McClure Jo-Ann, Lakhundi Sahreena, Niazy Amani, Dong George, Obasuyi Osahon, Gordon Paul, Chen Sidong, Conly John M, Zhang Kunyan
Centre for Antimicrobial Resistance, Alberta Health Services/Alberta Precision Laboratories/University of Calgary, Calgary, AB, Canada.
Department of Pathology & Laboratory Medicine, University of Calgary, Calgary, AB, Canada.
Front Microbiol. 2021 Feb 10;12:631845. doi: 10.3389/fmicb.2021.631845. eCollection 2021.
Despite initially being described in North America, (SA) sequence type ST59 is the most commonly isolated sequence type in Eastern Asia. The origins and evolution of this strain type remains unclear and therefore we gathered a collection of ST59 isolates from Canada and mainland China for a detailed genetic analysis of the lineage. Bayesian inference phylogenomic analysis of our isolates, along with previously published ST59 sequences indicated that the lineage could be divided into 6 distinct subgroups (WGS-1 thorough 6), each having distinct molecular characteristics. Analysis also demonstrated the concurrent but separate evolution of North American and East Asian lineages, as well as the extensive diversification of the East Asian lineage. The presence of a mobile element structure (MES) was found to be the major difference between these two continental lineages, absent in all North American isolates, and present in all East Asian ones. Other mobile genetic elements, such as the Immune Evasion Complex (IEC), Panton Valentine Leukocidin (PVL), and Staphylococcal Cassette Chromosome (SCC), showed significant variability within each sub-group and likely represents local selective pressures rather than major characteristics defining the groups. Our analysis also demonstrated the existence of a more ancient ST59 sub-lineage from North America, which was MES negative and contained some of the earliest reported ST59 isolates. Combined with the existence of a MES negative isolate from Taiwan, predicted to have appeared prior to diversification of the East Asian lineages, these results hint at the possibility of a North American origin for the lineage, which gained hold in Eastern Asia following acquisition of MES, and subsequently diversified.
尽管序列类型ST59最初是在北美被描述的，但它却是东亚地区最常分离出的序列类型。这种菌株类型的起源和进化仍不清楚，因此我们收集了来自加拿大和中国大陆的ST59分离株，对该谱系进行详细的基因分析。对我们的分离株以及先前发表的ST59序列进行贝叶斯推断系统发育基因组分析表明，该谱系可分为6个不同的亚组（WGS-1至6），每个亚组都有不同的分子特征。分析还表明，北美和东亚谱系同时但独立进化，以及东亚谱系的广泛多样化。发现移动元件结构（MES）的存在是这两个大陆谱系之间的主要差异，所有北美分离株中均不存在，而所有东亚分离株中均存在。其他移动遗传元件，如免疫逃避复合体（IEC）、杀白细胞素（PVL）和葡萄球菌盒式染色体（SCC），在每个亚组内表现出显著的变异性，可能代表局部选择压力而非定义这些组的主要特征。我们的分析还证明了北美存在一个更古老的ST59亚谱系，它是MES阴性的，包含一些最早报道的ST59分离株。结合来自台湾的一个MES阴性分离株的存在，预计它在东亚谱系多样化之前就已出现，这些结果暗示了该谱系可能起源于北美，在获得MES后在东亚扎根，随后多样化。
