RESUMO

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 erythrocytes, whereas no hemagglutination was observed using equine erythrocytes. By direct sequencing of reverse transcription polymerase chain reaction products, all the isolates had a predicted fusion cleavage sequence comparable to lentogenic NDV strains. Based on nucleotide sequence, the viruses could be grouped phylogenetically with the B1 vaccine-type virus. However, nucleotide sequences were not 100% similar to the B1 or La Sota NDV strains, indicating that minor genetic heterogeneity occurs among lentogenic field isolates of NDV.

Assuntos

Doença de Newcastle/virologia , Vírus da Doença de Newcastle/classificação , Filogenia , Proteínas Virais de Fusão/genética , Sequência de Aminoácidos , Animais , Bovinos , Galinhas , Testes de Hemaglutinação , Cavalos , Dados de Sequência Molecular , Vírus da Doença de Newcastle/genética , Vírus da Doença de Newcastle/isolamento & purificação , Reação em Cadeia da Polimerase , Aves Domésticas , Porto Rico , Homologia de Sequência de Aminoácidos , Sudeste dos Estados Unidos , Proteínas Virais de Fusão/química , Vacinas Virais , Virulência