Analysis and Comparison of the Phylogenetic Diversity Within Helicobacter pylori Isolates from Iranian and Global Populations by Multi-Locus Sequence Typing

Helicobacter pylori is a spiral-shaped bacterium that chronically resides in the human gastric epithelium. Helicobacter pylori strains are genetically diverse organisms encoding informative genotypic polymorphisms that can reflect both ancestral and human migrations history.

In this study we aimed to investigate the phylogenetic diversity of Iranian H. pylori isolates by using multi-locus sequence typing (MLST).

A total of 37 H. pylori isolates cultured from biopsy specimens from patients who referred to endoscopy unit at Taleghani Hospital in Tehran during 2015 to 2016 were included in this study. The MLST was performed for all the isolates using seven housekeeping genes, including atpA, efp, mutY, ppa, trpC, ureI and yphC . Phylogenetic analysis was performed using sequence datasets of our H. pylori strains intermingled with MLST datasets of neighboring countries and global populations.

Our results showed that approximately 38% (14/37) of the Iranian H. pylori strains were identical in at least three gene loci, with the ureI gene (48.6%, 18/37) found as the most identical allele. Additionally, the phylogenetic analyses showed that Iranian strains fall into distinct clusters, and were intermingled mostly amongst the hpEurope isolates, including isolates from Turkey, Palestine, Israel, Lebanon, Egypt, Greece, Germany, Netherlands, Spain, UK, Finland, and Italy. The present study revealed that Iranian H. pylori strains are drastically diverse, and are originally comparable to the ancestry of the hpEurope populations.

In conclusion, although similarity of the Iranian H. pylori strains is shown in few gene loci comparable to those mostly find in the hpEurope population, diversity at nucleotide sequences and STs is common among them.