IDENTIFICATION AND MAPPING OF FUNCTIONAL DOMAINS ON HUMAN T-CELL LYMPHOTROPIC VIRUS TYPE-1 ENVELOPE PROTEINS BY USING SYNTHETIC PEPTIDES

To identify the regions that are important in human T-cell leukemia vi rus type 1 (HTLV-1) envelope function, we synthesized 23 kinds of pept ides covering the envelope proteins and examined the inhibitory effect of each peptide on syncytium formation induced by HTLV-1-bearing cell s, Of the 23 synthetic peptides, 2, corresponding to amino acids 197 t o 216 on gp46 and 400 to 429 on gp21, inhibited syncytium formation in duced by HTLV-l-bearing cells but did not affect syncytium formation i nduced by human immunodeficiency virus type 1-producing cells, The pep tide concentrations giving 50% inhibition of syncytium formation for g p 16 197 to 216 and gp21 400 to 429 were 14.9 and 6.0 mu M, respective ly. A syncytium formation assay with overlapping synthetic peptides co ntaining amino acids 175 to 236 and 391 to 438 of the envelope protein s showed that syncytium formation was inhibited by peptides that conta ined the amino acid sequences 197 to 205 (Asp-His-Ile-Leu-Glu-Pro Ser- Ile-Pro) and 397 to 406 (Gln Glu-Gln-Cys-Arg-Phe Fro-Asn-Ile-Thr) Thes e observations suggest that the two regions corresponding to amino aci ds 197 to 216 and 400 to 429 are involved in HTLV-1 envelope function.