Antibodies against p40^tax Gene Product of Human T‐Lymphotropic Virus Type‐I (HTLV‐I) under Various Conditions of HTLV‐I Infection

Abstract

We investigated antibodies against pX gene product, p40 mx , by ELISA using recombinant p40 tax protein in HTLV‐I seropositive carriers as well as patients with adult T cell leukemia (ATL) and HTLV‐I‐associated myelopathy (HAM). Seventy (49.0%) out of 143 HTLV‐I healthy carriers were found to be positive for antibody against p40 tax antigen and the follow‐up samples at two‐year intervals revealed constant reactivity by ELISA in each carrier. The onset of antibody production was delayed 4 to 12 weeks as compared with anti‐HTLV‐I in primary infection cases. The anti‐p40 tax ‐positive rate (90%) in HAM patients was significantly higher than that of healthy carriers, acute and chronic ATL patients and their family members. Furthermore, HAM patients and a few healthy carriers showed high reactivities by ELISA. Children from mothers with anti‐p40 tax showed a higher anti‐HTLV‐I‐positive rate than that of children from mothers without anti‐p40 tax (54.5% versus 12.5%). Two men without anti‐p40 tax and one female with low anti‐p40 tax developed ATL during follow‐up studies. These results suggest that HTLV‐I carriers could be divided into 2 or 3 sub‐populations according to antibody response to p40 tax . A smaller population with anti‐p40 tax , especially a high antibody reactivity, could have a high risk of developing HAM and of transmission from mother to child. In addition, ATL may occur in a population with low or absent anti‐p40 tax .