VIRUS VARIATION, ESCAPE FROM CYTOTOXIC T-LYMPHOCYTES AND HUMAN RETROVIRAL PERSISTENCE

Viruses use a variety of mechanisms to escape recognition by cytotoxic T lymphocytes (CTL). The available evidence suggests that the main me chanisms of CTL escape caused by viral sequence variation are loss of epitope binding to MHC molecules or altered recognition by T cell rece ptors. These types of mutations occur in both human immunodeficiency v irus type 1 (HIV-1) and human T cell leukaemia virus type 1 (HTLV-1) i nfections. In HIV-1, CTL escape is one factor that may cause progressi on of disease. In HTLV-I, however, CTL escape mutants never predominat e in the viral population.