Location of the epitope recognized by monoclonal antibody 63G on the primary structure of human respiratory syncytial virus G glycoprotein and the ability of synthetic peptides containing this epitope to induce neutralizing antibodies.

The location of the epitope recognized by monoclonal antibody (MAb) 63G on the primary structure of the human respiratory syncytial virus G glycoprotein was determined by testing the reactivity of synthetic peptides with the MAb. The role of individual amino acids in this epitope was determined by using a set of 13-mer peptides containing single residue deletions. Residues 204 to 209 were found to be essential for antibody binding. These results are in full agreement with previous sequence data for escape mutants selected with MAb 63G. Several peptides, free or bound to keyhole limpet haemocyanin (KLH), were used to raise antisera in rabbits. The antipeptide antibodies reacted with the G protein in Western blots. However, only peptide G1-KLH (residues 187 to 200 bound to KLH) induced antibodies that reacted with the intact G protein and inhibited infectivity. These findings are discussed in terms of the antigenic structure of the G glycoprotein and the molecular engineering of peptide antigens.