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.

中文翻译：

---

新城疫病毒基因型VII匹配疫苗在商业层的保护效力。

新城疫病毒（NDV）对全世界的家禽业构成重大威胁，其基因型的多样性与所有家禽业的严重经济损失有关。尽管使用常规的活的和灭活的NDV疫苗进行了密集的疫苗接种计划，但中东和亚洲仍是II型VII型NDV基因型。在埃及，疾病不断传播，给家禽业造成严重的经济损失。在这个研究中; 在商业层中评估了商业灭活的重组基因型VII NDV配对疫苗（KBNP-C4152R2L株）对velogenic NDV株的攻击（Chicken / USC / Egypt / 2015）的保护作用。使用了两种疫苗接种方案；第10、18和120天的NDV基因型II（LaSota）活疫苗，在第14、42和120天使用灭活的NDV基因型II疫苗方案或灭活的NDV基因型VII匹配疫苗方案。在26周的产蛋高峰时，对这2种方案进行了攻击。在实验后对这2种方案的保护进行了评估根据死亡率，临床体征，严重病变，病毒脱落，血清转化和产蛋计划来确定是否感染。结果表明，这两种疫苗接种方案可保护商业蛋鸡免于死亡，但有些鸟类表现出轻度的临床体征并暂时降低了产蛋量。但是，结合气管拭子和（分别为20％和0％vs.）评估，活的NDV基因型II和重组灭活的基因型VII疫苗的结合提供了更好的保护，防止病毒脱落（20％和0％对60％和40％）。在攻击后3和5 D（dpc）分别收集泄殖腔拭子的20％和20％。此外，接受灭活的NDV基因型VII匹配疫苗方案的鸟类和接种灭活的基因型II疫苗的鸟类的产蛋量分别为76.6、79、82和87.4％，77.7、72.5、69和82.5％。 ，21和28 dpc。这项研究的结果表明，在田间条件下，重组基因型匹配的灭活疫苗以及减毒活疫苗可以减少病毒的释放，并提高在商业上受到velogenic基因型VII型病毒攻击的商业蛋鸡的产蛋量。这种制度可以确保适当的分层控制策略。接受灭活的NDV基因型VII匹配疫苗方案的鸟类和接种灭活的基因型II疫苗的鸟类的卵生产水平分别为76.6％，79％，82％和87.4％和77.7％，72.5％，69％和82.5％，和28 dpc。这项研究的结果表明，在田间条件下，重组基因型匹配的灭活疫苗以及减毒活疫苗可以减少病毒的释放，并提高在商业上受到velogenic基因型VII型病毒攻击的商业蛋鸡的产蛋量。该机制可以确保适当的分层控制策略。接受灭活的NDV基因型VII匹配疫苗方案的鸟类和接种灭活的基因型II疫苗的鸟类的卵生产水平分别为76.6％，79％，82％和87.4％和77.7％，72.5％，69％和82.5％，和28 dpc。这项研究的结果表明，在田间条件下，重组基因型匹配的灭活疫苗和减毒活疫苗可以减少病毒的释放，并提高在商业上受到velogenic基因型VII型病毒攻击的商业蛋鸡的产蛋量。该机制可以确保适当的分层控制策略。这项研究的结果表明，在田间条件下，重组基因型匹配的灭活疫苗以及减毒活疫苗可以减少病毒的释放，并提高在商业上受到velogenic基因型VII型病毒攻击的商业蛋鸡的产蛋量。该机制可以确保适当的分层控制策略。这项研究的结果表明，在田间条件下，重组基因型匹配的灭活疫苗以及减毒活疫苗可以减少病毒的释放，并提高在商业上受到velogenic基因型VII型病毒攻击的商业蛋鸡的产蛋量。该机制可以确保适当的分层控制策略。