Phylogenetic and histopathological characterization of newcastle disease viruses reveals high prevalence of very virulent strains of genotype viid in Egypt

الملخص EN

Newcastle disease virus (NDV) is a highly contagious disease in poultry, also considered as a major challenge for the commercial and traditional poultry industry in Egypt.

In this study clinicopathological and immunohistochemistry examination of fourteen flocks from different provinces in Egypt during 2013 and 2014 revealed velogenic ND features and positive staining for ND virus (NDV) antigen in pantropic organs of all strains which also revealed positive NDV by RRT-PCR, as it is alreadyconvinced that the fusion protein cleavage site has been deemed as responsible for the pathogenicity of NDV and selected as a target to identify and type lentogenic and velogenic strains, viral Genomic RNAs were extracted from representing swabs and organs of examined flocks, and partially amplifiedfor fusion gene of NDV using RT-PCR, then forwarded to gene sequencing.

Four chosen samples amplified for full fusion gene sequence using specific sets of newly designed primers from the available sequence data of NDV strains in Gen Bank, The resulted sequence showed motif 112RRQKRF117 which is indicative of velogenic character NDV strains, and indicate presence of 2 mutations E74D and D170N in two strains.

Phylogenetic analysis revealed that Egyptian strains are closely related to NDV genotype VIId strains of south East Asian countries based on the high nucleotide and amino acid similarity.