Galofré-Milà N, Correa-Fiz F, Lacouture S, Gottschalk M, Strutzberg-Minder K, Bensaid A, Pina-Pedrero S, Aragon V
IRTA, Centre de Recerca en Sanitat Animal (CReSA, IRTA-UAB), Campus de la Universitat Autònoma de Barcelona, 08193, Bellaterra, Spain.
Faculté de médecine vétérinaire, Université de Montréal, 3200, rue Sicotte, Saint-Hyacinthe, Québec, J2S 2M2, Canada.
BMC Vet Res. 2017 May 8;13(1):124. doi: 10.1186/s12917-017-1041-4.
Haemophilus parasuis is the etiological agent of Glässer's disease in swine. H. parasuis comprises strains with heterogeneous virulence capacity, from non-virulent to highly virulent. Determination of the pathogenic potential of the strains is important for diagnosis and disease control. The virulence-associated trimeric autotransporters (vtaA) genes have been used to predict H. parasuis virulence by PCR amplification of their translocator domains. Here, we report a new and improved PCR designed to detect a different domain of the vtaA genes, the leader sequence (LS) as a diagnostic tool to predict virulence.
A collection of 360 H. parasuis strains was tested by PCR with LS specific primers. Results of the PCR were compared with the clinical origin of the strains and, for a subset of strains, with their phagocytosis and serum resistance using a Chi-square test.
LS-PCR was specific to H. parasuis, and allowed the differential detection of the leader sequences found in clinical and non-clinical isolates. Significant correlation was observed between the results of the LS-PCR and the clinical origin (organ of isolation) of the strains, as well as with their phagocytosis and serum susceptibility, indicating that this PCR is a good predictor of the virulence of the strains. In addition, this new PCR showed a full correlation with the previously validated PCR based on the translocator domain. LS-PCR could be performed in a wide range of annealing temperatures without losing specificity.
This newly described PCR based on the leader sequence of the vtaA genes, LS-PCR, is a robust test for the prediction of the virulence potential of H. parasuis strains.
副猪嗜血杆菌是猪格氏病的病原体。副猪嗜血杆菌包括毒力能力各异的菌株，从无毒力到高毒力。确定菌株的致病潜力对于诊断和疾病控制很重要。毒力相关三聚体自转运蛋白（vtaA）基因已被用于通过PCR扩增其转运结构域来预测副猪嗜血杆菌的毒力。在此，我们报告一种新的改进型PCR，旨在检测vtaA基因的不同结构域，即前导序列（LS），作为预测毒力的诊断工具。
用LS特异性引物通过PCR对360株副猪嗜血杆菌进行检测。使用卡方检验将PCR结果与菌株的临床来源进行比较，并对一部分菌株，将其与吞噬作用和血清抗性进行比较。
LS-PCR对副猪嗜血杆菌具有特异性，能够区分临床和非临床分离株中发现的前导序列。在LS-PCR结果与菌株的临床来源（分离器官）及其吞噬作用和血清敏感性之间观察到显著相关性，表明该PCR是菌株毒力的良好预测指标。此外，这种新的PCR与先前基于转运结构域验证的PCR完全相关。LS-PCR可以在很宽的退火温度范围内进行而不会失去特异性。
这种新描述的基于vtaA基因前导序列的PCR，即LS-PCR，是预测副猪嗜血杆菌菌株毒力潜力的可靠检测方法。
