Human T-lymphotropic virus 1

Human T-lymphotropic virus 1
HTLV-1 and HIV
Virus classification
(unranked):	Virus
Realm:	Riboviria
Kingdom:	Pararnavirae
Phylum:	Artverviricota
Class:	Revtraviricetes
Order:	Ortervirales
Family:	Retroviridae
Genus:	Deltaretrovirus
Species:	Primate T-lymphotropic virus 1

Human T-cell lymphotropic virus type 1 or human T-lymphotropic virus (HTLV-I), also called the adult T-cell lymphoma virus type 1, is a retrovirus of the human T-lymphotropic virus (HTLV) family.

Most people with HTLV-1 infection do not appear to develop health conditions that can be directly linked to the infection. However, there is a subgroup of people who experience severe complications. The most well characterized are adult T-cell lymphoma (ATL) and HTLV-I-associated myelopathy/Tropical spastic paraparesis (HAM/TSP), both of which are only diagnosed in individuals testing positive to HTLV-1 infection. The estimated lifetime risk of ATL among people with HTLV-1 infection is approximately 5%, while that of HAM/TSP is approximately 2%.^[1][2][3]

In 1977, Adult T-cell lymphoma (ATL) was first described in a case series of individuals from Japan.^[4] The symptoms of ATL were different from other lymphomas known at the time. The common birthplace shared amongst most of the ATL patients was suggestive of an infectious cause, referred to as ATLV.^[5] Strikingly, ATLV had the transforming activity in vitro.^[6] These studies established that HTLV-1 was the causitive agent of ATL. The retrovirus is now generally called HTLV-I because later studies proved that ATLV is the same as the firstly identified human retrovirus called HTLV discovered by Bernard Poiesz and Francis Ruscetti and their co-workers in the laboratory of Robert C. Gallo at the National Cancer Institute.^[7] Persistent lifelong infection is established when HTLV-1 integrates into the host genome as a provirus. A patient infected with HTLV-1 can be diagnosed when antibodies against HTLV-1 are detected in the serum.^[8]