Department of Avian and Rabbit Medicine, Faculty of Veterinary Medicine, Zagazig University, Zagazig, Egypt.
Avian Pathol. 2023 Aug;52(4):251-263. doi: 10.1080/03079457.2023.2211548. Epub 2023 Jun 8.
Vaccines against vNDV are readily available and potentially protective; nevertheless, improved vaccination protocols are required to prevent clinical disease and discontinue the spread of the virus. This study assessed the effectiveness of two commercial recombinant herpesvirus of turkey vector vaccines (rHVT-NDV-IBDV) that express the fusion (F) protein of NDV and the virus protein 2 (VP2) of infectious bursal disease virus (IBDV). In commercial broilers with maternally-derived antibodies (MDAs) the efficacy of the rHVT-NDV-IBDV vaccines was evaluated when administered alone, in combination with live-attenuated NDV vaccine at one-day-old, or as part of a prime/boost strategy. The vaccinated birds were challenged with the genotype VIId vNDV strain (NDV/chicken/Egypt/1/2015) at various ages (14, 24 and 35 days). In comparison to sham-vaccinated control birds, the applied vaccination regimens were able to reduce or prevent mortality and virus shedding and clinical disease. Two weeks post-application, the two vector vaccines were serologically reactive with the MDAs and induced protective immune responses against the F protein. In the instance of early challenge at 14 days old, the combination of recombinant rHVT-NDV-IBDV with a live vaccine offered better protection and reduced virus shedding compared to the vector vaccine alone. Boosting with live NDV vaccine at 14 days old increased the protective effect of the vector vaccines and reduced virus shedding and the clinical index after challenge at 24 days old. Both combining and/or boosting with live vaccine together with the vector vaccine provided better protection and minimized virus shedding compared with vaccination with vector vaccine only in the instance of 5-week-old challenge.
针对 vNDV 的疫苗易于获得且具有潜在的保护作用；然而，需要改进疫苗接种方案以预防临床疾病并阻止病毒传播。本研究评估了两种表达 NDV 融合（F）蛋白和传染性法氏囊病病毒（IBDV）病毒蛋白 2（VP2）的商业重组火鸡疱疹病毒载体疫苗（rHVT-NDV-IBDV）的有效性。在具有母源抗体（MDA）的商业肉鸡中，当单独使用、与一日龄活减毒 NDV 疫苗联合使用或作为初免-加强策略的一部分时，评估了 rHVT-NDV-IBDV 疫苗的功效。接种疫苗的鸟类在不同年龄（14、24 和 35 天）用基因型 VIId vNDV 株（NDV/鸡/埃及/1/2015）进行攻毒。与假疫苗接种对照鸟类相比，应用的疫苗接种方案能够降低或预防死亡率、病毒脱落和临床疾病。接种后两周，两种载体疫苗与 MDA 血清学反应，并诱导针对 F 蛋白的保护性免疫反应。在 14 日龄早期攻毒的情况下，与单独使用载体疫苗相比，重组 rHVT-NDV-IBDV 与活疫苗联合使用提供了更好的保护效果，并降低了病毒脱落。在 14 日龄时用活 NDV 疫苗加强免疫增加了载体疫苗的保护效果，并降低了 24 日龄攻毒后的病毒脱落和临床指数。与仅接种载体疫苗相比，与活疫苗联合使用和/或加强免疫可提供更好的保护效果并最大限度地减少病毒脱落，特别是在 5 周龄攻毒的情况下。
