Molecular characterization of Newcastle disease viruses isolated from recent outbreaks in Taiwan

A reverse transcription-polymerase chain reaction (RT-PCP,) was described w hich amplified a portion of the F and HN genes of Newcastle disease virus ( NDV) isolated from recent outbreaks in Taiwan, The F protein plays an impor tant role in determining the virulence of NDV strains. Sequencing of a regi on specifying the F protein cleavage site was therefore undertaken and this verified the correlation between deduced amino sequences and pathogenicity . Analysis of the deduced amino acid sequences of the F protein cleavage si te showed that all recent Taiwanese isolates in 1999 were velogenic viruses . All the virulent viruses have the amino acid sequence (112)RRQKR(116) for the C-terminus of the F2 protein and phenylanine (F) at the N-terminus of the F1 protein, residue 117. A phylogenetic tree based on the nucleotide se quences of the F gene revealed that recent Taiwanese NDV isolates responsib le for recent outbreaks were classified into two distant genotypes (VI and VII). Genotype VI virus is the first finding in Taiwan and has a highly gen etic similarity to European isolates, suggesting that they might have origi nated from a common ancestor. (C) 2001 Elsevier Science B.V. All rights res erved.