A field study of infection with human T-cell leukemia virus among asian primates.

Asian nonhuman primates were surveyed seroepidemiologically for natural infection with human T-cell leukemia virus (ATLV/HTLV) or a closely related agent. Materials from various primates (three genera [Macaca, Presbytis, and Hylobates], 17 species, totalling 1,079 animals) under natural conditions were obtained in the field study. Virus infection was determined by the indirect immunofluorescence test using HTLV-specific antigens. Animals seropositive for HTLV were found only among macaques originating from various localities, toque monkeys in Sri Lanka (17.5%), crab-eating macaques in Thailand (1.3%), stumptailed macaques in Thailand (1.5%), rhesus monkeys in Thailand (3.3%), and Celebes macaques in Indonesia (16.9%). Langurs and gibbons were seronegative. Thus the wide distribution of HTLV in nature among various macaques suggests that the introduction of this virus into primates occurred in ancient times.