Typing of Helicobacter pylori vacA Gene and Detection of cagA Gene by PCR and Reverse Hybridization

Abstract

The present report describes an analysis of two virulence genes of Helicobacter pylori. Parts of the cagA gene, as well as parts from the signal (s) and middle (m) regions of the mosaic vacA gene, were amplified with biotin-labelled PCR primers and the products were subsequently analyzed by a single-step reverse hybridization line probe assay (LiPA). This assay comprises a strip containing multiple specific probes for the vacA s region (s1a, s1b, and s2 alleles), the vacA m region (m1 and m2 alleles), and the cagA gene. A total of 103 H. pylori-positive materials, including cultured isolates, gastric biopsy specimens, and surgical specimens from patients living in Portugal (n ‫؍‬ 55) and The Netherlands (n ‫؍‬ 48) were tested by the PCR-LiPA. cagA was detected in 84 and 73% of the Portuguese and Dutch patients, respectively. vacA typing results, as determined by reverse hybridization, were completely concordant with those of sequence analysis. Most Portuguese patients (72%) contained type s1b, whereas most Dutch patients (61%) contained type s1a (P < 0.001). The method is also very effective at detecting the presence of multiple genotypes in a single biopsy specimen. The prevalence of multiple strains in Portuguese patient samples was significantly higher (29%) than that in Dutch patient samples (8%) (P ‫؍‬ 0.001). There was a significant association between the presence of ulcers or gastric carcinoma and the presence of vacA type s1 (s1a or s1b; P ‫؍‬ 0.008) and cagA (P ‫؍‬ 0.003) genes.

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.…”

Importance of EGF receptor, HER2/Neu and Erk1/2 kinase signalling for host cell elongation and scattering induced by theHelicobacter pyloriCagA protein: antagonistic effects of the vacuolating cytotoxin VacA

“…Typing of the vacA gene was determined by PCR amplification of genomic DNA as described previously (van Doorn et al, 1998). In brief, to amplify the vacA s and m regions, described primer sets were used, resulting in fragments of 176 bp (type s1), 203 bp (type s2), 401 (type m1) or 476 bp (type m2) respectively.…”

Diversity of Helicobacter pylori cagA and vacA Genes in Costa Rica: Its Relationship with Atrophic Gastritis and Gastric Cancer

“…The genetic diversity of H. pylori has been helpful in predicting the clinical outcome of the infection. In Western studies, H. pylori cagA and vacA genes were significantly associated with gastric cancer [1,[11][12][13][14]. However, in Asian countries such as Japan, this association could not be determined due to the vast predominance of H. pylori cagA -and vacA s1-positive strains [15] demonstrating that H. pylori genotypic diversity has geographic variation [16,17].…”