Characterization of Newcastle Disease Virus (NDV) genotype VII isolated from wild birds and efficacy evaluation of genotype VII vaccines against velogenic NDV challenge

Wild birds have a critical role in transmission of wide variety of viral diseases to poultry flocks worldwide, and considered as a natural reservoir of Newcastle disease virus (NDV). However, no available data on the prevalence of NDV genotype VII isolated from wild birds especially in Egypt. For this purpose,240 samples were collected from (cattle egrets, sparrows and feral pigeons) in Kafrelsheikh Provence during the period (Septemper2016 to Aprii2018) For identification the most circulating NDV strain responsible for devastating out breaks with in poultry flocks. Oropharyngeal swabs were taken from diseased birds and slide agglutination test was done. The diseased birds suffered from ruffled feathers and whitish diarrhea with enteritis, congested pectoral muscles, lungs, liver and spleen with cloudiness of the air sacs. Amplification of (400bp) of (F) protein by RT-PCR in 2 out of28 samples from cattle egrets (7.1%), 1 out of 10 samples from sparrows (1%) and 1 out of 10 samples from feral pigeons (10%). Phylogenetic analysis depending on F gene partial sequence clustered these isolates in NDV genotype VII with identity (94.9%) with NDV-chicken china-SOWF-07-2011.The protection efficiency of commercially produced genotype VIINDV inactivated and live vaccines also evaluated when compared with existing programs of vaccination against challenge. The results revealed that the combination of recombinant and live virus of genotype VII vaccines give protection rate (99.6%) against challenge with isolated velogenic NDV in commercial broilers in comparison to inactivated genotype VII alone.