VacA is a secreted toxin that plays a role in Helicobacter pylori colonization of the stomach and that contributes to the pathogenesis of peptic ulcer disease. Studies of VacA structure and function have been hindered by the lack of an efficient system for expression and genetic manipulation of this toxin. In this study, we developed methodology for expression of a functionally active VacA toxi...

Helicobacter pylori interacts with gastric epithelial cells, activating signaling pathways important for carcinogenesis. In this study we examined the role of H. pylori on cell invasion and the molecular mechanisms underlying this process. The relevance of H. pylori cag pathogenicity island-encoded type IV secretion system (T4SS), CagA, and VacA for cell invasion was also investigated. We found...

BACKGROUND In this study, we evaluated the prevalence of primary resistance of Brazilian H. pylori isolates to metronidazole, clarithromycin, amoxicillin, tetracycline, and furazolidone. In addition, the vacA, iceA, cagA and cagE genotypes of strains isolated from Brazilian patients were determined and associated with clinical data in an effort to correlate these four virulence markers and anti...

Studies examining associations between Helicobacter pylori virulence markers and disease have concentrated on adults in developed countries. This study assessed adults and children in Mexico. Ninety patients were recruited, 56 adults (37 with active peptic ulceration and 19 with no ulcers) and 34 children (all with recurrent abdominal pain and no ulcers). H. pylori was cultured from gastric bio...

Helicobacter pylori causes chronic gastric inflammation and significantly increases the risk of duodenal and gastric ulcer disease and distal gastric carcinoma. In this study, we evaluated the Helicobacter pylori vacA and cagA genotypes in patients from a Brazilian region where there is a high prevalence of gastric cancer. Polymerase chain reaction (PCR) was used to investigate vacA mosaicism a...

Helicobacter pylori (Hp) vacuolating cytotoxin VacA induces cellular vacuolation in epithelial cells. We found that VacA could efficiently block proliferation of T cells by inducing a G1/S cell cycle arrest. It interfered with the T cell receptor/interleukin-2 (IL-2) signaling pathway at the level of the Ca2+-calmodulin-dependent phosphatase calcineurin. Nuclear translocation of nuclear factor ...

The vacuolating cytotoxin (VacA) is a major virulence factor of Helicobacter pylori which is not yet well characterised and is difficult to obtain in large quantities. Here we describe the production of a monoclonal antibody that recognises the native but not the denatured form of VacA. The antibody can be efficiently used in affinity chromatography for one-step purification of large quantities...

Infection with Helicobacter pylori strains harboring determinants of pathogenicity may lead to a strong inflammatory response in gastric mucosa. In this work, we examined the frequency of the cagA, vacA and iceA genotypes in H. pylori strains isolated from Brazilian patients and correlated these with the clinical manifestations. H. pylori was isolated from 165 patients [30 with non-ulcer dyspep...

In its mature form, the VacA toxin of Helicobacter pylori is a 95-kDa protein which is released from the bacteria as a low-activity complex. This complex can be activated by low-pH treatment that parallels the activity of the toxin on target cells. VacA has been previously shown to insert itself into lipid membranes and to induce anion-selective channels in planar lipid bilayers. Binding of Vac...