Animal Health Department, Faculty of Veterinary Science, University of León, León, Spain.
PLoS One. 2012;7(6):e39082. doi: 10.1371/journal.pone.0039082. Epub 2012 Jun 19.
Swine dysentery (SD) is a widespread diarrhoeal disease of pigs caused by infection of the large intestine with the anaerobic intestinal spirochaete Brachyspira hyodysenteriae. Understanding the dynamics of SD, and hence being able to develop more effective measures to counter its spread, depends on the ability to characterise B. hyodysenteriae variants and trace relationships of epidemic strains.
METHODOLOGY/PRINCIPAL FINDINGS: A collection of 51 Spanish and 1 Portuguese B. hyodysenteriae isolates was examined using a multilocus sequence typing (MLST) scheme based on the sequences of seven conserved genomic loci. The isolates were allocated to 10 sequence types (STs) in three major groups of descent. Isolates in four of the STs were widely distributed in farms around Spain. One farm was infected with isolates from more than one ST. Sequence data obtained from PubMLST for 111 other B. hyodysenteriae strains from other countries then were included in the analysis. Two of the predominant STs that were found in Spain also were present in other European countries. The 73 STs were arranged in eleven clonal complexes (Cc) containing between 2 and 26 isolates. A population snapshot based on amino acid types (AATs) placed 75% of the isolates from 32 of the 48 AATs into one major cluster. The founder type AAT9 included 22 isolates from 10 STs that were recovered in Spain, Australia, Sweden, Germany, Belgium, the UK, Canada, and the USA.
CONCLUSIONS/SIGNIFICANCE: This MLST scheme provided sufficient resolution power to unambiguously characterise B. hyodysenteriae isolates, and can be recommended as a routine typing tool that rapidly enables comparisons of isolates. Using this method it was shown that some of the main genetic lineages of B. hyodysenteriae in Spain also occurred in other countries, providing further evidence for international transmission. Finally, analysis of AATs appeared useful for deducing putative ancestral relationships between strains.
猪痢疾（SD）是一种广泛流行的猪腹泻病，由厌氧肠道螺旋体布氏密螺旋体感染大肠引起。了解 SD 的动态，从而能够开发更有效的措施来阻止其传播，取决于对 B. hyodysenteriae 变体进行特征描述和追踪流行菌株关系的能力。
方法/主要发现：使用基于七个保守基因组基因座序列的多位点序列分型（MLST）方案，对来自西班牙的 51 株和葡萄牙的 1 株 B. hyodysenteriae 分离株进行了检查。这些分离株被分为三个主要进化群的 10 个序列型（ST）。在西班牙的四个 ST 中，分离株分布广泛。一个农场被来自一个以上 ST 的分离株感染。从 PubMLST 获得的来自其他国家的 111 株其他 B. hyodysenteriae 菌株的序列数据也包括在分析中。在西班牙发现的两个主要 ST 也存在于其他欧洲国家。这 73 个 ST 被排列在包含 2 到 26 个分离株的 11 个克隆复合物（Cc）中。基于氨基酸类型（AAT）的种群快照将 32 个 AAT 中的 75%的分离株放入一个主要聚类中。创始人 AAT9 型包括来自 10 个 ST 的 22 株分离株，这些分离株在西班牙、澳大利亚、瑞典、德国、比利时、英国、加拿大和美国都有发现。
结论/意义：该 MLST 方案提供了足够的分辨率来明确地描述 B. hyodysenteriae 分离株，可以推荐作为一种常规的分型工具，能够快速比较分离株。使用这种方法表明，西班牙的一些 B. hyodysenteriae 主要遗传谱系也存在于其他国家，这进一步证明了国际传播的存在。最后，AAT 分析似乎有助于推断菌株之间的假定祖先关系。
