Identification of amino acids relevant to three antigenic determinants on the fusion protein of Newcastle disease virus that are involved in fusion inhibition and neutralization.

Nucleotide sequence analysis of F protein antigenic variants of Newcastle disease virus mapped three distinct antigenic determinants to positions 343, 72, and 161 on the protein. The high fusion-inhibiting and neutralizing capacities of all of the monoclonal antibodies used for selection suggested close functional and structural relationships of the three positions with the fusion-inducing N-terminal region of the F1 subunit. The former two positions were located at the cysteine cluster domain near the C terminus of the F1 subunit and at the major hydrophilic domain in the F2 subunit, respectively, and both domains appeared to represent the major antigenic determinants of paramyxovirus F protein.