10TH ANNIVERSARY PERSPECTIVES ON AIDS - PHYLOGENESIS AND GENETIC COMPLEXITY OF THE NONHUMAN PRIMATE RETROVIRIDAE

The three known groups of nonhuman primate retroviruses (simian immuno deficiency virus, sinian T cell lymphotrop/leukemic virus type I, and simian foamy virus) are thought to have equivalent human counterparts. This is clearly the case with human immunodeficiency virus types 1 an d 2, the causative agents of acquired immunodeficiency syndrome, and w ith human T cell lymphotropic/leukemia virus type I(HTLV-I), which cau ses T cell leukemia and a progressive form of myelopathy (tropical spa stic paraparesis/HTLV-I-associated myelopathy), and HTLV-II. However, the presence of spunaviruses (foamy viruses) in humans remains uncerta in. Data accumulated in the last 5 years suggest the possibility that the human retroviruses are indeed the result of transmission of simian retroviruses to humans. In this article we attempt to parallel the ge netic features of the simian retroviridae with their human counterpart s and argue for the possibility of horizontal transmission of these vi ruses from monkeys to humans.