Genetic structure of marine Borrelia garinii and population admixture with the terrestrial cycle of Lyme borreliosis
Genetic structure of marine Borrelia garinii and population admixture with the terrestrial cycle of Lyme borreliosis
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DOI：
10.1111/j.1462-2920.2011.02515.x
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发表时间：
2011-09-01
影响因子：
5.1
通讯作者：
Mccoy, Karen D.
中科院分区：
文献类型：
--
作者：
Gomez-Diaz, Elena;Boulinier, Thierry;Mccoy, Karen D.
尽管种群结构对致病菌的流行病学具有重要意义，但这些种群的空间和生态异质性往往特征不明显。本文研究了莱姆病（LB）螺旋体加里氏疏螺旋体在其海洋循环中的遗传多样性和种群结构，该循环涉及种群海鸟和不同宿主种族的海鸟蜱。8条染色体和2个质粒位点（ospA和ospC）的多位点序列分析（MLSA）表明，在海洋系统中循环的加里尼布氏杆菌具有高度的多样性。海洋加里尼贝的微进化似乎以克隆为主，但也发生了重组和选择。层序类型在地理区域间分布不均匀，大西洋和太平洋盆地之间存在较大的种群细分。然而，区域内没有明显的地理结构。选择分析的结果以及染色体和质粒位点之间的系统发育差异表明，该系统可能发生适应性进化，但没有发现宿主或载体相关的分化模式。重组分析显示，在陆地和海洋菌株之间存在种群混合的证据，表明LB螺旋体在这些地方性动物循环之间交换。重要的是，我们的结果强调需要明确考虑海洋系统，以全面了解莱姆病的进化生态学和全球流行病学。
Despite the importance of population structure for the epidemiology of pathogenic bacteria, the spatial and ecological heterogeneity of these populations is often poorly characterized. Here, we investigated the genetic diversity and population structure of the Lyme borreliosis (LB) spirochaete Borrelia garinii in its marine cycle involving colonial seabirds and different host races of the seabird tick Ixodes uriae. Multilocus sequence analyses (MLSA) on eight chromosomal and two plasmid loci (ospA and ospC) indicate that B. garinii circulating in the marine system is highly diverse. Microevolution in marine B. garinii seems to be mainly clonal, but recombination and selection do occur. Sequence types were not evenly distributed among geographic regions, with substantial population subdivision between Atlantic and Pacific Ocean basins. However, no geographic structuring was evident within regions. Results of selection analyses and phylogenetic discordance between chromosomal and plasmid loci indicate adaptive evolution is likely occurring in this system, but no pattern of host or vector-associated divergence was found. Recombination analyses showed evidence for population admixture between terrestrial and marine strains, suggesting that LB spirochaetes are exchanged between these enzootic cycles. Importantly, our results highlight the need to explicitly consider the marine system for a complete understanding of the evolutionary ecology and global epidemiology of Lyme borreliosis.