Pathotypic and genotypic characterization of two Bangladeshi isolates of Newcastle disease virus of chicken and pigeon origin.

Two Bangladeshi isolates of Newcastle disease virus (NDV), one from a chicken and one from a pigeon, were characterized in this study. Pathogenicity of the isolates was evaluated on the basis of intracerebral pathogenicity index (ICPI). Both the isolates were found to be of velogenic pathotype having ICPI of 1.83 and 1.51 for the chicken and pigeon isolate, respectively. Genotype of the isolates was determined by phylogenetic analysis based on partial F gene sequences. A 766-bp genome fragment spanning partial M and F gene was amplified by RT-PCR and sequenced. The first 354 bp of the coding region of F gene and corresponding deduced amino acid sequences (residues 1-118) of these two NDV isolates were aligned with that of other NDV strains retrieved from GenBank. A phylogenetic tree constructed from the alignment showed that the chicken isolate (BD-C162) belonged to the newly described genotype XIII and the pigeon isolate (BD-P01) to genotype VI. Both the chicken and pigeon isolates possessed a virulent-like fusion protein cleavage site (112) RRQKRF(117) .