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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.

SUBMITTER: Sultan HA

PROVIDER: S-EPMC7587656 | biostudies-literature | 2020 Mar

REPOSITORIES: biostudies-literature

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

Sultan Hesham A HA Talaat Shaimaa S Elfeil Wael K WK Selim Karim K Kutkat Mohamed A MA Amer Sameh A SA Choi Kang-Seuk KS

Poultry science 20200201 3

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 commercia ...[more]

PMID: 32111305

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Project description:Class II genotype VII Newcastle disease viruses (NDV) are predominant in the Middle East and Asia despite intensive vaccination programs using conventional live and inactivated NDV vaccines. In this study, the protective efficacies of three commercial vaccine regimes involving genotype II NDV, recombinant genotype VII NDV-matched, and an autogenous velogenic NDV genotype VII vaccine were evaluated against challenge with velogenic NDV genotype VII (accession number MG029120). Three vaccination regimes were applied as follows: group-1 received inactivated genotype II, group-2 received inactivated recombinant genotype VII NDV-matched, and group-3 received velogenic inactivated autogenous NDV genotype VII vaccines given on day 7; for the live vaccine doses, each group received the same live genotype II vaccine. The birds in all of the groups were challenged with NDV genotype VII, which was applied on day 28. Protection by the three regimes was evaluated after infection based on mortality rate, clinical signs, gross lesions, virus shedding, seroconversion, and microscopic changes. The results showed that these three vaccination regimes partially protected commercial broilers (73%, 86%, 97%, respectively, vs. 8.6% in non-vaccinated challenged and 0% in non-vaccinated non-challenged birds) against mortality at 10 days post-challenge (dpc). Using inactivated vaccines significantly reduced the virus shedding at the level of the number of shedders and the amount of virus that was shed in all vaccinated groups (G1-3) compared to in the non-vaccinated group (G-4). In conclusion, using closely genotype-matched vaccines (NDV-GVII) provided higher protection than using vaccines that were not closely genotype-matched and non-genotype-matched. The vaccine seeds that were closely related to genotype VII.1.1 provided higher protection against challenge against this genotype since it circulates in the Middle East region. Updating vaccine seeds with recent and closely related isolates provides higher protection.

Project description:Newcastle disease (ND) is endemic in Bangladesh. Locally produced or imported live Newcastle disease virus (NDV) vaccines based on lentogenic virus strains, locally produced live vaccines of the mesogenic Mukteswar strain, as well as imported inactivated vaccines of lentogenic strains, are being used in Bangladesh under different vaccination regimens. Despite these vaccinations, frequent outbreaks of ND are being reported in Bangladesh. Here we compared the efficacy of booster immunization with three different vaccines in chickens that had been primed with two doses of live LaSota vaccine. A total of 30 birds (Group A) were primed with two doses of live LaSota virus (genotype II) vaccine at days 7 and 28, while 20 birds (Group B) remained unvaccinated. At day 60, birds of Group A were divided into three sub-groups, which received booster immunizations with three different vaccines; A1: live LaSota vaccine, A2: inactivated LaSota vaccine, and A3: inactivated genotype XIII.2 vaccine (BD-C161/2010 strain from Bangladesh). Two weeks after booster vaccination (at day 74), all vaccinated birds (A1-A3) and half of the unvaccinated birds (B1) were challenged with a genotype XIII.2 virulent NDV (BD-C161/2010). A moderate antibody response was observed after the primary vaccination, which substantially increased after the booster vaccination in all groups. The mean HI titers induced by the inactivated LaSota vaccine (8.0 log2/5.0 log2 with LaSota/BD-C161/2010 HI antigen) and the inactivated BD-C161/2010 vaccine (6.7 log2/6.2 log2 with LaSota/BD-C161/2010 HI antigen) were significantly higher than those induced by the LaSota live booster vaccine (3.6 log2/2.6 log2 with LaSota/BD-C161/2010 HI antigen). Despite the differences in the antibody titers, all chickens (A1-A3) survived the virulent NDV challenge, while all the unvaccinated challenged birds died. Among the vaccinated groups, however, 50% of the chickens in Group A1 (live LaSota booster immunization) shed virus at 5- and 7-days post challenge (dpc), while 20% and 10% of the chickens in Group A2 (inactivated LaSota booster immunization) shed virus at 3 and 5 dpc, respectively, and only one chicken (10%) in Group A3 shed virus at 5 dpc. In conclusion, the genotype-matched inactivated NDV booster vaccine offers complete clinical protection and a significant reduction in virus shedding.

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

Publications

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

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