Sexual transmission of human T-cell leukemia virus type I associated with the presence of anti-Tax antibody.

Abstract

The tax gene product (Tax protein) of human T-cell leukemia virus type I (EHTLV-I) is a specific transcriptional activator of the viral long terminal repeat sequence and is essential for the replication cycle of the virus. To elucidate the relationship between the presence of anti-Tax antibody and the transmission of the viral infection, annual consecutive serum samples from married couples serologically discordant or concordant for HTLV-I were examined. These included 5 individuals whose spouses seroconverted during this 5-year follow-up study period. The samples were tested by a Western blot assay using a recombinant Tax protein as the antigen. The results showed that 24 of 32 (75%) men in the concordant couples (both husband and wife were HTLV-I carriers) had anti-Tax antibody, while only 5 of 18 (27.8%) men in the discordant couples (husband was carrier and wife was seronegative to HTLV-I) were positive for anti-Tax antibody (P = 0.0012). Furthermore, all spouses of the 5 seroconverters (4 women and 1 man) had anti-Tax antibody, while only 23 of 46 (50%) age-matched randomly selected HTLV-I carriers from the discordant-couple group had anti-Tax antibody. When the data were analyzed by gender, all husbands of the female seroconverters had anti-Tax antibodies, which was signiflcantly higher than the prevalence of anti-Tax antibodies in men who did not transmit the virus to their spouses during the follow-up period (P = 0.017). In addition, antibody reactivity to other HTLV-I antigens (including Env gp46, transmembrane protein gp21, and Gag p19 and p24) were examined. The results indicated no significant difference between the prevalence of antibody reactivity to any of the antigens in the spouses of the seroconverters and the reference group. We conclude that the presence of anti-Tax antibody in men may indicate a high risk of viral transmission to their wives via heterosexual routes.

Animal models for human T-lymphotropic virus type 1 (HTLV-1) infection and transformation

“…Inoculation of rabbits with HTLV-1-infected cell lines derived from patients with ATL or HAM/TSP demonstrate the heterogeneity in the biological response to HTLV-1 infection (Lairmore et al, 1992). Immunization of rabbits with synthetic peptides verified immunodominant epitopes of the viral envelope protein (Env) (Lal et al, 1991;Tanaka et al, 1991) and also defined regions of Env important for antibody-dependent cell-mediated cytotoxicity (Chen et al, 1991). Soon after, it was demonstrated that peptide immunization with amino acids 190-199 of the Env protein could protect rabbits from subsequent HTLV-1 challenge, opening the possibility for vaccine development (Tanaka et al, 1994).…”

Sexual transmission of human T-cell lymphotropic virus type 1

“…Using a Western blot assay with a recombinant Tax protein as the antigen, Chen et al 89 tested serum samples from married couples who were serologically discordant or concordant for HTLV-1. The results revealed that 24 of 32 (75%) men within the concordant group (in which both the husband and wife were HTLV-1 carriers) had anti-Tax antibodies, whereas 5 of 18 (27.8%) men in the discordant group (in which the husband was a carrier and the wife was seronegative for HTLV-1) were positive for anti-Tax antibodies.…”

Do T cells cause HTLV-1-associated disease?: a taxing problem

“…However, preliminary data from our laboratory suggest that anti-rex CTL can be found in healthy carriers. Further, IgM and IgA antibodies directed against tax and env are found in HAM/ TSP patients and IgG specific for gag, tax and env are found in HAM/TSP and healthy carriers [17,18].…”