Detection of type C virus particles in Japanese monkeys seropositive to adult T-cell leukemia-associated antigens.

Type C virus particles which were identical to adult T-cell leukemia virus (ATLV) in morphology were detected in phytohemagglutinin-stimulated peripheral lymphocytes from four out of four Japanese monkeys seropositive to adult T-cell leukemia-associated antigens. It is possible that non-human primates may be a natural reservoir of ATLV, and vector-borne transmission of ATLV from monkeys to humans should be explored.