Genetic and Pathogenic Characterization of a Newcastle Disease Virus Isolated from Pigeons in Egypt
Genetic and Pathogenic Characterization of a Newcastle Disease Virus Isolated from Pigeons in Egypt
Ahmed Samy1*, Hala Mohamed Nabil Tolba2, Gamelat Kotb Farag3 and Ahmed Abd El Halim1
ABSTRACT
Genotype VI Newcastle disease viruses (NDV), that designated pigeon paramyxovirus 1 (PPMV1) commonly isolated from pigeons (family Columbidae). PPMV1 not only represent a potential threat to pigeon but also it can infect chickens and its virulence enhanced upon passaging in chickens causing clinical signs and deaths. In the present study brain samples were collected from twelve pigeon flocks exhibiting signs of nervousness and diarrhea in a live bird market (LVM) in Egypt. All collected samples were positive for NDV and negative for avian influenza virus and infectious bronchitis virus. Seven positive samples were subjected for genotypic characterization based upon partial F gene sequencing. Partial F gene sequencing revealed that all tested isolates harbor a cleavage site with multi basic amino acid 112KRQKR/F117 characteristic of velogenic strains. However, phylogenetic analysis revealed clustering of all tested strains within sub-genotype VIg. Three isolates were assessed for pathogenicity based upon the mean death time (MDT), the intracerebral pathogenicity index (ICPI) and the intravenous pathogenicity index (IVPI) in chicken. The ICPI and MDT revealed that all tested isolates were of moderate virulence (Mesogenic) in chickens. Mature chickens showed no clinical signs or death as assessed by IVPI. Pigeon in Egypt reared in free rang system and sold in LBM mostly for restocking, that with extensive infection with PPMV represent a potential threat to chickens. Therefore, strict biosecurity measures and control measures at live bird markets, alongside the development of a vaccine may be required to reduce the risk of PPMV1 outbreaks.
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