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 viral proteins which actively fight the host immune response. The reviews in this book deal with the immuno modulators and inhibitors encoded by a variety of viruses, from the poxviruses, which are very well known in this respect, to the papillomaviruses, whose evasion from the host immune response has just begun being elucidated. In addition to being scientifically stimulating, the reviews, by highlighting the countermeasures operated by viruses to fight the host immune response, point the way to new potential anti-viral strategies.