IDENTIFICATION OF AMINO-ACIDS INVOLVED IN A SEROTYPE AND NEUTRALIZATION SPECIFIC EPITOPE WITHIN THE S1 SUBUNIT OF AVIAN INFECTIOUS-BRONCHITIS VIRUS

Localization of neutralizing, serotype specific epitopes of infectious bronchitis virus has been difficult because these epitopes are confor mationally dependent. We identified amino acids involved in a serotype specific, conformationally dependent epitope by analysis of the S1 ge ne of 13 monoclonal antibody-neutralization-resistant mutants. Substit utions in the predicted amino acid sequence of these mutants were loca ted at residues 304 and/or 386. Most of the substitutions at residue 3 04 were from threonine to isoleucine, whereas the substitutions at res idue 386 were from arginine to proline, histidine, cysteine, or trypto phan. Based on this data, it appears that AA residues at 304 and 386 o n the S1 glycoprotein are involved in a virus neutralizing serotype sp ecific epitope.