There are four human T-lymphotropic viruses (HTLV-1, 2, 3, 4) that have emerged from the transmission of simian viruses. HTLV-1 was the first retrovirus to be shown to be responsible for a human pathology. The expression of retroviral genes depends mostly on their 5'LTR, but it was revealed that HTLV have a promoter in their 3'LTR, capable of transcription from the antisense strand of their genome. These transcripts can be translated into proteins named HBZ, APH-2, APH-3 and APH-4. Antisense transcription in HTLV-1 and its encoded protein HBZ have been thoroughly studied and it has been suggested that HBZ plays an important role in viral replication and the development of ATL. Very few studies have been conducted on antisense transcription from the three other viruses, although it is likely that these genes are also implicated in viral replication.
Keywords: APH; ATL; HBZ; antisense protein; human T-lymphotropic virus.