scholarly journals Helicobacter pyloriOuter Membrane Protein 18 (Hp1125) Is Involved in Persistent Colonization by Evading Interferon-γSignaling

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Yuqun Shan ◽  
Xingxiao Lu ◽  
Yingnan Han ◽  
Xinpeng Li ◽  
Xiao Wang ◽  
...  
Keyword(s):  
Immune Response ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Immune Surveillance ◽  
Survival Rates ◽  
Wild Type ◽  
Qrt Pcr ◽  
H Pylori ◽  
Host Immune Surveillance

Outer membrane proteins (OMPs) can induce an immune response. Omp18 (HP1125) ofH. pyloriis a powerful antigen that can induce significant interferon-γ(IFN-γ) levels. Previous studies have suggested that IFN-γplays an important role inH. pyloriclearance. However,H. pylorihas multiple mechanisms to avoid host immune surveillance for persistent colonization. We generated anomp18mutant (H. pylori26695 andH. pyloriSS1) strain to examine whether Omp18 interacts with IFN-γand is involved inH. pyloricolonization. qRT-PCR revealed that IFN-γinduced Omp18 expression. qRT-PCR and western blot analysis revealed reduced expressions of virulence factors CagA and NapA inH. pylori26695 with IFN-γtreatment, but they were induced in the Δomp18strain. In C57BL/6 mice infected withH. pyloriSS1 and the Δomp18strain, the Δomp18strain conferred defective colonization and activated a stronger inflammatory response. Signal transducer phosphorylation and transcription 1 (STAT1) activator was downregulated by the wild-type strain but not the Δomp18strain in IFN-γ-treated macrophages. Furthermore, Δomp18strain survival rates were poor in macrophages compared to the wild-type strain. We concluded thatH. pyloriOmp18 has an important function influencing IFN-γ-mediated immune response to participate in persistent colonization.

scholarly journals Role of the Helicobacter pylori outer-membrane proteins AlpA and AlpB in colonization of the guinea pig stomach

2004 ◽  
Vol 53 (5) ◽  
pp. 375-379 ◽  
Author(s):  
Ramon de Jonge ◽  
Zarmina Durrani ◽  
Sjoerd G. Rijpkema ◽  
Ernst J. Kuipers ◽  
Arnoud H.M. van Vliet ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Membrane Proteins ◽  
Guinea Pig ◽  
Outer Membrane ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Wild Type ◽  
H Pylori

The human gastric pathogen Helicobacter pylori expresses several putative outer-membrane proteins (OMPs), but the role of individual OMPs in colonization of the stomach by H. pylori is still poorly understood. The role of four such OMPs (AlpA, AlpB, OipA and HopZ) in a guinea pig model of H. pylori infection has been investigated. Single alpA, alpB, hopZ and oipA isogenic mutants were constructed in the guinea pig-adapted, wild-type H. pylori strain GP15. Guinea pigs were inoculated intragastrically with the wild-type strain, single mutants or a mixture of the wild-type and a single mutant in a 1 : 1 ratio. Three weeks after infection, H. pylori could be isolated from stomach sections of all animals that were infected with the wild-type, the hopZ mutant or the oipA mutant, but from only five of nine (P = 0.18) and one of seven (P = 0.02) animals that were infected with the alpA or alpB mutants, respectively. The hopZ and oipA mutants colonized the majority of animals that were inoculated with the strain mixture, whereas alpA and alpB mutants could not be isolated from animals that were infected with the strain mixture (P < 0.01). Specific IgG antibody responses were observed in all animals that were infected with either the wild-type or a mutant, but IgG levels were lower in animals that were infected with either the alpA or the alpB mutants, compared to the wild-type strain (P < 0.05). In conclusion, absence of AlpA or AlpB is a serious disadvantage for colonization of the stomach by H. pylori.

scholarly journals Failure of Surface Ring Mutant Strains of Helicobacter mustelae To Persistently Infect the Ferret Stomach

2003 ◽  
Vol 71 (5) ◽  
pp. 2350-2355 ◽  
Author(s):  
M. M. Patterson ◽  
P. W. O'Toole ◽  
N. T. Forester ◽  
B. Noonan ◽  
T. J. Trust ◽  
...  
Keyword(s):  
Type Strain ◽  
Wild Type Strain ◽  
Gastric Body ◽  
Wild Type ◽  
Significant Difference ◽  
Specific Pathogen ◽  
Ring Structures ◽  
H Pylori ◽  
Successful Colonization ◽  
Persistently Infect

ABSTRACT Helicobacter mustelae, the gastric pathogen of ferrets, produces an array of surface ring structures which have not been described for any other member of the genus Helicobacter, including H. pylori. The unique ring structures are composed of a protein named Hsr. To investigate whether the Hsr rings are important for colonization of the ferret stomach, ferrets specific pathogen free for H. mustelae were inoculated with an Hsr-deficient mutant strain or the wild-type H. mustelae strain. Quantitative cultures from antral biopsy specimens obtained at 3, 6, and 9 weeks postinoculation demonstrated no significant difference in the levels of bacteria in the ferrets that received the Hsr-negative strain and the ferrets infected with the parent strain. However, when the ferrets were biopsied at 12 and 15 weeks and necropsied at 18 weeks after infection, the levels of bacteria of the Hsr-negative strain in the stomach antrum were significantly reduced. This decline contrasted the robust antral colonization by the wild-type strain. The Hsr-negative strain did not efficiently colonize the gastric body of the study ferrets. Histological examination at 18 weeks postinoculation revealed minimal gastric inflammation in the animals that received the mutant H. mustelae strain, a finding consistent with its waning infection status, whereas lesions characteristic of helicobacter infection were present in ferrets infected with the wild-type strain. Scant colonization by the Hsr-negative H. mustelae strain at the end of the 18-week study, despite initial successful colonization, indicates an inability of the mutant to persist, perhaps due to a specific host response.

scholarly journals Circulating γδ T Cells in Response to Salmonellaenterica Serovar Enteritidis Exposure in Chickens

2006 ◽  
Vol 74 (7) ◽  
pp. 3967-3978 ◽  
Author(s):  
Angela Berndt ◽  
Jana Pieper ◽  
Ulrich Methner
Keyword(s):  
Immune Response ◽  
T Cells ◽  
T Cell ◽  
Peripheral Blood ◽  
Type Strain ◽  
Wild Type Strain ◽  
Γδ T Cells ◽  
Immunohistochemical Analysis ◽  
Wild Type ◽  
Γδt Cells

ABSTRACT γδT cells are considered crucial to the outcome of various infectious diseases. The present study was undertaken to characterizeγδ (T-cell receptor 1+ [TCR1+]) T cells phenotypically and functionally in avian immune response. Day-old chicks were orally immunized with Salmonella enterica serovar Enteritidis live vaccine or S. enterica serovar Enteritidis wild-type strain and infected using the S. enterica serovar Enteritidis wild-type strain on day 44 of life. Between days 3 and 71, peripheral blood was examined flow cytometrically for the occurrence of γδ T-cell subpopulations differentiated by the expression of T-cell antigens. Three different TCR1+ cell populations were found to display considerable variation regarding CD8α antigen expression: (i) CD8α+high TCR1+ cells, (ii) CD8α+dim TCR1+ cells, and (iii) CD8α− TCR1+ cells. While most of the CD8α+high TCR1+ cells expressed the CD8αβ heterodimeric antigen, the majority of the CD8α+dim TCR1+ cells were found to express the CD8αα homodimeric form. After immunization, a significant increase of CD8αα+high γδ T cells was observed within the CD8α+high TCR1+ cell population. Quantitative reverse transcription-PCR revealed reduced interleukin-7 receptor α (IL-7Rα) and Bcl-x expression and elevated IL-2Rα mRNA expression of the CD8αα+highγδ T cells. Immunohistochemical analysis demonstrated a significant increase of CD8α+ and TCR1+ cells in the cecum and spleen and a decreased percentage of CD8β+ T cells in the spleen after Salmonella immunization. After infection of immunized animals, immune reactions were restricted to intestinal tissue. The study showed that Salmonella immunization of very young chicks is accompanied by an increase of CD8αα+high γδ T cells in peripheral blood, which are probably activated, and thus represent an important factor for the development of a protective immune response to Salmonella organisms in chickens.

scholarly journals Role of β-Lactamases and Porins in Resistance to Ertapenem and Other β-Lactams in Klebsiella pneumoniae

2004 ◽  
Vol 48 (8) ◽  
pp. 3203-3206 ◽  
Author(s):  
George A. Jacoby ◽  
Debra M. Mills ◽  
Nancy Chow
Keyword(s):  
Klebsiella Pneumoniae ◽  
Outer Membrane ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Wild Type ◽  
Resistant Mutants ◽  
High Level ◽  
Level Resistance

ABSTRACT High-level resistance to ertapenem was produced by β-lactamases of groups 1, 2f, and 3 in a strain of Klebsiella pneumoniae deficient in Omp35 and Omp36. From a wild-type strain producing ACT-1 β-lactamase, ertapenem-resistant mutants for which the ertapenem MICs were up to 128 μg/ml and expression of outer membrane proteins was diminished could be selected.

scholarly journals Involvement of CO2 generated by urease in multiplication of Helicobacter pylori

2021 ◽  
Vol 7 (3) ◽  
pp. 045-053
Author(s):  
Masaaki Minami ◽  
Shin-nosuke Hashikawa ◽  
Takafumi Ando ◽  
Hiroshi Kobayashi ◽  
Hidemi Goto ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Mutant Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Neutral Medium ◽  
Wild Type ◽  
In The Wild ◽  
H Pylori ◽  
Carbon Dioxide Co2 ◽  
The Relationship

Helicobacter pylori (H. pylori) urease generates both ammonia (NH3) and carbon dioxide (CO2) from urea. NH3 helps H. pylori to survive in the stomach in part by neutralizing gastric acid. However, the relationship between CO2 and H. pylori is not completed cleared. We examined the effect of CO2 generated by urease on multiplication of H. pylori by using isogenic ureB mutant and ureB complemented strain from H. pylori strain JP26. Wild-type strain survived in the medium supplement with 1mM urea in room air, however, the urease negative strain did not. To discern whether CO2 was incorporated into H. pylori, 14C in bacillus was counted after 6 hours incubation with 14C urea in both acidic and neutral medium. Significant more 14C uptake was detected in wild-type strain compared to ureB mutant strain and this uptake in the wild-type strain was more under acidic condition compared to under neutral condition, but no difference was identified in the mutant strain. These results suggest that CO2 generated by urease plays a role in multiplication of H. pylori.

scholarly journals Control of β-glucan exposure by the endo-1,3-glucanase Eng1 in Candida albicans modulates virulence

2020 ◽  
Author(s):  
Mengli Yang ◽  
Norma V. Solis ◽  
Michaela Marshall ◽  
Rachel Garleb ◽  
Tingting Zhou ◽  
...  
Keyword(s):  
Immune Response ◽  
Candida Albicans ◽  
Innate Immune Response ◽  
Type Strain ◽  
Wild Type Strain ◽  
Innate Immune ◽  
Yeast Cells ◽  
Parallel Mechanisms ◽  
Wild Type ◽  
Lectin Receptor

AbstractCandida albicans is a major cause of invasive candidiasis, which has a high mortality rate. The hyphal form of C. albicans is virulent and activates the host innate immune response, while the yeast form is hypovirulent and less immunogenic. The innate immune response is critical for host defense, but overactivation can cause tissue damage and sepsis. The innate immune response can be triggered when the C-type lectin receptor Dectin-1 recognizes β-glucans, which is protected by the outer mannan layer of the cell wall on C. albicans. Here, we demonstrate that there is low level of Dectin-1 binding at the septum of yeast cells, but high level of Dectin-1 binding over the entire surface of hyphae. We find that β-glucan masking in yeast is controlled by two highly expressed yeast proteins, the endo-1,3-β-glucanase Eng1 and the Yeast Wall Protein Ywp1. An eng1 deletion mutant shows enhanced Dectin-1 binding at the septa, while an eng1 ywp1 double mutant, but not an ywp1 single mutant, shows strong overall Dectin-1 binding. Thus, Eng1-mediated β-glucan trimming and Ywp1-mediated β-glucan masking are two parallel mechanisms utilized by C. albicans yeast to minimize recognition by Dectin-1. In the model of disseminated candidiasis, mice infected with the eng1 deletion mutant showed delayed mortality with an increased renal immune response in males compared to mice infected with the wild-type strain, but earlier mortality with a higher renal immune response in females. Using the eng1 mutant that is specifically defective in β-glucan masking in yeast, this study demonstrates that the level of β-glucan exposure is important for modulating the balance between immune protection and immunopathogenesis.Abstract ImportanceCandida albicans is a major opportunistic fungal pathogen of humans. Systemic Candidiasis has high mortality rates. C. albicans is also a constituent of the human microbiome and found in gastrointestinal and genitourinary tracts of most healthy individuals. C. albicans is able to switch reversibly between yeast and hyphae in response to environmental cues. The hyphal form is virulent, while the yeast form is hypovirulent and less immunogenic. This study demonstrates that β-glucan exposure in yeast is protected by two highly expressed yeast proteins, the endo-1,3-β-glucanase Eng1 and the Yeast Wall Protein Ywp1. Eng1-mediated β-glucan trimming and Ywp1-mediated β-glucan masking are two parallel mechanisms utilized by C. albicans yeast to minimize recognition by the host C-type lectin receptor Dectin-1. The eng1 mutant triggers a higher immune response and leads to earlier mortality compared to the wild-type strain. Thus, β-glucan masking in yeast keeps yeast cells less immunogenic and hypovirulent.

scholarly journals Novel Toluene Elimination System in a Toluene-Tolerant Microorganism

2000 ◽  
Vol 182 (22) ◽  
pp. 6451-6455 ◽  
Author(s):  
Hideki Kobayashi ◽  
Katsuyuki Uematsu ◽  
Hisako Hirayama ◽  
Koki Horikoshi
Keyword(s):  
Membrane Proteins ◽  
Cell Membrane ◽  
Outer Membrane ◽  
Parent Strain ◽  
Type Strain ◽  
Wild Type Strain ◽  
Outer Membrane Proteins ◽  
Membrane Vesicles ◽  
Wild Type ◽  
Sensitive Mutant

ABSTRACT In studies of Pseudomonas putida IH-2000, a toluene-tolerant microorganism, membrane vesicles (MVs) were found to be released from the outer membrane when toluene was added to the culture. These MVs were found to be composed of phospholipids, lipopolysaccharides (LPS), and very low amounts of outer membrane proteins. The MVs also contained a higher concentration of toluene molecules (0.172 ± 0.012 mol/mol of lipid) than that found in the cell membrane. In contrast to the wild-type strain, the toluene-sensitive mutant strain 32, which differs from the parent strain in LPS and outer membrane proteins, did not release MVs from the outer membrane. The toluene molecules adhering to the outer membrane are eliminated by the shedding of MVs, and this system appears to serve as an important part of the toluene tolerance system of IH-2000.

scholarly journals Effect of Trehalose and Trehalose Transport on the Tolerance ofClostridium perfringensto Environmental Stress in a Wild Type Strain and Its Fluoroquinolone-Resistant Mutant

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Miseon Park ◽  
Wilfrid J. Mitchell ◽  
Fatemeh Rafii
Keyword(s):  
Environmental Stress ◽  
Type Strain ◽  
Wild Type Strain ◽  
Resistant Mutant ◽  
Defined Medium ◽  
Low Ph ◽  
Bacterial Cells ◽  
Chemically Defined Medium ◽  
Wild Type ◽  
Qrt Pcr

Trehalose has been shown to protect bacterial cells from environmental stress. Its uptake and osmoprotective effect inClostridium perfringenswere investigated by comparing wild typeC. perfringensATCC 13124 with a fluoroquinolone- (gatifloxacin-) resistant mutant. In a chemically defined medium, trehalose and sucrose supported the growth of the wild type but not that of the mutant. Microarray data and qRT-PCR showed that putative genes for the phosphorylation and transport of sucrose and trehalose (via phosphoenolpyruvate-dependent phosphotransferase systems, PTS) and some regulatory genes were downregulated in the mutant. The wild type had greater tolerance than the mutant to salts and low pH; trehalose and sucrose further enhanced the osmotolerance of the wild type to NaCl. Expression of the trehalose-specific PTS was lower in the fluoroquinolone-resistant mutant. Protection ofC. perfringensfrom environmental stress could therefore be correlated with the ability to take up trehalose.

scholarly journals Antibody Responses 3-5 Months Post-Vaccination with mRNA-1273 or BNT163b2 in Nursing Home Residents

2021 ◽  
Author(s):  
Jessica A. Breznik ◽  
Ali Zhang ◽  
Angela Huynh ◽  
Matthew S. Miller ◽  
Ishac Nazy ◽  
...  
Keyword(s):  
Immune Response ◽  
Nursing Home ◽  
Humoral Immune Response ◽  
Type Strain ◽  
Wild Type Strain ◽  
Nursing Home Residents ◽  
Wild Type ◽  
Humoral Immune ◽  
Fold Reduction ◽  
Antibody Levels

AbstractNursing home residents often fail to mount robust responses to vaccinations and recent reports of breakthrough infections, particularly from variants of concern, raise questions about whether vaccination regimens elicit a sufficient humoral immune response or if booster doses are warranted. We examined SARS-CoV-2 antibody levels and neutralizing capacity in nursing home residents 3-5 months after 2 doses of mRNA-1273 or BNT163b2 vaccination as per recommended schedules.Nursing home residents were recruited from eight long-term care homes in Ontario, Canada, between March and July 2021. Antibody levels and neutralization capacity from a previously published convalescent cohort were used as a comparator. Serum SARS-CoV-2 IgA/G/M against spike (S) protein and its receptor-binding domain (RBD) were measured by validated ELISA, with assay cut-off at the mean and 3 standard deviations of a pre-COVID-19 population from the same geographic region. Antibody neutralization was measured against the wild-type strain of SARS-CoV-2 and the beta variant of concern (B.1.351).No neutralizing antibodies were detected in ∼20% of residents to the wild-type virus (30/155; 19%) or beta variant (27/134; 20%). Residents that received BNT163b2 had a ∼4-fold reduction in neutralization to the wild-type strain, and a ∼2-fold reduction in neutralization to the beta variant relative to those who received mRNA-1273.Current mRNA SARS-CoV-2 vaccine regimens may not have equivalent efficacy in nursing home residents. Our findings imply that differences in the humoral immune response may contribute to breakthrough infections, and suggest that consideration of the type of vaccine administered to older adults will have a positive impact on the generation of protective immunity.

scholarly journals Characterization of Human Bactericidal Antibodies to Bordetella pertussis

1999 ◽  
Vol 67 (3) ◽  
pp. 1424-1431 ◽  
Author(s):  
Alison A. Weiss ◽  
Paula S. Mobberley ◽  
Rachel C. Fernandez ◽  
ChrisAnna M. Mink
Keyword(s):  
Immune Response ◽  
Bactericidal Activity ◽  
Bordetella Pertussis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Resistance Mechanism ◽  
Wild Type ◽  
Occupationally Exposed ◽  
Bactericidal Activities

ABSTRACT The Bordetella pertussis BrkA protein protects against the bactericidal activity of complement and antibody; however, some individuals mount an immune response that overcomes this bacterial defense. To further characterize this process, the bactericidal activities of sera from 13 adults with different modes of exposure toB. pertussis (infected as adults, occupational exposure, immunized with an acellular vaccine, or no identified exposure) against a wild-type strain and a BrkA complement-sensitive mutant were evaluated. All of the sera killed the BrkA mutant, suggesting past exposure to B. pertussis or cross-reactive organisms. Several samples had no or minimal activity against the wild type. All of the sera collected from the infected and occupationally exposed individuals but not all of the sera from vaccinated individuals had bactericidal activity against the wild-type strain, suggesting that some types of exposure can induce an immune response that can overcome the BrkA resistance mechanism. Adsorbing serum with the wild-type strain removed the bactericidal antibodies; however, adsorbing the serum with a lipopolysaccharide (LPS) mutant or an avirulent (bvg mutant) strain did not always result in loss of bactericidal activity, suggesting that antibodies to either LPS orbvg-regulated proteins could be bactericidal. All the samples, including those that lacked bactericidal activity, contained antibodies that recognized the LPS of B. pertussis. Bactericidal activity correlated best with the presence of the immunoglobulin G3 (IgG3) antibodies to LPS, the IgG subtype that is most effective at fixing complement.

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