School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia.
Appl Environ Microbiol. 2011 Feb;77(3):768-75. doi: 10.1128/AEM.01993-10. Epub 2010 Dec 3.
Yersinia pseudotuberculosis is an enteric human pathogen but is widespread in the environment. Pathogenicity is determined by a number of virulence factors, including the virulence plasmid pYV, the high-pathogenicity island (HPI), and the Y. pseudotuberculosis-derived mitogen (YPM), a superantigen. The presence of the 3 virulence factors varies among Y. pseudotuberculosis isolates. We developed a multilocus sequence typing (MLST) scheme to address the population structure of Y. pseudotuberculosis and the evolution of its pathogenicity. The seven housekeeping genes selected for MLST were mdh, recA, sucA, fumC, aroC, pgi, and gyrB. An MLST analysis of 83 isolates of Y. pseudotuberculosis, representing 19 different serotypes and six different genetic groups, identified 61 sequence types (STs) and 12 clonal complexes. Out of 26 allelic changes that occurred in the 12 clonal complexes, 13 were mutational events while 13 were recombinational events, indicating that recombination and mutation contributed equally to the diversification of the clonal complexes. The isolates were separated into 2 distinctive clusters, A and B. Cluster A is the major cluster, with 53 STs (including Y. pestis strains), and is distributed worldwide, while cluster B is restricted to the Far East. The YPM gene is widely distributed on the phylogenetic tree, with ypmA in cluster A and ypmB in cluster B. pYV is present in cluster A only but is sporadically absent in some cluster A isolates. In contrast, an HPI is present only in a limited number of lineages and must be gained by lateral transfer. Three STs carry all 3 virulence factors and can be regarded as high-pathogenicity clones. Isolates from the same ST may not carry all 3 virulence factors, indicating frequent gain or loss of these factors. The differences in pathogenicity among Y. pseudotuberculosis strains are likely due to the variable presence and instability of the virulence factors.
假结核耶尔森菌是一种肠道人类病原体，但广泛存在于环境中。致病性由多种毒力因子决定，包括毒力质粒 pYV、高致病性岛 (HPI) 和假结核耶尔森菌衍生的丝裂原 (YPM)，一种超抗原。3 种毒力因子在假结核耶尔森菌分离株中的存在情况各不相同。我们开发了一种多位点序列分型 (MLST) 方案，以解决假结核耶尔森菌的种群结构及其致病性的进化问题。选择用于 MLST 的 7 个看家基因是 mdh、recA、sucA、fumC、aroC、pgi 和 gyrB。对代表 19 种不同血清型和 6 种不同遗传群的 83 株假结核耶尔森菌进行 MLST 分析，确定了 61 种序列类型 (ST) 和 12 个克隆复合体。在 12 个克隆复合体中发生的 26 个等位基因变化中，13 个是突变事件，13 个是重组事件，表明重组和突变对等位基因复合体的多样化做出了同样的贡献。这些分离株被分为 2 个不同的簇，A 和 B。A 簇是主要的簇，有 53 个 ST（包括鼠疫耶尔森氏菌株），分布于全球，而 B 簇仅限于远东地区。YPM 基因在系统发育树上广泛分布，ypmA 在 A 簇，ypmB 在 B 簇。pYV 仅存在于 A 簇，但在一些 A 簇分离株中偶尔缺失。相反，HPI 仅存在于有限的谱系中，必须通过横向转移获得。有 3 个 ST 携带所有 3 种毒力因子，可视为高致病性克隆。来自同一 ST 的分离株不一定携带所有 3 种毒力因子，表明这些因子经常获得或丢失。假结核耶尔森菌菌株之间的致病性差异可能是由于毒力因子的存在和不稳定性不同。
