La Tom, Phillips Nyree D, Harland Belinda L, Wanchanthuek Phatthanaphong, Bellgard Matthew I, Hampson David J
Animal Research Institute, Murdoch University, Western Australia, Australia.
Vet Microbiol. 2009 Sep 18;138(3-4):330-8. doi: 10.1016/j.vetmic.2009.03.025. Epub 2009 Mar 25.
The purpose of this study was to develop and apply a multilocus sequence typing (MLST) scheme to study the molecular epidemiology of Brachyspira hyodysenteriae, the aetiological agent of swine dysentery. Sequences of seven conserved genomic loci were examined in 111 B. hyodysenteriae strains. Fifty-eight of these previously had been analysed by multilocus enzyme electrophoresis (MLEE), and for some the results of pulsed field gel electrophoresis (PFGE), restriction endonuclease analysis (REA) and/or serotyping also were available. The discriminatory power of these methods was compared. The strains were divided into 67 sequence types (STs) and 46 amino acid types (AATs) by MLST. The Index of Association value was significantly different from zero, indication that the population was clonal. Eleven clonal complexes (Cc) comprising between 2 and 10 STs were recognised. A population snapshot based on AATs placed 77.5% of the isolates from 30 of the AATs into one major cluster. The founder type AAT9 included 13 strains from nine STs that were isolated in Australia, Sweden, Germany and Belgium, including one from a mallard. The MLST results were generally comparable to those produced by MLEE. The MLST system had a similar discriminatory power to PFGE, but was more discriminatory than REA, MLEE or serotyping. MLST data provided evidence for likely transmission of strains between farms, but also for the occurrence of temporal "micro-evolution" of strains on individual farms. Overall, the MLST system proved to be a useful new tool for investigating the molecular epidemiology and diversity of B. hyodysenteriae.
本研究的目的是开发并应用多位点序列分型（MLST）方案，以研究猪痢疾的病原体——猪痢疾短螺旋体的分子流行病学。对111株猪痢疾短螺旋体菌株的7个保守基因组位点的序列进行了检测。其中58株此前已通过多位点酶电泳（MLEE）进行分析，部分菌株还可获得脉冲场凝胶电泳（PFGE）、限制性内切酶分析（REA）和/或血清分型的结果。比较了这些方法的鉴别能力。通过MLST将这些菌株分为67个序列型（STs）和46个氨基酸型（AATs）。关联指数值显著不同于零，表明该群体是克隆性的。识别出11个克隆复合体（Cc），每个复合体包含2至10个STs。基于AATs的群体快照将来自30个AATs的77.5%的分离株归入一个主要聚类。原始型AAT9包括来自9个STs的13株菌株，这些菌株分别从澳大利亚、瑞典、德国和比利时分离得到，其中一株来自一只绿头鸭。MLST结果总体上与MLEE的结果相当。MLST系统与PFGE具有相似的鉴别能力，但比REA、MLEE或血清分型更具鉴别力。MLST数据为菌株在农场间可能的传播提供了证据，但也为单个农场中菌株的时间性“微进化”的发生提供了证据。总体而言，MLST系统被证明是研究猪痢疾短螺旋体分子流行病学和多样性的一种有用的新工具。
