​Infectious Diseases and Microbiology - Adult T- Cell Leukemia ( Human T lymphotropic virus type 1 (HTLV-1))

​Infectious Diseases and Microbiology - Adult T- Cell Leukemia ( Human T lymphotropic virus type 1 (HTLV-1))
Human T-lymphotropic virus type 1 (HTLV-1) adult T-cell leukemia
HTLV-1 is responsible for adult T-cell leukemia (ATL) and a neurological condition known as HTLV-1-associated myelopathy-tropical spastic paraparesis (HAM-TSP). HTLV-1 is predominantly linked to cells and is primarily transmitted through cells infected with HTLV-1, rather than through viral particles. HTLV-1 is spread through the transfer of infected lymphocytes present in breast milk, semen, and blood.

ATL is distinguished by a protracted asymptomatic phase of 20–50 years, elevated quantities of leukemia cells, skin abnormalities, widespread lymph node enlargement, enlargement of the liver and spleen, and excessive levels of calcium in the blood. The probability of an infected individual developing ATL over their lifetime is 3-5%. HAM-TSP is distinguished by a briefer amount of time before symptoms appear compared to ATL (2-4 years). It involves the damage of the long motor neurons in the spinal cord, resulting in muscle weakness in the legs, gradual stiffness, back discomfort, loss of bladder control, heightened reflexes, sensory abnormalities, and erectile dysfunction in males. The lifetime probability of developing HAM is approximately 1%.

HTLV-1 predominantly infects CD4+ T cells. The HTLV-1 encoded regulatory protein Tax enhances the proliferation and mitosis of CD4+ T lymphocytes by triggering cellular transcription factors that activate cellular growth factors and growth factor receptors, such as interleukin-2 (IL-2) and IL-2 receptor. The pathogenesis of HAM-TSP is distinguished by the invasion of HTLV-1 infected cells into the central nervous system and a significant immune response by cytotoxic lymphocytes, resulting in damage to neurological tissues.

The presence of HTLV-1 infection is identified by Enzyme Immunoassay (EIA) which detects virus-specific antibodies.
There is currently no targeted therapy or immunization available for HTLV-1. Implementing blood screening measures can effectively prevent the transmission of HTLV-1 through transfusions. Additionally, the cessation of breastfeeding by women infected with HTLV-1 will effectively eliminate the transmission of the virus from mother to newborn. Preventive methods implemented for HIV infection are also applicable for HTLV-1.