Detection of antibodies to human T-lymphotropic virus type III by using a synthetic peptide of 21 amino acid residues corresponding to a highly antigenic segment of gp41 envelope protein.

A peptide of 21 amino acids with the sequence Arg-Ile-Leu-Ala-Val-Glu-Arg-Tyr-Leu-Lys-Asp-Gln-Gln-Leu-Leu-Gly-Ile-Trp- Gly-Cys - Ser encoded by a segment in the env gene of human T-lymphotropic virus type III (HTLV-III), corresponding to amino acids 586-606 of the precursor envelope glycoprotein, has been synthesized by the Merrifield solid-phase method. Combined serological and chemical analyses of this peptide and related peptides have revealed the importance of certain amino acid residues in the antigenic determinant of the relevant peptide. Enzyme immunoassay (EIA) employing this peptide as an antigen adsorbent was shown to reproducibly detect antibodies in sera of patients with HTLV-III infection. This assay provided positive results with all sera that were reactive with gp41 envelope protein of HTLV-III in electrophoretic immunoblot analysis. Thus far, no false-positive sera have been encountered in control populations. Our EIA with this peptide as the coating antigen is shown to have advantages over that with the whole HTLV-III virus as an immunoadsorbent.