Single-step PCR amplification and enzyme restriction analysis of the entire Helicobacter pylori cytotoxin vacA gene for genetic variability studies.
ABSTRACT To monitor changes along the entire Helicobacter pylori vac A gene we carried out full-length single-step PCR amplification in 21 gastritis and gastric cancer isolates. HindIII restriction analysis led us to detect a > 400-bp internal insertion in vacA subsequently shown to be a direct 451-bp gene duplication. We found HindIII profiles for 16 genes that allowed their grouping into two restriction patterns that were related to theoretical profiles for previously sequenced Western genes. Comparisons with theoretical HindIII patterns for Japanese isolates appear suggestive of geographical H. pylori clonality. Full-length single-step PCR amplification seems suitable for quick restriction pattern assignment and detection of gene size changes.
SourceAvailable from: scielo.org.mxSalud publica de Mexico 06/2001; 43(3):237-247. · 0.94 Impact Factor
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ABSTRACT: Helicobacter pylori has acquired great importance during the last two decades, after being recognized as an important pathogen that infects a great portion of the human population. This microorganism is recognized as the main causal agent of chronic gastritis and duodenal ulcers, and it is associated with the subsequent development of gastric carcinoma. The pathogenic mechanisms of H. pylori and their relation to gastric ailments have not been clearly defined. However, at present it is well established that urease, vacuolating cytotoxin VacA, and the pathogenicity island (cag PAI) gene products, are the main factors of virulence of this organism. Thus, individuals infected with strains that express these virulence factors probably develop a severe local inflammation that may induce the development of peptic ulcer and gastric cancer. The way the infection spreads throughout the world suggests the possibility that there are multiple pathways of transmission. Due to the importance that H. pylori has acquired as a human pathogen, laboratories worldwide are attempting to develop a vaccine that confers long-term immunological protection against infection by this microorganism. Hence, the objective of this review is to present the most relevant findings of the biology of H. Pylori and its interaction with the human host.Salud publica de Mexico 01/2001; 43(3):237-47. DOI:10.1590/S0036-36342001000300010 · 0.94 Impact Factor
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ABSTRACT: Up to 28-fold differences in vacA expression in Helicobacter pylori strains grown in vitro were demonstrated by real time quantitative RT-PCR. These large differences in expression were unrelated to putative -35 and -10 motifs or to other untranslated sequences upstream of the ATG start site. The lack of correlation between promoter sequences and the vacA expression levels suggest the potential existence of a bacterial strain-specific factor, as earlier proposed by others on the basis of reporter gene fusions.Microbial Pathogenesis 10/2004; 37(3):163-7. DOI:10.1016/j.micpath.2004.06.003 · 2.00 Impact Factor