Discriminationof Human T-LymphotropicVirus Type-I and Type-Il Infections by Synthetic Peptides Representing Structural Epitopes from the Envelope

Synthetic peptides representing the immunodominant structural motifs of the envelope region of human T-lymphotropic virus types I (HTLV-I) (Env-1191214 and Env-52257) and II (HTLV-lI) (Env-201#{176}2and Env-2187209) were used to develop an enzyme immu-noassay that could discriminate between HTLV-l and HTLV-ll. Serum specimens from indMduals whose infec-tions were confirmed and typed by means of the polymer-ase chain reaction (PCR) were used to determine the sensitivity and specificity of the new assay. When 73 PCR-confirmed HTLV-l specimens were tested with the HTLV-l peptides, the absorbance values for 71(97.3%) were at least two times higher than the values obtained with the HTLV-ll peptides; these samples thus were classified as HTLV-l. Two specimens reacted with all the peptides and, therefore, could not be typed. Conversely, when 59 PCR-confirmed HTLV-ll specimens were tested with the HTLV-ll peptides, 55 (93%) produced high ab-sorbance values and were typed as HTLV-ll; 4 specimens could not be typed. None of the specimens was incor-rectly typed; hence, the specificity of this assay was 100%. When this assay was compared with other HTLV immunoassays, the degrees of sensitivity and specificity were similar. The main advantage of this new assay is that synthetic peptides representing variant sequences can easily be added as new variant HTLV strains are identified. IndexIng Terms: enzyme immunoassay retroviruses Human T-cell lymphotropic virus types I (HTLV-I) and H (HTLV-ll) are closely related retroviruses.2 HTLV-I is associated with adult T-cell leukemia (ATh) and HTLV-I-associated myelopathy (HAM), but HTL V-il is not associated with any specific disease (1). Infections with HTLV-I are endemic in Japan, the Caribbean, and South Pacific islands (2, 3), whereas infections with HTLV-il are endemic in highly isolated native Indian populations in the Americas (4,5). In th