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Transcriptional Profile of Helicobacter pylori Virulence Genes in Patients with Gastritis and Gastric Cancer. ACTA ACUST UNITED AC 2021; 2021:1309519. [PMID: 33628350 PMCID: PMC7889378 DOI: 10.1155/2021/1309519] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 01/01/2021] [Accepted: 02/01/2021] [Indexed: 12/14/2022]
Abstract
Introduction Numerous molecular epidemiology studies have been performed about the frequency of Helicobacter pylori virulence genes in patients with H. pylori infection so far. This study was conducted to detect transcriptional profile by cDNA of H. pylori virulence genes in gastric biopsy samples of gastritis and gastric carcinoma patients. Materials and Methods In a case-control study, based on the prevalence of gastritis and gastric cancer in Sanandaj city during 2018 and 2019, 23 and 11 gastric antral biopsy samples with H. pylori infection were collected from gastritis and gastric carcinoma patients by the consecutive and available sampling method. Pathological characters, including tumor grades and tumor areas for gastric carcinoma biopsy samples prepared from gastric cancer areas, were determined by the pathologist. Total RNA of gastric antral biopsy samples was extracted, and their cDNA was synthesized by TaKaRa kit. H. pylori virulence genes' cDNA using specific primers and PCR was detected. This study's results were analyzed by SPSS version 25 and statics chi-square tests for determination of relationship and correlation between cDNAs of H. pylori transcriptional profile and clinical outcomes of H. pylori infection, including gastritis, gastric carcinoma, tumor grades, and tumor area. Results The positive statistical correlations were observed between transcripts of cagA, cagA-EPIYAC, cagE, and cagY genes and H. pylori infection clinical outcomes (P < 0.05). Conclusion Detection of the H. pylori virulence genes' cDNA in gastric biopsy samples can help provide the prognosis of clinical outcomes.
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Hojo F, Osaki T, Yonezawa H, Hanawa T, Kurata S, Kamiya S. Acanthamoeba castellanii supports extracellular survival of Helicobacter pylori in co-culture. J Infect Chemother 2020; 26:946-954. [PMID: 32448734 DOI: 10.1016/j.jiac.2020.04.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 04/03/2020] [Accepted: 04/16/2020] [Indexed: 12/15/2022]
Abstract
This study aimed to demonstrate whether Helicobacter pylori is able to survive in co-culture with a protozoan, Acanthamoeba castellanii, in order to further investigate a possible aqueous environmental mode of transmission. Numbers of H. pylori in co-culture with A castellanii were assessed by colony forming unit (CFU) assay and cell morphology was observed by electron microscopy. Viable and intact H. pylori in co-culture were detected and the number of H. pylori in co-culture with A. castellanii was significantly higher than in bacterial single culture. It was also shown that co-culture of H. pylori with A. castellanii physically separated by a filter membrane negated this survival effect, suggesting that adherence of H. pylori to A. castellanii affects its survival. Scanning electron microscopy revealed helical forms of H. pylori in co-culture with A. castellanii, but not in single culture. These results imply that mutual interaction between H. pylori and A. castellanii in the environment is critical for survival of H. pylori. In addition, the H. pylori gene expression profile was found to differ between single and co-cultured cells using RNA-sequence analysis.
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Affiliation(s)
- Fuhito Hojo
- Institute of Laboratory Animals, Graduate School of Medicine, Kyorin University, 6-20-2 Shinkawa, Mitaka, Tokyo, Japan.
| | - Takako Osaki
- Department of Infectious Diseases, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo, Japan
| | - Hideo Yonezawa
- Department of Infectious Diseases, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo, Japan
| | - Tomoko Hanawa
- Department of Infectious Diseases, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo, Japan
| | - Satoshi Kurata
- Department of Infectious Diseases, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo, Japan
| | - Shigeru Kamiya
- Department of Infectious Diseases, Kyorin University School of Medicine, 6-20-2 Shinkawa, Mitaka, Tokyo, Japan; Faculty of Health Sciences, Kyorin University, 181-8612, 5-4-1 Shimorenjaku, Mitaka, Tokyo, Japan
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Blaser N, Backert S, Pachathundikandi SK. Immune Cell Signaling by Helicobacter pylori: Impact on Gastric Pathology. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1149:77-106. [PMID: 31049845 DOI: 10.1007/5584_2019_360] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Helicobacter pylori represents a highly successful colonizer of the human stomach. Infections with this Gram-negative bacterium can persist lifelong, and although in the majority of cases colonization is asymptomatic, it can trigger pathologies ranging from chronic gastritis and peptic ulceration to gastric cancer. The interaction of the bacteria with the human host modulates immune responses in different ways to enable bacterial survival and persistence. H. pylori uses various pathogenicity-associated factors such as VacA, NapA, CGT, GGT, lipopolysaccharide, peptidoglycan, heptose 1,7-bisphosphate, ADP-heptose, cholesterol glucosides, urease and a type IV secretion system for controlling immune signaling and cellular functions. It appears that H. pylori manipulates multiple extracellular immune receptors such as integrin-β2 (CD18), EGFR, CD74, CD300E, DC-SIGN, MINCLE, TRPM2, T-cell and Toll-like receptors as well as a number of intracellular receptors including NLRP3, NOD1, NOD2, TIFA and ALPK1. Consequently, downstream signaling pathways are hijacked, inducing tolerogenic dendritic cells, inhibiting effector T cell responses and changing the gastrointestinal microbiota. Here, we discuss in detail the interplay of bacterial factors with multiple immuno-regulatory cells and summarize the main immune evasion and persistence strategies employed by H. pylori.
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Affiliation(s)
- Nicole Blaser
- Department of Biology, Institute for Microbiology, Friedrich Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Steffen Backert
- Department of Biology, Institute for Microbiology, Friedrich Alexander University Erlangen-Nuremberg, Erlangen, Germany
| | - Suneesh Kumar Pachathundikandi
- Department of Biology, Institute for Microbiology, Friedrich Alexander University Erlangen-Nuremberg, Erlangen, Germany.
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Vázquez-Jiménez FE, Torres J, Flores-Luna L, Cerezo SG, Camorlinga-Ponce M. Patterns of Adherence of Helicobacter pylori Clinical Isolates to Epithelial Cells, and its Association with Disease and with Virulence Factors. Helicobacter 2016; 21:60-8. [PMID: 25908566 DOI: 10.1111/hel.12230] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND AND AIM Adherence to the gastric epithelium is one of the most important steps of Helicobacter pylori to remain and cause disease. The aim of this study was to analyze whether H. pylori isolates from patients with different gastroduodenal diseases present differences in the pattern of adherence to gastric epithelial cells (AGS), in the ability to induce IL-8, and in the presence of virulence genes. METHODS We tested 75 H. pylori strains isolated from nonatrophic gastritis, gastric cancer, and duodenal ulcer patients. The adhesion pattern and IL-8 induction were determined in AGS cells, and invasion of AGS cells was studied using a gentamicin protection assay. The IL-8 levels induced were determined by ELISA. RESULTS Helicobacter pylori strains presented diffuse adherence (DA) and localized (LA) adherence patterns, similar to those described for enteropathogenic E. coli (EPEC), were observed in AGS cells. A DA pattern was observed in 57% and LA in 43% of the strains, and DA was more frequent in isolates from patients with gastric cancer (p = 0.044). Strains with a LA pattern induced higher levels of IL-8 (p = 0.042) in AGS cells. CONCLUSION The adherence pattern was not associated with neither invasiveness nor with the presence of virulence genes. Our study shows that H. pylori strains present adherence patterns to AGS cells resembling those observed in EPEC and that these patterns may be associated with disease and with activity on AGS cells.
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Affiliation(s)
- Flor Elizabeth Vázquez-Jiménez
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias UMAE, Hospital de Pediatria, IMSS., México, DF, Mexico
| | - Javier Torres
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias UMAE, Hospital de Pediatria, IMSS., México, DF, Mexico
| | | | - Silvia Giono Cerezo
- Departamento de Microbiologia, Instituto Politecnico Nacional, Escuela Nacional de Ciencias Biologicas, Mexico, DF, Mexico
| | - Margarita Camorlinga-Ponce
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias UMAE, Hospital de Pediatria, IMSS., México, DF, Mexico
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Vannini A, Roncarati D, Spinsanti M, Scarlato V, Danielli A. In depth analysis of the Helicobacter pylori cag pathogenicity island transcriptional responses. PLoS One 2014; 9:e98416. [PMID: 24892739 PMCID: PMC4043881 DOI: 10.1371/journal.pone.0098416] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 05/01/2014] [Indexed: 01/15/2023] Open
Abstract
The severity of symptoms elicited by the widespread human pathogen Helicobacter pylori is strongly influenced by the genetic diversity of the infecting strain. Among the most important pathogen factors that carry an increased risk for gastric cancer are specific genotypes of the cag pathogenicity island (cag-PAI), encoding a type IV secretion system (T4SS) responsible for the translocation of the CagA effector oncoprotein. To date, little is known about the regulatory events important for the expression of a functional cag-T4SS. Here we demonstrate that the cag-PAI cistrons are subjected to a complex network of direct and indirect transcriptional regulations. We show that promoters of cag operons encoding structural T4SS components display homogeneous transcript levels, while promoters of cag operons encoding accessory factors vary considerably in their basal transcription levels and responses. Most cag promoters are transcriptionally responsive to growth-phase, pH and other stress-factors, although in many cases in a pleiotropic fashion. Interestingly, transcription from the Pcagζ promoter controlling the expression of transglycolase and T4SS stabilizing factors, is triggered by co-culture with a gastric cell line, providing an explanation for the increased formation of the secretion system observed upon bacterial contact with host cells. Finally, we demonstrate that the highly transcribed cagA oncogene is repressed by iron limitation through a direct apo-Fur regulation mechanism. Together the results shed light on regulatory aspects of the cag-PAI, which may be involved in relevant molecular and etiological aspects of H. pylori pathogenesis.
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Affiliation(s)
- Andrea Vannini
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, Bologna, Italy
| | - Davide Roncarati
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, Bologna, Italy
| | - Marco Spinsanti
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, Bologna, Italy
| | - Vincenzo Scarlato
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, Bologna, Italy
- * E-mail: (VS); (AD)
| | - Alberto Danielli
- Department of Pharmacy and Biotechnology (FaBiT), University of Bologna, Bologna, Italy
- * E-mail: (VS); (AD)
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Johnson EM, Gaddy JA, Cover TL. Alterations in Helicobacter pylori triggered by contact with gastric epithelial cells. Front Cell Infect Microbiol 2012; 2:17. [PMID: 22919609 PMCID: PMC3417513 DOI: 10.3389/fcimb.2012.00017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2011] [Accepted: 02/06/2012] [Indexed: 12/11/2022] Open
Abstract
Helicobacter pylori lives within the mucus layer of the human stomach, in close proximity to gastric epithelial cells. While a great deal is known about the effects of H. pylori on human cells and the specific bacterial products that mediate these effects, relatively little work has been done to investigate alterations in H. pylori that may be triggered by bacterial contact with human cells. In this review, we discuss the spectrum of changes in bacterial physiology and morphology that occur when H. pylori is in contact with gastric epithelial cells. Several studies have reported that cell contact causes alterations in H. pylori gene transcription. In addition, H. pylori contact with gastric epithelial cells promotes the formation of pilus-like structures at the bacteria–host cell interface. The formation of these structures requires multiple genes in the cag pathogenicity island, and these structures are proposed to have an important role in the type IV secretion system-dependent process through which CagA enters host cells. Finally, H. pylori contact with epithelial cells can promote bacterial replication and the formation of microcolonies, phenomena that are facilitated by the acquisition of iron and other nutrients from infected cells. In summary, the gastric epithelial cell surface represents an important niche for H. pylori, and upon entry into this niche, the bacteria alter their behavior in a manner that optimizes bacterial proliferation and persistent colonization of the host.
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Affiliation(s)
- Elizabeth M Johnson
- Department of Medicine, Vanderbilt University School of Medicine Nashville, TN, USA
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Kumar Pachathundikandi S, Brandt S, Madassery J, Backert S. Induction of TLR-2 and TLR-5 expression by Helicobacter pylori switches cagPAI-dependent signalling leading to the secretion of IL-8 and TNF-α. PLoS One 2011; 6:e19614. [PMID: 21573018 PMCID: PMC3090411 DOI: 10.1371/journal.pone.0019614] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2010] [Accepted: 04/09/2011] [Indexed: 12/11/2022] Open
Abstract
Helicobacter pylori is the causative agent for developing gastritis, gastric ulcer, and even gastric cancer. Virulent strains carry the cag pathogenicity island (cagPAI) encoding a type-IV secretion system (T4SS) for injecting the CagA protein. However, mechanisms of sensing this pathogen through Toll-like receptors (TLRs) and downstream signalling pathways in the development of different pathologies are widely unclear. Here, we explored the involvement of TLR-2 and TLR-5 in THP-1 cells and HEK293 cell lines (stably transfected with TLR-2 or TLR-5) during infection with wild-type H. pylori and isogenic cagPAI mutants. H. pylori triggered enhanced TLR-2 and TLR-5 expression in THP-1, HEK293-TLR2 and HEK293-TLR5 cells, but not in the HEK293 control. In addition, IL-8 and TNF-α cytokine secretion in THP-1 cells was induced in a cagPAI-dependent manner. Furthermore, we show that HEK293 cells are not competent for the uptake of T4SS-delivered CagA, and are therefore ideally suited for studying TLR signalling in the absence of T4SS functions. HEK293 control cells, which do not induce TLR-2 and TLR-5 expression during infection, only secreted cytokines in small amounts, in agreement with T4SS functions being absent. In contrast, HEK293-TLR2 and HEK293-TLR5 cells were highly competent for inducing the secretion of IL-8 and TNF-α cytokines in a cagPAI-independent manner, suggesting that the expression of TLR-2 or TLR-5 has profoundly changed the capability to trigger pro-inflammatory signalling upon infection. Using phospho-specific antibodies and luciferase reporter assays, we further demonstrate that H. pylori induces IRAK-1 and IκB phosphorylation in a TLR-dependent manner, and this was required for activation of transcription factor NF-κB. Finally, NF-κB activation in HEK293-TLR2 and HEK293-TLR5 cells was confirmed by expressing p65-GFP which was translocated from the cytoplasm into the nucleus. These data indicate that H. pylori-induced expression of TLR-2 and TLR-5 can qualitatively shift cagPAI-dependent to cagPAI-independent pro-inflammatory signalling pathways with possible impact on the outcome of H. pylori-associated diseases.
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Affiliation(s)
- Suneesh Kumar Pachathundikandi
- Institute for Medical Microbiology, Otto von Guericke University, Magdeburg, Germany
- Department of Biotechnology, University of Calicut, Calicut University (PO), Kerala, India
| | - Sabine Brandt
- Institute for Medical Microbiology, Otto von Guericke University, Magdeburg, Germany
| | - Joseph Madassery
- Department of Biotechnology, University of Calicut, Calicut University (PO), Kerala, India
| | - Steffen Backert
- Institute for Medical Microbiology, Otto von Guericke University, Magdeburg, Germany
- * E-mail:
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Carpenter BM, Gancz H, Gonzalez-Nieves RP, West AL, Whitmire JM, Michel SLJ, Merrell DS. A single nucleotide change affects fur-dependent regulation of sodB in H. pylori. PLoS One 2009; 4:e5369. [PMID: 19399190 PMCID: PMC2671405 DOI: 10.1371/journal.pone.0005369] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2008] [Accepted: 03/27/2009] [Indexed: 11/18/2022] Open
Abstract
Helicobacter pylori is a significant human pathogen that has adapted to survive the many stresses found within the gastric environment. Superoxide Dismutase (SodB) is an important factor that helps H. pylori combat oxidative stress. sodB was previously shown to be repressed by the Ferric Uptake Regulator (Fur) in the absence of iron (apo-Fur regulation) [1]. Herein, we show that apo regulation is not fully conserved among all strains of H. pylori. apo-Fur dependent changes in sodB expression are not observed under iron deplete conditions in H. pylori strains G27, HPAG1, or J99. However, Fur regulation of pfr and amiE occurs as expected. Comparative analysis of the Fur coding sequence between G27 and 26695 revealed a single amino acid difference, which was not responsible for the altered sodB regulation. Comparison of the sodB promoters from G27 and 26695 also revealed a single nucleotide difference within the predicted Fur binding site. Alteration of this nucleotide in G27 to that of 26695 restored apo-Fur dependent sodB regulation, indicating that a single base difference is at least partially responsible for the difference in sodB regulation observed among these H. pylori strains. Fur binding studies revealed that alteration of this single nucleotide in G27 increased the affinity of Fur for the sodB promoter. Additionally, the single base change in G27 enabled the sodB promoter to bind to apo-Fur with affinities similar to the 26695 sodB promoter. Taken together these data indicate that this nucleotide residue is important for direct apo-Fur binding to the sodB promoter.
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Affiliation(s)
- Beth M. Carpenter
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Hanan Gancz
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Reyda P. Gonzalez-Nieves
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Abby L. West
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, United States of America
| | - Jeannette M. Whitmire
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Sarah L. J. Michel
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland, United States of America
| | - D. Scott Merrell
- Department of Microbiology and Immunology, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
- * E-mail:
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Khoder G, Yamaoka Y, Fauchère JL, Burucoa C, Atanassov C. Proteomic Helicobacter pylori biomarkers discriminating between duodenal ulcer and gastric cancer. J Chromatogr B Analyt Technol Biomed Life Sci 2009; 877:1193-9. [PMID: 19328750 DOI: 10.1016/j.jchromb.2009.03.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2008] [Revised: 02/25/2009] [Accepted: 03/02/2009] [Indexed: 12/12/2022]
Abstract
Protein patterns of 129 Helicobacter pylori strains isolated from Korean and Colombian patients suffering from duodenal ulcer or gastric cancer were analyzed by the high-throughput methodology SELDI-TOF-MS. Eighteen statistically significant candidate biomarkers discriminating between the two clinical outcomes were selected by using the Mann-Whitney test. Three biomarker proteins were purified and identified as a neutrophil-activating protein NapA (HU HPAG1_0821), a RNA-binding protein (HPAG1_0813), and a DNA-binding histone-like protein HU, respectively (jhp0228). These novel biomarkers can be used for development of diagnostic assays predicting the evolution to gastric cancer in H. pylori-infected patients.
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Affiliation(s)
- Ghalia Khoder
- EA 4331 LITEC, Université de Poitiers, Poitiers, France
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Francois P, Hernandez D, Schrenzel J. Genome content determination in methicillin-resistant Staphylococcus aureus. Future Microbiol 2007; 2:187-98. [PMID: 17661655 DOI: 10.2217/17460913.2.2.187] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Staphylococcus aureus is a major pathogen responsible for both nosocomial and community-acquired infections. While the first S. aureus isolates displaying resistance to methicillin were reported in the early 1960s, endemic strains of methicillin-resistant S. aureus (MRSA) carrying multiple resistance determinants only became a worldwide nosocomial problem in the early 1980s, carrying a threefold attributable cost and a threefold excess length of hospital stay when compared with methicillin-susceptible S. aureus bacteremia. Recent efforts in the field of high-throughput sequencing resulted in the release of several MRSA genome sequences enabling the development of massively parallel tools to study clinical isolates of MRSA at the organism scale. Microarrays covering whole genomes and high-throughput sequencing devices are the two main techniques currently utilizable for whole-genome characterization. These tools not only provide information for the development of genotyping assays but also allow evaluation of potential virulence of the strains, by enumerating genetic-encoded resistance markers and toxin content. This appears particularly attractive for understanding the epidemiology of MRSA and the relationship between genome content on one side and virulence potential or epidemicity on the other side. In addition, sequence information is mandatory for the development of molecular tests allowing the rapid identification, genotyping and characterization of clinical isolates.
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Affiliation(s)
- Patrice Francois
- Service of Infectious Diseases, Genomic Research Laboratory, Department of Internal Medicine, Geneva 14, Switzerland.
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Oyarzabal OA, Rad R, Backert S. Conjugative transfer of chromosomally encoded antibiotic resistance from Helicobacter pylori to Campylobacter jejuni. J Clin Microbiol 2007; 45:402-8. [PMID: 17135441 PMCID: PMC1829062 DOI: 10.1128/jcm.01456-06] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Revised: 09/18/2006] [Accepted: 11/15/2006] [Indexed: 01/24/2023] Open
Abstract
Many strains of Helicobacter pylori are naturally competent for transformation and able to transfer chromosomal DNA among different isolates using a conjugation-like mechanism. In this study, we sought to determine whether H. pylori can transfer DNA into Campylobacter jejuni, a closely related species of the Campylobacterales group. To monitor the transfer, a chromosomally encoded streptomycin resistance cassette prearranged by a specific mutation in the rpsL gene of H. pylori was used. Mating of the bacteria on plates or in liquid broth medium produced C. jejuni progeny containing the streptomycin marker. DNA transfer was unidirectional, from H. pylori to C. jejuni, and the progeny were genetically identical to C. jejuni recipient strains. DNase I treatment reduced but did not eliminate transfer, and DNase I-treated cell supernatants did not transform, ruling out phage transduction. Recombinants also did not occur when the mating bacteria were separated by a membrane, suggesting that DNA transfer requires cell-to-cell contact. Transfer of the streptomycin marker was independent of the H. pylori comB transformation system, the cag pathogenicity island, and another type IV secretion system called tfs3. These findings indicated that a DNase I-resistant, conjugation-like mechanism may contribute to horizontal DNA transfer between different members of the Campylobacteriales group. The significance of this DNA uptake by C. jejuni in the context of acquiring antibiotic resistance is discussed.
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Affiliation(s)
- Omar A Oyarzabal
- Department of Poultry Science, Auburn University, Auburn, Alabama 36849, USA
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Rashid RA, Tabata TA, Oatley MJ, Besser TE, Tarr PI, Moseley SL. Expression of putative virulence factors of Escherichia coli O157:H7 differs in bovine and human infections. Infect Immun 2006; 74:4142-8. [PMID: 16790788 PMCID: PMC1489682 DOI: 10.1128/iai.00299-06] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Escherichia coli O157:H7 is a commensal organism in cattle, but it is a pathogen in humans. This differential expression of virulence suggests that specific virulence factors are regulated differently in human and bovine hosts. To test this hypothesis, relative real-time reverse transcription-PCR was used to relate the expression of several putative virulence genes (eae, espA, stx(2), rfbE, ehxA, and iha) to that of the "housekeeping" gene gnd during natural human and experimental bovine infection with E. coli O157:H7. We examined these genes in fecal samples from eight humans and four calves. iha and espA were significantly more expressed in bovine infections. rfbE and ehxA appeared to be more highly expressed in human infections, though these differences did not achieve statistical significance. Our results support the hypothesis that some virulence-associated genes of O157:H7 are differentially expressed in a host-specific manner.
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Affiliation(s)
- Rebecca A Rashid
- Department of Microbiology, University of Washington, 1959 N.E. Pacific St., Mail Stop 357242, Seattle, WA 98195, USA
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Backert S, Kwok T, König W. Conjugative plasmid DNA transfer in Helicobacter pylori mediated by chromosomally encoded relaxase and TraG-like proteins. MICROBIOLOGY-SGM 2005; 151:3493-3503. [PMID: 16272373 DOI: 10.1099/mic.0.28250-0] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
One of the striking characteristics of Helicobacter pylori is the extensive genetic diversity among clinical isolates. This diversity has been attributed to an elevated mutation rate, impaired DNA repair, DNA transfer and frequent recombination events. Plasmids have also been identified in H. pylori but it remained unknown whether conjugation can contribute to DNA transfer between clinical isolates. To examine whether H. pylori possesses intrinsic capability for conjugative plasmid transfer, shuttle vectors were introduced into H. pylori containing an oriT sequence of the conjugative IncPalpha plasmid RP4 but no mobilization (mob) genes. It was shown that these vectors could stably replicate and be mobilized among clinical H. pylori strains. It was also demonstrated that traG and relaxase (rlx) homologues carried on the H. pylori chromosome were important for plasmid transfer. Primer extension studies and mutagenesis further confirmed that the relaxase homologue rlx1 in H. pylori encodes a functional enzyme capable of acting on the RP4 oriT. Furthermore, the findings of this study indicate that traG and rlx1 act independently of the previously described type IV secretion systems, including that encoded by the cag pathogenicity island and the comB transformation apparatus, in mediating conjugative plasmid DNA transfer between H. pylori strains.
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Affiliation(s)
- Steffen Backert
- Department of Medical Microbiology, Otto von Guericke University, Leipziger Str. 44, D-39120 Magdeburg, Germany
| | - Terry Kwok
- Department of Medical Microbiology, Otto von Guericke University, Leipziger Str. 44, D-39120 Magdeburg, Germany
| | - Wolfgang König
- Department of Medical Microbiology, Otto von Guericke University, Leipziger Str. 44, D-39120 Magdeburg, Germany
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