[Classification of retroviruses].

The retroviridae comprise a large number of viruses. In both nature and laboratories these viruses are associated with numerous diseases, including rapid or long latency malignancies, neurological disorders and immunodeficiency. The replication cycle is characterized by integration of the viral DNA into the host's genome after the reverse transcriptase copied the viral RNA into DNA. The discovery of human retroviruses had a late start. It was not until 1980 that the first oncovirus, the human T-leukaemia virus 1 (HTLV-1), was identified. The human immunodeficiency viruses (HIV-1 and HIV-2), belonging to the lentivirus subfamily, cause AIDS. Several simian virus, called simian immunodeficiency viruses (SIV) and related to HIV-1 and/or HIV-2 have been identified in monkeys and chimpanzees.