13 research outputs found
Quantitative evaluation of inflammatory and immune responses in the early stages of chronic Helicobacter pylori infection
No full textThe early consequences of Helicobacter pylori infection and the role of bacterial virulence determinants in disease outcome remain to be established. The present study sought to measure the development of host inflammatory and immune responses and their relationship to the putative bacterial virulence factors cag pathogenicity island (cagPAI), vacA allele, and oipA in combination with bacterial colonization density in a feline model of the early stages of H. pylori infection. Gastric tissues obtained from infected and uninfected cats were evaluated for H. pylori ureB, cagPAI, vacA allele, and oipA and colonization density (urease, histology, and real-time PCR). Inflammation was assessed by measuring mRNA upregulation of gamma interferon (IFN-γ), interleukin (IL)-1α, IL-1β, IL-4, IL-6, IL-8, IL-10, and IL-12 p40 and histopathology. The mucosal immune response was characterized by morphometric analysis of lymphoid follicles and by differentiating lymphocyte populations with antibodies against surface markers. Infecting H. pylori strains were positive for vacAs1 but lacked cagPAI and an active oipA gene. Colonization density was uniform throughout the stomach. Upregulation of IFN-γ, IL-1α, IL-1β, and IL-8 and increased severity of inflammatory infiltrates and fibrosis were observed in infected cats. The median number and total area of lymphoid aggregates were 5 and 10 times greater, respectively, in the stomachs of infected than uninfected cats. Secondary lymphoid follicles in uninfected cats were rare and positive for BLA.36 and B220 but negative for CD3 and CD79α, whereas in infected cats they were frequent and positive for BLA.36, CD79α, and CD3 but negative for B220. Upregulation of IFN-γ, IL-1α, IL-1β, and IL-8 and marked hyperplasia of secondary lymphoid follicles are early consequences of H. pylori infection in cats. The response appears to be similar to that of infected people, particularly children, can develop independently of the pathogenicity factors cagPAI and oipA, and is not correlated with the degree of colonization density or urease activity
Helicobacter acinonychis: genetic and rodent infection studies of a Helicobacter pylori-like gastric pathogen of cheetahs and other big cats
No full textMultiple pathways of plasmid DNA transfer in Helicobacter pylori
No full textMany Helicobacter pylori (Hp) strains carry cryptic plasmids of different size and gene content, the function of which is not well understood. A subgroup of these plasmids (e.g. pHel4, pHel12), contain a mobilisation region, but no cognate type IV secretion system (T4SS) for conjugative transfer. Instead, certain H. pylori strains (e.g. strain P12 carrying plasmid pHel12) can harbour up to four T4SSs in their genome (cag-T4SS, comB, tfs3, tfs4). Here, we show that such indigenous plasmids can be efficiently transferred between H. pylori strains, even in the presence of extracellular DNaseI eliminating natural transformation. Knockout of a plasmid-encoded mobA relaxase gene significantly reduced plasmid DNA transfer in the presence of DNaseI, suggesting a DNA conjugation or mobilisation process. To identify the T4SS involved in this conjugative DNA transfer, each individual T4SS was consecutively deleted from the bacterial chromosome. Using a marker-free counterselectable gene deletion procedure (rpsL counterselection method), a P12 mutant strain was finally obtained with no single T4SS (P12ΔT4SS). Mating experiments using these mutants identified the comB T4SS in the recipient strain as the major mediator of plasmid DNA transfer between H. pylori strains, both in a DNaseI-sensitive (natural transformation) as well as a DNaseI-resistant manner (conjugative transfer). However, transfer of a pHel12::cat plasmid from a P12ΔT4SS donor strain into a P12ΔT4SS recipient strain provided evidence for the existence of a third, T4SS-independent mechanism of DNA transfer. This novel type of plasmid DNA transfer, designated as alternate DNaseI-Resistant (ADR) mechanism, is observed at a rather low frequency under in vitro conditions. Taken together, our study describes for the first time the existence of three distinct pathways of plasmid DNA transfer between H. pylori underscoring the importance of horizontal gene transfer for this species
CagI is an essential component of the Helicobacter pylori Cag type IV secretion system and forms a complex with CagL.
No full textHelicobacter pylori, the causative agent of type B gastritis, peptic ulcers, gastric adenocarcinoma and MALT lymphoma, uses the Cag type IV secretion system to induce a strong proinflammatory response in the gastric mucosa and to inject its effector protein CagA into gastric cells. CagA translocation results in altered host cell gene expression profiles and cytoskeletal rearrangements, and it is considered as a major bacterial virulence trait. Recently, it has been shown that binding of the type IV secretion apparatus to integrin receptors on target cells is a crucial step in the translocation process. Several bacterial proteins, including the Cag-specific components CagL and CagI, have been involved in this interaction. Here, we have examined the localization and interactions of CagI in the bacterial cell. Since the cagI gene overlaps and is co-transcribed with the cagL gene, the role of CagI for type IV secretion system function has been difficult to assess, and conflicting results have been reported regarding its involvement in the proinflammatory response. Using a marker-free gene deletion approach and genetic complementation, we show now that CagI is an essential component of the Cag type IV secretion apparatus for both CagA translocation and interleukin-8 induction. CagI is distributed over soluble and membrane-associated pools and seems to be partly surface-exposed. Deletion of several genes encoding essential Cag components has an impact on protein levels of CagI and CagL, suggesting that both proteins require partial assembly of the secretion apparatus. Finally, we show by co-immunoprecipitation that CagI and CagL interact with each other. Taken together, our results indicate that CagI and CagL form a functional complex which is formed at a late stage of secretion apparatus assembly
Evolutionary dynamics of insertion sequences in Helicobacter pylori
No full textProkaryotic insertion sequence (IS) elements behave like parasites in terms of their ability to invade and proliferate in microbial gene pools and like symbionts when they coevolve with their bacterial hosts. Here we investigated the evolutionary history of IS605 and IS607 of Helicobacter pylori, a genetically diverse gastric pathogen. These elements contain unrelated transposase genes (orfA) and also a homolog of the Salmonella virulence gene gipA (orfB). A total of 488 East Asian, Indian, Peruvian, and Spanish isolates were screened, and 18 and 14% of them harbored IS605 and IS607, respectively. IS605 nucleotide sequence analysis (n = 42) revealed geographic subdivisions similar to those of H. pylori; the geographic subdivision was blurred, however, due in part to homologous recombination, as indicated by split decomposition and homoplasy tests (homoplasy ratio, 0.56). In contrast, the IS607 populations (n = 44) showed strong geographic subdivisions with less homologous recombination (homoplasy ratio, 0.2). Diversifying selection (ratio of nonsynonymous change to synonymous change, ≫1) was evident in 1∼5% of the IS605 orfA codons analyzed but not in the IS607 orfA codons. Diversifying selection was also evident in ∼2% of the IS605 orfB and ∼10% of the IS607 orfB codons analyzed. We suggest that the evolution of these elements reflects selection for optimal transposition activity in the case of IS605 orfA and for interactions between the OrfB proteins and other cellular constituents that potentially contribute to bacterial fitness. Taken together, similarities in IS elements and H. pylori population genetic structures and evidence of adaptive evolution in IS elements suggest that there is coevolution between these elements and their bacterial hosts.link_to_OA_fulltex
Mixed infection with cagA positive and cagA negative strains of Helicobacter pylori lowers disease burden in The Gambia.
No full textBACKGROUND: The prevalence of Helicobacter pylori including strains with putatively virulent genotypes is high, whereas the H. pylori-associated disease burden is low, in Africa compared to developed countries. In this study, we investigated the prevalence of virulence-related H. pylori genotypes and their association with gastroduodenal diseases in The Gambia. METHODS AND FINDINGS: DNA extracted from biopsies and H. pylori cultures from 169 subjects with abdominal pain, dyspepsia or other gastroduodenal diseases were tested by PCR for H. pylori. The H. pylori positive samples were further tested for the cagA oncogene and vacA toxin gene. One hundred and twenty one subjects (71.6%) were H. pylori positive. The cagA gene and more toxigenic s1 and m1 alleles of the vacA gene were found in 61.2%, 76.9% and 45.5% respectively of Gambian patients harbouring H. pylori. There was a high prevalence of cagA positive strains in patients with overt gastric diseases than those with non-ulcerative dyspepsia (NUD) (p = 0.05); however, mixed infection by cagA positive and cagA negative strains was more common in patients with NUD compared to patients with gastric disease (24.5% versus 0%; p = 0.002). CONCLUSION: This study shows that the prevalence of H. pylori is high in dyspeptic patients in The Gambia and that many strains are of the putatively more virulent cagA+, vacAs1 and vacAm1 genotypes. This study has also shown significantly lower disease burden in Gambians infected with a mixture of cag-positive and cag-negative strains, relative to those containing only cag-positive or only cag-negative strains, which suggests that harbouring both cag-positive and cag-negative strains is protective
Functional adaptation of BabA, the <i>H-pylori</i> ABO blood group antigen binding adhesin
No full textReinfection after successful eradication of Helicobacter pylori: a 2-year prospective study in Alaska Natives
No full textPrevalence Of Helicobacter Pylori Caga, Icea And Baba2 Alleles In Brazilian Patients With Upper Gastrointestinal Diseases
No full textHelicobacter pylori is an important human pathogen associated with gastrointestinal diseases such as gastritis, gastric and duodenal ulcer (peptic ulcer disease, PUD), and gastric cancer. A number of pathogenic factors have been described for this bacterium, and some of them have been proposed as markers for the prediction of the clinical outcome. However, with the exception of the cag and vacA status, there is no universal consensus regarding the importance of the other virulence factors. Therefore, the aim of this study was to investigate the status of H. pylori strains regarding the babA and iceA alleles, as well as the cagA genotype, to reveal any association between these genotypes and clinical outcomes in Brazilian patients. The great majority (92.6%) of the strains were typed as iceA1, while 40.4% were found to possess the babA2 allele. The cagA gene was detected in 73.4% of the strains. The iceA2 and cagA genotypes were associated with PUD, while iceA1 was negatively correlated with PUD. However, considering the high percentage of strains typed as iceA1, these associations must be treated with caution. No clinical entity was associated with the babA2 allele. These results suggest that iceA1 is not a good marker for the diseases associated with H. pylori infection in Brazil. Further studies are needed in order to elucidate the relevance of the babA status, because other studies performed in Brazil have associated the babA2 allele with clinical outcomes. These results also indicate the existence of regional differences in the H. pylori genotypes and their association with clinical outcomes. © 2006.1003232240Alm, R.A., Ling, L.S., Moir, D.T., King, B.L., Brown, E.D., Doig, P.C., Smith, R.D., Trust, T.J., Genomic-sequence comparison of two unrelated isolates of the human gastric pathogen Helicobacter pylori (1999) Nature, 397, pp. 176-180Alm, R.A., Bina, B.M., Andrews, P., Doig, R.E., Handock, Trust, T.J., Comparative genomics of Helicobacter pylori: analysis of the outer membrane protein families (2000) Infect. Immun., 68, pp. 4155-4168Ashour, A.A.R., Collares, G.B., Mendes, E.M., Gusmão, V.R., Queiroz, D.D., Magalhães, P.P., Teles, A.S., Rocha, A.M.C., iceA genotype of Helicobacter pylori strains isolated from Brazilian children and adults (2001) J. Clin. Microbiol., 39, pp. 1746-1750Aspholm-Hurtig, M., Dailide, G., Lahmann, M., Kalia, A., Ilver, D., Roche, N., Vikstrom, S., Boren, T., Functional adaptation of BabA, the H. pylori ABO blood group antigen binding adhesin (2004) Science, 305, pp. 519-522Backstrom, A., Lundberg, C., Kersulyte, D., Berg, D.E., Boren, T., Arnqvist, A., Metastability of Helicobacter pylori bab adhesin genes and dynamics in Lewis b antigen binding (2004) Proc. Natl. Acad. Sci. U.S.A., 101, pp. 16923-16928Blaser, M.J., Ecology of Helicobacter pylori in the human stomach (1997) J. Clin. Invest., 100, pp. 759-762Blaser, M.J., Atherton, J.C., Helicobacter pylori persistence: biology and disease (2004) J. Clin. Invest., 113, pp. 321-333Brocchi, M., Covone, M.G., Palla, E., Galeotti, C.L., Integration of minitransposon for expression of the Escherichia coli elt gene at a preferred site in Salmonella typhimurium identifies a novel putative fimbrial locus (1999) Arch. Microbiol., 171, pp. 122-126Clayton, C.L., Kleanthous, H., Coates, P.J., Morgan, D.D., Tabaqchali, S., Sensitive detection of Helicobacter pylori by using polymerase chain reaction (1992) J. Clin. Microbiol., 30, pp. 192-200Covacci, A., Censini, S., Bugnoli, M., Petracca, R., Burroni, D., Macchia, G., Massone, A., Rappuoli, R., Molecular characterization of the 28-kDa immunodominant antigen of Helicobacter pylori associated with cytotoxicity and duodenal ulcer (1993) Proc. Natl. Acad. Sci. U.S.A., 90, pp. 5791-5795Dunn, B.E., Cohen, H., Blaser, M.J., Helicobacter pylori (1997) Clin. Microbiol. Rev., 10, pp. 720-741Figueiredo, C., Quint, W.G., Sanna, R., Sablon, E., Donahue, J.P., Xu, Q., Miller, G.G., van Doorn, L.J., Genetic organization and heterogeneity of the iceA locus of Helicobacter pylori (2000) Gene, 246, pp. 59-68Gatti, L.L., Fagundes e Souza, E.K., Leite, K.R., Bastos, E.L., Vicentini, L.R., Silva, L.C., Smith, M.A., Payao, S.L., cagA vacA alleles and babA2 genotypes of Helicobacter pylori associated with gastric disease in Brazilian adult patients (2005) Diagn. Microbiol. Infect. Dis., 51, pp. 231-235Gerhard, M., Lehn, N., Neumayer, N., Boren, T., Rad, R., Schepp, W., Mieklke, S., Prinz, C., Clinical relevance of the Helicobacter pylori gene for blood-group antigen-binding adhesin (1999) Proc. Natl. Acad. Sci. U.S.A., 96, pp. 12778-12783Glupczynski, Y., Culture of Helicobacter pylori from gastric biopsies and antimicrobial susceptibility testing (1996) H. pylori: Techniques for Clinical Diagnosis, pp. 17-32. , Lee A. (Ed), W.B. Saunders Company Ltd, LondonGodoy, A.P., Ribeiro, M.L., Benvengo, Y.H., Vitiello, L., Miranda, M.C., Mendonça, S., Pedrazzoli Jr., J., Analysis of antimicrobial susceptibility and virulence factors in Helicobacter pylori clinical isolates (2003) BMC Gastroenterol., 3, pp. 20-26Han, Y.H., Liu, W.Z., Zhu, H.Y., Xiao, S.D., Clinical relevance of iceA and babA2 genotypes of Helicobacter pylori in a Shanghai population (2004) Chin. J. Diagn. Dis., 5, pp. 181-185Heading, R.C., Castell, D.O., Clinical spectrum and diagnosis of gastroesophageal reflux disease (2004) The Esophagus, pp. 381-388. , Castell D.O., and Richter J.E. (Eds), Lippincott Williams & Wilkings, PhiladelphiaIlver, D., Arnqvist, A., Ogren, J., Frick, M., Kersulyte, D., Incecik, E.T., Berg, D.E., Boren, T., Helicobacter pylori adhesin binding fucosylated histo-blood group antigens revealed by retagging (1998) Science, 279, pp. 373-377Ito, Y., Azuma, T., Ito, S., Suto, H., Miyaji, H., Yamazaki, Y., Kato, T., Kuriyama, M., Sequence analysis and clinical significance of the iceA gene from Helicobacter pylori strains in Japan (2000) J. Clin. Microbiol, 36, pp. 483-488Kim, S.Y., Woo, C.W., Lee, Y.M., Son, B.R., Kim, J.W., Chae, H.B., Youn, S.J., Park, S.M., Genotyping CagA, VacA subtype, IceA1, and BabA of Helicobacter pylori isolates from Korean patients, and their association with gastroduodenal diseases (2001) J. Kor. Med. Sci., 16, pp. 579-584Lai, C.H., Kuo, C.H., Chen, Y.C., Chao, F.Y., Poon, S.K., Chang, C.S., Wang, W.C., High prevalence of cagA- and babA2-positive Helicobacter pylori clinical isolates in Taiwan (2002) J. Clin. Microbiol., 40, pp. 3860-3862Lamarque, D., Peek, R.M., Pathogenesis of Helicobacter pylori infection (2003) Helicobacter, 8 (SUPPL), pp. 21-30Mahdavi, J., Sonden, B., Hurtig, M., Olfat, F.O., Forsberg, L., Roche, N., Angstrom, J., Boren, T., Helicobacter pylori SabA adhesin in persistent infection and chronic inflammation (2002) Science, 297, pp. 573-578Mizushima, T., Toshiro, S., Komatsu, Y., Ishizuka, J., Mototsgu, K., Asaka, M., Clinical relevance of the babA2 genotype of Helicobacter pylori in Japanese clinical isolates (2001) J. Clin. Microbiol., 39, pp. 2463-2465Nishiya, D., Shimoyama, T., Fukuda, S., Yoshimura, T., Tanaka, M., Munakata, A., Evaluation of the relevance of the iceA1 gene in patients with Helicobacter pylori infection (2000) Scand. J. Gastroenterol., 35, pp. 36-39Oleastro, M., Gerhard, M., Lopes, A.I., Ramalho, P., Cabral, J., Sousa Guerreiro, A., Monteiro, L., Helicobacter pylori virulence genotypes in Portuguese children and adults with gastroduodenal pathology (2003) Eur. J. Clin. Microbiol. Infect. Dis., 22, pp. 85-91Oliveira, A.G., Santos, A., Guerra, J.B., Rocha, G.A., Rocha, A.M., Oliveira, C.A., Cabral, M.M., Queiroz, D.M., babA2- and cagA-positive Helicobacter pylori strains are associated with duodenal ulcer and gastric carcinoma in Brazil (2003) J. Clin. Microbiol., 41, pp. 3964-3966Parsonnet, J.E., The incidence of Helicobacter pylori infection (1995) Aliment. Pharmacol. Ther., 9 (SUPPL), pp. 45-52Peek, R.M., Thompson, S.A., Donahue, J.P., Tham, T.R., Atherton, J.C., Blaser, M.J., Miller, G.G., Adherence to gastric epithelial cells induces expression of a Helicobacter pylori gene iceA that is associated with clinical outcome (1998) Proc. Assoc. Am. Phys., L110, pp. 531-544Pounder, R.R., The prevalence of Helicobacter pylori in different countries (1995) Aliment. Pharmacol. Ther., 9, pp. 33-40Pride, D.T., Meinersmann, R.J., Blaser, M.J., Allelic variation within Helicobacter pylori babA and babB (2001) Infect. Immun., 69, pp. 1160-1171Ribeiro, M.L., Godoy, A.P.O., Benvengo, H.B., Mendonça, S., Pedrazzoli, J.J., Clinical relevance of the cagA, vacA and iceA genotypes of Helicobacter pylori in Brazilian clinical isolates (2003) FEMS Immun. Med. Microbiol., 36, pp. 181-185Salama, N., Guillemin, K., McDaniel, T.K., Sherlock, G., Tompkins, L., Falkow, S., A whole-genome microarray reveals genetic diversity among Helicobacter pylori strains (2000) Proc. Natl. Acad. Sci. U.S.A., 97, pp. 14668-14673Sambrook, J., Russel, D.W., (2001) Molecular Cloning: A Laboratory Manual, , Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York, NY 999 ppSmith, S.I., Kirsch, C., Oyedeji, K.S., Arigbabus, A.O., Coker, A.O., Bayerdoffer, E., Miehlke, A., Prevalence of Helicobacter pylori vacA, cagA and iceA genotypes in Nigerian patients with duodenal ulcer disease (2002) J. Med. Microbiol., 51, pp. 851-854Solnick, J.V., Hansen, L.M., Salama, N.R., Boonjakuakul, J.K., Syvanen, M., Modification of Helicobacter pylori outer membrane protein expression during experimental infection of rhesus macaques (2004) Proc. Natl. Acad. Sci. U.S.A., 101, pp. 2106-2111van Doorn, L.J., Figueredo, C., Sanna, R., Plaisier, A., Schneeberger, P., Boer, W.D., Quint, W., Clinical relevance of the cagA, vacA, and iceA, status of Helicobacter pylori (1998) Gastroenterology, 115, pp. 58-66Vasconcelos, A.T.R., Almeida, D.F., Almeida, F.C., Almeida, L.G.P., Almeida, R., Alves-Gomes, J.A., Andrade, E.M., Simpson, A.J.G., The complete genome sequence of Chromobacterium violaceum reveals remarkable and exploitable bacterial adaptability (2003) Proc. Natl. Acad. Sci. U.S.A., 100, pp. 11660-11665Xu, Q., Morgan, R.D., Roberts, R.J., Xu, S.Y., van Doorn, L.J., Donahue, J.P., Miller, G.G., Blaser, M.J., Functional analysis of iceA1, a CATG-recognizing restriction endonuclease gene in Helicobacter pylori (2002) Nucleic Acids Res., 30, pp. 3839-3847Yamaoka, Y., Kodama, T., Gutierrez, O., Kim, J.G., Kashima, K., Graham, D.Y., Relationship between Helicobacter pylori iceA, cagA, and vacA status and clinical outcome: studies in four different countries (1999) J. Clin. Microbiol., 37, pp. 2274-227
