Abstract
The binding site of a monoclonal antibody to the haemagglutinin-neuraminidase (HN) polypeptide of Newcastle disease virus (NDV) has been located. Complementary DNA or synthetic oligonucleotides corresponding to portions of the HN gene were cloned into the Escherichia coli vector pUC19 and fragments of the HN protein were thereby fused to the α-peptide of -galactosidase. Western blot analysis of E. coli lysates containing expressed fragments of the HN cDNA or synthetic oligonucleotides identified an antibody-binding peptide (Asp-Glu-Gln-Asp-Tyr-Gln-Ile-Arg; amino acid residues 346 to 353). Nucleotide sequence analysis of an antibody-resistant mutant of NDV revealed a Glu (wild-type) to Lys (mutant) substitution within the above sequence. The methods described could be useful for the location of continuous epitopes of other polypeptides.