High Prevalence of HIV/HTLV Co-Infection in Porto Alegre, Southern Brazil

Type 1 and type 2 human T-cell lymphotropic viruses (HTLV1 and HTLV2) were the first retroviruses described, in 1979 and 1981, respectively [1]. HTLV1 and 2 viruses share 60% of their genomes [2]. Despite the fact that most individuals infected by these viruses remain asymptomatic throughout life, it is known that these agents are responsible for clinical neoplastic, inflammatory or degenerative syndromes, and HTLV-2 poses lower risk for the development of pathologies [1-4]. HIV-1 virus was discovered in 1983, and it was considered the etiological agent of the Acquired Immunodeficiency Syndrome in 1984 [1] .Retroviruses display tropism for cytotoxic T-cells CD4 and CD8. While the HTLV 1 and HIV-1 viruses show tropism primarily for CD4+ T-cells, HTLV-2 displays tropism for CD8+ T-cells. It is known that HTLV-1 and 2 viruses infect about 10-20 million individuals worldwide, whereas HIV virus infects sixty million individuals [3]. Regions with higher prevalence of HTLV-1 are the southwestern area of Japan, the Caribbean, Central and South America, Melanesia, and Africa [5,1] .