scholarly journals Rickettsial outer-membrane protein B (rOmpB) mediates bacterial invasion through Ku70 in an actin, c-Cbl, clathrin and caveolin 2-dependent manner

2009 ◽  
Vol 11 (4) ◽  
pp. 629-644 ◽  
Author(s):  
Yvonne G. Y. Chan ◽  
Marissa M. Cardwell ◽  
Timothy M. Hermanas ◽  
Tsuneo Uchiyama ◽  
Juan J. Martinez
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Bacterial Invasion ◽  
Dependent Manner ◽  
Protein B

scholarly journals Molecular Basis of Immunity to Rickettsial Infection Conferred through Outer Membrane Protein B

2011 ◽  
Vol 79 (6) ◽  
pp. 2303-2313 ◽  
Author(s):  
Yvonne Gar-Yun Chan ◽  
Sean Phillip Riley ◽  
Emily Chen ◽  
Juan José Martinez
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Molecular Basis ◽  
Spotted Fever ◽  
Host Cells ◽  
Bacterial Invasion ◽  
Passenger Domain ◽  
Rickettsial Infection ◽  
Protein B

ABSTRACTPathogenic rickettsiae are the causative agents of Rocky Mountain spotted fever, typhus, and other human diseases with high mortality and an important impact on society. Although survivors of rickettsial infections are considered immune to disease, the molecular basis of this immunity or the identification of protective antigens that enable vaccine development was hitherto not known. By exploring the molecular pathogenesis ofRickettsia conorii, the agent of Mediterranean spotted fever, we report here that the autotransporter protein, rickettsial outer membrane protein B (rOmpB), constitutes a protective antigen for this group of pathogens. A recombinant, purified rOmpB passenger domain fragment comprised of amino acids 36 to 1334 is sufficient to elicit humoral immune responses that protect animals against lethal disease. Protective immunity requires folded antigen and production of antibodies that recognize conformational epitopes on the rickettsial surface. Monoclonal antibodies (MAbs) 5C7.27 and 5C7.31, which specifically recognize a conformation present in the folded, intact rOmpB passenger domain, are sufficient to confer immunityin vivo. Analysesin vitroindicate this protection involves a mechanism of complement-mediated killing in mammalian blood, a means of rickettsial clearance that has not been previously described. Considering the evolutionary conservation of rOmpB and its crucial contribution to bacterial invasion of host cells, we propose that rOmpB antibody-mediated killing confers immunity to rickettsial infection.

scholarly journals The Helicobacter pylori Autotransporter ImaA (HP0289) Modulates the Immune Response and Contributes to Host Colonization

2012 ◽  
Vol 80 (7) ◽  
pp. 2286-2296 ◽  
Author(s):  
William E. Sause ◽  
Andrea R. Castillo ◽  
Karen M. Ottemann
Keyword(s):  
Immune Response ◽  
Helicobacter Pylori ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Dependent Manner ◽  
Wild Type ◽  
Content Type ◽  
H Pylori ◽  
Murine Infections

ABSTRACTThe human pathogenHelicobacter pyloriemploys a diverse collection of outer membrane proteins to colonize, persist, and drive disease within the acidic gastric environment. In this study, we sought to elucidate the function of the host-induced geneHP0289, which encodes an uncharacterized outer membrane protein. We first generated an isogenicH. pylorimutant that lacksHP0289and found that the mutant has a colonization defect in single-strain infections and is greatly outcompeted in mouse coinfection experiments with wild-typeH. pylori. Furthermore, we used protease assays and biochemical fractionation coupled with an HP0289-targeted peptide antibody to verify that the HP0289 protein resides in the outer membrane. Our previous findings showed that theHP0289promoter is upregulated in the mouse stomach, and here we demonstrate thatHP0289expression is induced under acidic conditions in an ArsRS-dependent manner. Finally, we have shown that theHP0289mutant induces greater expression of the chemokine interleukin-8 (IL-8) and the cytokine tumor necrosis factor alpha (TNF-α) in gastric carcinoma cells (AGS). Similarly, transcription of the IL-8 homolog keratinocyte-derived chemokine (KC) is elevated in murine infections with the HP0289 mutant than in murine infections with wild-typeH. pylori. On the basis of this phenotype, we renamed HP0289 ImaA forimmunomodulatoryautotransporter protein. Our work has revealed that genes inducedin vivoplay an important role inH. pyloripathogenesis. Specifically, the outer membrane protein ImaA modulates a component of the host inflammatory response, and thus may allowH. pylorito fine tune the host immune response based on ImaA expression.

scholarly journals Yersinia outer-membrane protein B (YopB): a tool for identification of Yersinia pestis isolates

2006 ◽  
Vol 55 (4) ◽  
pp. 467-469 ◽  
Author(s):  
Rekha Khushiramani ◽  
Jyoti Shukla ◽  
Urmil Tuteja ◽  
Harsh Vardhan Batra
Keyword(s):  
Membrane Protein ◽  
Yersinia Pestis ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Protein B

scholarly journals Naturally Occurring IgG Antibodies Provide Innate Protection against Vibrio cholerae Bacteremia by Recognition of the Outer Membrane Protein U

2016 ◽  
Vol 8 (3) ◽  
pp. 269-283 ◽  
Author(s):  
Kyaw Min Aung ◽  
Annika E. Sjöström ◽  
Ulrich von Pawel-Rammingen ◽  
Kristian Riesbeck ◽  
Bernt Eric Uhlin ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Vibrio Cholerae ◽  
Outer Membrane Protein ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Immune Defense ◽  
Dependent Manner ◽  
Naturally Occurring ◽  
Serum Killing

Cholera epidemics are caused by Vibrio cholerae serogroups O1 and O139, whereas strains collectively known as non-O1/non-O139 V. cholerae are found in cases of extraintestinal infections and bacteremia. The mechanisms and factors influencing the occurrence of bacteremia and survival of V. cholerae in normal human serum have remained unclear. We found that naturally occurring IgG recognizing V. cholerae outer membrane protein U (OmpU) mediates a serum-killing effect in a complement C1q-dependent manner. Moreover, outer membrane vesicles (OMVs) containing OmpU caused enhanced survival of highly serum-sensitive classical V. cholerae in a dose-dependent manner. OMVs from wild-type and ompU mutant V. cholerae thereby provided a novel means to verify by extracellular transcomplementation the involvement of OmpU. Our data conclusively indicate that loss, or reduced expression, of OmpU imparts resistance to V. cholerae towards serum killing. We propose that the difference in OmpU protein levels is a plausible reason for differences in serum resistance and the ability to cause bacteremia observed among V. cholerae biotypes. Our findings provide a new perspective on how naturally occurring antibodies, perhaps induced by members of the microbiome, may play a role in the recognition of pathogens and the provocation of innate immune defense against bacteremia.

scholarly journals Serological Reactivity and Biochemical Characterization of Methylated and Unmethylated Forms of a Recombinant Protein Fragment Derived from Outer Membrane Protein B of Rickettsia typhi

2008 ◽  
Vol 15 (4) ◽  
pp. 684-690 ◽  
Author(s):  
Chien-Chung Chao ◽  
Zhiwen Zhang ◽  
Hui Wang ◽  
Abdulnaser Alkhalil ◽  
Wei-Mei Ching
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Mass Spectrometry Analysis ◽  
Enzyme Linked Immunosorbent Assay ◽  
Composition Analysis ◽  
Rickettsia Typhi ◽  
Serological Reactivity ◽  
Lysine Residues ◽  
Protein B

ABSTRACT Rickettsia typhi, an obligate intracellular bacterium that causes murine typhus, possesses a heavily methylated outer membrane protein B (OmpB) antigen. This immunodominant antigen is responsible for serological reactions and is capable of eliciting protective immune responses with a guinea pig model. Western blot analysis of partially digested OmpB with patient sera revealed that most of the reactive fragments are larger than 20 kDa. One of these fragments, which is located at the N terminus (amino acids 33 to 273), fragment A (At), has been expressed in Escherichia coli. The expressed protein (rAt) was purified by chromatography and properly refolded by sequential dialysis. The refolded rAt protein was recognized by at least 87% of the typhus group patient sera as determined by enzyme-linked immunosorbent assay (ELISA). However, the titers were lower than those obtained with OmpB of R. typhi. Since native OmpB is hypermethylated at lysine residues, we chemically methylated the lysine residues in rAt. The methylation was confirmed by amino acid composition analysis, and the methylation pattern of the methylated rAt (mrAt) protein was similar to that of native At from OmpB, as revealed by liquid chromatography-mass spectrometry analysis. Both rAt and mrAt were evaluated in an ELISA for their serological reactivity with patient sera. Among patient sera tested, 83% exhibited higher titers with mrAt than with rAt. These results suggest that rAt, with or without methylation, can potentially replace rickettsia-derived OmpB or whole-cell antigen for the diagnosis of R. typhi infection.

scholarly journals Moraxella catarrhalis Outer Membrane Protein CD Elicits Antibodies That Inhibit CD Binding to Human Mucin and Enhance Pulmonary Clearance of M. catarrhalis in a Mouse Model

2007 ◽  
Vol 75 (6) ◽  
pp. 2818-2825 ◽  
Author(s):  
Dai-Fang Liu ◽  
John C. McMichael ◽  
Steven M. Baker
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Moraxella Catarrhalis ◽  
Signal Sequence ◽  
Vaccine Antigen ◽  
Enzyme Linked Immunosorbent Assay ◽  
Dependent Manner ◽  
Bacterial Clearance ◽  
Vitro Assay

ABSTRACT The outer membrane protein CD of Moraxella catarrhalis is considered to be a potential vaccine antigen against Moraxella infection. We purified the native CD from isolate O35E, administered it to mice, and detected considerable titers of anti-CD antibodies. Anti-CD sera were cross-reactive towards six different M. catarrhalis isolates and promoted bacterial clearance of O35E in a pulmonary challenge model. To circumvent the difficulty of generating large quantities of CD from M. catarrhalis for vaccine use, the CD gene from O35E was cloned into Escherichia coli, and the recombinant CD, expressed without a signal sequence or fusion tags, represented ∼70% of the total E. coli proteins. The recombinant CD formed inclusion bodies that were solubilized with 6 M urea and then purified by ion-exchange chromatography, a procedure that produced soluble CD of high purity and yield. Mice immunized with the purified recombinant CD had significant titers of anti-CD antibodies that were cross-reactive towards 24 different M. catarrhalis isolates. Upon challenge, these mice showed enhanced bacterial clearance of both O35E and a heterologous M. catarrhalis isolate, TTA24. In an in vitro assay, antisera to either the native or the recombinant CD inhibited the binding activity of CD to human tracheobronchial mucin in a serum concentration-dependent manner, and the extent of inhibition appeared to correlate with the corresponding anti-CD antibody titer and whole-cell enzyme-linked immunosorbent assay titer. Our results demonstrate that the recombinant CD is a promising vaccine candidate for preventing Moraxella infection.

scholarly journals Evaluation of the New Outer Membrane Protein A Epitope-based Vaccines for Mice Model of Acinetobacter baumannii Associated Pneumonia and Sepsis Infection

2021 ◽  
Author(s):  
Kobra Mehdinejadiani ◽  
Ali Hashemi ◽  
Mojgan Bandehpour ◽  
Hoda Rahmani ◽  
Mohammad Mehdi Ranjbar ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Protein A ◽  
Survival Rates ◽  
The Other ◽  
Dependent Manner ◽  
Protective Function ◽  
Outer Membrane Protein A

Nosocomial infections caused by Acinetobacter baumannii (A. baumannii) are considered as a global serious problem in hospitalized patients because of emerging antibiotic resistance. Immunotherapy approaches are promising to prevent such infections. In our previous study, five antigenic epitopes of outer membrane protein A (OmpA), as the most dangerous virulence molecule in A. baumanii, were predicted in silico. In this study, the investigators evaluated some immunological aspects of the peptides.Five peptides were separately injected into C5BL/6 mice; then the cytokine production (interleukin-4 and interferon-gamma) of splenocytes and opsonophagocytic activity of immunized serum were assessed. To identify the protective function of the peptides, animal models of sepsis and pneumonia infections were actively and passively immunized with selected peptides and pooled sera of immunized mice, respectively. Then, their survival rates were compared with the non-infected controls.Based on the results, activated spleen cells in P127 peptide-immunized mice exhibited an increased level of IFN-γ compared with the other experimental groups, but not about the IL-4 concentration. The results of the opsonophagocytic assay revealed an appropriate killing the activity of produced antibodies against A. baumannii in a dose-dependent manner. Further, the survival rates of the mice under passive immunization with the immunized sera or active immunization with P127 peptide were significantly more than those in the control group. Moreover, the survival rate of the P127 peptide immunized group was considerably higher than that of the other peptide-immunized group.In conclusion, findings indicated that peptides derived from OmpA can be used as a promising tool for designing the epitope-based vaccines against infections caused by A. baumannii.   

scholarly journals Major Outer Membrane Protein from Legionella pneumophila Inhibits Phagocytosis but Enhances Chemotaxis of RAW 264.7 Macrophages by Regulating the FOXO1/Coronin-1 Axis

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zehui Yang ◽  
Yingying Chen ◽  
Qiang Zhang ◽  
Xiaodong Chen ◽  
Ze Deng
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Legionella Pneumophila ◽  
Major Outer Membrane Protein ◽  
Raw 264.7 ◽  
Dependent Manner ◽  
Raw 264.7 Macrophages ◽  
Expression Levels ◽  
Raw 264.7 Macrophage

Legionella pneumophila is an intracellular pathogen that can cause Legionnaire’s disease by invading alveolar epithelial cells and macrophages. The major outer membrane protein (MOMP) plays an important role in the interaction between bacteria and host cells. However, the role of MOMP in the process of L. pneumophila invasion of macrophages and its working mechanism remain unknown. We aimed to explore the effects of MOMP on phagocytosis and chemotaxis of RAW 264.7 macrophages. The chemotactic activity, toxicity, and phagocytosis of RAW 264.7 cocultured with different concentrations of MOMP were determined by Transwell, CCK-8, and neutral red uptake assays, respectively. Target genes were detected by double-luciferase and pull down assays. qRT-PCR and Western blot were performed to analyze the expression of several important proteins involved in the immune response pathway, including coronin-1, interleukins (IL-10), forkhead transcription factor 1 (FOXO1), nucleotide-binding oligomerization domain protein (NOD) 1, NOD2, and receptor-interacting protein (RIP) 2. After coculturing with MOMP, cytological observation indicated a decrease of phagocytosis and a marked increase of chemotaxis in RAW 264.7 macrophages. The phagocytosis degree of RAW 264.7 macrophage varied with the concentration gradient of MOMP in a time-dependent manner. MOMP could increase the expression levels of MCP-1, IL-10, NOD2, and RIP2 and decrease the expression levels of FOXO1 and coronin-1 in cell culture supernatants. In addition, we found that FOXO1 could promote its transcription by binding to the promoter of coronin-1. The results of the present study suggested that MOMP could inhibit phagocytosis and facilitate chemotaxis of RAW 264.7 macrophage, which might be associated with the FOXO1/coronin-1 axis.

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