Human T-lymphotropic virus 2

A virus closely related to HTLV-I, Human T-lymphotropic virus 2 (HTLV-II) shares approximately 70% genomic homology (structural similarity) with HTLV-I.

It is found predominantly in Native Americans, and South American Indian groups. And also in Asian countries. More common in Japan and Korea. It can be passed down from mother to child through breastmilk and genetically as well from either parent.

HTLV-II entry in target cells is mediated by the glucose transporter GLUT1.

Clinical significance

HTLV-II has not been clearly linked to any disease, but has been associated with several cases of myelopathy/tropical spastic paraparesis (HAM/TSP)- like neurological disease.

An impact on platelet count has been observed.

In the 1980s, HTLV-2 was identified in a patient with an unidentified T cell lymphoproliferative disease that was described as having characteristics similar to the B cell disorder, hairy cell leukemia. HTLV-2 was identified in a second patient with a T cell lymphoproliferative disease; this patient later developed hairy cell leukemia, but HTLV-2 was not found in the hairy cell clones. The cause of hairy cell leukemia is not known, but it is no longer believed to be related to viral infections.

Human T-lymphotropic virus

The human T-lymphotropic virus or human T-cell lymphotropic virus (HTLV) family of viruses are a group of human retroviruses that are known to cause a type of cancer called adult T-cell leukemia/lymphoma and a demyelinating disease called HTLV-I associated myelopathy/tropical spastic paraparesis (HAM/TSP). The HTLVs belong to a larger group of primate T-lymphotropic viruses (PTLVs). Members of this family that infect humans are called HTLVs, and the ones that infect old world monkeys are called Simian T-lymphotropic viruses (STLVs). To date, four types of HTLVs (human T-lymphotropic virus 1 [HTLV-I], human T-lymphotropic virus 2 [HTLV-II], HTLV-III, and HTLV-IV) and four types of STLVs (STLV-I, STLV-II, STLV-III, and STLV-V) have been identified. The HTLVs are believed to originate from intraspecies transmission of STLVs. The original name for HIV, the virus that causes AIDS, was HTLV-III; this term is no longer in use . The HTLV-1 genome is diploid, composed of two copies of a single-stranded RNA virus whose genome is copied into a double-stranded DNA form that integrates into the host cell genome, at which point the virus is referred to as a provirus. A closely related virus is bovine leukemia virus BLV.

HTLV-III

HTLV-III is:

Human T-lymphotropic virus 1

Human T-cell lymphotropic virus type 1 or human T-lymphotropic virus type 1 (HTLV-I), also called the adult T-cell lymphoma virus type 1, is a retrovirus of the human T-lymphotropic virus (HTLV) family that has been implicated in several kinds of diseases including very aggressive adult T-cell lymphoma (ATL), HTLV-I-associated myelopathy, uveitis, Strongyloides stercoralis hyper-infection and some other diseases. However, only about 1–5% of infected persons are thought to develop cancer as a result of the infection with HTLV-I over their lifetimes.

Adult T-cell lymphoma (ATL) was discovered in 1977 in Japan. The symptom of ATL is totally different from other lymphoma that were known at that time. It was suggested that ATL is caused by the infection of a retrovirus called ATLV. Strikingly, ATLV had the transforming activity in vitro. These studies established that the retrovirus infection is the cause 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. Infection with HTLV-I, like infection with other retroviruses, probably occurs for life. A patient infected with HTLV can be diagnosed when antibodies against HTLV-1 are detected in the serum.