Protective efficacy of the Newcastle disease virus genotype VII–matched vaccine in commercial layers

Abstract

Newcastle disease virus ( NDV ) is a major threat to the poultry industry worldwide, with a diversity of genotypes associated with severe economic losses in all poultry sectors. Class II genotype VII NDV are predominant in the Middle East and Asia, despite intensive vaccination programs using conventional live and inactivated NDV vaccines. In Egypt, the disease is continuously spreading, causing severe economical losses in the poultry industry. In this study; the protective efficacy of a commercial, inactivated recombinant genotype VII NDV–matched vaccine (KBNP-C4152R2L strain) against challenge with the velogenic NDV strain (Chicken/USC/Egypt/2015) was evaluated in commercial layers. Two vaccination regimes were used; live NDV genotype II (LaSota) vaccine on days 10, 18, and 120, with either the inactivated NDV genotype II regime or inactivated NDV genotype VII–matched vaccine regime on days 14, 42, and 120. The 2 regimes were challenged at the peak of egg production on week 26. Protection by the 2 regimes was evaluated after experimental infection, based on mortality rate, clinical signs, gross lesions, virus shedding, seroconversion, and egg production schedule. The results show that these 2 vaccination regimes protected commercial layer chickens against mortality, but some birds showed mild clinical signs and reduced egg production temporarily. However, the combination of live NDV genotype II and recombinant inactivated genotype VII vaccines provided better protection against virus shedding (20% and 0% vs. 60% and 40%) as assessed in tracheal swabs and (20% and 0% vs. 20% and 20%) in cloacal swabs collected at 3 and 5 D post challenge ( dpc ), respectively. In addition, egg production levels in birds receiving the inactivated NDV genotype VII–matched vaccine regime and in those given inactivated genotype II vaccines were 76.6, 79, 82, and 87.4% and 77.7, 72.5, 69, and 82.5% at 7, 14, 21, and 28 dpc, respectively. The results of this study indicate that recombinant genotype-matched inactivated vaccine along with a live attenuated vaccine can reduce virus shedding and improve egg production in commercial layers challenged with a velogenic genotype VII virus under field conditions. This regime may ensure a proper control strategy in layers.

Comparison of the Effectiveness of Two Different Vaccination Regimes for Avian Influenza H9N2 in Broiler Chicken

“…This may be referred to the amount of antigen in each vaccine, with vaccine A containing a higher amount of antigen (350 HAU unit/dose), while vaccine B contained around 200 HAU unit/dose [38]. As previously reported by , increasing the dose from 200 to 250 or 350 HAU can improve the immune response and protection against H9N2 [6].…”

“…), in addition to coccidia species. All these pathogens have caused severe economic losses and have badly affected the veterinary care strategies [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. Avian influenza (AI) is a contagious viral disease, belonging to the Orthomyxoviridae family, and is a segmented, single-stranded, negative sense RNA virus [ 11 , 12 ].…”

Sequence analysis and pathogenicity of Avian Orthoavulavirus 1 strains isolated from poultry flocks during 2015–2019

“…It had been established that homologous genotype vaccines are more effective in preventing virus replication and shedding after challenge than heterologous NDV genotype VII vaccine [52,54,55]. However, Sultan et al [56] recommended the combined vaccination regime of inactivated genotype VII-matched and live genotype II vaccines for three times along the rearing period in commercial layers for better protection against clinical disease, mortality and viral shedding confirming the results of Sedeik et al [57]. The aforementioned authors reported that the use of either inactivated genotype VII or II once alone induced the insufficient protection against clinical disease, mortality, and viral shedding in broiler chickens.…”

Correlation between ESβL Salmonella Serovars Isolated from Broilers and their Virulence Genes

“…T he poultry industry is exposed to several threats such as of viral origin like avian Influenza, Newcastle disease, infectious bronchitis, infectious bursal disease, avian adenovirus, or of bacterial origin like the Salmonellae species, Escherichia coli, Clostridium spp. (Ayoub et al 2019, Diab et al 2019, Elhady et al 2018, Fawzy et al 2020, Sedeik et al 2018, Sultan et al 2019a, Sultan et al 2019b, Sultan et al 2020. Salmonella is one of the most serious bacterial pathogens as it is associated with economic losses in poultry farms in addition to the zoonotic effects.…”