Efficacy of a Recombinant Genotype VII Vaccine against Challenge with Velogenic Newcastle Disease Virus

Abstract

Background: Newcastle disease virus (NDV) genotype VII has become the dominant genotype in China. However, NDV genotype II was used to make current commercial NDV vaccines. The mismatch of genotypes between circulating and vaccine strains of viruses may compromise the efficacy of vaccines. Methods:In this study, a current circulating NDV was attenuated by mutations of multiple basic amino acid motif of fusion cleavage site 112 RRQKGF 117 based on reverse genetic techniques. The recombinant virus was prepared as an inactivated vaccine to test its efficacy and compared with a commercial LaSota NDV vaccine on SPF chickens.Results: All vaccinated chickens survived by the end of the study. By contrast, the unvaccinated chickens were all dead before 5 days post-challenge (DPC). Compared to commercial LaSota vaccine, the experimental inactivated vaccine elicited earlier and higher titer of HI antibodies and had reduced titer and duration of virus shedding after challenge. Conclusion:The experimental inactivated NDV vaccine may work as a promising vaccine candidate to control the disease.NDV genotype II strains [7]. The cross-protection of vaccines to genotype VII virus was seldom explored. In this study, we developed an inactivated NDV genotype VII vaccine based on reverse genetic techniques and compared its efficacy with commercial LaSota vaccine on SPF chickens. Material and methods VirusNDV strain PLK-N-06 was isolated from an outbreak of ND in chickens and identified as velogenic [intracerebral pathogenicity index (ICPI) = 1.79, mean death time (MDT) = 49 h]. Phylogenetic analysis results showed that it belongs to NDV genotype VIId. The virus was grown in 10-day-old embryonated SPF chicken eggs. Allantoic fluid was collected for use.

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

“…Therefore, the experimentally prepared NDV vaccine induce the highest protective HI titers and enabled the challenged birds to exhibit better clinical protection and optimum efficacy against mortality. These results are harmonized with the recently reported by (Cheng et al, 2016;Mahmoud et al, 2019;Bello et al, 2020). Conversely, Adi et al (2019) found lower antibody titers induced by genotype VII NDV vaccines than of commercial genotype II, although it could fully protect chickens.…”

Preliminary Evidence on Passage Attenuation of Orthoavulavirus javaense Genotype VII.1.1 and Its Potency as a Living Vaccine Candidate

“…To prevent virus shedding and infection more than 6log 2 of antibody titers must be obtained (Kapczynski and King, 2005;Raghul et al, 2006;Han et al, 2017). Consequently, the attenuated virus was a potent inducer of an ascending titer of anti-hemagglutinin antibodies just 1 WPV (7 log2) in correlation with a high protection level in preventing mortalities and clinical manifestations and was consistent with earlier studies (Cheng et al, 2016;Bello et al, 2020).…”

Superior Efficacy of Apathogenic Genotype I (V4) over Lentogenic Genotype II (LaSota) Live Vaccines against Newcastle Disease Virus Genotype VII.1.1 in Pathogen-Associated Molecular Pattern-H9N2 Vaccinated Broiler Chickens

“…The antigenic differences in neutralizing epitopes between the circulating virulent viruses (e.g., genotype VII.1.1) and the vaccine strains may be responsible for the inadequate vaccine efficacy [4,13,15,16]. Furthermore, the higher matching percent of aa in the F and HN proteins of NDV vaccines and the field virus is essential for enhancing vaccine protection in terms of reduced infectivity and minimized viral shedding rate [6,14,15,[17][18][19][46][47][48]. Previously, high protection and a reduction in viral shedding have been reported in birds vaccinated with recombinant vaccines containing genotype I (D26) and challenged by heterologous genotypes VII.1.1, VII.2, and V of NDV [49][50][51][52].…”