Enhanced Protection and Blocked Viral Shedding for Broiler Chickens in Challenge with Newcastle Disease Virus Genotype VII by Generation of Oil Inactivated Vaccine Antigenically-Matched to The Endemic Virus in Egypt
Enhanced Protection and Blocked Viral Shedding for Broiler Chickens in Challenge with Newcastle Disease Virus Genotype VII by Generation of Oil Inactivated Vaccine Antigenically-Matched to The Endemic Virus in Egypt
Sameh Abdel-Moez Ahmed Amer1*, Aly Mohammed Ghetas1, Asmaa Mahmoud Maatouq1, Hagar Magdy Ahmed1, Khaled Mohamed El-Bayoumi1, Mohamed Abd El-Rahman Bosila1, Ahmed Ali El-Shemy2
ABSTRACT
The control of velogenic Newcastle disease virus (VNDV) is still a serious challenge, especially in endemic localities in Egypt. The phylogenetic proximity between used vaccines and field viruses can definitely protect against repeated NDV outbreaks. Therefore, the aim of the this work is to prepare a secure, sterile and potent an oil inactivated vaccine from a recent local isolate genotype VII 1.1 “NDV-CH-EGY-GIZA-VVTNRC-2021” and evaluates its efficacy against commercially available NDV genotype II vaccines in broiler chickens. Eighty chickens were housed in four groups (A, B, C and D) of 20 birds per group. Group A has been received the experimentally prepared inactivated genotype VII NDV vaccine by day 9 old, subsequently primed and boostered with commercial live attenuated genotype VII vaccine at 7 and 21 days-of age. While group B was treated with commercial live and killed genotype II NDV vaccines at the same days, respectively. Furthermore, groups C and D act as positive and negative non-vaccinated controls. At 30 days of age groups A, B and C were challenged with VNDV genotype VII1.1 isolate, where the clinical manifestations, gross post-mortem lesions, Humoral immune response and also quantification of virus shed post-challenge (PC) via real-time QRT-PCR were all screened and precisely recorded. The results revealed that, group A chickens developed the highest humoral antibody titers throughout the vaccination schedule and conferred a complete protection against mortality with milder clinical signs, moreover displayed a significant decrease in the shedding of NDV with drastically blocked shedding 7 days PC compared to group B with little clinical protection, higher mortalities, lower antibody titers and longest viral shedding PC. In conclusion, the NDV genotype VII-based vaccines homologous to challenge virus ensure a significant control on VNDV in terms of clinical protection, mortality, and virus shedding than the genotype II classic vaccines heterologous to the endemic virus in broiler chickens.
Keywords | Velogenic Newcastle disease virus, Experimentally prepared vaccine, Viral shedding quantification, Genotype VII-based vaccines, Broiler chickens
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September 2023
Vol. 11, Iss. 9, pp. 1411-1596
