Human Adult T-Cell Leukemia Virus Type 1 (HTLV1)

The human T-lymphotropic virus type 1 (HTLV1), or human T-cell leukemia virus type 1, is cancer-causing replication competent human retrovirus. The first retrovirus (discovered by Gallo’s et al.) ever linked with a human cancer affecting ten million globally. Virus has sporadic distribution of endemic areas, origin through founder effect, and exemplifies RNA virus genome and replication. It is an enveloped virus with 80–100 nm diameter of the virion having two covalently bonded ssRNA strands each of 9 kb within the nucleocapsid core. The virus evades the immune surveillance through smart molecular mechanism and is latent in the infected persons for a prolonged period. In 2–5% cases at a later stage, it manifests as severe to potentially fatal two discrete types of diseases: cancer of mature CD4+ T cells called adult T-cell leukemia–lymphoma (ATL) and a chronic inflammatory central nervous system disease HTLV1-associated myelopathy/tropical spastic paraparesis. HTLV1 is transmitted primarily through infected body fluids, including breast milk (vertical transmission—mother–child), blood, semen, cervical secretions, and organ transplant (horizontal transmission). In addition, there is a lack of therapeutic regime and prevention of transmission routes. Restricted breast feeding or formula feed with screening of potential blood and organ donors; use of condoms to prevent sexual transmission can contain the virus across the world. Surveillance for HTLV-1 based on routine reporting of new diagnoses of HTLV-1 or associated diseases or prevalence surveys if adopted by each country, in addition a proper registry for cancer (ATL), would contain the virus across the globe.