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Evolutionary history of Helicobacter pylori sequences reflect past human migrations in Southeast Asia.

Breurec S, Guillard B, Hem S, Brisse S, Dieye FB, Huerre M, Oung C, Raymond J, Tan TS, Thiberge JM, Vong S, Monchy D, Linz B - PLoS ONE (2011)

Bottom Line: The human population history in Southeast Asia was shaped by numerous migrations and population expansions.Their reconstruction based on archaeological, linguistic or human genetic data is often hampered by the limited number of informative polymorphisms in classical human genetic markers, such as the hypervariable regions of the mitochondrial DNA.In the future, the host range expansion of hpEurope strains among Asian populations, combined with human motility, may have a significant impact on gastric cancer incidence in Asia.

View Article: PubMed Central - PubMed

Affiliation: Unité de Biologie Médicale et Environnementale, Institut Pasteur, Dakar, Senegal. sbreurec@pasteur.sn

ABSTRACT
The human population history in Southeast Asia was shaped by numerous migrations and population expansions. Their reconstruction based on archaeological, linguistic or human genetic data is often hampered by the limited number of informative polymorphisms in classical human genetic markers, such as the hypervariable regions of the mitochondrial DNA. Here, we analyse housekeeping gene sequences of the human stomach bacterium Helicobacter pylori from various countries in Southeast Asia and we provide evidence that H. pylori accompanied at least three ancient human migrations into this area: i) a migration from India introducing hpEurope bacteria into Thailand, Cambodia and Malaysia; ii) a migration of the ancestors of Austro-Asiatic speaking people into Vietnam and Cambodia carrying hspEAsia bacteria; and iii) a migration of the ancestors of the Thai people from Southern China into Thailand carrying H. pylori of population hpAsia2. Moreover, the H. pylori sequences reflect iv) the migrations of Chinese to Thailand and Malaysia within the last 200 years spreading hspEasia strains, and v) migrations of Indians to Malaysia within the last 200 years distributing both hpAsia2 and hpEurope bacteria. The distribution of the bacterial populations seems to strongly influence the incidence of gastric cancer as countries with predominantly hspEAsia isolates exhibit a high incidence of gastric cancer while the incidence is low in countries with a high proportion of hpAsia2 or hpEurope strains. In the future, the host range expansion of hpEurope strains among Asian populations, combined with human motility, may have a significant impact on gastric cancer incidence in Asia.

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The distribution and phylogenetic differentiation of European (hpEurope) H. pylori isolates in Southeast Asia.(A) Map of sampling locations of hpEurope haplotypes in Southeast Asia. (B) The Neighbor-joining tree generated from pair-wise FST values indicates a common, non-European origin of the Southeast Asian hpEurope strains.
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pone-0022058-g001: The distribution and phylogenetic differentiation of European (hpEurope) H. pylori isolates in Southeast Asia.(A) Map of sampling locations of hpEurope haplotypes in Southeast Asia. (B) The Neighbor-joining tree generated from pair-wise FST values indicates a common, non-European origin of the Southeast Asian hpEurope strains.

Mentions: Strains of the hpEurope population were shown to be hybrids of two ancestral populations, AE1 from central Asia and AE2 from northeast Africa [13] while modern hpEastAsia strains are almost pure descendants of ancestral EastAsia. By using the linkage model of Structure [22] to estimate the proportion of nucleotides derived from each of the previously identified ancestral populations [13], [14], [16], we identified isolates from Khmer that had acquired significant proportions (>20%) of foreign nucleotides from other ancestral populations. Four hspEAsia strains (12.5%) harboured a high proportion of AE2 while eight hpEurope strains (23%) contained a significant EastAsian ancestral component (Figure S1), indicating long time co-evolution of hpEurope and hspEAsia bacteria in the area. Introgressed nucleotides from other ancestral populations might change the level of differentiation between the H. pylori populations and thus distort the pair-wise FST values. We stripped the dataset from isolates with a proportion of imported nucleotides from other ancestral populations >20% which did not change what populations were significantly differentiated from each other. In addition, the topology of the neighbor-joining trees (Figure 1; Figure 2) was unaffected (not shown), and there were only minor differences in the length of a few branches. Therefore, all the strains were included in the subsequent analyses.


Evolutionary history of Helicobacter pylori sequences reflect past human migrations in Southeast Asia.

Breurec S, Guillard B, Hem S, Brisse S, Dieye FB, Huerre M, Oung C, Raymond J, Tan TS, Thiberge JM, Vong S, Monchy D, Linz B - PLoS ONE (2011)

The distribution and phylogenetic differentiation of European (hpEurope) H. pylori isolates in Southeast Asia.(A) Map of sampling locations of hpEurope haplotypes in Southeast Asia. (B) The Neighbor-joining tree generated from pair-wise FST values indicates a common, non-European origin of the Southeast Asian hpEurope strains.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3139604&req=5

pone-0022058-g001: The distribution and phylogenetic differentiation of European (hpEurope) H. pylori isolates in Southeast Asia.(A) Map of sampling locations of hpEurope haplotypes in Southeast Asia. (B) The Neighbor-joining tree generated from pair-wise FST values indicates a common, non-European origin of the Southeast Asian hpEurope strains.
Mentions: Strains of the hpEurope population were shown to be hybrids of two ancestral populations, AE1 from central Asia and AE2 from northeast Africa [13] while modern hpEastAsia strains are almost pure descendants of ancestral EastAsia. By using the linkage model of Structure [22] to estimate the proportion of nucleotides derived from each of the previously identified ancestral populations [13], [14], [16], we identified isolates from Khmer that had acquired significant proportions (>20%) of foreign nucleotides from other ancestral populations. Four hspEAsia strains (12.5%) harboured a high proportion of AE2 while eight hpEurope strains (23%) contained a significant EastAsian ancestral component (Figure S1), indicating long time co-evolution of hpEurope and hspEAsia bacteria in the area. Introgressed nucleotides from other ancestral populations might change the level of differentiation between the H. pylori populations and thus distort the pair-wise FST values. We stripped the dataset from isolates with a proportion of imported nucleotides from other ancestral populations >20% which did not change what populations were significantly differentiated from each other. In addition, the topology of the neighbor-joining trees (Figure 1; Figure 2) was unaffected (not shown), and there were only minor differences in the length of a few branches. Therefore, all the strains were included in the subsequent analyses.

Bottom Line: The human population history in Southeast Asia was shaped by numerous migrations and population expansions.Their reconstruction based on archaeological, linguistic or human genetic data is often hampered by the limited number of informative polymorphisms in classical human genetic markers, such as the hypervariable regions of the mitochondrial DNA.In the future, the host range expansion of hpEurope strains among Asian populations, combined with human motility, may have a significant impact on gastric cancer incidence in Asia.

View Article: PubMed Central - PubMed

Affiliation: Unité de Biologie Médicale et Environnementale, Institut Pasteur, Dakar, Senegal. sbreurec@pasteur.sn

ABSTRACT
The human population history in Southeast Asia was shaped by numerous migrations and population expansions. Their reconstruction based on archaeological, linguistic or human genetic data is often hampered by the limited number of informative polymorphisms in classical human genetic markers, such as the hypervariable regions of the mitochondrial DNA. Here, we analyse housekeeping gene sequences of the human stomach bacterium Helicobacter pylori from various countries in Southeast Asia and we provide evidence that H. pylori accompanied at least three ancient human migrations into this area: i) a migration from India introducing hpEurope bacteria into Thailand, Cambodia and Malaysia; ii) a migration of the ancestors of Austro-Asiatic speaking people into Vietnam and Cambodia carrying hspEAsia bacteria; and iii) a migration of the ancestors of the Thai people from Southern China into Thailand carrying H. pylori of population hpAsia2. Moreover, the H. pylori sequences reflect iv) the migrations of Chinese to Thailand and Malaysia within the last 200 years spreading hspEasia strains, and v) migrations of Indians to Malaysia within the last 200 years distributing both hpAsia2 and hpEurope bacteria. The distribution of the bacterial populations seems to strongly influence the incidence of gastric cancer as countries with predominantly hspEAsia isolates exhibit a high incidence of gastric cancer while the incidence is low in countries with a high proportion of hpAsia2 or hpEurope strains. In the future, the host range expansion of hpEurope strains among Asian populations, combined with human motility, may have a significant impact on gastric cancer incidence in Asia.

Show MeSH
Related in: MedlinePlus