scholarly journals Expression of Members of the 28-Kilodalton Major Outer Membrane Protein Family of Ehrlichia chaffeensis during Persistent Infection

2004 ◽  
Vol 72 (8) ◽  
pp. 4336-4343 ◽  
Author(s):  
Jian-zhi Zhang ◽  
Hong Guo ◽  
Gary M. Winslow ◽  
Xue-jie Yu
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Multigene Family ◽  
Outer Membrane Proteins ◽  
Enzyme Linked Immunosorbent Assay ◽  
Ehrlichia Chaffeensis ◽  
Antigenic Peptides ◽  
Indirect Measure

ABSTRACT The 28-kDa immunodominant outer membrane proteins (P28 OMPs) of Ehrlichia chaffeensis are encoded by a multigene family. As an indirect measure of the in vivo expression of the members of the p28 multigene family of E. chaffeensis, sera from two beagle dogs experimentally infected with E. chaffeensis were evaluated for the presence of specific antibodies to P28 OMPs by enzyme-linked immunosorbent assay. Antigenic peptides unique to each of the P28s were identified within the first hypervariable region of each P28 OMP. Serological responses to peptides derived from all P28 OMPs were detected from day 30 postinoculation to day 468 and from day 46 until day 159 in the two beagles. Although antibody titers to the peptides fluctuated, the peak response to all of the peptides appeared simultaneously in each dog. The antibody responses to another outer membrane protein of E. chaffeensis (GP120) showed similar temporal and quantitative changes. These data suggest that the P28 OMPs are expressed concurrently during persistent Ehrlichia infection.

scholarly journals LipL32 Is an Extracellular Matrix-Interacting Protein of Leptospira spp. and Pseudoalteromonas tunicata

2008 ◽  
Vol 76 (5) ◽  
pp. 2063-2069 ◽  
Author(s):  
David E. Hoke ◽  
Suhelen Egan ◽  
Paul A. Cullen ◽  
Ben Adler
Keyword(s):  
Extracellular Matrix ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
Major Outer Membrane Protein ◽  
Interacting Proteins ◽  
Orthologous Protein ◽  
Pseudoalteromonas Tunicata

ABSTRACT LipL32 is the major outer membrane protein in pathogenic Leptospira. It is highly conserved throughout pathogenic species and is expressed in vivo during human infection. While these data suggest a role in pathogenesis, a function for LipL32 has not been defined. Outer membrane proteins of gram-negative bacteria are the first line of molecular interaction with the host, and many have been shown to bind host extracellular matrix (ECM). A search for leptospiral ECM-interacting proteins identified the major outer membrane protein, LipL32. To verify this finding, recombinant LipL32 was expressed in Escherichia coli and was found to bind Matrigel ECM and individual components of ECM, including laminin, collagen I, and collagen V. Likewise, an orthologous protein found in the genome of Pseudoalteromonas tunicata strain D2 was expressed and found to be functionally similar and immunologically cross-reactive. Lastly, binding activity was mapped to the C-terminal 72 amino acids. These studies show that LipL32 and an orthologous protein in P. tunicata are immunologically cross-reactive and function as ECM-interacting proteins via a conserved C-terminal region.

scholarly journals In Silico Design and Evaluation of Acinetobacter baumannii Outer Membrane Protein A (OmpA) Antigenic Peptides as Vaccine Candidate in Immunized Mice

2020 ◽  
Author(s):  
Kobra Mehdinejadiani ◽  
Mojgan Bandehpour ◽  
Ali Hashemi ◽  
Mohammad Mehdi Ranjbar ◽  
Sodabeh Taheri ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Protein A ◽  
Epitope Prediction ◽  
Effective Vaccine ◽  
Enzyme Linked Immunosorbent Assay ◽  
Antigenic Peptides ◽  
Outer Membrane Protein A

Acinetobacter baumannii is a Gram-negative bacterium that has recently been identified as a leading nosocomial pathogen. Infections by this pathogen result in significant mortality due to antibiotic resistance. An effective vaccine would help alleviate the burden of disease incurred by this pathogen; however, there are currently no licensed vaccines offering protection against Acinetobacter baumannii infection. In this study, considering the fact that outer membrane protein A is one of the most promising vaccine candidates, we predicted T cell and B cell epitopes on this protein using sequence-based epitope prediction tools and determined whether or not mice immunized with these peptides induce an immune response. We selected consensus epitopes including five peptides in different tools with the highest score. 48 female C5BL/6 SPF injected subcutaneously with the peptides (peptide1 to peptide 5 separately) in 100 μL of the solution and sham groups received adjuvant and PBS alone on the same schedule: on day 0 (primary dose) and two booster doses were administered on days 14 and 28. At the end of time, animals euthanized by Isoflurane, and collected sera for assessment of specific antibodies against each peptide by ELISA (Enzyme-linked immunosorbent assay). Immunization of mice showed one of the novel synthetic peptides (peptide 1 (24-50 amino acids)) elicited immune responses. We conclude to combine theoretical methods of epitope prediction and evaluating the potential of immunogenicity for developing vaccines is important.

scholarly journals Genetic Diversity of the 28-Kilodalton Outer Membrane Protein Gene in Human Isolates of Ehrlichia chaffeensis

1999 ◽  
Vol 37 (4) ◽  
pp. 1137-1143 ◽  
Author(s):  
Xue-Jie Yu ◽  
Jere W. McBride ◽  
David H. Walker
Keyword(s):  
Amino Acid ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Dna Sequence ◽  
Outer Membrane Protein ◽  
Signal Sequence ◽  
Outer Membrane Proteins ◽  
Protein A ◽  
Amino Acid Sequences ◽  
Ehrlichia Chaffeensis

The Ehrlichia chaffeensis 28-kDa outer membrane protein (p28) gene was sequenced completely by genomic walking with adapter PCR. The DNA sequence of the p28 gene was nearly identical to the previously reported sequence (N. Ohashi, N. Zhi, Y. Zhang, and Y. Rikihisa, Infect. Immun. 66:132–139, 1998), but analysis of a further 75 bp on the 5′ end of the gene revealed DNA that encoded a 25-amino-acid signal sequence. The leader sequence was removed from the N terminus of a 30-kDa precursor to generate the mature p28 protein. A monoclonal antibody (MAb), 1A9, recognizing four outer membrane proteins of E. chaffeensis (Arkansas strain) including the 25-, 26-, 27-, and 29-kDa proteins (X.-J. Yu, P. Brouqui, J. S. Dumler, and D. Raoult, J. Clin. Microbiol. 31:3284–3288, 1993) reacted with the recombinant p28 protein. This result indicated that the four proteins recognized by MAb 1A9 were encoded by the multiple genes of the 28-kDa protein family. DNA sequence alignment analysis revealed divergence of p28 among all five human isolates of E. chaffeensis. The E. chaffeensis strains could be divided into three genetic groups on the basis of the p28 gene. The first group consisted of the Sapulpa and St. Vincent strains. They had predicted amino acid sequences identical to each other. The second group contained strain 91HE17 and strain Jax, which only showed 0.4% divergence from each other. The third group contained the Arkansas strain only. The amino acid sequences of p28 differed by 11% between the first two groups, by 13.3% between the first and third groups, and by 13.1% between the second and third groups. The presence of antigenic variants of p28 among the strains of E. chaffeensis and the presence of multiple copies of heterogeneous genes suggest a possible mechanism by which E. chaffeensismight evade the host immune defenses. Whether or not immunization with the p28 of one strain of E. chaffeensis would confer cross-protection against other strains needs to be investigated.

Characterization of the complete transcriptionally active Ehrlichia chaffeensis 28 kDa outer membrane protein multigene family

Gene ◽  
2000 ◽  
Vol 248 (1-2) ◽  
pp. 59-68 ◽  
Author(s):  
Xue-jie Yu ◽  
Jere W McBride ◽  
Xiao-feng Zhang ◽  
David H Walker
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Multigene Family ◽  
Ehrlichia Chaffeensis

scholarly journals Dynamic periplasmic chaperone reservoir facilitates biogenesis of outer membrane proteins

2016 ◽  
Vol 113 (33) ◽  
pp. E4794-E4800 ◽  
Author(s):  
Shawn M. Costello ◽  
Ashlee M. Plummer ◽  
Patrick J. Fleming ◽  
Karen G. Fleming
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
Effective Rate ◽  
Stochastic Methods ◽  
Bacterial Physiology ◽  
Control Factors

Outer membrane protein (OMP) biogenesis is critical to bacterial physiology because the cellular envelope is vital to bacterial pathogenesis and antibiotic resistance. The process of OMP biogenesis has been studied in vivo, and each of its components has been studied in isolation in vitro. This work integrates parameters and observations from both in vivo and in vitro experiments into a holistic computational model termed “Outer Membrane Protein Biogenesis Model” (OMPBioM). We use OMPBioM to assess OMP biogenesis mathematically in a global manner. Using deterministic and stochastic methods, we are able to simulate OMP biogenesis under varying genetic conditions, each of which successfully replicates experimental observations. We observe that OMPs have a prolonged lifetime in the periplasm where an unfolded OMP makes, on average, hundreds of short-lived interactions with chaperones before folding into its native state. We find that some periplasmic chaperones function primarily as quality-control factors; this function complements the folding catalysis function of other chaperones. Additionally, the effective rate for the β-barrel assembly machinery complex necessary for physiological folding was found to be higher than has currently been observed in vitro. Overall, we find a finely tuned balance between thermodynamic and kinetic parameters maximizes OMP folding flux and minimizes aggregation and unnecessary degradation. In sum, OMPBioM provides a global view of OMP biogenesis that yields unique insights into this essential pathway.

scholarly journals Characterization of the Humoral Immune Response to Chlamydia Outer Membrane Protein 2 in Chlamydial Infection

2003 ◽  
Vol 10 (1) ◽  
pp. 103-107 ◽  
Author(s):  
I. Portig ◽  
J. C. Goodall ◽  
R. L. Bailey ◽  
J. S. H. Gaston
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Chlamydial Infection ◽  
Chlamydia Pneumoniae ◽  
Specific Protein ◽  
Enzyme Linked Immunosorbent Assay ◽  
Recent Infection ◽  
Humoral Immune ◽  
Immunodominant Antigen

ABSTRACT Detection of antibodies to an outer membrane protein 2 (OMP2) by enzyme-linked immunosorbent assay (ELISA) by using either the Chlamydia trachomatis- or the Chlamydia pneumoniae-specific protein was investigated. OMP2 is an immunodominant antigen giving rise to antibody responses in humans infected with different C. trachomatis serovars (A to C and D to K) or with C. pneumoniae, which could be detected by OMP2 ELISA. OMP2 ELISA is not species specific, but antibody titers were usually higher on the homologous protein. The sensitivity of this assay was high but varied according to the “gold standard” applied. Levels of antibody to C. pneumoniae OMP2 as detected by ELISA seem to return to background or near-background values within a shorter period of time compared to antibodies to C. pneumoniae detected by microimmunofluorescence (MIF), making it more likely that positive results in ELISA reflect recent infection. Thus, OMP2 ELISA has distinct advantages over MIF and commercially available ELISAs and might be a useful tool for the serodiagnosis of chlamydial infection.

Outer Membrane Protein Composition in Disease Isolates of Haemophilus influenzae : Pathogenic and Epidemiological Implications

1980 ◽  
Vol 30 (3) ◽  
pp. 709-717
Author(s):  
Marilyn R. Loeb ◽  
David H. Smith
Keyword(s):  
Membrane Proteins ◽  
Membrane Protein ◽  
Haemophilus Influenzae ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
Protein Composition ◽  
The Other ◽  
Major Protein ◽  
Single Strain

The outer membrane protein composition of 50 disease isolates of Haemophilus influenzae has been determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. All strains, including 28 strains of serotype b , one strain each of serotypes a, c, d, e , and f , and 17 untypable strains, had an outer membrane protein composition typical of gram-negative bacteria, i.e., these membranes contained two to three dozen proteins with four to six proteins accounting for most of their protein content. Variation in the mobility of these major outer membrane proteins from strain to strain was common but not universal; the observed patterns provided useful data and new insight into the epidemiology of type b disease. The basic findings can be summarized as follows: (i) All 50 strains possessed three proteins (one minor and two major) each having identical mobilities. The other proteins, both major and minor, varied in mobility. (ii) All type b strains possessed a fourth (major) protein of identical mobility. (iii) The 28 type b strains, on the basis of the mobility of the six major outer membrane proteins, could be divided into eight subtypes. Of all the other strains examined, both typable and untypable, only the serotype a strain belonged to one of these subtypes. (iv) The untypable strains showed considerable variation in the mobilities of their major outer membrane proteins. Of these 17 strains, 13 had an additional major outer membrane protein not present in encapsulated strains. (v) The outer membrane protein composition of a single strain remained unchanged after many passages on solid media, but varied with the growth phase. (vi) The outer membrane protein composition of isolates obtained from nine patients during an epidemic of type b meningitis varied, indicating that a single strain was not responsible for the epidemic. At least five different strains were responsible for these nine cases. (vii) Identical outer membrane protein compositions were observed in the following: in a type b strain and a mutant of this strain deficient in capsule production, indicating that the level of capsule synthesis is not obviously related to outer membrane protein composition; in type b strains isolated from different anatomic sites of patients acutely ill with meningitis, indicating that the strain associated with bacteremia is the same as that isolated from the cerebrospinal fluid; in type b strains isolated from siblings who contracted meningitis at about the same time, indicating infection with the same strain; and in type b strains isolated from the initial and repeat infection of a single patient, suggesting that reinfection was due to the same strain.

scholarly journals Sequence Polymorphism, Predicted Secondary Structures, and Surface-Exposed Conformational Epitopes of Campylobacter Major Outer Membrane Protein

2000 ◽  
Vol 68 (10) ◽  
pp. 5679-5689 ◽  
Author(s):  
Qijing Zhang ◽  
Jerrel C. Meitzler ◽  
Shouxiong Huang ◽  
Teresa Morishita
Keyword(s):  
Amino Acid ◽  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Outer Membrane Proteins ◽  
Major Outer Membrane Protein ◽  
Amino Acid Sequences ◽  
Variable Regions ◽  
Conserved Sequences ◽  
Conformational Epitopes

ABSTRACT The major outer membrane protein (MOMP), a putative porin and a multifunction surface protein of Campylobacter jejuni, may play an important role in the adaptation of the organism to various host environments. To begin to dissect the biological functions and antigenic features of this protein, the gene (designatedcmp) encoding MOMP was identified and characterized from 22 strains of C. jejuni and one strain of C. coli. It was shown that the single-copy cmp locus encoded a protein with characteristics of bacterial outer membrane proteins. Prediction from deduced amino acid sequences suggested that each MOMP subunit consisted of 18 β-strands connected by short periplasmic turns and long irregular external loops. Alignment of the amino acid sequences of MOMP from different strains indicated that there were seven localized variable regions dispersed among highly conserved sequences. The variable regions were located in the putative external loop structures, while the predicted β-strands were formed by conserved sequences. The sequence homology of cmp appeared to reflect the phylogenetic proximity of C. jejuni strains, since strains with identical cmp sequences had indistinguishable or closely related macrorestriction fragment patterns. Using recombinant MOMP and antibodies recognizing linear or conformational epitopes of the protein, it was demonstrated that the surface-exposed epitopes of MOMP were predominantly conformational in nature. These findings are instrumental in the design of MOMP-based diagnostic tools and vaccines.

scholarly journals Purification of the Major Outer Membrane Protein of Azospirillum brasilense, Its Affinity to Plant Roots, and Its Involvement in Cell Aggregation

2001 ◽  
Vol 14 (4) ◽  
pp. 555-561 ◽  
Author(s):  
Saul Burdman ◽  
Gabriella Dulguerova ◽  
Yaacov Okon ◽  
Edouard Jurkevitch
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Azospirillum Brasilense ◽  
Outer Membrane Proteins ◽  
Cell Aggregation ◽  
Major Outer Membrane Protein ◽  
Adhesion Assay ◽  
Fab Fragments

The major outer membrane protein (MOMP) of the nitrogen-fixing rhizobacterium Azospirillum brasilense strain Cd was purified and isolated by gel filtration, and antiserum against this protein was obtained. A screening of the binding of outer membrane proteins (OMPs) of A. brasilense to membrane-immobilized root extracts of various plant species revealed different affinities for the MOMP, with a stronger adhesion to extracts of cereals in comparison with legumes and tomatoes. Moreover, this protein was shown to bind to roots of different cereal seedlings in an in vitro adhesion assay. Incubation of A. brasilense cells with MOMP-antiserum led to fast agglutination, indicating that the MOMP is a surface-exposed protein. Cells incubated with Fab fragments obtained from purified MOMP-antiserum immunoglobulin G exhibited significant inhibition of bacterial aggregation as compared with controls. Bacteria preincubated with Fab fragments showed weaker adhesion to corn roots in comparison to controls without Fab fragments. These findings suggest that the A. brasilense MOMP acts as an adhesin involved in root adsorption and cell aggregation of this bacterium.

scholarly journals Localization of Haemophilus ducreyi at the Pustular Stage of Disease in the Human Model of Infection

2000 ◽  
Vol 68 (4) ◽  
pp. 2309-2314 ◽  
Author(s):  
Margaret E. Bauer ◽  
Stanley M. Spinola
Keyword(s):  
Membrane Protein ◽  
Outer Membrane ◽  
Outer Membrane Protein ◽  
Human Subjects ◽  
Haemophilus Ducreyi ◽  
Human Model ◽  
Stage Of Disease ◽  
The One ◽  
Secondary Antibodies

ABSTRACT To localize Haemophilus ducreyi in vivo, human subjects were experimentally infected with H. ducreyi until they developed a painful pustule or for 14 days. Lesions were biopsied, and biopsy samples were fixed in 4% paraformaldehyde, and cryosectioned. Sections were stained with polyclonal anti-H. ducreyi antiserum or H. ducreyi-specific monoclonal antibodies (MAbs) and fluorescently tagged secondary antibodies and examined by confocal microscopy. We identified H. ducreyi in 16 of 18 pustules but did not detect bacteria in the one papule examined. H. ducreyi was observed as individual cells and in clumps or chains. Staining with MAbs 2D8, 5C9, 3B9, 2C7, and 9D12 demonstrated that H. ducreyi expresses the major pilus subunit, FtpA, the 28-kDa outer membrane protein Hlp, the 18-kDa outer membrane protein PAL, and the major outer membrane protein (MOMP) or OmpA2 in vivo. By dual staining with polyclonal anti-H. ducreyi antiserum and MAbs that recognize human skin components, we observed bacteria within the neutrophilic infiltrates of all positively staining pustules and in the dermis of 10 of 16 pustules. We were unable to detect bacteria associated with keratinocytes in the samples examined. The data suggest that H. ducreyi is found primarily in association with neutrophils and in the dermis at the pustular stage of disease in the human model of infection.

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