Antibody responses to the env epitopes of human T-lymphotropic virus type I in rhesus macaques' naturally infected with simian T-lymphotropic virus type I.

Synthetic peptides derived from the env protein of human T-lymphotropic virus type I (HTLV-I) were used to identify the immunodominant motifs in rhesus macaques naturally infected with simian T-lymphotropic virus type I (STLV-I). Of the 13 peptides derived from the env protein of HTLV-I, Env-1(191-214) and Env-5(242-257) reacted with 81% (44/54) and 54% (29/54) of specimens from infected monkeys, respectively. A recombinant protein (MTA-I162-209) reacted with 53 of 54 (98%) STLV-I-infected serum specimens. While similar immune reactivities to Env-1 and MTA-1 were observed in both HTLV-I-infected human sera and STLV-I-infected monkey sera, the reactivity to Env-5 was significantly higher in HTLV-I-infected human sera. Differential reactivities may be attributed to the differences in the secondary structures of the STLV-I and HTLV-I envelope protein in the Env-5 region, since homologous peptide with STLV-I sequence did not result in enhanced sensitivity of anti-Env-5 antibody detection.