Abstract
Both host defense and viral genetic factors influence the development of viral infection and disease. Due to the presence of the blood-brain barrier, infection of the central nervous system creates additional complexities in interactions between a virus and its host. Stages in viral pathogenesis defined as (1) virus entry, (2) spread, (3) tropism, (4) virulence and injury to the host, and (5) the outcome of infection are discussed for viral infections in general and those aspects unique to infections of the central nervous system. Information about neuronal physiology and function has also been revealed through studying virus infection. An increased understanding of viral pathogenetic mechanisms and host response to infection raises interesting possibilities for vaccine development and for basic studies in neurology and neurobiology.