Detection of High Pathogenicity Island(HPI) in Pathogenic Escherichia coli of Mink by PCR

[Objective] The paper was to analyze the carrying status of high pathogenicity island （HPI） in pathogenic Escherichia coli of mink. [Method] Eight strains of E. coli were isolated from dead mink, and conducted pathogenicity test of artificial infection. The carrying status of HPI （irp2, fyuA） was detected by PCR. [Result] Eight strains of E. coli were pathogenic E. coli, and the carrying rate of HPI （irp2, fyuA） was 100%, positively correlated with the pathogenicity. [Conclusion] The results lay a foundation for further exploring the pathogenic mechanism of E. coli..

Finding Pathogenicity Islands in Genome Data with ICA

A novel technique for finding pathogenicity islands in genome data with independent component analyses(ICA) is present. First denoise the genomic signal sequences with ICA and detect G+C patterns in genomes by comparing the result sequence with original sequences. The results on G+C patterns analysis of Dradiodurans chromosome I and N.serogroup A strain Z2491 are present. A set of loci that have very different G+C content and have not previously described are detected. The findings show that ICA is a powerful tool to detect differences within and between genomes and to separate small (gene level) and large (putative pathogenicity islands) genomic regions that have different composition characteristics.

Interleukin-1 and TNF-α polymorphisms and Helicobacter pylori in a Brazilian Amazon population

AIM： To study the association between Interleukin-1 （IL-1） and tumor necrosis factor （TNF）-α polymorphisms, infection by Helicobacter pylori （H pylori） and the development of gastrointestinal diseases.METHODS： Genomic DNA was extracted from the peripheral blood of 177 patients with various gastrointestinal diseases and from 100 healthy volunteers. The polymorphisms in IL-1β and TNF-α genes were analyzed using the polymerase chain reactionrestriction fragment length polymorphism method （PCRRFLP） and those from IL-1RN with PCR. The presence of infection due to H pylori and the presence of the CagA toxin were detected by serology. The histopathological parameters in the gastric biopsies of the patients were according to the Sydney classification.RESULTS： A comparison of the frequencies of the different polymorphisms studied among the patients and the control group demonstrated that the allele IL- 1RN＊2 was more frequent among patients with gastric ulcers and adenocarcinoma. Carriers of the allele IL- RN＊2 and those with reactive serology for anti-CagA IgG had a greater risk of developing peptic ulcer and gastric adenocarcinoma, as well as a higher degree of inflammation and neutrophilic activity in the gastricCONCLUSION： Our results indicate a positive association between IL-1RN gene polymorphism and infection by positive H pylori CagA strains and the development of gastric ulcers and adenocarcinoma.

Induction of CD69 expression by cag PAI-positive Helicobacter pylori infection

AIM: To investigate and elucidate the molecular mechanism that regulates inducible expression of CD69 by Helicobacter pylori (H. pylori ) infection. METHODS: The expression levels of CD69 in a T-cell line, Jurkat, primary human peripheral blood mononuclear cells (PBMCs), and CD4 + T cells, were assessed by immunohistochemistry, reverse transcription polymerase chain reaction, and flow cytometry. Activation of CD69 promoter was detected by reporter gene. Nuclear factor (NF)-κB activation in Jurkat cells infected with H. pylori was evaluated by electrophoretic mobility shift assay. The role of NF-κB signaling in H. pylori-induced CD69 expression was analyzed using inhibitors of NF-κB and dominant-negative mutants. The isogenic mutants with disrupted cag pathogenicity island (cag PAI) and virD4 were used to elucidate the role of cag PAI-encoding type Ⅳ secretion system and CagA in CD69 expression.RESULTS: CD69 staining was detected in mucosal lymphocytes and macrophages in specimens of pa- tients with H. pylori-positive gastritis. Although cag PAI- positive H. pylori and an isogenic mutant of virD4 induced CD69 expression, an isogenic mutant of cag-PAI failed to induce this in Jurkat cells. H. pylori also induced CD69 expression in PBMCs and CD4 + T cells. The activation of the CD69 promoter by H. pylori was mediated through NF-κB. Transfection of dominant-negative mutants of IκBs, IκB kinases, and NF-κB-inducing kinase inhibited H. pylori-induced CD69 activation. Inhibitors of NF-κB suppressed H. pylori-induced CD69 mRNA expression. CONCLUSION: The results suggest that H. pylori induces CD69 expression through the activation of NF-κB. cagPAI might be relevant in the induction of CD69 expression in T cells. CD69 in T cells may play a role in H. pylori-induced gastritis.

Helicobacter pyloristrain-specific modulation of gastric inflammation in Mongolian gerbils

AIM: The cag pathogenicity island (PAI) is one of potential virulence determinants of Helicobacter pylori. The Mongolian gerbil is a suitable experimental animal for the screening of virulence factors of H pylori.METHODS: Five-week-old Mongolian gerbils were inoculated with a standard H pylori strain (ATCC 43504)possessing the cag PAI or a clinical isolate lacking the genes' cluster (OHPC-0002). The animals were killed at 2, 4, 8, 24 and 48 wk after inoculation (n = 5 each), and macroscopic and histopathological findings in the stomachs were compared.RESULTS: In gerbils infected with ATCC 43504, a more severe degree of infiltration of polynuclear and mononuclear cells and lymphoid follicles was observed from 4 wk after inoculation compared to gerbils infected with OHPC-0002 especially in the antrum and transitional zone from the fundic to pyloric gland area. In addition,glandular atrophy, intestinal metaplasia, gastric ulcer and hyperplastic polyps were noted in gerbils infected with ATCC 43504, whereas only mild gastric erosions occurred in those infected with OHPC-0002.CONCLUSION: Our results indicate that the cag PAI could be directly involved in gastric immune and inflammatory responses in the Mongolian gerbils, leading to a more advanced gastric disease.

Deletions in the pyruvate pathway of Salmonella Typhimurium alter SPI1-mediated gene expression and infectivity

Background： Salmonella enter/ca serovar Typhimurium is a major foodborne pathogen worldwide. S. Typhimurium encodes type III secretion systems via Salmonella pathogenicity islands （SPI）, producing the major effector proteins of virulence. Previously, we identified two genes of Salmonella pyruvate metabolism that were up-regulated during chicken cell infection： pyruvate formate lyase I （pf/B） and b/functional acetaldehyde-CoA/alcohol dehydrogenase （adhE）. We were therefore interested in examining the role these genes may play in the transmission of Salmonella to humans. Methods： Mutant strains of Salmonella with single gene deletions for pflB and adhE were created. Invasion and growth in human HCT-8 intestinal epithelial cells and THP-1 macrophages was examined. Quantitative PCR was performed on 19 SPI-1 genes. Results： In HCT-8 cells, both mutant strains had significantly higher intracellular counts than the wild-type from 4 to 48 h post-infection. Various SPI-1 genes in the mutants were up-regulated over the wild-type as early as 1 h and lasting until 24 h post-infection. In THP-1 cells, no significant difference in internal Salmonella counts was observed; however, SPI-1 genes were largely down-regulated in the mutants during the time-course of infection. We also found five SPI-1 genes - hilA, hiIC hill）, sicP and rtsA - which were up-regulated in at least one of the mutant strains in log-phase broth cultures alone. We have therefore identified a set of SPI-1 virulence genes whose regulation is effected by the central metabolism of Salmonella.