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 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 Bacterial entry and intracellular processing of Neisseria gonorrhoeae in epithelial cells: immunomorphological evidence for alterations in the major outer membrane protein P.IB.

1991 ◽  
Vol 174 (3) ◽  
pp. 705-715 ◽  
Author(s):  
J F Weel ◽  
C T Hopman ◽  
J P van Putten
Keyword(s):  
Epithelial Cells ◽  
Membrane Protein ◽  
Host Cell ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Major Outer Membrane Protein ◽  
Host Cells ◽  
Eukaryotic Cells ◽  
Bacterial Invasion ◽  
Intracellular Processing

The fate of the major outer membrane protein of the gonococcus, P.IB, during the adherence, entry, and intracellular processing of the bacteria in infected epithelial cells was investigated using post-embedding immunoelectron microscopy. Various domains of the P.IB molecule were probed at different stages in the infection. These studies revealed that P.IB epitope exposure remained unaltered during the initial attachment of the bacteria to the host cells. In contrast, upon secondary attachment of the bacteria to the eukaryotic cells, apparent zones of adhesion were formed between the gonococci and the host cell membrane, which were characterized by loss of a defined P.IB epitope. These zones of adhesion with the altered P.IB immunoreactivity continued to exist and increased in number during cellular penetration, suggesting that they were essential to bacterial invasion into the eukaryotic cells. After bacterial entry, two classes of gonococci could be recognized; morphologically intact, P.IB-positive bacteria and disintegrated organisms that showed a change in, and, in a later stage, a complete loss of P.IB immunoreactivity. The intracellular alterations in the P.IB antigen could be prevented by treatment of the host cells with the lysosomotropic agent chloroquine. These observations point to a mechanism by which a subpopulation of intracellular gonococci can escape the epithelial cell defense by preventing or resisting exposure to host cell proteolytic activity.

scholarly journals Subinhibitory Concentrations of Antimicrobial Agents Reduce the Uptake of Legionella pneumophila into Acanthamoeba castellanii and U937 Cells by Altering the Expression of Virulence-Associated Antigens

1998 ◽  
Vol 42 (11) ◽  
pp. 2870-2876 ◽  
Author(s):  
P. Christian Lück ◽  
Jürgen W. Schmitt ◽  
Arne Hengerer ◽  
Jürgen H. Helbig
Keyword(s):  
Monoclonal Antibodies ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Legionella Pneumophila ◽  
Antimicrobial Agents ◽  
Acanthamoeba Castellanii ◽  
Host Cells ◽  
Uncharacterized Protein ◽  
Subinhibitory Concentrations

ABSTRACT We determined the MICs of ampicillin, ciprofloxacin, erythromycin, imipenem, and rifampin for two clinical isolates of Legionella pneumophila serogroup 1 by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction assay and by quantitative culture. To test the influence of subinhibitory concentrations (sub-MICs) of antimicrobial agents on Legionella uptake into Acanthamoeba castellanii and U937 macrophage-like cells, both strains were pretreated with 0.25 MICs of the antibiotics for 24 h. In comparison to that for the untreated control, subinhibitory concentrations of antibiotics significantly reducedLegionella uptake into the host cells. Measurement of the binding of monoclonal antibodies against several Legionellaantigens by enzyme-linked immunoassays indicated that sub-MIC antibiotic treatment reduced the expression of the macrophage infectivity potentiator protein (Mip), the Hsp 60 protein, the outer membrane protein (OmpM), an as-yet-uncharacterized protein of 55 kDa, and a few lipopolysaccharide (LPS) epitopes. In contrast, the expression of some LPS epitopes recognized by monoclonal antibodies 8/5 and 30/4 as well as a 45-kDa protein, a 58-kDa protein, and the major outer membrane protein (OmpS) remained unaffected.

scholarly journals Anaplasma phagocytophilum Outer Membrane Protein A Interacts with Sialylated Glycoproteins To Promote Infection of Mammalian Host Cells

2012 ◽  
Vol 80 (11) ◽  
pp. 3748-3760 ◽  
Author(s):  
Nore Ojogun ◽  
Amandeep Kahlon ◽  
Stephanie A. Ragland ◽  
Matthew J. Troese ◽  
Juliana E. Mastronunzio ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Anaplasma Phagocytophilum ◽  
Protein A ◽  
Host Cells ◽  
Mammalian Host ◽  
Content Type ◽  
Outer Membrane Protein A ◽  
Sialylated Glycoproteins

ABSTRACTAnaplasma phagocytophilumis the tick-transmitted obligate intracellular bacterium that causes human granulocytic anaplasmosis (HGA).A. phagocytophilumbinding to sialyl Lewis x (sLex) and other sialylated glycans that decorate P selectin glycoprotein 1 (PSGL-1) and other glycoproteins is critical for infection of mammalian host cells. Here, we demonstrate the importance ofA. phagocytophilumouter membrane protein A (OmpA) APH_0338 in infection of mammalian host cells. OmpA is transcriptionally induced during transmission feeding ofA. phagocytophilum-infected ticks on mice and is upregulated during invasion of HL-60 cells. OmpA is presented on the pathogen's surface. Sera from HGA patients and experimentally infected mice recognize recombinant OmpA. Pretreatment ofA. phagocytophilumorganisms with OmpA antiserum reduces their abilities to infect HL-60 cells. The OmpA N-terminal region is predicted to contain the protein's extracellular domain. GlutathioneS-transferase (GST)-tagged versions of OmpA and OmpA amino acids 19 to 74 (OmpA19-74) but not OmpA75-205bind to, and competitively inhibitA. phagocytophiluminfection of, host cells. Pretreatment of host cells with sialidase or trypsin reduces or nearly eliminates, respectively, GST-OmpA adhesion. Therefore, OmpA interacts with sialylated glycoproteins. This study identifies the firstA. phagocytophilumadhesin-receptor pair and delineates the region of OmpA that is critical for infection.

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 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.

Immunization with a portion of rickettsial outer membrane protein A stimulates protective immunity against spotted fever rickettsiosis

Vaccine ◽  
2001 ◽  
Vol 20 (5-6) ◽  
pp. 979-988 ◽  
Author(s):  
P.A Crocquet-Valdes ◽  
C.M Dı́az-Montero ◽  
H.M Feng ◽  
H Li ◽  
A.D.T Barrett ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Protective Immunity ◽  
Spotted Fever ◽  
Protein A ◽  
Outer Membrane Protein A

scholarly journals Anaplasma marginale Outer Membrane Protein A Is an Adhesin That Recognizes Sialylated and Fucosylated Glycans and Functionally Depends on an Essential Binding Domain

2016 ◽  
Vol 85 (3) ◽  
Author(s):  
Kathryn S. Hebert ◽  
David Seidman ◽  
Aminat T. Oki ◽  
Jerilyn Izac ◽  
Sarvani Emani ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Protein A ◽  
Anaplasma Marginale ◽  
Binding Domain ◽  
Host Cells ◽  
Content Type ◽  
Outer Membrane Protein A ◽  
Glycan Receptors

ABSTRACT Anaplasma marginale causes bovine anaplasmosis, a debilitating and potentially fatal tick-borne infection of cattle. Because A. marginale is an obligate intracellular organism, its adhesins that mediate entry into host cells are essential for survival. Here, we demonstrate that A. marginale outer membrane protein A (AmOmpA; AM854) contributes to the invasion of mammalian and tick host cells. AmOmpA exhibits predicted structural homology to OmpA of A. phagocytophilum (ApOmpA), an adhesin that uses key lysine and glycine residues to interact with α2,3-sialylated and α1,3-fucosylated glycan receptors, including 6-sulfo-sialyl Lewis x (6-sulfo-sLex). Antisera against AmOmpA or its predicted binding domain inhibits A. marginale infection of host cells. Residues G55 and K58 are contributory, and K59 is essential for recombinant AmOmpA to bind to host cells. Enzymatic removal of α2,3-sialic acid and α1,3-fucose residues from host cell surfaces makes them less supportive of AmOmpA binding. AmOmpA is both an adhesin and an invasin, as coating inert beads with it confers adhesiveness and invasiveness. Recombinant forms of AmOmpA and ApOmpA competitively antagonize A. marginale infection of host cells, but a monoclonal antibody against 6-sulfo-sLex fails to inhibit AmOmpA adhesion and A. marginale infection. Thus, the two OmpA proteins bind related but structurally distinct receptors. This study provides a detailed understanding of AmOmpA function, identifies its essential residues that can be targeted by blocking antibody to reduce infection, and determines that it binds to one or more α2,3-sialylated and α1,3-fucosylated glycan receptors that are unique from those targeted by ApOmpA.

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