On Jan. 12, 1961, the National Cancer Institute (NCI) established the Laboratory of Viral Oncology, a new intramural research program directed by Ray Bryan, who had developed the high-titer strain of Rous sarcoma virus (RSV). A large amount of funding was also devoted to a new Virology Research Resources Branch.

This industrial-style operation was intended to produce a vaccine against a yet unidentified human leukemia virus. Reports of the identification and isolation of such viruses initially generated a lot of excitement, but these turned out to be laboratory artifacts or contamination by viruses from other animal species.

Although two bona fide human leukemia viruses (HTLV-1 and -2) were eventually isolated in the 1980s by the laboratories of Robert Gallo and Yorio Hinuma, these retroviruses are rare causes of human disease.