Generalized immunosuppression: how viruses undermine the immune response

Following infection, a virus must battle against the host's immune response . Viruses have developed many ways to escape immune surveillance and downre gulate the host's immune response. Some viruses cause a generalized immunos uppression, thereby inhibiting or depressing the immune response towards th emselves as well as towards unrelated pathogens. This review will focus on the mechanisms involved in the three main human viral infections causing im munosuppression: measles, human immunodeficiency virus and cytomegalovirus. We will also discuss what has been learned from the extensively studied mo use models of viral-induced immunosuppression: lymphocytic choriomeningitis virus and Rauscher leukemia virus. All of these viruses that induce genera lized immunosuppression appear to do so by very similar mechanisms. They hi nder antigen presentation to T cells and/or hematopoiesis. We will highligh t the similarities in the viral targets as well as present evidence for alt ernate mechanisms.