Influenza vaccines have long been the first line of defence against flu, but they come with a significant challenge. These vaccines are designed to target specific strains of the virus, which change rapidly each year. As new variant strains emerge, the protection offered by these vaccines quickly diminishes, necessitating annual updates and making it harder to combat potential epidemic or pandemic threats.
Scientists are therefore on a mission to create influenza vaccines that could protect against multiple strains, eliminating the need for annual updates.
Rather than focusing solely on antibodies - proteins that help the immune system fight off infections – the approach taken by the Pandemic Sciences Institute and the Pirbright Institute scientists aims to activate T-cells, a different part of the immune system that can recognise and respond to a variety of flu viruses. Additionally, the team explored the use of aerosol vaccines, delivered directly to the respiratory tract, a powerful way to stimulate our immune response.
In the study, the researchers immunised pigs pre-exposed to pH1N1 using aerosolised viral vectored vaccines (ChAdOx2 and MVA) that express the influenza matrix protein (M1) and nucleoprotein (NP). The results showed T-cell responses induced through aerosol immunisation can offer significant protection.
The pig model is particularly valuable in influenza research as pigs are large natural hosts for influenza A viruses and share many physiological and immunological similarities with humans.
Professor Elma Tchlian, head of Pirbright’s Mucosal Immunology Group, said 'This study shows the importance of targeting the respiratory tract through aerosol administration to induce local immunity and prevent severe disease. This approach has significant implications for both human and veterinary medicine and highlights the potential of respiratory vaccines for influenza and other respiratory pathogens.'
Professor Dame Sarah Gilbert, Saïd Professor of Vaccinology at the Pandemic Sciences Institute, said 'To our knowledge this is the first evidence in a large animal that T cell responses in the lung induced by aerosol immunisation are protective. We believe that these results are a significant advance and highly relevant to the development of next generation vaccines for influenza and other respiratory pathogens.'
The research represents a major immunological advance and paves the way for next-generation influenza vaccines that could offer broad and durable protection across multiple strains. This advance could significantly reduce the global burden of influenza and provide a crucial tool in preventing future epidemics and pandemics.
Read the full paper on the NPJ Vaccines website: https://www.nature.com/articles/s41541-024-00989-8