Involvement of human T lymphotropic virus type I in human neoplasia.

: Of 211 human tissues analyzed by PCR-SSCP and direct sequencing for HTLV-I genes, 165 (78.2%) gave positive signals. Signals detected in family members of adult T cell leukemia (ATL) patients showed mutations distinct from those in ATL. HTLV-I gene sequences showed variability in same persons examined at different times. Lymphocytes with prototypic HTLV-I genes showed higher sister chromatid exchange following MNNG treatment than those without. Nasopharyngeal carcinomas carrying both HTLV-I and Epstein-Barr virus genes showed markedly abnormal gene product expression. HTLV-I genes in human DNA may cause deregulation of host cell genes upon exposure to carcinogens including viruses.