The human T-lymphotropic virus, human T-cell lymphotropic virus, or human T-cell leukemia-lymphoma 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-1 associated myelopathy/tropical spastic paraparesis (HAM/TSP). The HTLVs belong to a larger group of primate T-lymphotropic viruses (PTLVs).
To date, four types of HTLVs (HTLV-1, HTLV-2, HTLV-3, and HTLV-4) HTLV types HTLV-1 and HTLV-2 viruses are the first retroviruses which were discovered. Both belong to the oncovirus subfamily of retroviruses and can transform human lymphocytes so that they are self-sustaining in vitro.
HTLV-1 has been implicated in several kinds of diseases, including tropical spastic paraparesis, and as a virus cancer link for leukemia.
HTLV-2 is closely related to HTLV-1. HTLV-2 may be linked to Cutaneous T-cell lymphoma (CTCL).
HTLV-3 and HTLV-4 have been used to describe recently characterized viruses, discovered in rural Cameroon in 2005. Presumably, transmitted from monkeys to hunters of monkeys through bites and scratches.
HTLV-2 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 and may cause chronic lung problems.