Molecular characterization of an unassigned Israeli Newcastle disease virus isolate.

Detection of Newcastle disease virus (NDV) and avian pathotyping of NDV isolates are extremely important because the appearance of virulent virus has significant economic consequences in terms of vaccination, eradication, and the ability to export poultry products. By using nucleotide and amino acid (aa) homology analysis, we could demonstrate that a NDV broiler isolate is a velogenic virus. This analysis was done after mean death time and intracerebral pathogenicity index tests gave inconsistent results. By establishing a nucleotide sequence dendrogram, we found that the disputed Ber-Tuvia was clearly in the same group as the known Herev-Laet, a velogenic isolate. The difference between Ber-Tuvia 92 and the Herev-Laet velogenic isolate was 6% as opposed to > 16% of the meso- and lentogenic isolates. The Ber-Tuvia isolate contains the Arg/Arg and Lys/Arg aa at positions 112, 113 and 115, 116, respectively, in the fusion protein cleavage aa sequence, which is typical for virulent NDV isolates.