Cardenas-Garcia Stivalis, Diel Diego G, Susta Leonardo, Lucio-Decanini Eduardo, Yu Qingzhong, Brown Corrie C, Miller Patti J, Afonso Claudio L
Southeast Poultry Research Laboratory, 934 College Station Rd., Athens, GA 30605, USA; Department of Veterinary Pathology, College of Veterinary Medicine, The University of Georgia, College of Veterinary Medicine, 501 D. W. Brooks Dr., Athens, GA, USA.
Department of Veterinary and Biomedical Sciences, Animal Disease Research and Diagnostic Laboratory, South Dakota State University, Brookings, SD 57007, USA.
Biologicals. 2015 Mar;43(2):136-45. doi: 10.1016/j.biologicals.2014.11.003. Epub 2014 Dec 12.
While there is typically 100% survivability in birds challenged with vNDV under experimental conditions, either with vaccines formulated with a strain homologous or heterologous (different genotype) to the challenge virus, vaccine deficiencies are often noted in the field. We have developed an improved and more stringent protocol to experimentally evaluate live NDV vaccines, and showed for the first time under experimental conditions that a statistically significant reduction in mortality can be detected with genotype matched vaccines. Using both vaccine evaluation protocols (traditional and improved), birds were challenged with a vNDV of genotype XIII and the efficacy of live heterologous (genotype II) and homologous (genotype XIII) NDV vaccines was compared. Under traditional vaccination conditions there were no differences in survival upon challenge, but the homologous vaccine induced significantly higher levels of antibodies specific to the challenge virus. With the more stringent challenge system (multiple vaccine doses and early challenge with high titers of vNDV), the birds administered the homologous vaccine had superior humoral responses, reduced clinical signs, and reduced mortality levels than those vaccinated with the heterologous vaccine. These results provide basis for the implementation of more sensitive methods to evaluate vaccine efficacy.
虽然在实验条件下，用与攻击病毒同源或异源（不同基因型）毒株配制的疫苗对感染新城疫病毒（vNDV）的鸟类进行攻毒时，其存活率通常为100%，但在实际应用中，疫苗缺陷却屡见不鲜。我们开发了一种改进且更严格的方案来实验性评估新城疫病毒活疫苗，并首次在实验条件下表明，使用基因型匹配的疫苗可检测到死亡率有统计学意义的降低。使用两种疫苗评估方案（传统方案和改进方案），用基因型XIII的vNDV对鸟类进行攻毒，并比较了异源（基因型II）和同源（基因型XIII）新城疫病毒活疫苗的效力。在传统疫苗接种条件下，攻毒后的存活率没有差异，但同源疫苗诱导产生的针对攻击病毒的特异性抗体水平显著更高。在更严格的攻毒系统（多剂疫苗和高滴度vNDV早期攻毒）下，接种同源疫苗的鸟类比接种异源疫苗的鸟类具有更好的体液免疫反应、减轻的临床症状和更低的死亡率。这些结果为实施更敏感的方法来评估疫苗效力提供了依据。
