Tang Yue, Davies Rob, Petrovska Liljana
Department of Bacteriology, Animal and Plant Health Agency, Addlestone, United Kingdom.
Front Vet Sci. 2019 Dec 18;6:447. doi: 10.3389/fvets.2019.00447. eCollection 2019.
Enteritidis is a major cause of salmonellosis worldwide and more than 80% of outbreaks investigated in Europe have been associated with the consumption of poorly cooked eggs or foods containing raw eggs. Vaccination has been proven to be one of the most important measures to control Enteritidis infections in poultry farms as it can decrease colonization of the reproductive organs and intestinal tract of laying hens, thereby reducing egg contamination. Differentiation of live vaccine from field or wild type . Enteritidis isolates in poultry is essential for monitoring of veterinary isolates and targetting control actions. Due to decreasing costs, whole genome sequencing (WGS) is becoming a key tool for characterization of isolates, including vaccine strains. Using WGS we described the genetic changes in the live attenuated Salmovac 440 and AviPro SALMONELLA VAC E vaccine strains and developed a method for differentiation from the wildtype . Enteritidis strains. SNP analysis confirmed that streptomycin resistance was associated with a Lys43Arg missense mutation in the L gene whilst 3 missense mutations in and 1 missense mutation in confer erythromycin sensitivity in AviPro SALMONELLA VAC E. Further mutations Arg242His in and Gly236Arg in the gene were related to adenine and histidine dependencies in Salmovac 440. Unique SNPs were used to construct a database of variants for differentiation of vaccine from the wildtype isolates. Two fragments from each vaccine were represented in the database to ensure high accuracy. Each of the two selected Salmovac 440 fragments differed by 6 SNPs from the wildtype and the AviPro SALMONELLA VAC E fragments differed by 4 and 6 SNPs, respectively. CD-hit software was applied to cluster similar fragments that produced the best fit output when searched with SRST2. The developed vaccine differentiation method was tested with 1,253 genome samples including field isolates of Salmovac 440 ( = 51), field isolates of AviPro SALMONELLA VAC E ( = 13), . Gallinarum ( = 19), . Pullorum ( = 116), . Enteritidis ( = 244), . Typhimurium ( = 810) and achieved 100% sensitivity and specificity.
肠炎沙门氏菌是全球沙门氏菌病的主要病因，在欧洲调查的疫情中，超过80%与食用未煮熟的鸡蛋或含有生鸡蛋的食物有关。疫苗接种已被证明是控制家禽养殖场肠炎沙门氏菌感染的最重要措施之一，因为它可以减少蛋鸡生殖器官和肠道的定植，从而减少鸡蛋污染。区分家禽中活疫苗与野外或野生型肠炎沙门氏菌分离株对于监测兽医分离株和采取针对性控制措施至关重要。由于成本降低，全基因组测序（WGS）正成为鉴定分离株（包括疫苗株）的关键工具。我们利用WGS描述了减毒活疫苗Salmovac 440和AviPro SALMONELLA VAC E疫苗株的基因变化，并开发了一种区分野生型肠炎沙门氏菌菌株的方法。单核苷酸多态性（SNP）分析证实，链霉素抗性与L基因中的Lys43Arg错义突变有关，而AviPro SALMONELLA VAC E中的3个错义突变和1个错义突变赋予了对红霉素的敏感性。Salmovac 440中进一步的突变Arg242His和基因中的Gly236Arg与腺嘌呤和组氨酸依赖性有关。独特的SNP被用于构建一个变异数据库，以区分疫苗和野生型分离株。数据库中每个疫苗的两个片段被展示出来以确保高准确性。所选的两个Salmovac 440片段与野生型相比，每个片段分别有6个SNP差异，AviPro SALMONELLA VAC E片段分别有4个和6个SNP差异。应用CD-hit软件对相似片段进行聚类，当用SRST2搜索时，产生最佳拟合输出。用1253个基因组样本对所开发的疫苗区分方法进行了测试，这些样本包括Salmovac 440的野外分离株（n = 51）、AviPro SALMONELLA VAC E的野外分离株（n = 13）、鸡伤寒沙门氏菌（n = 19）、鸡白痢沙门氏菌（n = 116）、肠炎沙门氏菌（n = 244）、鼠伤寒沙门氏菌（n = 810），该方法的敏感性和特异性均达到100%。
