needed to curtail the current epidemic. MVA85A is a subunit vaccine that could enhance immunity from BCG vaccination. To determine MVA85A safety and immunogenicity as well as interactions with other routine vaccines administered in infancy, we randomized healthy 4-month-old infants who had received Bacille Calmette-Guérin at birth to receive Expanded Program on Immunization (EPI) vaccines alone, EPI and MVA85A simultaneously, or MVA85A alone. Adverse events were monitored throughout. Blood samples obtained before vaccination and at 1, 4, and 20 weeks after vaccination were used to assess safety and immunogenicity. The safety profile of both low and standard doses was comparable, but the standard dose was more immunogenic and therefore was selected for the second stage of the study. In total, 72 (first stage) and 142 (second stage) infants were enrolled. MVA85A was safe and well tolerated and induced a potent cellular immune response. Coadministration of MVA85A with EPI vaccines was associated with a significant reduction in MVA85A immunogenicity, but did not affect humoral responses to the EPI vaccines. These results provide important information regarding timing of immunizations, which is required for the design of infant efficacy trials with MVA85A, and suggest that modifications to the standard EPI schedule may be required to incorporate a new generation of T cell-inducing vaccines.

Minassian AM, Ronan EO, Poyntz H, Hill AV, McShane H. 2011. Preclinical development of an in vivo BCG challenge model for testing candidate TB vaccine efficacy. PLoS One, 6 (5), pp. e19840. | Show Abstract | Read more

There is an urgent need for an immunological correlate of protection against tuberculosis (TB) with which to evaluate candidate TB vaccines in clinical trials. Development of a human challenge model of Mycobacterium tuberculosis (M.tb) could facilitate the detection of such correlate(s). Here we propose a novel in vivo Bacille Calmette-Guérin (BCG) challenge model using BCG immunization as a surrogate for M.tb infection. Culture and quantitative PCR methods have been developed to quantify BCG in the skin, using the mouse ear as a surrogate for human skin. Candidate TB vaccines have been evaluated for their ability to protect against a BCG skin challenge, using this model, and the results indicate that protection against a BCG skin challenge is predictive of BCG vaccine efficacy against aerosol M.tb challenge. Translation of these findings to a human BCG challenge model could enable more rapid assessment and down selection of candidate TB vaccines and ultimately the identification of an immune correlate of protection.

McShane H, Williams A. 2011. Tuberculosis vaccine promises sterilizing immunity. Nat Med, 17 (10), pp. 1185-1186. | Read more

Burl S, Adetifa UJ, Cox M, Touray E, Ota MO, Marchant A, Whittle H, McShane H, Rowland-Jones SL, Flanagan KL. 2010. Delaying bacillus Calmette-Guérin vaccination from birth to 4 1/2 months of age reduces postvaccination Th1 and IL-17 responses but leads to comparable mycobacterial responses at 9 months of age. J Immunol, 185 (4), pp. 2620-2628. | Show Abstract | Read more

Bacillus Camette-Guérin (BCG) vaccine is the only licensed vaccine against tuberculosis, yet its protective efficacy is highly variable between different geographical regions. We hypothesized that exposure to nontuberculous mycobacteria attenuates BCG immunogenicity by inducing mycobacterial-specific regulatory T cells (Tregs). Gambian neonates were recruited at birth and randomized to receive BCG vaccination either at birth or at 4 1/2 mo. Mycobacterial immune responses were assessed at birth, 4 1/2, and 9 mo of age. At 4 1/2 mo of age the BCG naive individuals had detectable mycobacterial responses, including increased IL-10 production suggesting environmental priming. Vaccination at birth significantly enhanced Th1, Th2, IL-6, IL-17, and Treg responses in mycobacterial cultures at 4 1/2 mo compared with the BCG naive group. Analyzing results at 4 1/2 mo postvaccination revealed lower IFN-gamma, IL-6, and IL-17 responses in the delayed BCG vaccine group compared with those vaccinated at birth, but this did not relate to Treg levels prevaccination. When comparing responses pre- and post-BCG vaccination in the delayed vaccine group, there was no priming of mycobacterial IL-17. Mycobacterial responses waned over 9 mo in those vaccinated at birth, leading to comparable mycobacterial immunity in both groups at 9 mo of age. Overall, these data suggest that vaccination at birth induces a broad Th1/Th2/IL-17/Treg mycobacterial response but the Th1/Th-17 response was reduced when delaying the vaccine. The evidence did not suggest that mycobacterial specific naturally occurring Tregs accounted for this attenuated immunogenicity.

Smith SG, Lalor MK, Gorak-Stolinska P, Blitz R, Beveridge NE, Worth A, McShane H, Dockrell HM. 2010. Mycobacterium tuberculosis PPD-induced immune biomarkers measurable in vitro following BCG vaccination of UK adolescents by multiplex bead array and intracellular cytokine staining. BMC Immunol, 11 (1), pp. 35. | Show Abstract | Read more

BACKGROUND: The vaccine efficacy reported following Mycobacterium bovis Bacillus Calmette Guerin (BCG) administration to UK adolescents is 77% and defining the cellular immune response in this group can inform us as to the nature of effective immunity against tuberculosis. The aim of this study was to identify which cytokines and lymphocyte populations characterise the peripheral blood cellular immune response following BCG vaccination. RESULTS: Diluted blood from before and after vaccination was stimulated with Mycobacterium tuberculosis purified protein derivative for 6 days, after which soluble biomarkers in supernatants were assayed by multiplex bead array. Ten out of twenty biomarkers measured were significantly increased (p < 0.0025) 1 month after BCG vaccination when compared to paired samples (n = 12) taken prior to vaccination (IFNgamma, TNFalpha, IL-1alpha, IL-2, IL-6, IL-10, IL-17, GM-CSF, MIP1alpha, IP-10). All of these remained detectable by multiplex bead array in samples taken 12 months after BCG vaccination of a partially overlapping adolescent group (n = 12). Intracellular cytokine staining after 24 hour Mycobacterium tuberculosis purified protein derivative stimulation of PBMC samples from the 12 month group revealed that IFNgamma expression was detectable in CD4 and CD8 T-cells and natural killer cells. Polyfunctional flow cytometry analysis demonstrated that cells expressing IFNgamma alone formed the majority in each subpopulation of cells. Only in CD4 T-cells and NK cells were there a notable proportion of responding cells of a different phenotype and these were single positive, TNFalpha producers. No significant expression of the cytokines IL-2, IL-17 or IL-10 was seen in any population of cells. CONCLUSIONS: The broad array of biomarker responses detected by multiplex bead array suggests that BCG vaccination is capable, in this setting, of inducing a complex immune phenotype. Although polyfunctional T-cells have been proposed to play a role in protective immunity, they were not present in vaccinated adolescents who, based on earlier epidemiological studies, should have developed protection against pulmonary tuberculosis. This may be due to the later sampling time point available for testing or on the kinetics of the assays used.

Sharpe SA, McShane H, Dennis MJ, Basaraba RJ, Gleeson F, Hall G, McIntyre A, Gooch K et al. 2010. Establishment of an aerosol challenge model of tuberculosis in rhesus macaques and an evaluation of endpoints for vaccine testing. Clin Vaccine Immunol, 17 (8), pp. 1170-1182. | Show Abstract | Read more

The establishment of an aerosol challenge model in nonhuman primates (NHPs) for the testing of vaccines against Mycobacterium tuberculosis would assist the global effort to optimize novel vaccination strategies. The endpoints used in preclinical challenge studies to identify measures of disease burden need to be accurate and sensitive enough to distinguish subtle differences and benefits afforded by different tuberculosis (TB) vaccine regimens when group sizes are inevitably small. This study sought to assess clinical and nonclinical endpoints as potentially sensitive measures of disease burden in a challenge study with rhesus macaques by using a new protocol of aerosol administration of M. tuberculosis. Immunological and clinical readouts were assessed for utility in vaccine evaluation studies. This is the first example of TB vaccine evaluation with rhesus macaques where long-term survival was one of the primary endpoints. However, we found that in NHP vaccine efficacy studies with maximum group sizes of six animals, survival did not provide a valuable endpoint. Two approaches used in human clinical trials for the evaluation of the gamma interferon (IFN-gamma) response to vaccination (enzyme-linked immunospot [ELISpot] assay and enzyme-linked immunosorbent assay [ELISA]) were included in this study. The IFN-gamma profiles induced following vaccination were found not to correlate with protection, nor did the level of purified protein derivative (PPD)-specific proliferation. The only readout to reliably distinguish vaccinated and unvaccinated NHPs was the determination of lung lesion burden using magnetic resonance (MR) imaging combined with stereology at the end of the study. Therefore, the currently proposed key markers were not shown to correlate with protection, and only imaging offered a potentially reliable correlate.

Scriba TJ, Tameris M, Mansoor N, Smit E, van der Merwe L, Isaacs F, Keyser A, Moyo S et al. 2010. Modified vaccinia Ankara-expressing Ag85A, a novel tuberculosis vaccine, is safe in adolescents and children, and induces polyfunctional CD4+ T cells. Eur J Immunol, 40 (1), pp. 279-290. | Show Abstract | Read more

Modified vaccinia Ankara-expressing Ag85A (MVA85A) is a new tuberculosis (TB) vaccine aimed at enhancing immunity induced by BCG. We investigated the safety and immunogenicity of MVA85A in healthy adolescents and children from a TB endemic region, who received BCG at birth. Twelve adolescents and 24 children were vaccinated and followed up for 12 or 6 months, respectively. Adverse events were documented and vaccine-induced immune responses assessed by IFN-gamma ELISpot and intracellular cytokine staining. The vaccine was well tolerated and there were no vaccine-related serious adverse events. MVA85A induced potent and durable T-cell responses. Multiple CD4+ T-cell subsets, based on expression of IFN-gamma, TNF-alpha, IL-2, IL-17 and GM-CSF, were induced. Polyfunctional CD4+ T cells co-expressing IFN-gamma, TNF-alpha and IL-2 dominated the response in both age groups. A novel CD4+ cell subset co-expressing these three Th1 cytokines and IL-17 was induced in adolescents, while a novel CD4+ T-cell subset co-expressing Th1 cytokines and GM-CSF was induced in children. Ag-specific CD8+ T cells were not detected. We conclude that in adolescents and children MVA85A safely induces the type of immunity thought to be important in protection against TB. This includes induction of novel Th1-cell populations that have not been previously described in humans.

Burl S, Adetifa UJ, Cox M, Touray E, Whittle H, McShane H, Rowland-Jones SL, Flanagan KL. 2010. The tuberculin skin test (TST) is affected by recent BCG vaccination but not by exposure to non-tuberculosis mycobacteria (NTM) during early life. PLoS One, 5 (8), pp. e12287. | Show Abstract | Read more

The tuberculin skin test (TST) is widely used in TB clinics to aid Mycobacterium tuberculosis (M.tb) diagnosis, but the definition and the significance of a positive test in very young children is still unclear. This study compared the TST in Gambian children at 4(1/2) months of age who either received BCG vaccination at birth (Group 1) or were BCG naïve (Group 2) in order to examine the role of BCG vaccination and/or exposure to environmental mycobacteria in TST reactivity at this age. Nearly half of the BCG vaccinated children had a positive TST (>or=5 mm) whereas all the BCG naïve children were non-reactive, confirming that recent BCG vaccination affects TST reactivity. The BCG naïve children demonstrated in vitro PPD responses in peripheral blood in the absence of TST reactivity, supporting exposure to and priming by environmental mycobacterial antigens. Group 2 were then vaccinated at 4(1/2) months of age and a repeat TST was performed at 20-28 months of age. Positive reactivity (>or=5 mm) was evident in 11.1% and 12.5% infants from Group 1 and Group 2 respectively suggesting that the timing of BCG vaccination had little effect by this age. We further assessed for immune correlates in peripheral blood at 4(1/2) months of age. Mycobacterial specific IFNgamma responses were greater in TST responders than in non-responders, although the size of induration did not correlate with IFNgamma. However the IFNgamma: IL-10 ratio positively correlated with TST induration suggesting that the relationship between PPD induced IFNgamma and IL-10 in the peripheral blood may be important in controlling TST reactivity. Collectively these data provide further insights into how the TST is regulated in early life, and how a positive response might be interpreted.

Smith SG, Joosten SA, Verscheure V, Pathan AA, McShane H, Ottenhoff TH, Dockrell HM, Mascart F. 2009. Identification of major factors influencing ELISpot-based monitoring of cellular responses to antigens from Mycobacterium tuberculosis. PLoS One, 4 (11), pp. e7972. | Show Abstract | Read more

A number of different interferon-gamma ELISpot protocols are in use in laboratories studying antigen-specific immune responses. It is therefore unclear how results from different assays compare, and what factors most significantly influence assay outcome. One such difference is that some laboratories use a short in vitro stimulation period of cells before they are transferred to the ELISpot plate; this is commonly done in the case of frozen cells, in order to enhance assay sensitivity. Other differences that may be significant include antibody coating of plates, the use of media with or without serum, the serum source and the number of cells added to the wells. The aim of this paper was to identify which components of the different ELISpot protocols influenced assay sensitivity and inter-laboratory variation. Four laboratories provided protocols for quantifying numbers of interferon-gamma spot forming cells in human peripheral blood mononuclear cells stimulated with Mycobacterium tuberculosis derived antigens. The differences in the protocols were compared directly. We found that several sources of variation in assay protocols can be eliminated, for example by avoiding serum supplementation and using AIM-V serum free medium. In addition, the number of cells added to ELISpot wells should also be standardised. Importantly, delays in peripheral blood mononuclear cell processing before stimulation had a marked effect on the number of detectable spot forming cells; processing delay thus should be minimised as well as standardised. Finally, a pre-stimulation culture period improved the sensitivity of the assay, however this effect may be both antigen and donor dependent. In conclusion, small differences in ELISpot protocols in routine use can affect the results obtained and care should be given to conditions selected for use in a given study. A pre-stimulation step may improve the sensitivity of the assay, particularly when cells have been previously frozen.

Vordermeier HM, Villarreal-Ramos B, Cockle PJ, McAulay M, Rhodes SG, Thacker T, Gilbert SC, McShane H, Hill AV, Xing Z, Hewinson RG. 2009. Viral booster vaccines improve Mycobacterium bovis BCG-induced protection against bovine tuberculosis. Infect Immun, 77 (8), pp. 3364-3373. | Show Abstract | Read more

Previous work with small-animal laboratory models of tuberculosis has shown that vaccination strategies based on heterologous prime-boost protocols using Mycobacterium bovis bacillus Calmette-Guérin (BCG) to prime and modified vaccinia virus Ankara strain (MVA85A) or recombinant attenuated adenoviruses (Ad85A) expressing the mycobacterial antigen Ag85A to boost may increase the protective efficacy of BCG. Here we report the first efficacy data on using these vaccines in cattle, a natural target species of tuberculous infection. Protection was determined by measuring development of disease as an end point after M. bovis challenge. Either Ad85A or MVA85A boosting resulted in protection superior to that given by BCG alone: boosting BCG with MVA85A or Ad85A induced significant reduction in pathology in four/eight parameters assessed, while BCG vaccination alone did so in only one parameter studied. Protection was particularly evident in the lungs of vaccinated animals (median lung scores for naïve and BCG-, BCG/MVA85A-, and BCG/Ad85A-vaccinated animals were 10.5, 5, 2.5, and 0, respectively). The bacterial loads in lymph node tissues were also reduced after viral boosting of BCG-vaccinated calves compared to those in BCG-only-vaccinated animals. Analysis of vaccine-induced immunity identified memory responses measured by cultured enzyme-linked immunospot assay as well as in vitro interleukin-17 production as predictors of vaccination success, as both responses, measured before challenge, correlated positively with the degree of protection. Therefore, this study provides evidence of improved protection against tuberculosis by viral booster vaccination in a natural target species and has prioritized potential correlates of vaccine efficacy for further evaluation. These findings also have implications for human tuberculosis vaccine development.

Fletcher HA, Hawkridge T, McShane H. 2009. A New Vaccine for Tuberculosis: The Challenges of Development and Deployment JOURNAL OF BIOETHICAL INQUIRY, 6 (2), pp. 219-228. | Show Abstract | Read more

Tuberculosis (TB) is one of the world's leading causes of death due to infection and efforts to control TB would be substantially aided by the availability of an improved TB vaccine. There are currently nine new TB vaccines in clinical development, and the first efficacy trials are due to commence in 2009. There are many complex ethical issues which arise at all stages of TB vaccine development, from the need to conduct trials in developing countries to informed consent and the process of ethical review. While it is important that these issues are discussed, it may also be timely to consider the challenges which may arise if a vaccine in clinical development proves to be highly effective. We examine a number of scenarios where decisions on the deployment of a new TB vaccine may impact on the rights and liberty of the individual. © The Author(s) 2009.

McShane H. 2009. Need for more TB vaccine field sites. Indian J Exp Biol, 47 (6), pp. 445-446. | Show Abstract

Efforts to control the tuberculosis (TB) epidemic have been challenged by both the geographical overlap with the HIV pandemic, and the emergence of multi - and extensively - drug-resistant strains of Mycobacterium tuberculosis. There is, therefore, an urgent global need for an improved vaccine. However, the development of an improved vaccine is scientifically and logistically challenging. Immunological correlates or biomarkers of protection are not known and there is no perfect preclinical animal model with which to predict success in humans. Indeed, vaccine development in general is time-consuming and costly. One of the many road-blocks to the development of new TB vaccines is the availability of field sites that are suitable for large scale Phase IIb/III efficacy testing. Because disease incidence is low, even though prevalence is high, Phase IIb efficacy trials involve several thousand subjects, and require lengthy follow-up. Phase III licensure trials will need to be even larger, and are likely to require the involvement of multiple field sites. There is currently inadequate capacity within high-burden TB countries to conduct these essential trials. We need to invest now to expand current capacity if we are to reduce the time taken to develop new vaccines.

Sander CR, Pathan AA, Beveridge NE, Poulton I, Minassian A, Alder N, Van Wijgerden J, Hill AV et al. 2009. Safety and immunogenicity of a new tuberculosis vaccine, MVA85A, in Mycobacterium tuberculosis-infected individuals. Am J Respir Crit Care Med, 179 (8), pp. 724-733. | Show Abstract | Read more

RATIONALE: An effective new tuberculosis (TB) vaccine regimen must be safe in individuals with latent TB infection (LTBI) and is a priority for global health care. OBJECTIVES: To evaluate the safety and immunogenicity of a leading new TB vaccine, recombinant Modified Vaccinia Ankara expressing Antigen 85A (MVA85A) in individuals with LTBI. METHODS: An open-label, phase I trial of MVA85A was performed in 12 subjects with LTBI recruited from TB contact clinics in Oxford and London or by poster advertisements in Oxford hospitals. Patients were assessed clinically and had blood samples drawn for immunological analysis over a 52-week period after vaccination with MVA85A. Thoracic computed tomography scans were performed at baseline and at 10 weeks after vaccination. Safety of MVA85A was assessed by clinical, radiological, and inflammatory markers. The immunogenicity of MVA85A was assessed by IFNgamma and IL-2 ELISpot assays and FACS. MEASUREMENTS AND MAIN RESULTS: MVA85A was safe in subjects with LTBI, with comparable adverse events to previous trials of MVA85A. There were no clinically significant changes in inflammatory markers or thoracic computed tomography scans after vaccination. MVA85A induced a strong antigen-specific IFN-gamma and IL-2 response that was durable for 52 weeks. The magnitude of IFN-gamma response was comparable to previous trials of MVA85A in bacillus Calmette-Guérin-vaccinated individuals. Antigen 85A-specific polyfunctional CD4(+) T cells were detectable prior to vaccination with statistically significant increases in cell numbers after vaccination. CONCLUSIONS: MVA85A is safe and highly immunogenic in individuals with LTBI. These results will facilitate further trials in TB-endemic areas. Clinical trial registered with www.clinicaltrials.gov (NCT00456183).

McShane H. 2009. Vaccine strategies against tuberculosis. Swiss Med Wkly, 139 (11-12), pp. 156-160. | Show Abstract

The need for an improved vaccine against tuberculosis has never been more urgent. The HIV epidemic and the emergence of multi and extensively drug-resistant strains of Mycobacterium tuberculosis mean that global control of this pathogen remains inadequate. The existing vaccine, BCG, confers only variable protection against pulmonary disease. Exposure to environmental mycobacteria may contribute to this variability in protective efficacy. Protective immunity against Mycobacterium tuberculosis is dependant on a cell-mediated immune response. Boosting BCG with a subunit vaccine, and/or replacing BCG with an improved BCG are both strategies currently being investigated. Since 2002, there have been increasing numbers of TB vaccine candidates entering into clinical trials. The first of these candidates, MVA85A, is safe and highly immunogenic in all trials to date. In addition, the cellular immune response induced is highly polyfunctional. The protective efficacy of MVA85A will be evaluated in a Phase IIb trial commencing in early 2009 in South African infants.

Tchilian EZ, Desel C, Forbes EK, Bandermann S, Sander CR, Hill AV, McShane H, Kaufmann SH. 2009. Immunogenicity and protective efficacy of prime-boost regimens with recombinant (delta)ureC hly+ Mycobacterium bovis BCG and modified vaccinia virus ankara expressing M. tuberculosis antigen 85A against murine tuberculosis. Infect Immun, 77 (2), pp. 622-631. | Show Abstract | Read more

In the light of the recent emergence of multidrug-resistant and extensively drug-resistant strains of Mycobacterium tuberculosis, the epidemic of tuberculosis (TB) in populations coinfected with human immunodeficiency virus, and the failure of Mycobacterium bovis bacillus Calmette-Guerin (BCG) to protect against disease, new vaccines against TB are urgently needed. Two promising new vaccine candidates are the recombinant DeltaureC hly(+) BCG (recBCG), which has been developed to replace the current BCG vaccine strain, and modified vaccinia virus Ankara (MVA) expressing M. tuberculosis antigen 85A (MVA85A), which is a leading candidate vaccine designed to boost the protective efficacy of BCG. In the present study, we examined the effect of MVA85A boosting on the protection afforded at 12 weeks postchallenge by BCG and recBCG by using bacterial CFU as an efficacy readout. recBCG-immunized mice were significantly better protected against aerosol challenge with M. tuberculosis than mice immunized with the parental strain of BCG. Intradermal boosting with MVA85A did not reduce the bacterial burden any further. In order to identify a marker for the development of a protective immune response against M. tuberculosis challenge, we analyzed splenocytes after priming or prime-boosting by using intracytoplasmic cytokine staining and assays for cytokine secretion. Boosting with MVA85A, but not priming with BCG or recBCG, greatly increased the antigen 85A-specific T-cell response, suggesting that the mechanism of protection may differ from that against BCG or recBCG. We show that the numbers of systemic multifunctional cytokine-producing cells did not correlate with protection against aerosol challenge in BALB/c mice. This emphasizes the need for new biomarkers for the evaluation of TB vaccine efficacy.

Verreck FA, Vervenne RA, Kondova I, van Kralingen KW, Remarque EJ, Braskamp G, van der Werff NM, Kersbergen A et al. 2009. MVA.85A boosting of BCG and an attenuated, phoP deficient M. tuberculosis vaccine both show protective efficacy against tuberculosis in rhesus macaques. PLoS One, 4 (4), pp. e5264. | Show Abstract | Read more

BACKGROUND: Continuous high global tuberculosis (TB) mortality rates and variable vaccine efficacy of Mycobacterium bovis Bacille Calmette-Guérin (BCG) motivate the search for better vaccine regimes. Relevant models are required to downselect the most promising vaccines entering clinical efficacy testing and to identify correlates of protection. METHODS AND FINDINGS: Here, we evaluated immunogenicity and protection against Mycobacterium tuberculosis in rhesus monkeys with two novel strategies: BCG boosted by modified vaccinia virus Ankara expressing antigen 85A (MVA.85A), and attenuated M. tuberculosis with a disrupted phoP gene (SO2) as a single-dose vaccine. Both strategies were well tolerated, and immunogenic as evidenced by induction of specific IFNgamma responses. Antigen 85A-specific IFNgamma secretion was specifically increased by MVA.85A boosting. Importantly, both MVA.85A and SO2 treatment significantly reduced pathology and chest X-ray scores upon infectious challenge with M. tuberculosis Erdman strain. MVA.85A and SO2 treatment also showed reduced average lung bacterial counts (1.0 and 1.2 log respectively, compared with 0.4 log for BCG) and significant protective effect by reduction in C-reactive protein levels, body weight loss, and decrease of erythrocyte-associated hematologic parameters (MCV, MCH, Hb, Ht) as markers of inflammatory infection, all relative to non-vaccinated controls. Lymphocyte stimulation revealed Ag85A-induced IFNgamma levels post-infection as the strongest immunocorrelate for protection (spearman's rho: -0.60). CONCLUSIONS: Both the BCG/MVA.85A prime-boost regime and the novel live attenuated, phoP deficient TB vaccine candidate SO2 showed significant protective efficacy by various parameters in rhesus macaques. Considering the phylogenetic relationship between macaque and man and the similarity in manifestations of TB disease, these data support further development of these primary and combination TB vaccine candidates.

Whelan KT, Pathan AA, Sander CR, Fletcher HA, Poulton I, Alder NC, Hill AV, McShane H. 2009. Safety and immunogenicity of boosting BCG vaccinated subjects with BCG: comparison with boosting with a new TB vaccine, MVA85A. PLoS One, 4 (6), pp. e5934. | Show Abstract | Read more

OBJECTIVES: To investigate the safety and immunogenicity of a booster BCG vaccination delivered intradermally in healthy, BCG vaccinated subjects and to compare with a previous clinical trial where BCG vaccinated subjects were boosted with a new TB vaccine, MVA85A. DESIGN: Phase I open label observational trial, in the UK. Healthy, HIV-negative, BCG vaccinated adults were recruited and vaccinated with BCG. The primary outcome was safety; the secondary outcome was cellular immune responses to antigen 85, overlapping peptides of antigen 85A and tuberculin purified protein derivative (PPD) detected by ex vivo interferon-gamma (IFN-gamma) ELISpot assay and flow cytometry. RESULTS AND CONCLUSIONS: BCG revaccination (BCG-BCG) was well tolerated, and boosting of pre-existing PPD-specific T cell responses was observed. However, when these results were compared with data from a previous clinical trial, where BCG was boosted with MVA85A (BCG-MVA85A), MVA85A induced significantly higher levels (>2-fold) of antigen 85-specific CD4+ T cells (both antigen and peptide pool responses) than boosting with BCG, up to 52 weeks post-vaccination (p = 0.009). To identify antigen 85A-specific CD8+ T cells that were not detectable by ex vivo ELISpot and flow cytometry, dendritic cells (DC) were used to amplify CD8+ T cells from PBMC samples. We observed low, but detectable levels of antigen 85A-specific CD8+ T cells producing IFNgamma (1.5% of total CD8 population) in the BCG primed subjects after BCG boosting in 1 (20%) of 5 subjects. In contrast, in BCG-MVA85A vaccinated subjects, high levels of antigen 85A-specific CD8+ T cells (up to 14% total CD8 population) were observed after boosting with MVA85A, in 4 (50%) of 8 subjects evaluated. In conclusion, revaccination with BCG resulted in modest boosting of pre-existing immune responses to PPD and antigen 85, but vaccination with BCG-MVA85A induced a significantly higher response to antigen 85 and generated a higher frequency of antigen 85A-specific CD8+ T cells. TRIAL REGISTRATION: ClinicalTrials.gov NCT00654316 NCT00427830.

Minassian AM, McShane H. 2008. Tuberculosis vaccines: present and future. Expert Rev Respir Med, 2 (6), pp. 721-738. | Show Abstract | Read more

There has never been a greater need for a new protective tuberculosis vaccine. Bacille Calmette-Guerin remains the cornerstone of any vaccine strategy, but improving its immunogenicity and efficacy has now become an urgent global health priority. This review discusses the main vaccines currently in clinical development and other novel vaccine strategies in the pipeline. It addresses the key questions in vaccine design, including antigen selection, route of vaccine delivery and immune correlates of vaccine-induced protection. There is an opportunity to identify such correlates from ongoing and future Phase II/III trials and, as these emerge, they can be used to validate the most relevant and predictive animal models with which to develop the next generation of new vaccines.

Beveridge NE, Fletcher HA, Hughes J, Pathan AA, Scriba TJ, Minassian A, Sander CR, Whelan KT et al. 2008. A comparison of IFNgamma detection methods used in tuberculosis vaccine trials. Tuberculosis (Edinb), 88 (6), pp. 631-640. | Show Abstract | Read more

Interferon gamma (IFNgamma) is a critical component of the pro-inflammatory immune response that provides protection against Mycobacterium tuberculosis. In the absence of an immunological correlate of protection, antigen-specific production of IFNgamma is a commonly used marker of a protective immune response. To facilitate the evaluation of tuberculosis candidate vaccines three different IFNgamma detection methods were compared. The cultured whole blood ELISA, ex vivo IFNgamma ELISpot and whole blood ex vivo intracellular cytokine staining (ICS) assays were performed head-to-head during a Phase I clinical trial using the candidate vaccine MVA85A. Whilst all three assays detected significant increases in IFNgamma production immediately following vaccination, distinctions between the assays were apparent. Higher baseline IFNgamma responses were detected using the cultured whole blood ELISA, whereas the ex vivo ELISpot assay was the most sensitive in detecting long-term (52 weeks) post-vaccination responses. The whole blood ex vivo ICS assay provided novel information by dissecting the IFNgamma response into responding CD4, CD8 and gamma/delta T cell subsets. Future tuberculosis vaccine trials and immunology studies should ideally include a combination of ex vivo and cultured assays to ensure a thorough and multifaceted evaluation of the immune response is achieved.

Forbes EK, Sander C, Ronan EO, McShane H, Hill AV, Beverley PC, Tchilian EZ. 2008. Multifunctional, high-level cytokine-producing Th1 cells in the lung, but not spleen, correlate with protection against Mycobacterium tuberculosis aerosol challenge in mice. J Immunol, 181 (7), pp. 4955-4964. | Show Abstract

Boosting bacillus Calmette-Guérin (BCG)-primed mice with a recombinant adenovirus expressing Mycobacterium tuberculosis Ag 85A by different administration routes has very different effects on protection against aerosol challenge with M. tuberculosis. Mice boosted intradermally make very strong splenic CD4 and CD8 Th1 cytokine responses to Ag 85A, but show no change in lung mycobacterial burden over BCG primed animals. In contrast, intranasally boosted mice show greatly reduced mycobacterial burden and make a much weaker splenic response but a very strong lung CD4 and CD8 response to Ag 85A and an increased response to purified protein derivative. This effect is associated with the presence in the lung of multifunctional T cells, with high median fluorescence intensity and integrated median fluorescence intensity for IFN-gamma, IL-2, and TNF. In contrast, mice immunized with BCG alone have few Ag-specific cells in the lung and a low proportion of multifunctional cells, although individual cells have high median fluorescence intensity. Successful immunization regimes appear to induce Ag-specific cells with abundant intracellular cytokine staining.

Fletcher HA, Pathan AA, Berthoud TK, Dunachie SJ, Whelan KT, Alder NC, Sander CR, Hill AV, McShane H. 2008. Boosting BCG vaccination with MVA85A down-regulates the immunoregulatory cytokine TGF-beta1. Vaccine, 26 (41), pp. 5269-5275. | Show Abstract | Read more

In clinical trials recombinant-modified vaccinia virus Ankara expressing the Mycobacterium tuberculosis antigen 85A (MVA85A) induces approximately 10 times more effector T cells than any other recombinant MVA vaccine. We have found that in BCG primed subjects MVA85A vaccination reduces transforming growth factor beta 1 (TGF-beta1) mRNA in peripheral blood lymphocytes and reduces TGF-beta1 protein in the serum, but increases IFN-gamma ELISPOT responses to the recall antigen SK/SD. TGF-beta1 is essential for the generation of regulatory T cells and we see a correlation across vaccinees between CD4+CD25hiFoxP3+ cells and TGF-beta1 serum levels. This apparent ability to counteract regulatory T cell effects suggests a potential use of MVA85A as an adjuvant for less immunogenic vaccines.

Hawkridge T, Scriba TJ, Gelderbloem S, Smit E, Tameris M, Moyo S, Lang T, Veldsman A et al. 2008. Safety and immunogenicity of a new tuberculosis vaccine, MVA85A, in healthy adults in South Africa. J Infect Dis, 198 (4), pp. 544-552. | Show Abstract | Read more

BACKGROUND: The efficacy of bacille Calmette-Guérin (BCG) may be enhanced by heterologous vaccination strategies that boost the BCG-primed immune response. One leading booster vaccine, MVA85A (where "MVA" denotes "modified vaccinia virus Ankara"), has shown promising safety and immunogenicity in human trials performed in the United Kingdom. We investigated the safety and immunogenicity of MVA85A in mycobacteria-exposed--but Mycobacterium tuberculosis-uninfected--healthy adults from a region of South Africa where TB is endemic. METHODS: Twenty-four adults were vaccinated with MVA85A. All subjects were monitored for 1 year for adverse events and for immunological assessment. RESULTS: MVA85A vaccination was well tolerated and induced potent T cell responses, as measured by interferon (IFN)-gamma enzyme-linked immunospot assay, which exceeded prevaccination responses up to 364 days after vaccination. BCG-specific CD4+ T cells boosted by MVA85A were comprised of multiple populations expressing combinations of IFN-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-2, and IL-17, as measured by polychromatic flow cytometry. IFN-gamma-expressing and polyfunctional IFN-gamma+TNF-gamma+IL-2+ CD4+ T cells were boosted during the peak BCG-specific response, which occurred 7 days after vaccination. CONCLUSION: The excellent safety profile and quantitative and qualitative immunogenicity data strongly support further trials assessing the efficacy of MVA85A as a boosting vaccine in countries where TB is endemic. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00460590.

Brookes RH, Hill PC, Owiafe PK, Ibanga HB, Jeffries DJ, Donkor SA, Fletcher HA, Hammond AS et al. 2008. Safety and immunogenicity of the candidate tuberculosis vaccine MVA85A in West Africa. PLoS One, 3 (8), pp. e2921. | Show Abstract | Read more

BACKGROUND: Vaccination with a recombinant modified vaccinia Ankara expressing antigen 85A from Mycobacterium tuberculosis, MVA85A, induces high levels of cellular immune responses in UK volunteers. We assessed the safety and immunogenicity of this new vaccine in West African volunteers. METHODS AND FINDINGS: We vaccinated 21 healthy adult male subjects (11 BCG scar negative and 10 BCG scar positive) with MVA85A after screening for evidence of prior exposure to mycobacteria. We monitored them over six months, observing for clinical, haematological and biochemical adverse events, together with assessment of the vaccine induced cellular immune response using ELISPOT and flow cytometry. MVA85A was well tolerated with no significant adverse events. Mild local and systemic adverse events were consistent with previous UK trials. Marked immunogenicity was found whether individuals had a previous BCG scar or not. There was not enhanced immunogenicity in those with a BCG scar, and induced T cell responses were better maintained in apparently BCG-naïve Gambians than previously studied BCG-naïve UK vaccinees. Although responses were predominantly attributable to CD4+ T cells, we also identified antigen specific CD8+ T cell responses, in subjects who were HLA B-35 and in whom enough blood was available for more detailed immunological analysis. CONCLUSIONS: These data on the safety and immunogenicity of MVA85A in West Africa support its accelerated development as a promising booster vaccine for tuberculosis. TRIAL REGISTRATION: ClinicalTrials.gov NCT00423839.

Hanekom WA, Dockrell HM, Ottenhoff TH, Doherty TM, Fletcher H, McShane H, Weichold FF, Hoft DF, Parida SK, Fruth UJ. 2008. Immunological outcomes of new tuberculosis vaccine trials: WHO panel recommendations. PLoS Med, 5 (7), pp. e145. | Read more

Ota MO, Brookes RH, Hill PC, Owiafe PK, Ibanga HB, Donkor S, Awine T, McShane H, Adegbola RA. 2007. The effect of tuberculin skin test and BCG vaccination on the expansion of PPD-specific IFN-gamma producing cells ex vivo. Vaccine, 25 (52), pp. 8861-8867. | Show Abstract | Read more

Understanding the immunogenicity of BCG in a population where it has failed will facilitate the design of new TB vaccines. We assessed the immunogenicity of M. bovis BCG over 12 months by ELISPOT assay. Forty-one adolescents and young Gambian male adults received a tuberculin skin test (TST) which was followed one week later by BCG vaccination, but the 23 control subjects received neither of these. TST alone significantly induced PPD-specific IFN-gamma producing cells. Twenty-three percent of subjects did not respond to BCG, which was associated with higher pre-existing ex vivo response to PPD. Paradoxically, amongst BCG responders there was a correlation between pre-existing response and subsequent response to BCG. We conclude that BCG is immunogenic, but this effector response is short-lived and can be limited in higher pre-existing anti-mycobacterial immunity, suggesting a possible threshold beyond which BCG immunogenicity is inhibited.

O'Sullivan DM, Sander C, Shorten RJ, Gillespie SH, Hill AVS, McHugh TD, McShane H, Tchilian EZ. 2007. Evaluation of liquid culture for quantitation of Mycobacterium tuberculosis in murine models VACCINE, 25 (49), pp. 8203-8205. | Show Abstract | Read more

Quantitation of bacterial load in tissues is essential for experimental investigation of Mycobacterium tuberculosis infection and immunity. We have used an automated liquid culture system to determine the number of colony forming units (CFU) in murine tissues and compared the results to those obtained by conventional plating on Middlebrook agar. There is an overall good correlation between results obtained by the two methods. Although less consistency and more contamination was observed in the automated liquid culture, the method is more sensitive, less labour intensive and allows the processing of large numbers of samples. © 2007 Elsevier Ltd. All rights reserved.

Beveridge NE, Price DA, Casazza JP, Pathan AA, Sander CR, Asher TE, Ambrozak DR, Precopio ML et al. 2007. Immunisation with BCG and recombinant MVA85A induces long-lasting, polyfunctional Mycobacterium tuberculosis-specific CD4+ memory T lymphocyte populations. Eur J Immunol, 37 (11), pp. 3089-3100. | Show Abstract | Read more

In the search for effective vaccines against intracellular pathogens such as HIV, tuberculosis and malaria, recombinant viral vectors are increasingly being used to boost previously primed T cell responses. Published data have shown prime-boost vaccination with BCG-MVA85A (modified vaccinia virus Ankara expressing antigen 85A) to be highly immunogenic in humans as measured by ex vivo IFN-gamma ELISPOT. Here, we used polychromatic flow cytometry to investigate the phenotypic and functional profile of these vaccine-induced Mycobacterium tuberculosis (M.tb) antigen 85A-specific responses in greater detail. Promisingly, antigen 85A-specific CD4(+) T cells were found to be highly polyfunctional, producing IFN-gamma, TNF-alpha, IL-2 and MIP-1beta. Surface staining showed the responding CD4(+) T cells to be relatively immature (CD45RO(+) CD27(int)CD57(-)); this observation was supported by the robust proliferative responses observed following antigenic stimulation. Furthermore, these phenotypic and functional properties were independent of clonotypic composition and epitope specificity, which was maintained through the different phases of the vaccine-induced immune response. Overall, these data strongly support the use of MVA85A in humans as a boosting agent to expand polyfunctional M.tb-specific CD4(+) T cells capable of significant secondary responses.

Im EJ, Saubi N, Virgili G, Sander C, Teoh D, Gatell JM, McShane H, Joseph J, Hanke T. 2007. Vaccine platform for prevention of tuberculosis and mother-to-child transmission of human immunodeficiency virus type 1 through breastfeeding. J Virol, 81 (17), pp. 9408-9418. | Show Abstract | Read more

Most children in Africa receive their vaccine against tuberculosis at birth. Those infants born to human immunodeficiency virus type 1 (HIV-1)-positive mothers are at high risk of acquiring HIV-1 infection through breastfeeding in the first weeks of their lives. Thus, the development of a vaccine which would protect newborns against both of these major global killers is a logical yet highly scientifically, ethically, and practically challenging aim. Here, a recombinant lysine auxotroph of Mycobacterium bovis bacillus Calmette-Guérin (BCG), a BCG strain that is safer than those currently used and expresses an African HIV-1 clade-derived immunogen, was generated and shown to be stable and to induce durable, high-quality HIV-1-specific CD4(+)- and CD8(+)-T-cell responses. Furthermore, when the recombinant BCG vaccine was used in a priming-boosting regimen with heterologous components, the HIV-1-specific responses provided protection against surrogate virus challenge, and the recombinant BCG vaccine alone protected against aerosol challenge with M. tuberculosis. Thus, inserting an HIV-1-derived immunogen into the scheduled BCG vaccine delivered at or soon after birth may prime HIV-1-specific responses, which can be boosted by natural exposure to HIV-1 in the breast milk and/or by a heterologous vaccine such as recombinant modified vaccinia virus Ankara delivering the same immunogen, and decrease mother-to-child transmission of HIV-1 during breastfeeding.

Sander C, McShane H. 2007. Translational mini-review series on vaccines: Development and evaluation of improved vaccines against tuberculosis. Clin Exp Immunol, 147 (3), pp. 401-411. | Show Abstract | Read more

Tuberculosis (TB) continues to be a major global health disaster, despite the widespread use of BCG and effective drug therapies. The development of an efficacious new TB vaccine would be an important component of disease control in the future. Many approaches are being utilised to enhance understanding of the requirements of a successful vaccine. Numerous vaccines are being designed and assessed in a series of animal models, with a few progressing to clinical trials. Here, the steps involved in the development and evaluation of TB vaccines will be discussed, including description of the most frequently used animal models and the processes involved in advancing vaccines to phase III trials.

Pathan AA, Sander CR, Fletcher HA, Poulton I, Alder NC, Beveridge NE, Whelan KT, Hill AV, McShane H. 2007. Boosting BCG with recombinant modified vaccinia ankara expressing antigen 85A: different boosting intervals and implications for efficacy trials. PLoS One, 2 (10), pp. e1052. | Show Abstract | Read more

OBJECTIVES: To investigate the safety and immunogenicity of boosting BCG with modified vaccinia Ankara expressing antigen 85A (MVA85A), shortly after BCG vaccination, and to compare this first with the immunogenicity of BCG vaccination alone and second with a previous clinical trial where MVA85A was administered more than 10 years after BCG vaccination. DESIGN: There are two clinical trials reported here: a Phase I observational trial with MVA85A; and a Phase IV observational trial with BCG. These clinical trials were all conducted in the UK in healthy, HIV negative, BCG naïve adults. Subjects were vaccinated with BCG alone; or BCG and then subsequently boosted with MVA85A four weeks later (short interval). The outcome measures, safety and immunogenicity, were monitored for six months. The immunogenicity results from this short interval BCG prime-MVA85A boost trial were compared first with the BCG alone trial and second with a previous clinical trial where MVA85A vaccination was administered many years after vaccination with BCG. RESULTS: MVA85A was safe and highly immunogenic when administered to subjects who had recently received BCG vaccination. When the short interval trial data presented here were compared with the previous long interval trial data, there were no significant differences in the magnitude of immune responses generated when MVA85A was administered shortly after, or many years after BCG vaccination. CONCLUSIONS: The clinical trial data presented here provides further evidence of the ability of MVA85A to boost BCG primed immune responses. This boosting potential is not influenced by the time interval between prior BCG vaccination and boosting with MVA85A. These findings have important implications for the design of efficacy trials with MVA85A. Boosting BCG induced anti-mycobacterial immunity in either infancy or adolescence are both potential applications for this vaccine, given the immunological data presented here. TRIAL REGISTRATION: ClinicalTrials.gov NCT00427453 (short boosting interval), NCT00427830 (long boosting interval), NCT00480714 (BCG alone).

Ibanga HB, Brookes RH, Hill PC, Owiafe PK, Fletcher HA, Lienhardt C, Hill AV, Adegbola RA, McShane H. 2006. Early clinical trials with a new tuberculosis vaccine, MVA85A, in tuberculosis-endemic countries: issues in study design. Lancet Infect Dis, 6 (8), pp. 522-528. | Show Abstract | Read more

Tuberculosis remains a substantial global health problem despite effective drug treatments. The efficacy of BCG, the only available vaccine, is variable, especially in tuberculosis-endemic regions. Recent advances in the development of new vaccines against tuberculosis mean that the first of these are now entering into early clinical trials. A recombinant modified vaccinia virus Ankara expressing a major secreted antigen from Mycobacterium tuberculosis, antigen 85A, was the first new tuberculosis vaccine to enter into clinical trials in September 2002. This vaccine is known as MVA85A. In a series of phase I clinical trials in the UK, MVA85A had an excellent safety profile and was highly immunogenic. MVA85A was subsequently evaluated in a series of phase I trials in The Gambia, a tuberculosis-endemic area in west Africa. This vaccine is the only new subunit tuberculosis vaccine to enter into clinical trials in Africa to date. Here, we discuss some of the issues that were considered in the protocol design of these studies including recruitment, inclusion and exclusion criteria, reimbursement of study participants, and HIV testing. These issues are highly relevant to early clinical trials with all new tuberculosis vaccines in the developing world.

Gilbert SC, Moorthy VS, Andrews L, Pathan AA, McConkey SJ, Vuola JM, Keating SM, Berthoud T, Webster D, McShane H, Hill AV. 2006. Synergistic DNA-MVA prime-boost vaccination regimes for malaria and tuberculosis. Vaccine, 24 (21), pp. 4554-4561. | Show Abstract | Read more

T-cell-mediated responses against the liver-stage of Plasmodium falciparum are critical for protection in the human irradiated sporozoite model and several animal models. Heterologous prime-boost approaches, employing plasmid DNA and viral vector delivery of malarial DNA sequences, have proved particularly promising for maximising T-cell-mediated protection in animal models. The T-cell responses induced by this prime-boost regime, in animals and humans, are substantially greater than the sum of the responses induced by DNA or MVA vaccines used alone, leading to the term introduced here of "synergistic" prime-boost immunisation. The insert in our first generation clinical constructs is known as multiple epitope-thrombospondin-related adhesion protein (ME-TRAP). We have performed an extensive series of phase I/II trials evaluating various prime-boost combination regimens for delivery of ME-TRAP in over 500 malaria-naïve and malaria-exposed individuals. The three delivery vectors are DNA, modified vaccinia virus Ankara (MVA) and, more recently, fowlpox strain 9 (FP9). Administration was intra-epidermal and intramuscular for DNA and intradermal for MVA and FP9. Doses of DNA ranged from 4 microg to 2mg. Doses of MVA were up to 1.5 x 10(8) plaque forming units (pfu) and of FP9, up to 1.0 x 10(8)pfu. Further trials employing bacille Calmette-Guérin (BCG) as the priming agent and MVA expressing antigen 85A of Mycobacterium tuberculosis as the boosting agent has extended the scope of synergistic prime-boost vaccination. In this review we summarise the safety, immunogenicity and efficacy results from these malaria and tuberculosis vaccine clinical trials.

Fletcher H, McShane H. 2006. Tuberculosis vaccines: current status and future prospects. Expert Opin Emerg Drugs, 11 (2), pp. 207-215. | Show Abstract | Read more

There is an urgent need to develop more effective tuberculosis vaccines as chemotherapy and Bacille Calmette-Guérin (BCG) have failed to control the current epidemic. BCG does have some protective effect in childhood, so using a second vaccine to boost BCG would be the most ethical and logistically feasible strategy. The cost of tuberculosis efficacy trials will be high and return on investment into the development of a tuberculosis vaccine will be low. Incentives such as orphan drug status could encourage industrial interest. As more vaccines enter into early clinical trials, there is an urgent need for the identification of correlates of protection to aid decisions about which vaccines should go forward into efficacy testing. Research efforts that focus on reducing the cost and risk of conducting clinical trials will be of direct benefit to tuberculosis vaccine development.

Sutherland R, Yang H, Scriba TJ, Ondondo B, Robinson N, Conlon C, Suttill A, McShane H, Fidler S, McMichael A, Dorrell L. 2006. Impaired IFN-gamma-secreting capacity in mycobacterial antigen-specific CD4 T cells during chronic HIV-1 infection despite long-term HAART. AIDS, 20 (6), pp. 821-829. | Show Abstract | Read more

OBJECTIVE: To determine whether long-term HAART in chronic HIV-1 infection restores fully functional Mycobacterium tuberculosis (MTB)-specific CD4 T-cell responses. DESIGN: A cross-sectional study of HIV-1-seropositive subjects on continuous HAART for over one year with CD4 cell counts greater than 300 cells/microl and undetectable viraemia, antiretroviral-naive individuals with primary HIV-1 infection (PHI), and healthy bacillus Calmette-Guérin-vaccinated low-risk controls. METHODS: Purified protein derivative (PPD)-specific cytokine-secreting CD4 T cells were quantified ex vivo by enzyme-linked immunospot assay and intracellular cytokine staining. Lymphoproliferation was detected by [3H]-thymidine incorporation. RESULTS: PPD-specific IFN-gamma-secreting CD4 T cells were markedly reduced in chronic HAART-treated HIV-1-positive and PHI subjects compared with healthy controls [medians 30, 155 and 582 spot-forming cells/million peripheral blood mononuclear cells (PBMC), respectively, P < 0.0001 and P < 0.002], but the frequency of these cells was, nonetheless, significantly greater in viraemic PHI subjects than in aviraemic chronic HIV-1-positive subjects (P < 0.01). In the latter, low frequencies of PPD-specific IL-2 and IL-4-secreting CD4 T cells were also observed. However, lymphoproliferation was evident after the in-vitro stimulation of PBMC with PPD, indicating that MTB-specific T cells were present. The defect in IFN-gamma secretion could be overcome by culture with IL-12. CONCLUSION: Despite an improvement in CD4 T-cell counts after HAART, MTB-specific CD4 T cells from chronically infected patients have impaired IFN-gamma-secreting capacity. The early initiation of HAART might preserve functional CD4 T-cell responses to MTB, and warrants evaluation in populations with a high risk of dual infection.

Cebere I, Dorrell L, McShane H, Simmons A, McCormack S, Schmidt C, Smith C, Brooks M et al. 2006. Phase I clinical trial safety of DNA- and modified virus Ankara-vectored human immunodeficiency virus type 1 (HIV-1) vaccines administered alone and in a prime-boost regime to healthy HIV-1-uninfected volunteers. Vaccine, 24 (4), pp. 417-425. | Show Abstract | Read more

DNA- and modified virus Ankara (MVA)-vectored candidate vaccines expressing human immunodeficiency virus type 1 (HIV-1) clade A-derived p24/p17 gag fused to a string of HLA class I epitopes, called HIVA, were tested in phase I trials in healthy, HIV-1/2-uninfected adults in Oxford, United Kingdom. Eighteen volunteers were vaccinated with pTHr.HIVA DNA (IAVI-001) alone, 8 volunteers received MVA.HIVA (IAVI-003) alone and 9 volunteers from study IAVI-001 were boosted with MVA.HIVA 9-14 months after DNA priming (IAVI-005). Immunogenicity results observed in these trials was published previously [Mwau M, Cebere I, Sutton J, Chikoti P, Winstone N, Wee EG-T, et al. An HIV-1 clade A vaccine in clinical trials: stimulation of HIV-specific T cell responses by DNA and recombinant modified vaccinia virus Ankara (MVA) vaccines in humans. J Gen Virol 2004;85:911-9]. Here, we report on the safety of the two vaccines and the vaccine regimes. Overall, both candidate vaccines were safe and well tolerated. There were no reported vaccine-related adverse events over the 6-month period of the study and up to 2 years after the last vaccination. There were no moderate or severe local symptoms recorded after the pTHr.HIVA DNA intramuscular administration. Almost all participants experienced local reactogenicity events such as redness and induration after MVA.HIVA intradermal injection. Thus, the results from these initial small phase I trials administering the pTHr.HIVA DNA and MVA.HIVA vaccines either alone or in a prime-boost regime to healthy HIV-1/2-negative adults indicated that the vaccines were safe and warranted further testing of this approach in larger phase I/II studies.

Lang T, Hill AV, McShane H, Shah R, Towse A, Pritchard C, Garau M. 2005. New TB vaccine granted orphan drug status. BMJ, 331 (7530), pp. 1476. | Read more

Williams A, Goonetilleke NP, McShane H, Clark SO, Hatch G, Gilbert SC, Hill AV. 2005. Boosting with poxviruses enhances Mycobacterium bovis BCG efficacy against tuberculosis in guinea pigs. Infect Immun, 73 (6), pp. 3814-3816. | Show Abstract | Read more

Tuberculosis is rising in the developing world due to poor health care, human immunodeficiency virus type 1 infection, and the low protective efficacy of the Mycobacterium bovis BCG vaccine. A new vaccination strategy that could protect adults in the developing world from tuberculosis could have a huge impact on public health. We show that BCG boosted by poxviruses expressing antigen 85A induced unprecedented 100% protection of guinea pigs from high-dose aerosol challenge with Mycobacterium tuberculosis, suggesting a strategy for enhancing and prolonging the efficacy of BCG.

McShane H, Hill A. 2005. Prime-boost immunisation strategies for tuberculosis. Microbes Infect, 7 (5-6), pp. 962-967. | Show Abstract | Read more

Vaccines against intracellular pathogens such as Mycobacterium tuberculosis need to induce strong cellular immune responses. Heterologous prime-boost immunisation strategies induce higher levels of both CD4+ and CD8+ T cells than homologous boosting with the same vector. Recombinant pox-viruses are particularly good at boosting previously primed T cell responses. Using BCG as the priming immunisation in such a heterologous prime-boost strategy is a practical solution, which allows the beneficial effects of BCG in children to be maintained.

McShane H. 2005. Co-infection with HIV and TB: double trouble. Int J STD AIDS, 16 (2), pp. 95-100. | Show Abstract | Read more

Co-infection with HIV and Mycobacterium tuberculosis is common, particularly in the developing world. Tuberculosis (TB) is the commonest co-infection in HIV-positive individuals, who are at increased risk of both reactivation of latent infection and acquisition of new infection. As the degree of immunosuppression increases, the risks of developing TB disease also increase. The patho-physiology, clinical picture, differential diagnosis and diagnostic tests are discussed, together with the interactions between antiretroviral therapy and anti-tuberculous chemotherapy. Indications for chemoprophylaxis and vaccination against TB are reviewed.

McShane H, Pathan AA, Sander CR, Goonetilleke NP, Fletcher HA, Hill AV. 2005. Boosting BCG with MVA85A: the first candidate subunit vaccine for tuberculosis in clinical trials. Tuberculosis (Edinb), 85 (1-2), pp. 47-52. | Show Abstract | Read more

There is an urgent need for an improved vaccine against tuberculosis. Heterologous prime-boost immunization regimes induce higher levels of cellular immunity than homologous boosting with the same vaccine. Using BCG as the priming immunization in such a regime allows for the retention of the beneficial protective effects of BCG against disseminated disease in childhood. Recombinant poxviruses are powerful boosting agents, for both CD4+ and CD8+ T cells. Here we review the preclinical data from a BCG prime-recombinant modified vaccinia virus Ankara expressing antigen 85A (MVA85A) boost strategy. MVA85A is now in clinical trials in the UK and Africa and the design of these trials, including the ethical and regulatory issues are discussed.

Williams A, Hatch GJ, Clark SO, Gooch KE, Hatch KA, Hall GA, Huygen K, Ottenhoff TH et al. 2005. Evaluation of vaccines in the EU TB Vaccine Cluster using a guinea pig aerosol infection model of tuberculosis. Tuberculosis (Edinb), 85 (1-2), pp. 29-38. | Show Abstract | Read more

The TB Vaccine Cluster project funded by the EU Fifth Framework programme aims to provide novel vaccines against tuberculosis that are suitable for evaluation in humans. This paper describes the studies of the protective efficacy of vaccines in a guinea pig aerosol-infection model of primary tuberculosis. The objective was to conduct comparative evaluations of vaccines that had previously demonstrated efficacy in other animal models. Groups of 6 guinea pigs were immunized with vaccines provided by the relevant EU Vaccine Cluster partners. Survival over 17 or 26 weeks was used as the principal measure of vaccine efficacy following aerosol challenge with H37Rv. Counts of mycobacteria in lungs and spleens, and histopathological changes in the lungs, were also used to provide evidence of protection. A total of 24 vaccines were evaluated in 4 experiments each of a different design. A heterologous prime-boost strategy of DNA and MVA, each expressing Ag85A and a fusion protein of ESAT-6 and Ag85B in adjuvant, protected the guinea pigs to the same extent as BCG. Genetically modified BCG vaccines and boosted BCG strategies also protected guinea pigs to the same extent as BCG but not statistically significantly better. A relatively high aerosol-challenge dose and evaluation over a protracted time post-challenge allowed superior protection over BCG to be demonstrated by BCG boosted with MVA and fowl pox vectors expressing Ag85A.

McShane H, Pathan AA, Sander CR, Keating SM, Gilbert SC, Huygen K, Fletcher HA, Hill AV. 2004. Recombinant modified vaccinia virus Ankara expressing antigen 85A boosts BCG-primed and naturally acquired antimycobacterial immunity in humans. Nat Med, 10 (11), pp. 1240-1244. | Show Abstract | Read more

Protective immunity against Mycobacterium tuberculosis depends on the generation of a T(H)1-type cellular immune response, characterized by the secretion of interferon-gamma (IFN-gamma) from antigen-specific T cells. The induction of potent cellular immune responses by vaccination in humans has proven difficult. Recombinant viral vectors, especially poxviruses and adenoviruses, are particularly effective at boosting previously primed CD4(+) and CD8(+) T-cell responses against a number of intracellular pathogens in animal studies. In the first phase 1 study of any candidate subunit vaccine against tuberculosis, recombinant modified vaccinia virus Ankara (MVA) expressing antigen 85A (MVA85A) was found to induce high levels of antigen-specific IFN-gamma-secreting T cells when used alone in bacille Calmette-Guerin (BCG)-naive healthy volunteers. In volunteers who had been vaccinated 0.5-38 years previously with BCG, substantially higher levels of antigen-specific IFN-gamma-secreting T cells were induced, and at 24 weeks after vaccination these levels were 5-30 times greater than in vaccinees administered a single BCG vaccination. Boosting vaccinations with MVA85A could offer a practical and efficient strategy for enhancing and prolonging antimycobacterial immunity in tuberculosis-endemic areas.

Ayuk PT, Dudley S, McShane H, Rees M, Mackenzie IZ. 2004. Efficacy of follow-up and contact tracing of women who test positive for genital tract chlamydia trachomatis prior to pregnancy termination. J Obstet Gynaecol, 24 (6), pp. 687-689. | Show Abstract | Read more

We examined the efficacy of follow-up, contact tracing and the need for retreatment in women who were screen-positive for genital tract Chlamydia trachomatis prior to termination of pregnancy. Eighty-six of 1363 (6.3%) women screened positive. These women were significantly younger than those who screened negative (P < 0.0001). The genitourinary medicine (GUM) clinic was notified of 73 (84.9%) screen-positive women and 41 (47.7%) attended for follow-up. Contact tracing was undertaken in 38 (92.7%) women who attended and 29 (70.7%) women who attended required retreatment for Chlamydia. The median duration between pregnancy termination and GUM clinic attendance was significantly longer in women who required retreatment compared to those who did not require retreatment (P = 0.003). In conclusion, follow-up and contact-tracing of women who screen positive for genital tract C. trachomatis was incomplete. This may substantially compromise the cost-effectiveness of a screen-and-treat programme.

McShane H. 2004. Developing an improved vaccine against tuberculosis. Expert Rev Vaccines, 3 (3), pp. 299-306. | Show Abstract | Read more

Despite the availability of a vaccine for over 80 years, the tuberculosis epidemic continues to be a major cause of mortality and morbidity throughout the world. The factors contributing to the resurgence of tuberculosis and the possible explanations for the failure of the current vaccine, bacille Calmette-Guérin, are discussed. The nature of protective immunity to Mycobacterium tuberculosis and how this relates to the development of new candidate vaccines is then considered. The issues surrounding the progression of the most promising candidates into Phase I clinical trials are also discussed.

Mwau M, Cebere I, Sutton J, Chikoti P, Winstone N, Wee EG, Beattie T, Chen YH et al. 2004. A human immunodeficiency virus 1 (HIV-1) clade A vaccine in clinical trials: stimulation of HIV-specific T-cell responses by DNA and recombinant modified vaccinia virus Ankara (MVA) vaccines in humans. J Gen Virol, 85 (Pt 4), pp. 911-919. | Show Abstract | Read more

The immunogenicities of candidate DNA- and modified vaccinia virus Ankara (MVA)-vectored human immunodeficiency virus (HIV) vaccines were evaluated on their own and in a prime-boost regimen in phase I clinical trials in healthy uninfected individuals in the United Kingdom. Given the current lack of approaches capable of inducing broad HIV-neutralizing antibodies, the pTHr.HIVA DNA and MVA.HIVA vaccines focus solely on the induction of cell-mediated immunity. The vaccines expressed a common immunogen, HIVA, which consists of consensus HIV-1 clade A Gag p24/p17 proteins fused to a string of clade A-derived epitopes recognized by cytotoxic T lymphocytes (CTLs). Volunteers' fresh peripheral blood mononuclear cells were tested for HIV-specific responses in a validated gamma interferon enzyme-linked immunospot (ELISPOT) assay using four overlapping peptide pools across the Gag domain and three pools of known CTL epitopes present in all of the HIVA protein. Both the DNA and the MVA vaccines alone and in a DNA prime-MVA boost combination were safe and induced HIV-specific responses in 14 out of 18, seven out of eight and eight out of nine volunteers, respectively. These results are very encouraging and justify further vaccine development.

Brookes RH, Pathan AA, McShane H, Hensmann M, Price DA, Hill AV. 2003. CD8+ T cell-mediated suppression of intracellular Mycobacterium tuberculosis growth in activated human macrophages. Eur J Immunol, 33 (12), pp. 3293-3302. | Show Abstract | Read more

Animal models of tuberculosis point to a protective role for MHC class I-restricted CD8(+) T cells, yet it is unclear how these cells protect or whether such findings extend to humans. Here we report that macrophages infected with Mycobacterium tuberculosis, rapidly process and present an early secreted antigenic target (ESAT-6)-specific HLA class I-restricted CD8(+) T cell epitope. When cocultured with CD8(+) T cells restricted through classical HLA class I molecules the growth of bacilli within macrophages is significantly impaired after 7 days. This slow antimycobacterial activity did not correlate with macrophage lysis but required cell contact. We also found that inhibitors of apoptosis either had no effect or augmented the CD8-mediated suppressive activity, suggesting that an activation signal might be involved. Indeed we show that CD8(+) T cells were able to activate macrophages through receptors that include CD95 (Fas). Consistent with these findings the CD8-mediated suppression of mycobacterial growth was partially reversed by Fas blockade. These data identify a previously unrecognized CD8(+) T cell-mediated mechanism used to control an intracellular infection of macrophages.

Goonetilleke NP, McShane H, Hannan CM, Anderson RJ, Brookes RH, Hill AV. 2003. Enhanced immunogenicity and protective efficacy against Mycobacterium tuberculosis of bacille Calmette-Guérin vaccine using mucosal administration and boosting with a recombinant modified vaccinia virus Ankara. J Immunol, 171 (3), pp. 1602-1609. | Show Abstract

Heterologous prime-boost immunization strategies can evoke powerful T cell immune responses and may be of value in developing an improved tuberculosis vaccine. We show that recombinant modified vaccinia virus Ankara, expressing Mycobacterium tuberculosis Ag 85A (M.85A), strongly boosts bacille Calmette-Guérin (BCG)-induced Ag 85A specific CD4(+) and CD8(+) T cell responses in mice. A comparison of intranasal (i.n.) and parenteral immunization of BCG showed that while both routes elicited comparable T cell responses in the spleen, only i.n. delivery elicited specific T cell responses in the lung lymph nodes, and these responses were further boosted by i.n. delivery of M.85A. Following aerosol challenge with M. tuberculosis, i.n. boosting of BCG with either BCG or M.85A afforded unprecedented levels of protection in both the lungs (2.5 log) and spleens (1.5 log) compared with naive controls. Protection in the lung correlated with the induction of Ag 85A-specific, IFN-gamma-secreting T cells in lung lymph nodes. These findings support further evaluation of mucosally targeted prime-boost vaccination approaches for tuberculosis.

McShane H. 2003. Susceptibility to tuberculosis--the importance of the pathogen as well as the host. Clin Exp Immunol, 133 (1), pp. 20-21. | Read more

McShane H, Behboudi S, Goonetilleke N, Brookes R, Hill AV. 2002. Protective immunity against Mycobacterium tuberculosis induced by dendritic cells pulsed with both CD8(+)- and CD4(+)-T-cell epitopes from antigen 85A. Infect Immun, 70 (3), pp. 1623-1626. | Show Abstract | Read more

Immunization with DNA followed by modified vaccinia virus Ankara strain, both expressing the antigen 85A, induced both CD4(+)- and CD8(+)-T-cell responses in BALB/c mice. Following challenge with Mycobacterium tuberculosis, this prime-boost regimen produced protection equivalent to that conferred by Mycobacterium bovis BCG. Following immunization with dendritic cells pulsed with an antigen 85A CD4(+)- or CD8(+)-restricted epitope, alone or in combination, copresentation of both epitopes on the same dendritic cell was required for protection, demonstrating that induced CD8(+) T cells can play a protective role against tuberculosis.

McShane H. 2002. Prime-boost immunization strategies for infectious diseases. Curr Opin Mol Ther, 4 (1), pp. 23-27. | Show Abstract

New vaccination strategies that induce the cellular arm of the immune response are needed for the development of effective prophylactic and therapeutic vaccines against a number of intracellular pathogens. DNA vaccines, recombinant viral vectors and recombinant proteins are all effective antigen delivery systems for inducing cellular immunity; however, when used alone, the levels of specific responses they induce are low. Prime-boost immunization strategies involve using two different vaccines, each encoding the same antigen, some weeks apart. Such strategies have been shown to enhance cellular immunity in several different animal and disease models.

Pathan AA, Wilkinson KA, Klenerman P, McShane H, Davidson RN, Pasvol G, Hill AV, Lalvani A. 2001. Direct ex vivo analysis of antigen-specific IFN-gamma-secreting CD4 T cells in Mycobacterium tuberculosis-infected individuals: associations with clinical disease state and effect of treatment. J Immunol, 167 (9), pp. 5217-5225. | Show Abstract

The wide spectrum of clinical outcomes following infection with Mycobacterium tuberculosis is largely determined by the host immune response; therefore, we studied several clinically defined groups of individuals (n = 120) that differ in their ability to contain the bacillus. To quantitate M. tuberculosis-specific T cells directly ex vivo, we enumerated IFN-gamma-secreting CD4 T cells specific for ESAT-6, a secreted Ag that is highly specific for M. tuberculosis, and a target of protective immune responses in animal models. We found that frequencies of circulating ESAT-6 peptide-specific IFN-gamma-secreting CD4 T cells were higher in latently infected healthy contacts and subjects with minimal disease and low bacterial burdens than in patients with culture-positive active pulmonary tuberculosis (p = 0.009 and p = 0.002, respectively). Importantly, the frequency of these Ag-specific CD4 T cells fell progressively in all groups with treatment (p = 0.005), suggesting that the lower responses in patients with more extensive disease were not due to tuberculosis-induced immune suppression. This population of M. tuberculosis Ag-specific Th1-type CD4 T cells appears to correlate with clinical phenotype and declines during successful therapy; these features are consistent with a role for these T cells in the containment of M. tuberculosis in vivo. Such findings may assist in the design and evaluation of novel tuberculosis vaccine candidates.

Lalvani A, Pathan AA, McShane H, Wilkinson RJ, Latif M, Conlon CP, Pasvol G, Hill AV. 2001. Rapid detection of Mycobacterium tuberculosis infection by enumeration of antigen-specific T cells. Am J Respir Crit Care Med, 163 (4), pp. 824-828. | Show Abstract | Read more

There is no reliable means of detecting latent M. tuberculosis infection, and even in patients with active tuberculosis, infection is often unconfirmed. We hypothesized that M. tuberculosis antigen-specific T cells might reliably indicate infection. We enumerated peripheral blood-derived interferon gamma (IFN-gamma)-secreting T cells responding to epitopes from ESAT-6, an antigen that is highly specific for M. tuberculosis complex but absent from BCG, in four groups of individuals. Forty-five of 47 patients with bacteriologically confirmed tuberculosis had ESAT-6-specific IFN-gamma-secreting T cells, compared with four of 47 patients with nontuberculous illnesses, indicating that these T cells are an accurate marker of M. tuberculosis infection. This assay thus has a sensitivity of 96% (95% confidence interval [CI] 92-100) for detecting M. tuberculosis infection in this patient population. By comparison, of the 26 patients with tuberculosis who had a diagnostic tuberculin skin test (TST), only 18 (69%) were positive (p = 0.003). In addition, 22 of 26 (85%) TST-positive exposed household contacts had ESAT-6-specific T cells, whereas zero of 26 unexposed BCG-vaccinated subjects responded. This approach enables rapid detection of M. tuberculosis infection in patients with active tuberculosis and in exposed asymptomatic individuals at high risk of latent infection; it also successfully distinguishes between M. tuberculosis infection and BCG vaccination. This capability may facilitate tuberculosis control in nonendemic regions.

McShane H, Brookes R, Gilbert SC, Hill AV. 2001. Enhanced immunogenicity of CD4(+) t-cell responses and protective efficacy of a DNA-modified vaccinia virus Ankara prime-boost vaccination regimen for murine tuberculosis. Infect Immun, 69 (2), pp. 681-686. | Show Abstract | Read more

DNA vaccines whose DNA encodes a variety of antigens from Mycobacterium tuberculosis have been evaluated for immunogenicity and protective efficacy. CD8(+) T-cell responses and protection achieved in other infectious disease models have been optimized by using a DNA immunization to prime the immune system and a recombinant virus encoding the same antigen(s) to boost the response. A DNA vaccine (D) and recombinant modified vaccinia virus Ankara (M) in which the DNA encodes early secreted antigenic target 6 and mycobacterial protein tuberculosis 63 synthesized, and each was found to generate specific gamma interferon (IFN-gamma)-secreting CD4(+) T cells. Enhanced CD4(+) IFN-gamma T-cell responses were produced by both D-M and M-D immunization regimens. Significantly higher levels of IFN-gamma were seen with a D-D-D-M immunization regimen. The most immunogenic regimens were assessed in a challenge study and found to produce protection equivalent to that produced by Mycobacterium bovis BCG. Thus, heterologous prime-boost regimens boost CD4(+) as well as CD8(+) T-cell responses, and the use of heterologous constructs encoding the same antigen(s) may improve the immunogenicity and protective efficacy of DNA vaccines against tuberculosis and other diseases.

Pathan AA, Wilkinson KA, Wilkinson RJ, Latif M, McShane H, Pasvol G, Hill AV, Lalvani A. 2000. High frequencies of circulating IFN-gamma-secreting CD8 cytotoxic T cells specific for a novel MHC class I-restricted Mycobacterium tuberculosis epitope in M. tuberculosis-infected subjects without disease. Eur J Immunol, 30 (9), pp. 2713-2721. | Show Abstract | Read more

MHC class I-restricted CD8 cytotoxic T lymphocytes (CTL) are essential for protective immunity to Mycobacterium tuberculosis in animal models but their role in humans remains unclear. We therefore studied subjects who had successfully contained M. tuberculosis infection in vivo, i.e. exposed healthy household contacts and individuals with inactive self-healed pulmonary tuberculosis. Using the ELISPOT assay for IFN-gamma, we screened peptides from ESAT-6, a secreted antigen that is highly specific for M. tuberculosis. We identified a novel nonamer epitope: unstimulated peripheral blood-derived CD8 T cells displayed peptide-specific IFN-gamma release ex vivo while CD8 T cell lines and clones exhibited HLA-A68.02-restricted cytolytic activity and recognized endogenously processed antigen. The frequency of CD8 CTL specific for this single M. tuberculosis epitope, 1/2500 peripheral blood lymphocytes, was equivalent to the combined frequency of all IFN-gamma-secreting purified protein derivative-reactive T cells ex vivo. This highly focused CTL response was maintained in an asymptomatic contact over 2 years and is the most potent antigen-specific antimycobacterial CD8 CTL response hitherto described. Thus, human M. tuberculosis-specific CD8 CTL are not necessarily associated with active disease per se. Rather, our results are consistent with a protective role for these ESAT-6-specific CD8 T cells in the long-term control of M. tuberculosis in vivo in humans.

McShane H, Tang CM, Conlon CP. 1998. Disseminated Penicillium marneffei infection presenting as a right upper lobe mass in an HIV positive patient. Thorax, 53 (10), pp. 905-906. | Show Abstract | Read more

A 35 year old HIV positive patient from Hong Kong presented with a fever, cough and a skin rash in association with a lung mass, all of which were due to disseminated Penicillium marneffei infection. He made a good response to antifungal therapy. The lung mass is a previously undescribed pulmonary manifestation of disseminated Penicillium marneffei infection. Infections with this fungus should be suspected in any patient with HIV and respiratory symptoms who has visited southeast Asia.

Tanner R, O'Shea MK, Fletcher HA, McShane H. 2016. In vitro mycobacterial growth inhibition assays: A tool for the assessment of protective immunity and evaluation of tuberculosis vaccine efficacy. Vaccine, 34 (39), pp. 4656-4665. | Show Abstract | Read more

Tuberculosis (TB) continues to pose a serious global health threat, and the current vaccine, BCG, has variable efficacy. However, the development of a more effective vaccine is severely hampered by the lack of an immune correlate of protection. Candidate vaccines are currently evaluated using preclinical animal models, but experiments are long and costly and it is unclear whether the outcomes are predictive of efficacy in humans. Unlike measurements of single immunological parameters, mycobacterial growth inhibition assays (MGIAs) represent an unbiased functional approach which takes into account a range of immune mechanisms and their complex interactions. Such a controlled system offers the potential to evaluate vaccine efficacy and study mediators of protective immunity against Mycobacterium tuberculosis (M.tb). This review discusses the underlying principles and relative merits and limitations of the different published MGIAs, their demonstrated abilities to measure mycobacterial growth inhibition and vaccine efficacy, and what has been learned about the immune mechanisms involved.

Zelmer A, Tanner R, Stylianou E, Damelang T, Morris S, Izzo A, Williams A, Sharpe S et al. 2016. A new tool for tuberculosis vaccine screening: Ex vivo Mycobacterial Growth Inhibition Assay indicates BCG-mediated protection in a murine model of tuberculosis. BMC Infect Dis, 16 (1), pp. 412. | Show Abstract | Read more

BACKGROUND: In the absence of a validated animal model and/or an immune correlate which predict vaccine-mediated protection, large-scale clinical trials are currently the only option to prove efficacy of new tuberculosis candidate vaccines. Tools to facilitate testing of new tuberculosis (TB) vaccines are therefore urgently needed. METHODS: We present here an optimized ex vivo mycobacterial growth inhibition assay (MGIA) using a murine Mycobacterium tuberculosis infection model. This assay assesses the combined ability of host immune cells to inhibit mycobacterial growth in response to vaccination. C57BL/6 mice were immunized with Bacillus Calmette-Guérin (BCG) and growth inhibition of mycobacteria by splenocytes was assessed. Mice were also challenged with Mycobacterium tuberculosis Erdman, and bacterial burden was assessed in lungs and spleen. RESULTS: Using the growth inhibition assay, we find a reduction in BCG CFU of 0.3-0.8 log10 after co-culture with murine splenocytes from BCG vaccinated versus naïve C57BL/6 mice. BCG vaccination in our hands led to a reduction in bacterial burden after challenge with Mycobacterium tuberculosis of approx. 0.7 log10 CFU in lung and approx. 1 log10 CFU in spleen. This effect was also seen when using Mycobacterium smegmatis as the target of growth inhibition. An increase in mycobacterial numbers was found when splenocytes from interferon gamma-deficient mice were used, compared to wild type controls, indicating that immune mechanisms may also be investigated using this assay. CONCLUSIONS: We believe that the ex vivo mycobacterial growth inhibition assay could be a useful tool to help assess vaccine efficacy in future, alongside other established methods. It could also be a valuable tool for determination of underlying immune mechanisms.

McShane H, Hatherill M, Hanekom W, Evans T. 2016. Effects of MVA85A vaccine on tuberculosis challenge in animals: systematic review. Int J Epidemiol, 45 (2), pp. 580. | Read more

Fletcher HA, Snowden MA, Landry B, Rida W, Satti I, Harris SA, Matsumiya M, Tanner R et al. 2016. T-cell activation is an immune correlate of risk in BCG vaccinated infants. Nat Commun, 7 pp. 11290. | Show Abstract | Read more

Vaccines to protect against tuberculosis (TB) are urgently needed. We performed a case-control analysis to identify immune correlates of TB disease risk in Bacille Calmette-Guerin (BCG) immunized infants from the MVA85A efficacy trial. Among 53 TB case infants and 205 matched controls, the frequency of activated HLA-DR(+) CD4(+) T cells associates with increased TB disease risk (OR=1.828, 95% CI=1.25-2.68, P=0.002, FDR=0.04, conditional logistic regression). In an independent study of Mycobacterium tuberculosis-infected adolescents, activated HLA-DR(+) CD4(+) T cells also associate with increased TB disease risk (OR=1.387, 95% CI=1.068-1.801, P=0.014, conditional logistic regression). In infants, BCG-specific T cells secreting IFN-γ associate with reduced risk of TB (OR=0.502, 95% CI=0.29-0.86, P=0.013, FDR=0.14). The causes and impact of T-cell activation on disease risk should be considered when designing and testing TB vaccine candidates for these populations.

Chen T, Blanc C, Eder AZ, Prados-Rosales R, Souza AC, Kim RS, Glatman-Freedman A, Joe M et al. 2016. Association of Human Antibodies to Arabinomannan With Enhanced Mycobacterial Opsonophagocytosis and Intracellular Growth Reduction. J Infect Dis, 214 (2), pp. 300-310. | Show Abstract | Read more

BACKGROUND: The relevance of antibodies (Abs) in the defense against Mycobacterium tuberculosis infection remains uncertain. We investigated the role of Abs to the mycobacterial capsular polysaccharide arabinomannan (AM) and its oligosaccharide (OS) fragments in humans. METHODS: Sera obtained from 29 healthy adults before and after primary or secondary bacillus Calmette-Guerin (BCG) vaccination were assessed for Ab responses to AM via enzyme-linked immunosorbent assays, and to AM OS epitopes via novel glycan microarrays. Effects of prevaccination and postvaccination sera on BCG phagocytosis and intracellular survival were assessed in human macrophages. RESULTS: Immunoglobulin G (IgG) responses to AM increased significantly 4-8 weeks after vaccination (P < .01), and sera were able to opsonize BCG and M. tuberculosis grown in both the absence and the presence of detergent. Phagocytosis and intracellular growth inhibition were significantly enhanced when BCG was opsonized with postvaccination sera (P < .01), and these enhancements correlated significantly with IgG titers to AM (P < .05), particularly with reactivity to 3 AM OS epitopes (P < .05). Furthermore, increased phagolysosomal fusion was observed with postvaccination sera. CONCLUSIONS: Our results provide further evidence for a role of Ab-mediated immunity to tuberculosis and suggest that IgG to AM, especially to some of its OS epitopes, could contribute to the defense against mycobacterial infection in humans.

Ndiaye BP, Thienemann F, Ota M, Landry BS, Camara M, Dièye S, Dieye TN, Esmail H et al. 2015. Safety, immunogenicity, and efficacy of the candidate tuberculosis vaccine MVA85A in healthy adults infected with HIV-1: a randomised, placebo-controlled, phase 2 trial. Lancet Respir Med, 3 (3), pp. 190-200. | Show Abstract | Read more

BACKGROUND: HIV-1 infection is associated with increased risk of tuberculosis and a safe and effective vaccine would assist control measures. We assessed the safety, immunogenicity, and efficacy of a candidate tuberculosis vaccine, modified vaccinia virus Ankara expressing antigen 85A (MVA85A), in adults infected with HIV-1. METHODS: We did a randomised, double-blind, placebo-controlled, phase 2 trial of MVA85A in adults infected with HIV-1, at two clinical sites, in Cape Town, South Africa and Dakar, Senegal. Eligible participants were aged 18-50 years, had no evidence of active tuberculosis, and had baseline CD4 counts greater than 350 cells per μL if they had never received antiretroviral therapy or greater than 300 cells per μL (and with undetectable viral load before randomisation) if they were receiving antiretroviral therapy; participants with latent tuberculosis infection were eligible if they had completed at least 5 months of isoniazid preventive therapy, unless they had completed treatment for tuberculosis disease within 3 years before randomisation. Participants were randomly assigned (1:1) in blocks of four by randomly generated sequence to receive two intradermal injections of either MVA85A or placebo. Randomisation was stratified by antiretroviral therapy status and study site. Participants, nurses, investigators, and laboratory staff were masked to group allocation. The second (booster) injection of MVA85A or placebo was given 6-12 months after the first vaccination. The primary study outcome was safety in all vaccinated participants (the safety analysis population). Safety was assessed throughout the trial as defined in the protocol. Secondary outcomes were immunogenicity and vaccine efficacy against Mycobacterium tuberculosis infection and disease, assessed in the per-protocol population. Immunogenicity was assessed in a subset of participants at day 7 and day 28 after the first and second vaccination, and M tuberculosis infection and disease were assessed at the end of the study. The trial is registered with ClinicalTrials.gov, number NCT01151189. FINDINGS: Between Aug 4, 2011, and April 24, 2013, 650 participants were enrolled and randomly assigned; 649 were included in the safety analysis (324 in the MVA85A group and 325 in the placebo group) and 645 in the per-protocol analysis (320 and 325). 513 (71%) participants had CD4 counts greater than 300 cells per μL and were receiving antiretroviral therapy; 136 (21%) had CD4 counts above 350 cells per μL and had never received antiretroviral therapy. 277 (43%) had received isoniazid prophylaxis before enrolment. Solicited adverse events were more frequent in participants who received MVA85A (288 [89%]) than in those given placebo (235 [72%]). 34 serious adverse events were reported, 17 (5%) in each group. MVA85A induced a significant increase in antigen 85A-specific T-cell response, which peaked 7 days after both vaccinations and was primarily monofunctional. The number of participants with negative QuantiFERON-TB Gold In-Tube findings at baseline who converted to positive by the end of the study was 38 (20%) of 186 in the MVA85A group and 40 (23%) of 173 in the placebo group, for a vaccine efficacy of 11·7% (95% CI -41·3 to 44·9). In the per-protocol population, six (2%) cases of tuberculosis disease occurred in the MVA85A group and nine (3%) occurred in the placebo group, for a vaccine efficacy of 32·8% (95% CI -111·5 to 80·3). INTERPRETATION: MVA85A was well tolerated and immunogenic in adults infected with HIV-1. However, we detected no efficacy against M tuberculosis infection or disease, although the study was underpowered to detect an effect against disease. Potential reasons for the absence of detectable efficacy in this trial include insufficient induction of a vaccine-induced immune response or the wrong type of vaccine-induced immune response, or both. FUNDING: European & Developing Countries Clinical Trials Partnership (IP.2007.32080.002), Aeras, Bill & Melinda Gates Foundation, Wellcome Trust, and Oxford-Emergent Tuberculosis Consortium.

Satti I, Meyer J, Harris SA, Manjaly Thomas ZR, Griffiths K, Antrobus RD, Rowland R, Ramon RL et al. 2014. Safety and immunogenicity of a candidate tuberculosis vaccine MVA85A delivered by aerosol in BCG-vaccinated healthy adults: a phase 1, double-blind, randomised controlled trial. Lancet Infect Dis, 14 (10), pp. 939-946. | Show Abstract | Read more

BACKGROUND: Intradermal MVA85A, a candidate vaccine against tuberculosis, induces high amounts of Ag85A-specific CD4 T cells in adults who have already received the BCG vaccine, but aerosol delivery of this vaccine might offer immunological and logistical advantages. We did a phase 1 double-blind trial to compare the safety and immunogenicity of aerosol-administered and intradermally administered MVA85A METHODS: In this phase 1, double-blind, proof-of-concept trial, 24 eligible BCG-vaccinated healthy UK adults were randomly allocated (1:1) by sequentially numbered, sealed, opaque envelopes into two groups: aerosol MVA85A and intradermal saline placebo or intradermal MVA85A and aerosol saline placebo. Participants, the bronchoscopist, and immunologists were masked to treatment assignment. The primary outcome was safety, assessed by the frequency and severity of vaccine-related local and systemic adverse events. The secondary outcome was immunogenicity assessed with laboratory markers of cell-mediated immunity in blood and bronchoalveolar lavage samples. Safety and immunogenicity were assessed for 24 weeks after vaccination. Immunogenicity to both insert Ag85A and vector modified vaccinia virus Ankara (MVA) was assessed by ex-vivo interferon-γ ELISpot and serum ELISAs. Since all participants were randomised and vaccinated according to protocol, our analyses were per protocol. This trial is registered with ClinicalTrials.gov, number NCT01497769. FINDINGS: Both administration routes were well tolerated and immunogenic. Respiratory adverse events were rare and mild. Intradermal MVA85A was associated with expected mild local injection-site reactions. Systemic adverse events did not differ significantly between the two groups. Three participants in each group had no vaccine-related systemic adverse events; fatigue (11/24 [46%]) and headache (10/24 [42%]) were the most frequently reported symptoms. Ag85A-specific systemic responses were similar across groups. Ag85A-specific CD4 T cells were detected in bronchoalveolar lavage cells from both groups and responses were higher in the aerosol group than in the intradermal group. MVA-specific cellular responses were detected in both groups, whereas serum antibodies to MVA were only detectable after intradermal administration of the vaccine. INTERPRETATION: Further clinical trials assessing the aerosol route of vaccine delivery are merited for tuberculosis and other respiratory pathogens. FUNDING: The Wellcome Trust and Oxford Radcliffe Hospitals Biomedical Research Centre.

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McShane H, Williams A. 2014. A review of preclinical animal models utilised for TB vaccine evaluation in the context of recent human efficacy data Tuberculosis, 94 (2), pp. 105-110. | Show Abstract | Read more

Summary There is an urgent need for an improved TB vaccine. Vaccine development is hindered by the lack of immune correlates and uncertain predictive value of preclinical animal models. As data become available from human efficacy trials, there is an opportunity to evaluate the predictive value of the criteria used to select candidate vaccines. Here we review the efficacy in animal models of the MVA85A candidate vaccine in light of recent human efficacy data and propose refinements to the preclinical models with the aim of increasing their predictive value for human efficacy. © 2013 Elsevier Ltd. All rights reserved.

Scriba TJ, Tameris M, Smit E, van der Merwe L, Hughes EJ, Kadira B, Mauff K, Moyo S et al. 2012. A phase IIa trial of the new tuberculosis vaccine, MVA85A, in HIV- and/or Mycobacterium tuberculosis-infected adults. Am J Respir Crit Care Med, 185 (7), pp. 769-778. | Show Abstract | Read more

RATIONALE: Novel tuberculosis (TB) vaccines should be safe and effective in populations infected with Mycobacterium tuberculosis (M.tb) and/or HIV for effective TB control. OBJECTIVE: To determine the safety and immunogenicity of MVA85A, a novel TB vaccine, among M.tb- and/or HIV-infected persons in a setting where TB and HIV are endemic. METHODS: An open-label, phase IIa trial was conducted in 48 adults with M.tb and/or HIV infection. Safety and immunogenicity were analyzed up to 52 weeks after intradermal vaccination with 5 × 10(7) plaque-forming units of MVA85A. Specific T-cell responses were characterized by IFN-γ enzyme-linked immunospot and whole blood intracellular cytokine staining assays. MEASUREMENTS AND MAIN RESULTS: MVA85A was well tolerated and no vaccine-related serious adverse events were recorded. MVA85A induced robust and durable response of mostly polyfunctional CD4(+) T cells, coexpressing IFN-γ, tumor necrosis factor-α, and IL-2. Magnitudes of pre- and postvaccination T-cell responses were lower in HIV-infected, compared with HIV-uninfected, vaccinees. No significant effect of antiretroviral therapy on immunogenicity of MVA85A was observed. CONCLUSIONS: MVA85A was safe and immunogenic in persons with HIV and/or M.tb infection. These results support further evaluation of safety and efficacy of this vaccine for prevention of TB in these target populations.

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Ota MOC, Odutola AA, Owiafe PK, Donkor S, Owolabi OA, Brittain NJ, Williams N, Rowland-Jones S, Hill AVS, Adegbola RA, McShane H. 2011. Immunogenicity of the Tuberculosis Vaccine MVA85A Is Reduced by Coadministration with EPI Vaccines in a Randomized Controlled Trial in Gambian Infants SCIENCE TRANSLATIONAL MEDICINE, 3 (88), pp. 88ra56-88ra56. | Show Abstract | Read more

New tuberculosis vaccines are urgently needed to curtail the current epidemic. MVA85A is a subunit vaccine that could enhance immunity from BCG vaccination. To determine MVA85A safety and immunogenicity as well as interactions with other routine vaccines administered in infancy, we randomized healthy 4-month-old infants who had received Bacille Calmette-Guérin at birth to receive Expanded Program on Immunization (EPI) vaccines alone, EPI and MVA85A simultaneously, or MVA85A alone. Adverse events were monitored throughout. Blood samples obtained before vaccination and at 1, 4, and 20 weeks after vaccination were used to assess safety and immunogenicity. The safety profile of both low and standard doses was comparable, but the standard dose was more immunogenic and therefore was selected for the second stage of the study. In total, 72 (first stage) and 142 (second stage) infants were enrolled. MVA85A was safe and well tolerated and induced a potent cellular immune response. Coadministration of MVA85A with EPI vaccines was associated with a significant reduction in MVA85A immunogenicity, but did not affect humoral responses to the EPI vaccines. These results provide important information regarding timing of immunizations, which is required for the design of infant efficacy trials with MVA85A, and suggest that modifications to the standard EPI schedule may be required to incorporate a new generation of T cell-inducing vaccines.

Sander CR, Pathan AA, Beveridge NE, Poulton I, Minassian A, Alder N, Van Wijgerden J, Hill AV et al. 2009. Safety and immunogenicity of a new tuberculosis vaccine, MVA85A, in Mycobacterium tuberculosis-infected individuals. Am J Respir Crit Care Med, 179 (8), pp. 724-733. | Show Abstract | Read more

RATIONALE: An effective new tuberculosis (TB) vaccine regimen must be safe in individuals with latent TB infection (LTBI) and is a priority for global health care. OBJECTIVES: To evaluate the safety and immunogenicity of a leading new TB vaccine, recombinant Modified Vaccinia Ankara expressing Antigen 85A (MVA85A) in individuals with LTBI. METHODS: An open-label, phase I trial of MVA85A was performed in 12 subjects with LTBI recruited from TB contact clinics in Oxford and London or by poster advertisements in Oxford hospitals. Patients were assessed clinically and had blood samples drawn for immunological analysis over a 52-week period after vaccination with MVA85A. Thoracic computed tomography scans were performed at baseline and at 10 weeks after vaccination. Safety of MVA85A was assessed by clinical, radiological, and inflammatory markers. The immunogenicity of MVA85A was assessed by IFNgamma and IL-2 ELISpot assays and FACS. MEASUREMENTS AND MAIN RESULTS: MVA85A was safe in subjects with LTBI, with comparable adverse events to previous trials of MVA85A. There were no clinically significant changes in inflammatory markers or thoracic computed tomography scans after vaccination. MVA85A induced a strong antigen-specific IFN-gamma and IL-2 response that was durable for 52 weeks. The magnitude of IFN-gamma response was comparable to previous trials of MVA85A in bacillus Calmette-Guérin-vaccinated individuals. Antigen 85A-specific polyfunctional CD4(+) T cells were detectable prior to vaccination with statistically significant increases in cell numbers after vaccination. CONCLUSIONS: MVA85A is safe and highly immunogenic in individuals with LTBI. These results will facilitate further trials in TB-endemic areas. Clinical trial registered with www.clinicaltrials.gov (NCT00456183).

Verreck FA, Vervenne RA, Kondova I, van Kralingen KW, Remarque EJ, Braskamp G, van der Werff NM, Kersbergen A et al. 2009. MVA.85A boosting of BCG and an attenuated, phoP deficient M. tuberculosis vaccine both show protective efficacy against tuberculosis in rhesus macaques. PLoS One, 4 (4), pp. e5264. | Show Abstract | Read more

BACKGROUND: Continuous high global tuberculosis (TB) mortality rates and variable vaccine efficacy of Mycobacterium bovis Bacille Calmette-Guérin (BCG) motivate the search for better vaccine regimes. Relevant models are required to downselect the most promising vaccines entering clinical efficacy testing and to identify correlates of protection. METHODS AND FINDINGS: Here, we evaluated immunogenicity and protection against Mycobacterium tuberculosis in rhesus monkeys with two novel strategies: BCG boosted by modified vaccinia virus Ankara expressing antigen 85A (MVA.85A), and attenuated M. tuberculosis with a disrupted phoP gene (SO2) as a single-dose vaccine. Both strategies were well tolerated, and immunogenic as evidenced by induction of specific IFNgamma responses. Antigen 85A-specific IFNgamma secretion was specifically increased by MVA.85A boosting. Importantly, both MVA.85A and SO2 treatment significantly reduced pathology and chest X-ray scores upon infectious challenge with M. tuberculosis Erdman strain. MVA.85A and SO2 treatment also showed reduced average lung bacterial counts (1.0 and 1.2 log respectively, compared with 0.4 log for BCG) and significant protective effect by reduction in C-reactive protein levels, body weight loss, and decrease of erythrocyte-associated hematologic parameters (MCV, MCH, Hb, Ht) as markers of inflammatory infection, all relative to non-vaccinated controls. Lymphocyte stimulation revealed Ag85A-induced IFNgamma levels post-infection as the strongest immunocorrelate for protection (spearman's rho: -0.60). CONCLUSIONS: Both the BCG/MVA.85A prime-boost regime and the novel live attenuated, phoP deficient TB vaccine candidate SO2 showed significant protective efficacy by various parameters in rhesus macaques. Considering the phylogenetic relationship between macaque and man and the similarity in manifestations of TB disease, these data support further development of these primary and combination TB vaccine candidates.

Beveridge NE, Fletcher HA, Hughes J, Pathan AA, Scriba TJ, Minassian A, Sander CR, Whelan KT et al. 2008. A comparison of IFNgamma detection methods used in tuberculosis vaccine trials. Tuberculosis (Edinb), 88 (6), pp. 631-640. | Show Abstract | Read more

Interferon gamma (IFNgamma) is a critical component of the pro-inflammatory immune response that provides protection against Mycobacterium tuberculosis. In the absence of an immunological correlate of protection, antigen-specific production of IFNgamma is a commonly used marker of a protective immune response. To facilitate the evaluation of tuberculosis candidate vaccines three different IFNgamma detection methods were compared. The cultured whole blood ELISA, ex vivo IFNgamma ELISpot and whole blood ex vivo intracellular cytokine staining (ICS) assays were performed head-to-head during a Phase I clinical trial using the candidate vaccine MVA85A. Whilst all three assays detected significant increases in IFNgamma production immediately following vaccination, distinctions between the assays were apparent. Higher baseline IFNgamma responses were detected using the cultured whole blood ELISA, whereas the ex vivo ELISpot assay was the most sensitive in detecting long-term (52 weeks) post-vaccination responses. The whole blood ex vivo ICS assay provided novel information by dissecting the IFNgamma response into responding CD4, CD8 and gamma/delta T cell subsets. Future tuberculosis vaccine trials and immunology studies should ideally include a combination of ex vivo and cultured assays to ensure a thorough and multifaceted evaluation of the immune response is achieved.

Fletcher HA, Pathan AA, Berthoud TK, Dunachie SJ, Whelan KT, Alder NC, Sander CR, Hill AV, McShane H. 2008. Boosting BCG vaccination with MVA85A down-regulates the immunoregulatory cytokine TGF-beta1. Vaccine, 26 (41), pp. 5269-5275. | Show Abstract | Read more

In clinical trials recombinant-modified vaccinia virus Ankara expressing the Mycobacterium tuberculosis antigen 85A (MVA85A) induces approximately 10 times more effector T cells than any other recombinant MVA vaccine. We have found that in BCG primed subjects MVA85A vaccination reduces transforming growth factor beta 1 (TGF-beta1) mRNA in peripheral blood lymphocytes and reduces TGF-beta1 protein in the serum, but increases IFN-gamma ELISPOT responses to the recall antigen SK/SD. TGF-beta1 is essential for the generation of regulatory T cells and we see a correlation across vaccinees between CD4+CD25hiFoxP3+ cells and TGF-beta1 serum levels. This apparent ability to counteract regulatory T cell effects suggests a potential use of MVA85A as an adjuvant for less immunogenic vaccines.

Hawkridge T, Scriba TJ, Gelderbloem S, Smit E, Tameris M, Moyo S, Lang T, Veldsman A et al. 2008. Safety and immunogenicity of a new tuberculosis vaccine, MVA85A, in healthy adults in South Africa. J Infect Dis, 198 (4), pp. 544-552. | Show Abstract | Read more

BACKGROUND: The efficacy of bacille Calmette-Guérin (BCG) may be enhanced by heterologous vaccination strategies that boost the BCG-primed immune response. One leading booster vaccine, MVA85A (where "MVA" denotes "modified vaccinia virus Ankara"), has shown promising safety and immunogenicity in human trials performed in the United Kingdom. We investigated the safety and immunogenicity of MVA85A in mycobacteria-exposed--but Mycobacterium tuberculosis-uninfected--healthy adults from a region of South Africa where TB is endemic. METHODS: Twenty-four adults were vaccinated with MVA85A. All subjects were monitored for 1 year for adverse events and for immunological assessment. RESULTS: MVA85A vaccination was well tolerated and induced potent T cell responses, as measured by interferon (IFN)-gamma enzyme-linked immunospot assay, which exceeded prevaccination responses up to 364 days after vaccination. BCG-specific CD4+ T cells boosted by MVA85A were comprised of multiple populations expressing combinations of IFN-gamma, tumor necrosis factor (TNF)-alpha, interleukin (IL)-2, and IL-17, as measured by polychromatic flow cytometry. IFN-gamma-expressing and polyfunctional IFN-gamma+TNF-gamma+IL-2+ CD4+ T cells were boosted during the peak BCG-specific response, which occurred 7 days after vaccination. CONCLUSION: The excellent safety profile and quantitative and qualitative immunogenicity data strongly support further trials assessing the efficacy of MVA85A as a boosting vaccine in countries where TB is endemic. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00460590.

Beveridge NE, Price DA, Casazza JP, Pathan AA, Sander CR, Asher TE, Ambrozak DR, Precopio ML et al. 2007. Immunisation with BCG and recombinant MVA85A induces long-lasting, polyfunctional Mycobacterium tuberculosis-specific CD4+ memory T lymphocyte populations. Eur J Immunol, 37 (11), pp. 3089-3100. | Show Abstract | Read more

In the search for effective vaccines against intracellular pathogens such as HIV, tuberculosis and malaria, recombinant viral vectors are increasingly being used to boost previously primed T cell responses. Published data have shown prime-boost vaccination with BCG-MVA85A (modified vaccinia virus Ankara expressing antigen 85A) to be highly immunogenic in humans as measured by ex vivo IFN-gamma ELISPOT. Here, we used polychromatic flow cytometry to investigate the phenotypic and functional profile of these vaccine-induced Mycobacterium tuberculosis (M.tb) antigen 85A-specific responses in greater detail. Promisingly, antigen 85A-specific CD4(+) T cells were found to be highly polyfunctional, producing IFN-gamma, TNF-alpha, IL-2 and MIP-1beta. Surface staining showed the responding CD4(+) T cells to be relatively immature (CD45RO(+) CD27(int)CD57(-)); this observation was supported by the robust proliferative responses observed following antigenic stimulation. Furthermore, these phenotypic and functional properties were independent of clonotypic composition and epitope specificity, which was maintained through the different phases of the vaccine-induced immune response. Overall, these data strongly support the use of MVA85A in humans as a boosting agent to expand polyfunctional M.tb-specific CD4(+) T cells capable of significant secondary responses.

Ibanga HB, Brookes RH, Hill PC, Owiafe PK, Fletcher HA, Lienhardt C, Hill AV, Adegbola RA, McShane H. 2006. Early clinical trials with a new tuberculosis vaccine, MVA85A, in tuberculosis-endemic countries: issues in study design. Lancet Infect Dis, 6 (8), pp. 522-528. | Show Abstract | Read more

Tuberculosis remains a substantial global health problem despite effective drug treatments. The efficacy of BCG, the only available vaccine, is variable, especially in tuberculosis-endemic regions. Recent advances in the development of new vaccines against tuberculosis mean that the first of these are now entering into early clinical trials. A recombinant modified vaccinia virus Ankara expressing a major secreted antigen from Mycobacterium tuberculosis, antigen 85A, was the first new tuberculosis vaccine to enter into clinical trials in September 2002. This vaccine is known as MVA85A. In a series of phase I clinical trials in the UK, MVA85A had an excellent safety profile and was highly immunogenic. MVA85A was subsequently evaluated in a series of phase I trials in The Gambia, a tuberculosis-endemic area in west Africa. This vaccine is the only new subunit tuberculosis vaccine to enter into clinical trials in Africa to date. Here, we discuss some of the issues that were considered in the protocol design of these studies including recruitment, inclusion and exclusion criteria, reimbursement of study participants, and HIV testing. These issues are highly relevant to early clinical trials with all new tuberculosis vaccines in the developing world.

An immunological understanding of aerosol vaccination for tuberculosis

There is much interest in delivering TB vaccines direct to the respiratory mucosa. Studies in animal models suggest this may be the most effective way to confer protection. We are conducting a series of Phase I clinical trials with BCG and candidate TB vaccines, delivered by aerosol or systemically, to healthy human subjects and subjects with latent M.tuberculosis infection. Blood, PBMC, serum and bronchoalveolar lavage fluid samples are available from these trials, which allow us to determine ...

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Using Mass Spectrometry to identify new antigens for TB vaccines

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), is a successful intracellular pathogen that resides and grows inside macrophages. Infected cells are known to present antigenic peptides through the MHC molecules. These peptides can be recognized by T-cells that mount an adaptive response against the pathogen. We want to explore this biologic process to develop a new generation of subunit TB vaccine candidates to boost the current BCG vaccine.With the aim of discovering new ...

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