Viruses and the immune system

The host response to viral infection involves the immune system; a range of lymphocytes and soluble proteins that act to curtail virus replication, destroy infected cells, and block infection of new cells. The presence of virus proteins (antigens) stimulates nonspecific responses such as the action of phagocytic and lytic cells that attack infected host cells. Viral antigens also react specifically with lymphocytes such as B cells and T cells that respond to provide lytic cells and antibodies directed in a precise manner targeting the virus in question. A successful immune response eliminates virus and infected cells from the host and establishes a ‘memory’ of the virus to promote rapid response in the face of a future infection by the same (or a closely related) virus.