Surveillance and molecular characterization of newcastle disease virus from chickens in north Egypt during 2015-2017

الملخص EN

In the present study, fifty chickens flocks (47 broiler and 3 native Saso) suspected to be infected with Newcastle disease virus (NDV) in 5 northern Egyptian provinces: El Beheira (n: 21), Kafr El Sheikh (n: 8), El Gharbia (n: 7), Alexandaria (n: 7) and Marsa Matrouh (n: 7) during the period (from September 2015 to February 2017), were investigated for clinical and postmortem examination as well as virus isolation and molecular identification.

The results of virus isolation on SPF embryonated chicken eggs (ECE) revealed that 16/50 samples were haemagglutinatig agents by slide haemagglutination test.

These haemagglutinating agents were confirmed as NDV by real time polymerase chain reaction rRT-PCR .The deduced amino acid sequences of the fusion protein of selected 8 positive isolates revealed that (7/8) isolates possessed the motif 112RRQKRF117at the cleavage site, indicating that these isolates are velogenic, whereas the other (1/8) isolates carries the motif 112GRQGRL117indicating a lentogenic strain.

Phylogenetic analysis demonstrated that the 7 strains belong to the velogenic NDV (vNDV) genotype VIId and the other strain was of genotype II.

These velogenic isolates were detected even in vaccinated flocks indicating the wide spreading of vNDV outbreaks in Egypt