More than 20% of all human cancers are related to infectious agents. HTLV-1 was discovered and identified as the first human oncoretrovirus more than thirty years ago. It infects 5-20 million people worldwide. HTLV-2 was identified in 1983, and HTLV-3 in 2005. The origin of HTLV-1 is linked to episodes of interspecies transmission between STLV-1 (the simian homologue of HTLV-1) infected non-human primates and humans. HTLV-1 is etiologically linked to two diseases: Adult T Leukemia/Lymphoma, and Tropical Spastic Paraparesis/HTLV-1 Associated Myelopathy. Interestingly, despite a high percentage of similarity in its genomic organization with HTLV-1, HTLV-2 was only associated with lymphocytosis, but not with leukemia, and no pathology has been associated so far with HTLV-3 infection. The long period of clinical latency between primo-infection and disease outcome suggests that HTLV-1 pathogenesis is a complex multistep process that our group aims at understanding.
HTLV-1/-2 proviral genomes encompasse a unique set of non-structural regulatory proteins that ensue viral replication and induce immortalization / transformation of infected cells.