The best hope for ending the human immunodeficiency virus (HIV-1) pandemic is the development of a safe and effective vaccine. However, HIV does not lend itself to traditional methods of vaccine development and a deeper understanding of the interplay between the virus and its human host is badly needed at present. This project aims to address this need and is a collaboration between the Iversen group (Human immunology, WIMM) and the Harkiolaki group (Structural Immunology, WTCHG).
The proposed research is the natural successor to our previous studies of HIV evolution and antigen processing of HIV proteins and aims to decipher the functional and structural basis for CTL-responses targeting HLA complexes with naturally processed HIV epitope-peptide forms. In specific, we will analyze CTL-responses to HIV epitopes both in vivo and in vitro and we will aim to produce atomic resolution molecular structures for a range of TCR-peptide-HLA complexes. The comparison of functional and structural data will advance our understanding of HIV-specific CTL responses and will likely contribute towards future vaccine design attempts.
This project is multi-disciplinary in its approach and will provide an opportunity for training in molecular and cellular immunology, virology and structural biology. The successful candidate will benefit from the state-of-the-art infrastructure and extensive scientific expertise of the MRC Human Immunology Unit, the Medawar and the Division of Structural Biology.
Students will acquire skills in molecular DNA and RNA techniques, flow cytometry, surface Plasmon resonance, recombinant protein production in both prokaryotic and eukaryotic systems, protein purification, cell culture and HLA-peptide refolding, crystallization and structure determination and analysis.
Immunology & Infectious Disease
Project reference number: 279
| Name | Department | Institution | Country | |
|---|---|---|---|---|
| Dr Astrid Iversen | Experimental Medicine Division | Oxford University | UK | astrid.iversen@imm.ox.ac.uk |
| Dr Maria Harkiolaki | Structural Biology | Oxford University | UK | maria@strubi.ox.ac.uk |
2006. Conflicting selective forces affect T cell receptor contacts in an immunodominant human immunodeficiency virus epitope. Nat. Immunol., 7 (2), pp. 179-89. Read abstract | Read more
Cytotoxic T lymphocytes (CTLs) are critical for the control of human immunodeficiency virus, but containment of virus replication can be undermined by mutations in CTL epitopes that lead to virus escape. We analyzed the evolution in vivo of an immunodominant, HLA-A2-restricted CTL epitope and found two principal, diametrically opposed evolutionary pathways that exclusively affect T cell-receptor contact residues. One pathway was characterized by acquisition of CTL escape mutations and the other by selection for wild-type amino acids. The pattern of CTL responses to epitope variants shaped which variant(s) prevailed in the virus population. The pathways notably influenced the amount of plasma virus, as patients with efficient CTL selection had lower plasma viral loads than did patients without efficient selection. Thus, viral escape from CTL responses does not necessarily correlate with disease progression. Hide abstract
2009. Antigen processing influences HIV-specific cytotoxic T lymphocyte immunodominance. Nat. Immunol., 10 (6), pp. 636-46. Read abstract | Read more
Although cytotoxic T lymphocytes (CTLs) in people infected with human immunodeficiency virus type 1 can potentially target multiple virus epitopes, the same few are recognized repeatedly. We show here that CTL immunodominance in regions of the human immunodeficiency virus type 1 group-associated antigen proteins p17 and p24 correlated with epitope abundance, which was strongly influenced by proteasomal digestion profiles, affinity for the transporter protein TAP, and trimming mediated by the endoplasmatic reticulum aminopeptidase ERAAP, and was moderately influenced by HLA affinity. Structural and functional analyses demonstrated that proteasomal cleavage 'preferences' modulated the number and length of epitope-containing peptides, thereby affecting the response avidity and clonality of T cells. Cleavage patterns were affected by both flanking and intraepitope CTL-escape mutations. Our analyses show that antigen processing shapes CTL response hierarchies and that viral evolution modifies cleavage patterns and suggest strategies for in vitro vaccine optimization. Hide abstract