The discovery of HTLV
Human T-cell Lymphotropic Virus (HTLV) was isolated, from an Afro-American with a T-cell lymphoma infiltrating his skin, in 1980 by Dr Poiesz and others in the laboratory of Dr Gallo
In 1982 the same group identified a related virus from lymphocytes which they called HTLV-2.
In 1983, two research teams, one in France and Dr. Gallo's team in the USA found the causative agents of the then newly-described condition Acquired Immunodeficiency Syndrome. Barré-Sinoussi's team called this virus LAV whilst Gallo's team called it HTLV-3. This virus belongs to a different family of retroviruses and was renamed Human Immunodeficiency Virus (HIV-1).
HTLV-1 and the closely related HTLV-2 were the first discovered human retroviruses.
HTLV-3 & 4
There is very little information available about HTLV-3 and HTLV-4, with it being unclear about how many individuals are infected with these strains of the virus or even whether they can spread from person to person and become established within a community, or even if they cause illness. However, given the fact that a related virus, HTLV-1 is known to cause serious diseases, it is imperative to monitor the possible spread of these viruses and to determine their disease potential.
The appearance of these new viruses serves as a reminder that increased contact between humans and primates enhances the likelihood that a virus will cross species, as occurred when HIV was transmitted from chimpanzees into humans. Our experience with HIV has taught us that we need to be vigilant when new viruses arise in humans.