Service of Hospital Preventive Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, 1011 Lausanne, Switzerland.
Infect Genet Evol. 2010 Oct;10(7):1117-23. doi: 10.1016/j.meegid.2010.07.013. Epub 2010 Jul 21.
The population structure of Staphylococcus aureus is generally described as highly clonal and is consequently subdivided into several clonal complexes (CCs). Recent data suggested that recombination might occur more frequently within than among CCs. To test this hypothesis as well as to understand how genetic diversity is created in S. aureus, we analyzed a collection of 182 isolates with MLST and five highly variable core adhesion (ADH) genes. As expected the polymorphism of ADH genes was higher than MLST genes. However both categories of genes showed low within CCs diversity with a dominant haplotype and its single nucleotide variants. Several recombination events were detected but none involved intra-CC recombination. This did not confirm the hypothesis of higher recombination within CCs. Nevertheless, molecular analyses of variance indicated that these few recombination events have a significant impact on the genetic diversity within CCs. In addition, although most ADH genes were under purifying selection, signs of positive selection associated with a recombinant group were detected. These data highlight the importance of recombination on the evolution of the highly clonal S. aureus and suggest that recombination when combined with demographic mechanisms as well as selection might favor the rapid creation of new clonal complexes.
金黄色葡萄球菌的种群结构通常被描述为高度克隆，因此分为几个克隆复合体（CCs）。最近的数据表明，重组可能在 CC 内比在 CC 间更频繁地发生。为了验证这一假设，并了解金黄色葡萄球菌中的遗传多样性是如何产生的，我们分析了一个由 182 个分离株组成的集合，这些分离株具有 MLST 和五个高度可变的核心粘附（ADH）基因。正如预期的那样，ADH 基因的多态性高于 MLST 基因。然而，这两类基因在 CC 内的多样性都很低，只有一个主要单倍型及其单一核苷酸变体。检测到了几个重组事件，但没有一个涉及 CC 内重组。这并没有证实 CC 内重组更高的假设。然而，方差的分子分析表明，这些少数重组事件对 CC 内的遗传多样性有重大影响。此外，尽管大多数 ADH 基因受到纯化选择的影响，但与重组群相关的正选择迹象被检测到。这些数据强调了重组对高度克隆的金黄色葡萄球菌进化的重要性，并表明重组与人口机制以及选择相结合，可能有利于新的克隆复合体的快速产生。
