MUTATIONS IN THE FUSION PEPTIDE AND HEPTAD REPEAT REGIONS OF THE NEWCASTLE-DISEASE VIRUS FUSION PROTEIN BLOCK FUSION

Nonconservative mutations were introduced by site-specific mutagenesis into the fusion peptide and the adjacent heptad repeat region of the fusion protein of Newcastle disease virus in order to determine the ro le of both regions in the fusion activity of the protein. Mutations in both regions that allowed for proper folding and intracellular transp ort of the protein blocked the fusion activity of the protein when ass ayed in the presence of the hemagglutinin-neuraminidase protein.