Epidemiological Surveillance for the Newly Classified Newcastle Disease Virus Genotype VII.1.1 in Chicken Flocks in Egypt
Epidemiological Surveillance for the Newly Classified Newcastle Disease Virus Genotype VII.1.1 in Chicken Flocks in Egypt
Sameh Abdel-Moez Ahmed Amer1*, Mohamed Abdel-Aziz Kutkat1, Mohamed Mahmoud Abdel-Baki1, Asmaa Mahmoud Maatouq1, Omnia Mohamed Kutkat2, Hagar Magdy Ahmed1, Khaled Mohamed El-Bayoumi1
ABSTRACT
Newcastle disease virus (NDV) has been recently considered as one of the major problematic diseases affecting poultry flocks in Egypt. The conventional vaccines can no longer provide an adequate protection for birds against ND outbreaks, where expected to be due to genotype mis-matched vaccines to the rapidly evoluted NDV field strains. Herein, the present study investigated the prevalence and the phylography of currently epidemic genotypes of NDV. Out of 550 samples were collected during an active surveillance in 2020 and 2021 from different poultry farms in five Egyptian governorates, 100 pooled samples were tested for NDV identification. NDV replication and growth was detected by embryo mortality after inoculation of all samples in one passage in embryonated chicken eggs and further testing by haemagglutination test. Whereas, reverse transcription polymerase chain reaction (RT-PCR) using specific primers to amplify 1681 base pair (bp) of the whole NDV F-gene was carried out to confirm the presence of NDV and then sequenced. Our results demonstrated that, RT-PCR was successfully detecting 62 NDV samples. While, Sequencing and phylogenesis of six selected isolates revealed that, all isolates were virulent NDV with amino acid motive 112RRQKRF117 at F protein cleavage site. Furthermore, all isolates were clustered together with NDV genotype VII.1.1 (former GVIId) in a high similarity with previously reported strains from Egypt since 2012 till now, as well as with other neighboring and geographically close countries. In conclusion, the recent NDV outbreaks have been likely caused by the distinctive genotype VII.1.1 which seems to be the predominant strain circulated in Egypt. So as to, it is recommended to be used as a contemporary vaccinal strain against the frequent NDV genotype VII outbreaks.
Keywords | Newcastle disease virus, Genotype VII.1.1, Prevalence, Phylogenesis, NDV outbreaks
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