Antigenic variations of retrovirus in Japanese cancer patients

Previously we demonstrated the prevalence of human T lymphotropic virus type I (HTVL-I) infection among cancer patients in Japan. This study was carried out to examine antigenic properties of retroviruses prevalent among Japanese cancer patients. Sera of 126 Japanese patients with cancer of different organs and with no history of blood transfusion, 94 in adult T cell leukemia (ATL)-endemic area and 32 in ATL-nonendemic area, were surveyed for antibodies to HTLV-I and HTLV-II by enzyme-linked immunosorbent assay (ELISA), Western blot analysis, and indirect immunogold electron microscopy. Among patients who were seropositive to HTLV-I, 39 of 56 (69.6%) in ATL-endemic area and 9 of 9 (100%) in ATL-nonendemic area were seropositive also to HTLV-II. Of 48 sera positive to both HTLV-I and HTLV-II, 34 (70.8%) showed stronger reactivities to HTLV-I than to HTLV-II. Among patients who were seronegative to HTLV-I, 3 of 38 (7.9%) in ATL-endemic area and 5 of 23 (21.7%) in ATL-nonendemic area were seropositive to HTLV-II. Antibodies appearing and disappearing in sera of patients examined during the clinical course reacted with peptide species of HTLV-I and/or HTLV-II not always consistent with peptide species cross-reactive between HTLV-I and HTLV-II. These results indicate the antigenic diversity of retroviruses prevalent among Japanese cancer patients.