Serologic confirmation of simian T-lymphotropic virus type I infection by using immunoassays developed for human T-lymphotropic virus antibody detection

Serum specimens from diverse species of Old World monkeys, categorized as seropositive (n = 97) or seronegative (n = 23) for human T-lymphotropic virus (HTLV) infection, were tested by using recombinant env-spiked Western immunoblot assays and synthetic peptide assays for simultaneous detection and discrimination of simian T-lymphotropic virus (STLV) infection. Of the 97 seropositive specimens, 93 reacted with the recombinant transmembrane (r21(env)) protein and 90 reacted with a recombinant, MTA-1, derived from the central region of the external glycoprotein of HTLV-1 (rgp46(env)), thus yielding test sensitivities of 96 and 93%, respectively. While 1 of the 23 negative monkey specimens reacted with r21(env), none reacted with rgp46(env), for overall specificities of 96 and 100%, respectively. Analysis of synthetic peptide-based immunoassays demonstrated that while 85 of 97 (88%) seropositive specimens reacted with HTLV-I-specific epitope (p19(gag)), none of the specimens reacted with HTLV-II-specific epitope (gp52(env)). These results show that recombinant envelope-spiked Western blots provide a simple means for serologic confirmation of STLV-I infection and that type- specific synthetic peptides can be used to confirm the virus type in seropositive monkey specimens.