Serologic Differentiation of Human T Lymphotropic Virus Type I from Type II Infection by Synthetic Peptide Immunoassays

Synthetic peptide-based serologic assays (Select-HTLV and SynthEIA) that distinguish the closely related human T-cell lymphotropic virus types I (HTLV-I) and II (HTLV-II) were tested blindly for their ability to correctly identify infection caused by either virus type. Of 57 HTLV-I and 38 HTLV-II specimens from individuals whose infections were confirmed by polymerase chain reaction, the Select-HTLV assay categorized 56 (98%) as HTLV-I, 36 (95%) as HTLV-II, and 3 (3%) as nontypeable. Similarly, the SynthEIA assay categorized 54 (95%) as HTLV-I, 29 (76%) as HTLV-II, and 12 (13%) as nontypeable. More importantly, no specimen was wrongly classified by either assay (100% specificity). Further, analysis of serial specimens from six patients also demonstrated concordant results with the PCR findings. Our results suggest that serotyping of HTLV infections can be achieved reliably by these peptide assays, thus the need for technically complex PCR-based HTLV typing, while not eliminated, can be greatly reduced.