Ancestral European roots ofHelicobacter pyloriin India

Background. The human gastric pathogenHelicobacter pyloriis co-evolved with its host and therefore, origins and expansion of multiple populations and sub populations ofH. pylorimirror ancient human migrations. Ancestral origins ofH. pyloriin the vast Indian subcontinent are debatable. It is not clear how different waves of human migrations in South Asia shaped the population structure ofH. pylori. We tried to address these issues through mapping genetic origins of present dayH. pyloriin India and their genomic comparison with hundreds of isolates from different geographic regions.Results. We 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 ofcagPAI genes within these strains was analyzed by using PCR and the geographic type ofcagA phosphorylation motif EPIYA was determined by gene sequencing. All the isolates analyzed revealed European ancestry and belonged toH. pylorisub-population, hpEurope. ThecagPAI harbored by Indian strains revealed European features upon PCR based analysis and whole PAI sequencing.Conclusion. These observations suggest thatH. pyloristrains 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.