Ancestral European roots of Helicobacter pylori in India

Abstract

BackgroundThe human gastric pathogen Helicobacter pylori is co-evolved with its host and therefore, origins and expansion of multiple populations and sub populations of H. pylori mirror ancient human migrations. Ancestral origins of H. pylori in the vast Indian subcontinent are debatable. It is not clear how different waves of human migrations in South Asia shaped the population structure of H. pylori. We tried to address these issues through mapping genetic origins of present day H. pylori in India and their genomic comparison with hundreds of isolates from different geographic regions.ResultsWe attempted to dissect genetic identity of strains by multilocus sequence typing (MLST) of the 7 housekeeping genes (atpA, efp, ureI, ppa, mutY, trpC, yphC) and phylogeographic analysis of haplotypes using MEGA and NETWORK software while incorporating DNA sequences and genotyping data of whole cag pathogenicity-islands (cagPAI). The distribution of cagPAI genes within these strains was analyzed by using PCR and the geographic type of cagA phosphorylation motif EPIYA was determined by gene sequencing. All the isolates analyzed revealed European ancestry and belonged to H. pylori sub-population, hpEurope. The cagPAI harbored by Indian strains revealed European features upon PCR based analysis and whole PAI sequencing.ConclusionThese observations suggest that H. pylori strains in India share ancestral origins with their European counterparts. Further, non-existence of other sub-populations such as hpAfrica and hpEastAsia, at least in our collection of isolates, suggest that the hpEurope strains enjoyed a special fitness advantage in Indian stomachs to out-compete any endogenous strains. These results also might support hypotheses related to gene flow in India through Indo-Aryans and arrival of Neolithic practices and languages from the Fertile Crescent.

Prevalence, diversity and disease association of Helicobacter pylori in dyspeptic patients from Pakistan

“…Although s2m1 positive H. pylori strains have previously been observed in many countries including Cuba, India, China, South Africa and the Middle East [53][54][55][56], they are still regarded as an "alien" in gastroenterology due to their infrequent presence. Such strains are generally considered to be non-toxic [57], which, to some extent justifies their presence in patients with intact mucosa and indicates less likely involvement in disease pathology.…”

Diverse Characteristics of the cagA Gene of Helicobacter pylori Strains Collected from Patients from Southern Vietnam with Gastric Cancer and Peptic Ulcer

“…However, when examining the cagA gene, most phylogenetic studies have analyzed the 3Ј region or 5Ј region only, with or without nucleotide sequences of the vacA gene or other housekeeping genes (12,18,28,29,61). Some studies from Japan that carried out a phylogenetic analysis based on full genomic sequences of the cagA gene or cagPAI region were reported, but unfortunately they focused mainly on intergroup examinations of Japanese H. pylori strains (5, 64) or had very few H. pylori reference strains from other countries (25).…”

Multilocus Sequence Typing of the Porcine and Human Gastric Pathogen Helicobacter suis

“…As a genotyping method and technique, MLST has often been used in strain typing studies and can be considered a gold standard (15,18,(20)(21)(22). For MLST analysis of strains of H. pylori, a closely related major human gastric pathogen, 7 housekeeping genes are used (atpA, efp, mutY, ppa, trpC, yphC, and ureI) (17,19). The whole-genome sequences of H. suis strains 1 and 5 revealed the presence of a homologue for all of these genes (25).…”

“…However, given the extremely fastidious nature of this microorganism, a culture-independent method should be used, allowing typing of H. suis directly in stomach samples. Multilocus sequence typing (MLST), introduced in 1998, has been widely used in molecular epidemiology and population biology of bacterial species (13)(14)(15)(16) and has proven its usefulness for typing strains of other Helicobacter species (17)(18)(19). In addition, this technique uses the unambiguousness and portability of nucleotide sequence data, which allows results from different laboratories to be compared without exchanging strains (20)(21)(22).…”