SIMIAN IMMUNODEFICIENCY VIRUS VARIANTS - THREAT OF NEW LENTIVIRUSES

Infection in humans with the lentivirus HIV-1 typically results in the development of a chronic disease state characterized by the slow decl ine of CD4+ lymphocytes, the development of immunosuppression, and the development of opportunistic infections, ultimately leading to death. Although the average course of disease runs approximately 10 years, s horter and longer progression times have been noted. These alterations are presumed to be, at least partially, a factor of viral variation. The simian immunodeficiency viruses (SIVs) are the nonhuman primate co unterparts to HIV. Several of these isolates, including SIV from sooty mangabey monkeys, induce a remarkably similar disease in Asian macaqu es. Recently, variants of SIV from sooty mangabey monkeys and SIV from African green monkeys have been described, which are increasingly mor e pathogenic. As in HIV-1 infections, this is probably due to genetic variation. On the basis of these findings, atypical viruses with treme ndous pathogenic potential can arise from apathogenic or moderately pa thogenic viruses.