Identification of a Latin American-specific BabA adhesin variant through whole genome sequencing of Helicobacter pylori patient isolates from Nicaragua
Journal article, 2016

Background: Helicobacter pylori (H. pylori) is one of the most common bacterial infections in humans and this infection can lead to gastric ulcers and gastric cancer. H. pylori is one of the most genetically variable human pathogens and the ability of the bacterium to bind to the host epithelium as well as the presence of different virulence factors and genetic variants within these genes have been associated with disease severity. Nicaragua has particularly high gastric cancer incidence and we therefore studied Nicaraguan clinical H. pylori isolates for factors that could contribute to cancer risk. Methods: The complete genomes of fifty-two Nicaraguan H. pylori isolates were sequenced and assembled de novo, and phylogenetic and virulence factor analyses were performed. Results: The Nicaraguan isolates showed phylogenetic relationship with West African isolates in whole-genome sequence comparisons and with Western and urban South-and Central American isolates using MLSA (Multi-locus sequence analysis). A majority, 77 % of the isolates carried the cancer-associated virulence gene cagA and also the s1/i1/m1 vacuolating cytotoxin, vacA allele combination, which is linked to increased severity of disease. Specifically, we also found that Nicaraguan isolates have a blood group-binding adhesin (BabA) variant highly similar to previously reported BabA sequences from Latin America, including from isolates belonging to other phylogenetic groups. These BabA sequences were found to be under positive selection at several amino acid positions that differed from the global collection of isolates. Conclusion: The discovery of a Latin American BabA variant, independent of overall phylogenetic background, suggests hitherto unknown host or environmental factors within the Latin American population giving H. pylori isolates carrying this adhesin variant a selective advantage, which could affect pathogenesis and risk for sequelae through specific adherence properties.

Virulence factors

Phylogeny

Whole-genome sequencing

BabA

Helicobacter

Author

Kaisa Thorell

University of Gothenburg

Chalmers, Biology and Biological Engineering, Systems and Synthetic Biology

Seyed Vali Hesseini

Chalmers, Biology and Biological Engineering, Food and Nutrition Science

Rvpp Gonzales

Hospital Salud Integral

Chatchai Chaotham

University of Gothenburg

D. Y. Graham

Baylor College of Medicine

L. Paszat

University of Toronto

L. Rabeneck

University of Toronto

Samuel B Lundin

University of Gothenburg

Intawat Nookaew

Chalmers, Biology and Biological Engineering, Systems and Synthetic Biology

Åsa Sjöling

University of Gothenburg

BMC Evolutionary Biology

1471-2148 (ISSN)

Vol. 16 1 art no 53- 53

Subject Categories

Clinical Medicine

DOI

10.1186/s12862-016-0619-y

More information

Latest update

5/18/2018