Antibodies against p40tax 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, p40mx, by ELISA using recombinant p40tax 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 p40tax 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‐p40tax‐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‐p40tax showed a higher anti‐HTLV‐I‐positive rate than that of children from mothers without anti‐p40tax (54.5% versus 12.5%). Two men without anti‐p40tax and one female with low anti‐p40tax 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 p40tax. A smaller population with anti‐p40tax, 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‐p40tax.