| virus characterization and sequence of the fusion protein gene cleavage site of recent newcastle disease virus field isolates from the southeastern united states and puerto rico. | nine newcastle disease virus (ndv) isolates obtained from puerto rico, georgia, alabama, mississippi, and texas were analyzed for in vivo pathogenicity, biological properties (hemagglutination of mammalian erythrocytes), and for sequence variation at the amino acid and sense rna level of the fusion protein cleavage site. intracerebral pathogenicity index values ranged from 0 to 0.3 and the intravenous pathogenicity index obtained for all isolates was 0. four isolates hemagglutinated bovine eryth ... | 1996 | 8790890 |