title: Genotyping of Helicobacter pylori virulence-associated genes shows high diversity of strains infecting patients in western Venezuela.
abstract: BACKGROUND
  Helicobacter pylori is a major cause of chronic gastritis and an established risk factor for gastric adenocarcinoma. This bacterium also exhibits an extraordinarily high genetic diversity.
  
  
  METHODS
  The genetic diversity of H. pylori strains from Venezuelan patients with chronic gastritis was evaluated by PCR-typing of vacA, cagA, iceA, and babA2 virulence-associated genes using DNA extracted directly from biopsies. The nucleotide sequence and prevalence of size variants of iceA1, iceA2, and babA2 PCR products were introduced in this analysis.
  
  
  RESULTS
  The frequency of vacA s1 was associated (p<0.01) with moderate/severe grades of atrophic gastritis. The cagA, iceA1, iceA2, and babA2 genotypes were found in 70.6%, 66.4%, 33.6%, and 92.3% of strains, respectively. The frequency of iceA2 and its subtype iceA2_D were higher (p<0.015) in cases with moderate/severe granulocytic inflammation. The most prevalent combined genotypes were vacA s1m1/cagA/iceA1/babA2 (26.3%), vacA s2m2/iceA1/babA2 (19.5%), and vacA s1m1/cagA/iceA2/babA2 (18.8%). Sequence analysis of iceA1, iceA2, and babA2 PCR-amplified fragments allowed us to define allelic variants and to increase the number of genotypes detected (from 19 to 62). A phylogenetic tree made with iceA1 sequences showed that the H. pylori strains analyzed here were grouped with those of Western origin.
  
  
  CONCLUSIONS
  Our results show that patients from the western region of Venezuela have an elevated prevalence of infection with H. pylori strains carrying known virulence genotypes with high genetic diversity. This highlights the importance of identifying gene variants for an early detection of virulent genotypes.
authors.affiliation: Laboratorio de Genética Molecular Dr. Jorge Yunis-Turbay, Decanato de Ciencias de la Salud, Universidad Centroccidental Lisandro Alvarado (UCLA), Barquisimeto, Venezuela. mchiurillo@ucla.edu.ve
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Chiurillo
authors.forename: Yeinmy
authors.initials: Y
authors.lastname: Moran
authors.forename: Miryan
authors.initials: M
authors.lastname: Cañas
authors.forename: Elvis
authors.initials: E
authors.lastname: Valderrama
authors.forename: Nashdalish
authors.initials: N
authors.lastname: Granda
authors.forename: Marjorie
authors.initials: M
authors.lastname: Sayegh
authors.forename: José Luis
authors.initials: JL
authors.lastname: Ramírez
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005756:Gastritis / Q000382:microbiology*; D005798:Genes, Bacterial; D014644:Genetic Variation; D005838:Genotype; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000145:classification / Q000235:genetics* / Q000472:pathogenicity; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D058885:Multilocus Sequence Typing; D010802:Phylogeny; D014687:Venezuela; D014774:Virulence / Q000235:genetics*; D055815:Young Adult
keywords: Genetic diversity; Helicobacter pylori; Venezuelan patients; Virulence-associated genes