Diversity of Helicobacter pylori isolates in expression of antigens and induction of antibodies

Abstract

AIM:To obtain evidence for selection of antigens used in genetically engineered vaccine against Helicobacter pylori (H pylori ). METHODS:Enzyme linked immunoabsorbent assay (ELISA) was established on the basis of recombinant protein antigens rUreB, rHpaA, rVacA, rCagA1, rNapA, rFlaA and rFlaB of H pylori to detect expression rates of the antigens in bacterial isolates as well as positive rates of the antibodies in sera from H pylori -infected patients. PCR was applied to the detection of carrying rates of the genes encoding antigens in the isolates. RESULTS: The outputs of rUreB, rHpaA, rVacA, rCagA1, rNapA, rFlaA and rFlaB were approximately 35%, 32%, 15%, 23%, 56%, 25% and 20% of the total bacterial proteins, respectively. One hundred and fifty-one strains of H pylori were isolated from 347 biopsy specimens of chronic gastritis, peptic ulcer or gastric adenocarcinoma, with a positive rate of 43.5%. All of the isolates expressed UreB, HpaA, FlaA and FlaB while 52.3%, 92.1% and 93.4% of the isolates expressed VacA, CagA and NapA, respectively. In the sera of 151 H pylori -infected patients, the positive rates of IgG antibodies against UreB, HpaA, VacA, CagA, NapA, FlaA and FlaB were 100%, 87.4%, 43%, 71.5%, 89.4%, 84.8% and 79.5%, respectively. Furthermore, the expression frequencies of VacA and NapA were found to be relative to the severity of gastric diseases (P = 0.016 and P < 0.0001, respectively). CONCLUSION:UreB antigen is the top option of developing genetically engineered vaccine against H pylori followed by NapA or HpaA.

Antigenic Diversity Among Portuguese Clinical Isolates of Helicobacter pylori

“…CagA and VacA proteins are two of the best studied virulence factors of this bacterium and of the most used as vaccine candidates [5,45]. However, questioning their application, the seroprevalence of specific anti-CagA and anti-VacA antibodies in sera of H. pylori infected patients varies among geographical regions and ethnic groups [14].…”

Multiple Gene Status in <i>Helicobacter pylori</i> Strains and Risk of Gastric Cancer Development

“…The enormous genetic diversity of H. pylori motivates many researchers to characterize bacterial virulence determinants in order to predict disease outcomes. The heterogeneous nature of H. pylori is more evident in the two putative virulence markers at the genotypic as well as the phenotypic level; vacA (vacuolationg cytotoxin gene) and cagA (cytotoxin-associated gene) [4, 5]. Although vacA gene is present in every H. pylori strain, considerable variations in vacuolating activity and target specificity exist amongst strains [6].…”

Immunoproteomics of Helicobacter pylori infection in patients with atrophic body gastritis, a predisposing condition for gastric cancer

“…Three of these proteins, namely HpaA, the flagellar sheath adhesin, and TlpD, were of particular interest because they belong to the outer membrane envelope structure, probably associated with the ability of H. pylori to colonize the gastric mucosa (Svennerholm and Lundgren, 2007). In particular, HpaA is considered a protective antigen for H. pylori and a candidate for developing engineered vaccines (Tang et al, 2008). Very recently, TlpD has been identified to be a methyl-accepting, chemotaxislike sensor molecule involved in the directed motility of H. pylori responding to internal energetic conditions (Schweinitzer et al, 2008).…”