ABSTRACT
Ever since the early twentieth century retroviruses—and their possible association to human disease—have been the subject of research by virologists and clinical scientists. In 1980, however, a team of researchers led by Dr. Robert Gallo[1–4] isolated and described the first human disease linked retrovirus[5–9]—initially called human T-lymphotropic virus (HTLV), but later renamed (HTLV-I), after a second retrovirus (HTLV-II) was discovered in 1982,[9–13] Two additional viruses—HTLV-III and HTLV-IV—were later discovered and added to the HTLV family of retroviruses, but they were renamed human immunodeficiency virus (HIV) since they differ significantly in their structure and in the pathology of the diseases they cause.[9] Too, whereas HTLV-I and HTLV-II belong to the oncovirus subfamily of retroviruses, the human immunodeficiency viruses (HIV-I and HIV-II) belong to the lentivirus subfamily and cause the acquired immunodeficiency syndrome (AIDS).[14] Despite these important differences, the four members of the HTLV family have some common epidemiologic features in that: (a) they are exogenous human infecting viruses and (b) their transmission occurs by whole blood or its derivatives and through sexual intercourse.[15]
