This study focused on characterizing Newcastle Disease Virus (NDV) isolates previously obtained from live bird markets and commercial poultry farms in Zaria and environs. Ten NDV isolates, six from local chickens in live bird markets and four from exotic chickens, were isolated between November 2014 and January 2015. The isolates were collected for molecular study. They were amplified using RT-PCR, followed by sequencing of partial F gene. Eight of the ten isolates were successfully sequenced. The results indicated that all the NDV sequences were virulent based on their cleavage site motifs within the F gene. Phylogenetic analysis revealed significant divergence (>20%) between these strains and commonly used vaccine strains like La Sota, V4, and Komarov. Notably, all analyzed NDVs grouped within sub-genotype XIVb during phylogenetic clustering, displaying shared amino acid substitutions across different positions relative to other members of this sub-genotype. These findings offer insights into potential reasons behind NDV vaccine failures by highlighting genetic differences among circulating strains versus those used in vaccines- a rationale warranting further investigation through challenge studies to improve vaccine efficacy against emerging NDV variants.
Hamisu et al. (Wed,) studied this question.