Rapid evolution of distinct Helicobacter pylori subpopulations in the Americas.
Rapid evolution of distinct Helicobacter pylori subpopulations in the Americas.
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DOI：
10.1371/journal.pgen.1006546
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发表时间：
2017-02
期刊：
影响因子：
4.5
通讯作者：
Falush D
中科院分区：
文献类型：
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作者：
Thorell K;Yahara K;Berthenet E;Lawson DJ;Mikhail J;Kato I;Mendez A;Rizzato C;Bravo MM;Suzuki R;Yamaoka Y;Torres J;Sheppard SK;Falush D
在过去的500年里，美洲一直是一个大熔炉，既有遗传多样性的人类，也有与之相关的致病和寄生生物。其中一种微生物是胃内细菌幽门螺杆菌，它在拉丁美洲非常普遍，因为它与胃癌有很强的关联，所以它是当前主要的公共卫生挑战。通过对H. pylori分离在北美，中美和南美，我们发现的证据之间的混合H。幽门螺杆菌的欧洲和非洲起源遍布美洲，没有大量的输入从前哥伦布（hspAmerind）细菌。在美国，非洲和欧洲起源的菌株在遗传上仍然不同，而在哥伦比亚和尼加拉瓜，瓶颈和分离株之间猖獗的遗传交换导致了国家基因库的形成。我们发现了三个外膜蛋白与非典型水平的亚洲血统的美国菌株，以及等位基因，几乎是固定的，特别是在南美的分离株，这表明在传入菌株的殖民化的主机的种族构成的作用。结果表明，新的H.在人口流动期间，幽门螺杆菌亚群可以迅速出现、传播和适应，这表明高流行率和低流行率地区之间的传播生态学差异可能实质上影响细菌种群的组成。幽门螺杆菌是细菌与人类之间密切联系的最佳研究例子之一，因为它能够在胃中定植数十年并代代相传。许多研究试图将H.幽门螺杆菌与人类迁徙之间的关系，但也有一些不一致的信号，例如在过去几千年中“走出非洲”的传播，在细菌基因组中留下了比人类基因组更强的信号。为了理解这种差异是如何产生的，我们研究了H。幽门螺杆菌在美洲的殖民化过程中。我们发现细菌种群进化迅速，可以迅速传播给不同种族的人。在哥伦比亚，从欧洲来源形成了独特的新细菌亚群，在尼加拉瓜和美国，从非洲来源形成了独特的新细菌亚群。细菌种群之间的遗传交换在中美洲和南美洲很猖獗，但在北美并不常见，这可能反映了流行率的差异。我们的研究结果还表明，细菌对特定人类种族的适应可能仅限于与免疫系统相互作用的少数基因。
For the last 500 years, the Americas have been a melting pot both for genetically diverse humans and for the pathogenic and commensal organisms associated with them. One such organism is the stomach-dwelling bacterium Helicobacter pylori, which is highly prevalent in Latin America where it is a major current public health challenge because of its strong association with gastric cancer. By analyzing the genome sequence of H. pylori isolated in North, Central and South America, we found evidence for admixture between H. pylori of European and African origin throughout the Americas, without substantial input from pre-Columbian (hspAmerind) bacteria. In the US, strains of African and European origin have remained genetically distinct, while in Colombia and Nicaragua, bottlenecks and rampant genetic exchange amongst isolates have led to the formation of national gene pools. We found three outer membrane proteins with atypical levels of Asian ancestry in American strains, as well as alleles that were nearly fixed specifically in South American isolates, suggesting a role for the ethnic makeup of hosts in the colonization of incoming strains. Our results show that new H. pylori subpopulations can rapidly arise, spread and adapt during times of demographic flux, and suggest that differences in transmission ecology between high and low prevalence areas may substantially affect the composition of bacterial populations. Helicobacter pylori is one of the best studied examples of an intimate association between bacteria and humans, due to its ability to colonize the stomach for decades and to transmit from generation to generation. A number of studies have sought to link diversity in H. pylori to human migrations but there are some discordant signals such as an “out of Africa” dispersal within the last few thousand years that has left a much stronger signal in bacterial genomes than in human ones. In order to understand how such discrepancies arise, we have investigated the evolution of H. pylori during the recent colonization of the Americas. We find that bacterial populations evolve quickly and can spread rapidly to people of different ethnicities. Distinct new bacterial subpopulations have formed in Colombia from a European source and in Nicaragua and the US from African sources. Genetic exchange between bacterial populations is rampant within Central and South America but is uncommon within North America, which may reflect differences in prevalence. Our results also suggest that adaptation of bacteria to particular human ethnic groups may be confined to a handful of genes involved in interaction with the immune system.