Towards pandemic influenza vaccines

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The world has suddenly been alerted to the threat of pandemic influenza with the recent deaths in Asia of patients and their close contacts from which the avian influenza H5N1 virus has been isolated. Experts believe that it is only a matter of time before this virus mutates and acquires the ability to rapidly spread within the human population. The currently available vaccines have virtually no capacity to prevent infection by a new pandemic virus. Once the virus strikes appropriate vaccines can be made against it but this procedure takes at least 6 months, the time predicted for the virus to have already spread throughout the globe. We are proposing that a vaccine designed to induce killer T cells (called CTLs) that target the conserved regions shared by all influenza viruses, could be used as a preventative measure without prior knowledge of the exact type of virus that will emerge. This sort of vaccine will not prevent against infection but will greatly lessen the severity of the disease. We have already designed a vaccine that that will induce high levels of CTLs that can greatly speed up the clearance of viruses of the type that are currently in the human population, when tested in animal models. However, we predict that a new pandemic virus will be much more vigorous in its growth and so our vaccines will have to be improved to cope with this. This project looks at ways of increasing the number and effectiveness of the CTLs that are induced by our vaccines. This will require an understanding of how we can modulate the function of other specialised cells, dendritic cells and helper T cells, that play a role in starting and maintaining the CTL response, as well as modulating the CTLs themselves.