Fine-structure molecular typing of Irish Helicobacter pylori isolates and their genetic relatedness to strains from four different continents

Abstract

Genotyping of 74 Irish Helicobacter pylori isolates was performed at four different loci (vacA signal sequence and mid-region, insertion-deletion polymorphisms at the 3' end of the cag pathogenicity island, and cagA). The predominant vacA alleles and insertion-deletion motifs suggest an ancestral relationship between Irish isolates and either specific East Asian or Northern European strains. In addition, fluorescent amplified fragment length polymorphism-PCR genotyping and phylogenetic analysis of 32 representative Irish H. pylori isolates and 22 isolates from four different continents demonstrated that the Irish H. pylori isolates examined were weakly clonal and showed some association with both European and Asian isolates. These three genotyping techniques show that Irish H. pylori isolates have distinctive features that may have evolved in this insular European population.

FIG. 1.

Phylogenetic tree of 32 Irish H. pylori isolates. The neighbor-joining network was developed from the binary data obtained by the Genotyper macro. The scale at the bottom shows percentage heterogeneity among the isolates based on sharing of FAFLP fragments.

FIG. 2.

Phylogenetic tree of various H. pylori isolates from different geographic regions. The neighbor-joining network was developed from the binary data obtained by the Genotyper macro. Clustering of isolates is based on sharing of FAFLP fragments. Clustering resulted in two main clusters (1 and 2) and six distinct subgroups (A to F).