Genomes of Helicobacter pylori from native Peruvians suggest admixture of ancestral and modern lineages and reveal a western type cag-pathogenicity island.
Genomes of Helicobacter pylori from native Peruvians suggest admixture of ancestral and modern lineages and reveal a western type cag-pathogenicity island.
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DOI：
10.1186/1471-2164-7-191
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发表时间：
2006-07-27
期刊：
影响因子：
4.4
通讯作者：
Ahmed N
中科院分区：
文献类型：
--
作者：
Devi SM;Ahmed I;Khan AA;Rahman SA;Alvi A;Sechi LA;Ahmed N
幽门螺杆菌被认为是与其人类宿主共同进化的，在遗传水平上是一种高度多样化的胃病原体。幽门螺旋杆菌在新大陆的古老起源仍有争议。目前尚不清楚南美洲不同的人类迁徙浪潮如何促进幽门螺杆菌菌株多样性的进化。我们的“系统地理学”研究的目的是通过绘制秘鲁土著（美洲印第安人血统）幽门螺杆菌的遗传起源，并将其与西班牙和日本分离的幽门螺杆菌进行基因组比较，获得对这些问题的新见解。为此，我们试图通过荧光扩增片段长度多态性（FAFLP）分析、7个持家基因（atpA、efp、ureI、ppa、mutY、trpC、yphC）的多位点序列分型（MLST）分析以及babB粘附素和oipA基因的序列分析来剖析菌株的遗传特性。采用PCR方法分析了这些菌株的cagPAI全致病性，并通过基因测序确定了cagA磷酸化基序EPIYA的地理类型。我们观察到，虽然欧洲基因型（hp-Europe）在秘鲁本土菌株中占主导地位，但这些菌株中约有20%代表具有美洲印第安血统的亚群（hsp-Amerind）。然而，所有这些菌株，不管它们的祖先隶属关系如何，都拥有一个完整的“西方”型cagPAI及其周围的图案。这表明在数十年的共定殖过程中，hsp-美国菌株可能从欧洲菌株获得cagPAI。我们的观察表明，幽门螺杆菌祖先（hsp-Amerind）在秘鲁美洲印第安人中存在，可能与大约500年前到达新大陆的西班牙菌株竞争并存活下来。我们认为，这可能发生在秘鲁本土幽门螺杆菌菌株获得cagPAI序列之后，要么是通过在cag阴性菌株中获得新的菌株，要么是通过在cag阳性的美洲印第安菌株中重组。
Helicobacter pylori is presumed to be co-evolved with its human host and is a highly diverse gastric pathogen at genetic levels. Ancient origins of H. pylori in the New World are still debatable. It is not clear how different waves of human migrations in South America contributed to the evolution of strain diversity of H. pylori. The objective of our 'phylogeographic' study was to gain fresh insights into these issues through mapping genetic origins of H. pylori of native Peruvians (of Amerindian ancestry) and their genomic comparison with isolates from Spain, and Japan. For this purpose, we attempted to dissect genetic identity of strains by fluorescent amplified fragment length polymorphism (FAFLP) analysis, multilocus sequence typing (MLST) of the 7 housekeeping genes (atpA, efp, ureI, ppa, mutY, trpC, yphC) and the sequence analyses of the babB adhesin and oipA genes. The whole cag pathogenicity-island (cagPAI) from these strains was analyzed using PCR and the geographic type of cagA phosphorylation motif EPIYA was determined by gene sequencing. We observed that while European genotype (hp-Europe) predominates in native Peruvian strains, approximately 20% of these strains represent a sub-population with an Amerindian ancestry (hsp-Amerind). All of these strains however, irrespective of their ancestral affiliation harbored a complete, 'western' type cagPAI and the motifs surrounding it. This indicates a possible acquisition of cagPAI by the hsp-Amerind strains from the European strains, during decades of co-colonization. Our observations suggest presence of ancestral H. pylori (hsp-Amerind) in Peruvian Amerindians which possibly managed to survive and compete against the Spanish strains that arrived to the New World about 500 years ago. We suggest that this might have happened after native Peruvian H. pylori strains acquired cagPAI sequences, either by new acquisition in cag-negative strains or by recombination in cag positive Amerindian strains.
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