Ewies SS, Ali A, Tamam SM, Madbouly MM. Molecular characterization of Newcastle disease virus (genotype VII) from broiler chickens in Egypt, Beni-Suef University Journal of Basic and Applied Sciences, 2017, ISSN 2314-8535, https://doi.org/10.1016/j.bjbas.2017.04.004

ملخص البحث

Newcastle disease (ND) outbreaks have been occurred in the Egyptian poultry causing high mortalities with severe economic losses. Samples were collected from 3 to 4 weeks-old broiler chickens suffering from high mortalities respiratory and/or nervous signs, located at Beni-Suef, Minia, Fayoum, Ismailia and Menofia governorates and Postmortem examination showed hemorrhages at both proventricular glands and cecal tonsils. The samples were subjected to virus isolation trials by inoculation of the processed samples in the allantoic sac of 9-day-old specific pathogen free eggs (SPF). Hemagglutinating activity was tested by hemagglutination test and the isolated viruses were molecularly characterized by RT-PCR targeting the partial F-gene of NDV. Partial F gene sequence analysis showed that the isolated NDV strains belong to genotype VII with the characteristic amino acid sequences of the F0 protein proteolytic cleavage site motifs (112RRQKRF117) for the velogenic NDV strains. No significant differences in both nucleotide and amino acid sequences were observed among different examined strains. The vNDV isolates in this study were identical to each other and they were similar to strains isolated from Egypt during 2012–2014 with minor genetic variation. This study indicated that though intensive ND vaccination programs using LaSota like strains, the vNDV strains of genotype VII are still circulating in the field causing significant economic losses. The genetic variation between the used vaccine strains and the circulating NDV viruses may explain the inability of the currently used vaccines to protect chicken against vNDV genotype VII. Further studies are needed to screen the protection of the currently used vaccines against recently isolated vNDV strains.

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