Viruses must be able to overcome the host immune response to replicate themselves and produce infectious progeny. Although eventually the host immune response succeeds in eliminating viruses and virus-infected cells, viruses have evolved a variety of mechanisms to escape immuno surveillance and survive in a hostile environment. In addition to rapid antigenic variation (HIV), latent infection (herpesvirus) or modality of life cycle (papillomaviruses), these mechanisms include the production of vi