History of the discoveries of the first human retroviruses: HTLV-1 and HTLV-2.

HTLV-1 was discovered in the US in 1979, and published in 1980. This was rapidly followed by four additional reports in early 1981 describing additional isolates, characterization of some of the HTLV-1 proteins, serological assays for specific antibodies indicative of HTLV-1 infection, and evidence for integrated DNA proviruses in infected cells. None of this early work was dependent upon or influenced by the subclassification of some T-cell malignancies as ATL (in Japan). Instead, I was stimulated by prior work from many investigators in the US and Europe on retroviruses which caused leukemia in animals and our discoveries were made possible by our technical approaches developed in the 1970s involving especially sensitive assays for RT as a surrogate marker for a retrovirus and our discovery of Il-2 which made it possible to culture human T cells. However, following our reports the same virus was isolated in Japan, and both groups provided evidence that HTLV-1 caused ATL, a subclassification of T-cell malignancies first recognized in Japan.