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I have been given the question:

Explain how our knowledge of viral immune evasion strategies might help in the design of new vaccines?

Not really sure where to start on this and so was wondering whether SMP had any knowledge/experience.

Cheers

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This really ought to be fairly easy to look up. Go to your library and get any new Immunology textbook, or even just try searching through Medline or Pubmed for some ideas. There is a ton of information on host evasion and cell surface markers. I'm not sure exactly what level you are at here, but basically the way we detect viruses is that all the cells in our body have a cell surface marker called MHC I. These MHC I proteins continually sample from their own intercellular environment basically random proteins and then display them on the surface to any T cells that might be passing by. In healthy persons, they present "self" proteins which are recognized by the T cells as such and left alone. Infected cells, however, will eventually randomly present proteins that contain "non-self" or viral proteins. The T-cells (called cytotoxic T cells or Tc or CD8 T cells) recognize these non-self proteins and initiate destruction of those cells.

Viruses and other invading pathogens have developed several strategies to try and counterract this system. For example, some viruses will cause the endocytosis (basically the eating up) of the MHC I molecules on the surface of the cell, and thus no non-self proteins will be presented to the T cells and the T cells cant kill the infected cells. We have a way around that, and they are called Natural Killer or NK cells. These cells wander around and kill any cells that dont have MHC I molecules. They are sort of like bad-ass fascist cops...I mean, if you dont have anything to hide, why dont you show me your MHC I? Thats it pal, up against the wall.

There are other ways of avoiding these defenses. Each T cell can only recognize very specific proteins in an MHC molecule, and they build up a mnestic or memory response. Once that protein is seen again, the response is much more rapid, long-acting and severe. Some viruses, like HIV, mutate at an incredibly fast rate so that they never show the T cells the same proteins twice. This circumvents the mnestic response and you just get a much weaker initial response that has a hard time clearing the virus.