Construction of hpaA gene from a clinical isolate of Helicobacter pylori and identification of fusion protein

Antibiotic resistance and virulence genes in Helicobacter pylori strains isolated from children in Shanghai, China (2019-2022)

BACKGROUND

The increasing prevalence of antibiotic-resistant Helicobacter pylori strains poses a significant threat to children's health. This study investigated antibiotic resistance rates in Helicobacter pylori strains isolated from children in Shanghai and analyzed the presence of virulence genes in these strains.

METHODS

We obtained 201 Helicobacter pylori strains from pediatric patients with upper gastrointestinal symptoms who underwent gastrointestinal endoscopy between 2019 and 2022. Subsequently, we performed antibiotic susceptibility tests and virulence gene PCR assays on these strains.

RESULTS

Helicobacter pylori resistance rates of 45.8%, 15.4%, 1.0%, and 2.5% were detected for metronidazole, clarithromycin, amoxicillin, and levofloxacin, respectively. Among all isolates, 64.7% exhibited resistance to at least one antibiotic. Resistance to metronidazole and clarithromycin increased from 2019 to 2022. The predominant vacA gene subtype was vacA s1a/m2. The prevalence of vacA m2 and dupA exhibited an upward trend, while oipA presented a decreasing trend from 2019 to 2022. The prevalence of dupA was significantly higher in gastritis than peptic ulcer disease, and in non-treatment compared to treatment groups.

CONCLUSIONS

Helicobacter pylori antibiotic resistance remains high in children and has risen in recent years. Therefore, the increasing use of metronidazole and clarithromycin requires increased monitoring in children. No association was observed between antibiotic resistance and virulence gene phenotypes.

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

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.

Review article: Deoxyribonucleic acid-based diagnostic techniques to detect Helicobacter pylori

Helicobacter pylori is an important cause of many gastrointestinal disorders, ranging from chronic gastritis to gastric lymphoma and adenocarcinoma. The deoxyribonucleic acid-based assays have the potential to be a powerful diagnostic tool given its ability to specifically identify H. pylori deoxyribonucleic acid. Markers used to include general H. pylori structures and pathogenetic factors like ureaseA, cagA, vacA, iceA. Deoxyribonucleic acid or bacterial ribonucleic acid for polymerase chain reaction assays can be collected from gastric biopsy, gastric juice, stool, buccal specimens. Polymerase chain reaction can yield quantitative and genotyping results with sensitivity and specificity that approaches 100%. A clear trend in the direction of the determination of quantitative H. pylori infection by real-time polymerase chain reaction can be observed. Fluorescent in situ hybridization is suggested for routine antibiotic resistance determination. To identify the organism, deoxyribonucleic acid structure and its virulence factors may be feasible by using oligonucleotide microarray specifically recognizing and discriminating bacterial deoxyribonucleic acid and various virulence factors. Deoxyribonucleic acid-based H. pylori diagnosis yields higher sensitivity, however, specificity requires sophisticated labour environment and associated with higher costs.

Prokaryotic expression of fusion gene of vacuolating segment of vacA and hpaA in Helicobacter pylori

AIM: The prokaryotic expression vector of the fusion gene with v segment of the vacuolating cytotoxin and hpaA of Helicobacter pylori (H. pylori) was constructed and expressed. It would lay a foundation for prophylaxis and therapy of H. pylori infection.

METHODS: By using the primer with a fragment encoding 12 amino acids of N-terminal of human interleukin-3 (IL-3), the vacuolating cytotoxin gene of Hp with linker was amplified from pQE30-V plasmid by PCR. The gene was cloned into plasmid pTrc99A-HpaA and fused with the hpaA gene. The fusion gene was cloned into prokaryotic expression vector pQE30. The recombinant plasmid of pQE30-V-HpaA was transformed into E.coli. DH5a and expressed in the presence of IPTG. The expression product was analyzed by SDS-PAGE, its antigenicity of the expression product was identified by Western blotting.

RESULTS: Mr of recombinant protein was about 65 000 and represented 35% total protein of E.coli. Western blotting showed the recombinant protein could be recognized by the antiserum against H. pylori.

CONCLUSION: The fusion gene and its prokaryotic expression vector pQE30-V-HpaA is constructed and expressed in DH5asuccessfully. It provides the antigen basis for further studying the biological function of fusion protein and obtaining vaccine against the infection of H. pylori.

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