VacA s1m1 genotype and cagA EPIYA-ABC pattern are predominant among Helicobacter pylori strains isolated from Mexican patients with chronic gastritis.

Josefina Atrisco-Morales,Gloria Fernández-Tilapa,Judit Alarcón-Millán,Iván Cruz-Del Carmen,Dinorah N Martínez-Carrillo,Verónica I Martínez-Santos,Adolfo Román-Román,José De Sampedro-Reyes

doi:10.1099/jmm.0.000660

Josefina Atrisco-Morales, Gloria Fernández-Tilapa + Show 6 more

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https://doi.org/10.1099/jmm.0.000660

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Abstract

PurposeVirulent genotypes of Helicobacter pylori vacA s1m1/cagA+/babA2+ have been associated with severe gastric diseases. VacA, CagA and BabA are polymorphic proteins, and their association with the disease is allele-dependent. The aims of this work were: (i) to determine the prevalence of H. pylori by type of chronic gastritis; (ii) to describe the frequency of cagA, babA2 and vacA genotypes in strains from patients with different types of chronic gastritis; (iii) to characterize the variable region of cagA alleles.MethodologyA total of 164 patients with chronic gastritis were studied. Altogether, 50 H. pylori strains were isolated, and the status of cagA, babA2 and vacA genotypes was examined by PCR. cagA EPIYA segment identification was performed using PCR and sequencing of cagA fragments of six randomly selected strains.Results/Key findingsThe overall prevalence of H. pylori was 30.5 %. Eighty percent of the isolated strains were vacA s1m1, and the cagA and babA2 genes were detected in 74 and 32 % of the strains, respectively. The most frequent genotypes were vacA s1m1/cagA+/babA2- and vacA s1m1/cagA+/babA2+, with 40 % (20/50) and 28 % (14/50), respectively. In cagA+, the most frequent EPIYA motif was -ABC (78.4 %), and EPIYA-ABCC and -ABCCC motifs were found in 10.8 % of the strains. A modified EPIYT-B motif was found in 66.6 % of the sequenced strains.ConclusionH. pylori strains carrying vacA s1m1, cagA+ and babA2- genotypes were the most prevalent in patients with chronic gastritis from the south of Mexico. In the cagA+ strains, the EPIYA-ABC motif was the most common.

Highlights

Helicobacter pylori is a Gram-negative bacterium that colonizes the gastrointestinal tract of humans, mainly the gastric mucosa
Among H. pylori strains associated with severe gastric diseases are those that carry the babA2 and cagA genes, especially in combination with the genotype of vacA, s1m1 [7]. vacA encodes the protein VacA, a vacuolating cytotoxin secreted through the type V secretion system (T5SS) or autotransporter [8]
The aims of this work were: (i) to determine the prevalence of H. pylori by type of chronic gastritis; (ii) to determine the frequency of cagA, babA2 and vacA genotypes in H. pylori strains isolated from Mexican patients diagnosed with different types of chronic gastritis; and (iii) to characterize the variable region of cagA alleles that encode the C-terminal region of CagA in order to determine the type and number of EPIYA motifs, as well as the frequency of their combinations

Summary

Introduction

Helicobacter pylori is a Gram-negative bacterium that colonizes the gastrointestinal tract of humans, mainly the gastric mucosa. These bacteria colonize around half of the world’s population, their prevalence varies among geographical regions within a country, as well as between rural and urban areas, due to the socio-economic conditions, age and population ethnicity [1, 2]. Among H. pylori strains associated with severe gastric diseases are those that carry the babA2 and cagA genes, especially in combination with the genotype of vacA, s1m1 [7]. The vacA gene is present in all H. pylori strains It has several isoforms, of which s1m1 is the most virulent, while the isoform s2m2 is the least virulent, and combinations of these result in isoforms of intermediate virulence [10].

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