Department of Birds and Rabbits Medicine, Faculty of Veterinary Medicine, Sadat City University, Menoufiya 32958, Egypt; Animal and Plant Quarantine Agency, Gimcheon, Republic of Korea.
Department of Birds and Rabbits Medicine, Faculty of Veterinary Medicine, Sadat City University, Menoufiya 32958, Egypt.
Poult Sci. 2020 Mar;99(3):1275-1286. doi: 10.1016/j.psj.2019.10.063. Epub 2020 Feb 1.
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.
新城疫病毒（NDV）是全球家禽业的主要威胁，各种基因型与所有家禽部门的严重经济损失有关。中东和亚洲主要流行 II 类基因型 VII NDV，尽管使用常规活疫苗和灭活疫苗进行了密集的疫苗接种计划。在埃及，该疾病持续传播，导致家禽业遭受严重的经济损失。在这项研究中；评估了一种商业的、灭活的重组基因型 VII NDV 匹配疫苗（KBNP-C4152R2L 株）对毒力 NDV 株（鸡/美国/埃及/2015）挑战的保护效力在商业蛋鸡中。使用了两种疫苗接种方案；在第 10、18 和 120 天使用活 NDV 基因型 II（Lasota）疫苗，在第 14、42 和 120 天使用灭活 NDV 基因型 II 或灭活 NDV 基因型 VII 匹配疫苗方案。在第 26 周产蛋高峰期对这两种方案进行了挑战。根据死亡率、临床症状、大体病变、病毒脱落、血清转化和产蛋计划，在实验感染后评估这两种方案的保护效果。结果表明，这两种疫苗接种方案可以保护商业蛋鸡免受死亡，但一些鸡只表现出轻微的临床症状并暂时减少产蛋量。然而，活 NDV 基因型 II 和重组灭活基因型 VII 疫苗的联合使用可更好地降低病毒脱落（在气管拭子中分别为 20%和 0%与 60%和 40%）和（在泄殖腔拭子中分别为 20%和 0%与 20%和 20%）在 3 和 5 天攻毒后（dpc）。此外，接受灭活 NDV 基因型 VII 匹配疫苗方案和灭活基因型 II 疫苗的鸡的产蛋水平分别为 76.6%、79%、82%和 87.4%和 77.7%、72.5%、69%和 82.5%在 7、14、21 和 28 dpc。这项研究的结果表明，重组基因型匹配的灭活疫苗与活减毒疫苗联合使用可以减少病毒脱落，并在田间条件下感染强毒基因型 VII 病毒的商业蛋鸡中提高产蛋率。该方案可能确保蛋鸡的适当控制策略。
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