STLVvirussen

STLVvirussen, or Simian T-lymphotropic viruses, are a group of retroviruses that naturally infect non-human primates. They are closely related to the human T-lymphotropic viruses (HTLV) and together form part of the genus Deltaretrovirus within the Retroviridae family. The best described members are STLV-1, STLV-2 and STLV-3, each associated with specific primate hosts.

They have a typical retroviral genome consisting of positive-sense single-stranded RNA with gag, pol and env genes, plus regulatory elements such as tax and rex. Replication occurs via reverse transcription of RNA into DNA and integration into the host genome, with long terminal repeats controlling transcription. Like other deltaretroviruses, STLVs establish persistent infection in their hosts.

Natural history and transmission: STLVvirussen infect a broad range of Old World primates, including macaques, baboons and colobus. Transmission occurs mainly through blood-to-blood contact, bites and, less commonly, sexual contact; vertical transmission can occur through breastfeeding. In many infected individuals, infections are asymptomatic; some STLV-1 infections have been linked to lymphoproliferative disease in captive primates, though severe disease is less consistently observed than with HTLV in humans.

Zoonotic potential and evolution: STLV and HTLV share a common ancestor and diverged over evolutionary timescales, making STLV a key model for studying deltaretrovirus evolution and cross-species transmission. Although not a major public health concern, sporadic zoonotic transmissions to humans have been documented in people with close contact to infected primates.