Identification and Analysis of a New vacA Genotype Variant of Helicobacter pylori in Different Patient Groups in Germany

Abstract

The vacuolating cytotoxin of Helicobacter pylori (VacA) is known to cause cell damage to mammalian cells and is suspected to give rise to gastric epithelial lesions that might lead to peptic ulcer disease. As shown recently, the gene encoding VacA exhibits genetic variation, with three different families of signal sequences (s1a, s1b, and s2) and two families of midregion sequences (m1 and m2). In order to investigate the relationship between the presence of specificvacA genotypes and peptic ulceration, the vacAgenotypes of 158 clinical isolates of H. pylori were determined. The study group consisted of 106 patients with duodenal ulceration; 52 patients with nonulcer dyspepsia (NUD) were used as controls. H. pylori of genotype s1 was isolated from 96% of the patients with ulcerations, whereas genotype s2 was only present in 4%, indicating a strong correlation between thevacA genotype and peptic ulceration (P < 0.001). In contrast, 31% of the patients from the NUD control group were infected with strains of vacA genotype s2. Particular midregion genotypes (m1 and m2) were not associated with clinical manifestations. The midregions from 18% of the isolates could not be classified by the proposed scheme. DNA sequencing revealed high homology between the untypeable midregions and that of genotype m1, with multiple base pair exchanges, some affecting the primer annealing site. Compared to those of m1 and m2 alleles, the divergent midregions from untypeable strains showed clustering, indicating the presence of a further subfamily of sequences in the midregion of vacA in German isolates, for which we propose the term “m1a.” A new specific primer that we designed for typing m1a isolates might be useful in other studies.

Test of the hypothesis that vacA genotypes of helicobacter pylori correlate with CagA status, cytotoxin production, or clinical outcome

“…Other recent data are consistent with our finding that vacA genotyping appears to offer little in the way of discrimination with regard to clinical presentation. A MEDLINE search of the English language literature, starting with Atherton's first vacA publication in July 1995 and continuing to July 1998, as well as the present study, identify a number of studies reporting vacA genotyping in patients with peptic ulcer or nonulcer dyspepsia from a number of different countries, including 12 studies from Europe (Portugal, The Netherlands, UK, Germany, France, Sweden) or the United States and 4 from Asia (Japan, China, Taiwan) [7,8,20,[23][24][25][26][27][28][29][30][31][32][33][34]. Overall, the available data concern more than 1500 patients (Table 7).…”

“…This pattern was in marked contrast to Asia where the s1 vacA genotype is dominant irrespective of clinical presentation (99.7% vs. 99.7%). There are 6 studies from Europe/United States that provide subtyping data and the s1a genotype was more common in peptic ulcer disease (163 of 210) than in those with nonulcer dyspepsia (56 of 99) (77.6% vs. or 56.6% for peptic ulcer vs. nonulcer dyspepsia, respectively; p Ͻ .001) [7,8,[23][24][25][26][27]. Despite the overall higher prevalence of the s1a genotype compared to the s1b genotype in ulcer disease, the presence of the s1a genotype had no predictive value as it was found in the majority of cases irrespective of clinical presentation.…”

“…One possible explanation for the association of the vacA genotype and peptic ulcer in Western countries and lack of an association in Asia is the fact that the s1 genotype correlates with the presence of the cagA genotype [7,[25][26][27][28][29][30][31][32]. Overall, 86% of the 483 genotype s1 isolates reported from Europe or the United States were cagA-positive (p Ͻ .002 compared to cagA-negative s1 strains) [8,[25][26][27][28][29]31,32].…”

Analysis of therdxAgene in high-level metronidazole-resistant clinical isolates confirms a limited use ofrdxAmutations as a marker for prediction of metronidazole resistance inHelicobacter pylori

“…b Isolates are resistant (R) and susceptible (S) to Mtz as indicated. c Signal sequence (s) and mid-region (m) subtypes of vacA and the cagA status were determined as described [16]. d Genotypes were analyzed as previously described [18].…”

The role of Helicobacter pylori virulence factors in interleukin production by monocytic cells

“…The presence or absence of the cag PAI genes was detected by polymerase chain reaction (PCR) and con¢rmed by DNA dot-blot hybridization. The vacA types of the H. pylori strains were determined by PCR analysis essentially as described [10].…”