Insights into origins of Human T-cell Lymphotropic Virus Type 1 based on new strains from aboriginal people of Canada

► We collected LTR sequence data from 13 newly reported HTLV-1 strains from Canada. ► We collected 2 proviral genomes from aboriginal residents of Nunavut. ► We used phylogenetic analyses to test an ancient versus recent origin of HTLV in Canada. ► Using three alternative dating approaches, we demonstrate an ancient origin of HTLV in Canada.