Document Type : Original Article
Authors
1
Birds and Rabbit Medicin Department, Fac. of Vet. Medicin, Sadat City University, Menofia, Egypt
2
Poultry Disease Department, Fac. of Vet. Medicin, Cairo University, Cairo, Egypt
3
Birds and Rabbits Medicine department, Faculty of Veterinary Medicine, Sadat City University, Menoufia, Egypt
Abstract
The protective efficacy of live and inactivated NDV- genotype II vaccines against challenge with velogenic Newcastle disease virus (VNDV) genotype VII (Chicken/USC/Egypt/2014), was evaluated in vaccinated groups (G1, G2, G3, G4 and G5) with inactivated vaccine on day 7 and live vaccine (LaSota) on days 7 and 15, in addition, with live V4 strain either on day 1 (G1) or on day 25 (G2) or in both days 1 and 25 (G3) and challenged on day 32 of age. The protection percentages were 96%, 96%, 96% and 88% in G1, G2, G3 & G4, respectively, vs 4% in non-vaccinated challenged chickens (G5). Moreover, the tracheal and cloacal viral shedding were 30% & 100% ; 0% & 0% ; 0% & 30%; 0% & 30% in vaccinated challenged G1, G2, G3 & G4, respectively, vs 100% & 60% in non-vaccinated challenged G5 at 3 DPC, whereas, the tracheal and cloacal viral shedding were 0% & 30% ; 0% & 0% ; 0% & 0% ; 30% & 60% in vaccinated challenged G1, G2, G3 & G4, respectively, vs 100% & 100% non-vaccinated challenged G5 at 7 dpc. However, the clinical signs, gross lesions and serological response were monitored till 14 dpc. Our results revealed that the inclusion of V4 vaccine strain in vaccination program is providing superior protection against NDV genotype VII and good safely replace live (LaSota) in early and late vaccination practices.
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