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Amerindian Helicobacter pylori strains go extinct, as european strains expand their host range.

Domínguez-Bello MG, Pérez ME, Bortolini MC, Salzano FM, Pericchi LR, Zambrano-Guzmán O, Linz B - PLoS ONE (2008)

Bottom Line: We found that all strains that had been cultured from Africans were African strains (hpAfrica1), all from Spanish were European (hpEurope) and all from Koreans were hspEAsia but that Amerindians and Mestizos carried mixed strains: hspAmerind and hpEurope strains had been cultured from Amerindians and hpEurope and hpAfrica1 were cultured from Mestizos.If diversity is important for the success of H. pylori, then the low diversity of Amerindian strains might be linked to their apparent tendency to disappear.This suggests that Amerindian strains may lack the needed diversity to survive the diversity brought by non-Amerindian hosts.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Puerto Rico, San Juan, Puerto Rico, USA.

ABSTRACT
We studied the diversity of bacteria and host in the H. pylori-human model. The human indigenous bacterium H. pylori diverged along with humans, into African, European, Asian and Amerindian groups. Of these, Amerindians have the least genetic diversity. Since niche diversity widens the sets of resources for colonizing species, we predicted that the Amerindian H. pylori strains would be the least diverse. We analyzed the multilocus sequence (7 housekeeping genes) of 131 strains: 19 cultured from Africans, 36 from Spanish, 11 from Koreans, 43 from Amerindians and 22 from South American Mestizos. We found that all strains that had been cultured from Africans were African strains (hpAfrica1), all from Spanish were European (hpEurope) and all from Koreans were hspEAsia but that Amerindians and Mestizos carried mixed strains: hspAmerind and hpEurope strains had been cultured from Amerindians and hpEurope and hpAfrica1 were cultured from Mestizos. The least genetically diverse H. pylori strains were hspAmerind. Strains hpEurope were the most diverse and showed remarkable multilocus sequence mosaicism (indicating recombination). The lower genetic structure in hpEurope strains is consistent with colonization of a diversity of hosts. If diversity is important for the success of H. pylori, then the low diversity of Amerindian strains might be linked to their apparent tendency to disappear. This suggests that Amerindian strains may lack the needed diversity to survive the diversity brought by non-Amerindian hosts.

Show MeSH
Development of inter-strain genetic diversity over time as two populations recombine.In the context of our hypothesis, a low diversity H. pylori population (P1) arose from co-evolution with the isolated Amerindian host population. With the introduction of new H. pylori strains (P2) the new population formed (P3) is more diverse than any of the source populations alone. Selection acts and strains recombine with the consequent homogenization of the population (P3′). The cycle is repeated when new populations (P4) arrive. Given time and isolation (no gene flow), population diversity will be reduced (P6). Based on their mosaic structure and high genetic distances, it seems that current H. pylori from Amerindians and Mestizos are in one of the intermediate states (P3′ or P5′). Arrows indicate introduction of new populations.
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pone-0003307-g004: Development of inter-strain genetic diversity over time as two populations recombine.In the context of our hypothesis, a low diversity H. pylori population (P1) arose from co-evolution with the isolated Amerindian host population. With the introduction of new H. pylori strains (P2) the new population formed (P3) is more diverse than any of the source populations alone. Selection acts and strains recombine with the consequent homogenization of the population (P3′). The cycle is repeated when new populations (P4) arrive. Given time and isolation (no gene flow), population diversity will be reduced (P6). Based on their mosaic structure and high genetic distances, it seems that current H. pylori from Amerindians and Mestizos are in one of the intermediate states (P3′ or P5′). Arrows indicate introduction of new populations.

Mentions: The consumption of antibiotics and other drugs (such as proton pump inhibitors that reduce gastric acidity) might also be currently affecting the bacterial populations by increasing selection pressure in favor of particular variants, thus shaping the genome of indigenous microbes in modern humans. Modern human admixture results not only in increased human diversity but also in increased microbial diversity of the human microbiome. In the long term, however, one can predict that maximum genetic distances will be succeeded by homogenization of the genomic structure in strain variants (all mosaic or recombinant strains) and humans (all Mestizos) and decreased within population genetic distances brought by further recombination and lack of isolation, as illustrated in Figure 4. Since no influx of genetic variation is expected from outside the global village, low genetic flow in both microbes and hosts will eventually result in decreased human and microbiome diversity.


Amerindian Helicobacter pylori strains go extinct, as european strains expand their host range.

Domínguez-Bello MG, Pérez ME, Bortolini MC, Salzano FM, Pericchi LR, Zambrano-Guzmán O, Linz B - PLoS ONE (2008)

Development of inter-strain genetic diversity over time as two populations recombine.In the context of our hypothesis, a low diversity H. pylori population (P1) arose from co-evolution with the isolated Amerindian host population. With the introduction of new H. pylori strains (P2) the new population formed (P3) is more diverse than any of the source populations alone. Selection acts and strains recombine with the consequent homogenization of the population (P3′). The cycle is repeated when new populations (P4) arrive. Given time and isolation (no gene flow), population diversity will be reduced (P6). Based on their mosaic structure and high genetic distances, it seems that current H. pylori from Amerindians and Mestizos are in one of the intermediate states (P3′ or P5′). Arrows indicate introduction of new populations.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2551748&req=5

pone-0003307-g004: Development of inter-strain genetic diversity over time as two populations recombine.In the context of our hypothesis, a low diversity H. pylori population (P1) arose from co-evolution with the isolated Amerindian host population. With the introduction of new H. pylori strains (P2) the new population formed (P3) is more diverse than any of the source populations alone. Selection acts and strains recombine with the consequent homogenization of the population (P3′). The cycle is repeated when new populations (P4) arrive. Given time and isolation (no gene flow), population diversity will be reduced (P6). Based on their mosaic structure and high genetic distances, it seems that current H. pylori from Amerindians and Mestizos are in one of the intermediate states (P3′ or P5′). Arrows indicate introduction of new populations.
Mentions: The consumption of antibiotics and other drugs (such as proton pump inhibitors that reduce gastric acidity) might also be currently affecting the bacterial populations by increasing selection pressure in favor of particular variants, thus shaping the genome of indigenous microbes in modern humans. Modern human admixture results not only in increased human diversity but also in increased microbial diversity of the human microbiome. In the long term, however, one can predict that maximum genetic distances will be succeeded by homogenization of the genomic structure in strain variants (all mosaic or recombinant strains) and humans (all Mestizos) and decreased within population genetic distances brought by further recombination and lack of isolation, as illustrated in Figure 4. Since no influx of genetic variation is expected from outside the global village, low genetic flow in both microbes and hosts will eventually result in decreased human and microbiome diversity.

Bottom Line: We found that all strains that had been cultured from Africans were African strains (hpAfrica1), all from Spanish were European (hpEurope) and all from Koreans were hspEAsia but that Amerindians and Mestizos carried mixed strains: hspAmerind and hpEurope strains had been cultured from Amerindians and hpEurope and hpAfrica1 were cultured from Mestizos.If diversity is important for the success of H. pylori, then the low diversity of Amerindian strains might be linked to their apparent tendency to disappear.This suggests that Amerindian strains may lack the needed diversity to survive the diversity brought by non-Amerindian hosts.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of Puerto Rico, San Juan, Puerto Rico, USA.

ABSTRACT
We studied the diversity of bacteria and host in the H. pylori-human model. The human indigenous bacterium H. pylori diverged along with humans, into African, European, Asian and Amerindian groups. Of these, Amerindians have the least genetic diversity. Since niche diversity widens the sets of resources for colonizing species, we predicted that the Amerindian H. pylori strains would be the least diverse. We analyzed the multilocus sequence (7 housekeeping genes) of 131 strains: 19 cultured from Africans, 36 from Spanish, 11 from Koreans, 43 from Amerindians and 22 from South American Mestizos. We found that all strains that had been cultured from Africans were African strains (hpAfrica1), all from Spanish were European (hpEurope) and all from Koreans were hspEAsia but that Amerindians and Mestizos carried mixed strains: hspAmerind and hpEurope strains had been cultured from Amerindians and hpEurope and hpAfrica1 were cultured from Mestizos. The least genetically diverse H. pylori strains were hspAmerind. Strains hpEurope were the most diverse and showed remarkable multilocus sequence mosaicism (indicating recombination). The lower genetic structure in hpEurope strains is consistent with colonization of a diversity of hosts. If diversity is important for the success of H. pylori, then the low diversity of Amerindian strains might be linked to their apparent tendency to disappear. This suggests that Amerindian strains may lack the needed diversity to survive the diversity brought by non-Amerindian hosts.

Show MeSH