Clonal population structure of Legionella pneumophila inferred from allelic profiling
Clonal population structure of Legionella pneumophila inferred from allelic profiling
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DOI：
10.1099/mic.0.2007/012336-0
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发表时间：
2008-03-01
期刊：
影响因子：
2.8
通讯作者：
Harrison, Timothy G.
中科院分区：
文献类型：
--
作者：
Edwards, Martin T.;Fry, Norman K.;Harrison, Timothy G.
通过对335株临床和环境来源的335株嗜肺军团菌的6个基因座(FlaA、Pell、ASD、MIP、ompS和ProA)的核苷酸序列分析，研究了29年(1977-2006年)嗜肺军团菌的种群结构。数据来自欧洲(n=270)、日本(n=31)、加拿大(n=7)、美国(n=24)和澳大利亚(n=1)的无关分离株。两个菌株的原产地尚不清楚。对这些菌株的分析表明，这6个基因座之间存在显著的连锁不平衡。六个基于序列的重组检测测试的应用没有显示重组的证据，但第七个测试对重组和突变率的估计表明，重组发生的速度可能与突变的速度相似，但可能低于突变的速度。在有和没有重组的模型下推断的系谱彼此一致，没有提供关于重组的确凿证据，并且与用图方法鉴定的序列簇一致。进一步的证据支持嗜肺乳杆菌亚种三个亚种中的两个具有不同的性质。Fraseri和亚种。Pascullei，也被发现。对每组等位基因的非同义核苷酸多态与同义核苷酸多态的比率进行了分析，发现可能的致病基因座MOMPS和PILL承受着多样性的压力，而另外三个与致病相关的基因座(FlaA、ProA和MIP)的等位基因区域则没有表现出多样性。
The population structure of Legionella pneumophila was investigated by analysing nucleotide sequences from six loci (flaA, pilE, asd, mip, mompS and proA) of 335 globally distributed isolates from clinical and environmental sources over a 29-year period (1977-2006). Data were obtained from unrelated isolates from Europe (n=270), Japan (n=31), Canada (n=7), the USA (n=24) and Australia (n=1). The country of origin of two strains was unknown. Analysis of these isolates indicated significant linkage disequilibrium between the six loci. Application of six sequence-based recombination detection tests did not reveal evidence of recombination, but estimates of rates of recombination and mutation made by a seventh test suggested that recombination could have occurred at a rate similar to, but probably lower than, that of mutation. Genealogies inferred under models with and without recombination were congruent with each other, providing no definitive evidence regarding recombination, and were in agreement with sequence clusters identified by graph methods. Further evidence supporting the distinct nature of two of the three subspecies of L. pneumophila, subsp. fraseri and subsp. pascullei, was also found. The ratios of non-synonymous to synonymous nucleotide polymorphisms for each of the allele sets were examined and revealed that the putative virulence loci mompS and pilE are under diversifying pressure, while the allelic regions of three other loci linked to virulence (flaA, proA and mip) do not appear to be.