Abstract
A synthetic peptide derived from the external glycoprotein of human T cell lymphotropic virus type I (HTLV-I) (Env-5; amino acids 242 to 256) reacted with IgG antibodies in serum specimens from HTLV-I-infected individuals. C-terminal residues of Env-5 were crucial for the antibody reactivity. Polyclonal rabbit antibodies to Env-5 did not inhibit syncytium formation but such antibodies reacted specifically with gp68env and gp46env glycoproteins of HTLV-I in an immunoblot analysis. Immunoprecipitation of the surface-labelled MT-2 (HTLV-I-infected) cell line with anti-Env-5 precipitated the gp68env precursor protein. It was concluded that peptide Env-5 mimics a surface-exposed epitope on the HTLV-I external glycoprotein.