The molecular details of the HIV replication cycle largely determine the pathogenesis of the diseases caused by HIV and constrain the possible therapeutic strategies. Optimal diagnosis, assessment, and treatment of HIV infection in children thus require knowledge of the viral replication cycle, the viral targets affected by the antiretroviral agents, and the components of the virus detected by the tests used to manage the disease.
Classification and origin of HIV
HIV-1 is a member of the Lentivirus genus of retroviruses (reviewed in ). The virus is believed to have entered the human population in Africa about 70 years ago , probably as humans hunted and butchered chimpanzees for “bush meat” . The animal virus most closely related to HIV-1, a simian immunodeficiency virus (SIV) designated SIVCPZ, is found in chimpanzees, and certain chimpanzee populations continue to harbor large numbers of retroviruses . HIV-2, a less pathogenic relative of HIV-1, infects some human populations in western Africa, with a relatively small number of cases in other parts of the world . HIV-2 is believed to derive from an immunodeficiency virus that infects monkeys. The closest relative to HIV-2 is a simian immunodeficiency virus, SIVSMM, with SMM denoting sooty mangabey monkey. HIV-2 has some biological properties that distinguish it from HIV-1, and the disease caused by HIV-2 differs from the disease caused by HIV-1. Untreated, HIV-2 disease is generally a much less fulminant disorder than the disease caused by HIV-1.