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Immunization with the recombinant Burkholderia pseudomallei outer membrane protein Omp85 induces protective immunity in mice

Su YC, Wan KL, Mohamed R, Nathan S

Vaccine, 2010 Jul 12;28(31):5005-11.
PMID: 20546831 DOI: 10.1016/j.vaccine.2010.05.022

Burkholderia pseudomallei is resistant to a wide range of antibiotics, leading to relapse and recrudescence of melioidosis after cessation of antibiotic therapy. More effective immunotherapies are needed for better management of melioidosis. We evaluated the prophylactic potential of the immunogenic outer membrane protein Omp85 as a vaccine against murine melioidosis. Immunization of BALB/c mice with recombinant Omp85 (rOmp85) triggered a Th2-type immune response. Up to 70% of the immunized animals were protected against infectious challenge of B. pseudomallei with reduced bacterial load in extrapulmonary organs. Mouse anti-rOmp85 promoted complement-mediated killing and opsonophagocytosis of B. pseudomallei by human polymorphonuclear cells. In conclusion, we demonstrated that B. pseudomallei Omp85 is potentially able to induce protective immunity against melioidosis.

Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology*
Fulltext Immunogenic Burkholderia pseudomallei outer membrane proteins as potential candidate vaccine targets

Hara Y, Mohamed R, Nathan S

PLoS One, 2009 Aug 05;4(8):e6496.
PMID: 19654871 DOI: 10.1371/journal.pone.0006496

BACKGROUND: Burkholderia pseudomallei is the causative agent of melioidosis, a disease of significant morbidity and mortality in both human and animals in endemic areas. There is no vaccine towards the bacterium available in the market, and the efficacy of many of the bacterium's surface and secreted proteins are currently being evaluated as vaccine candidates.
METHODOLOGY/PRINCIPAL FINDINGS: With the availability of the B. pseudomallei whole genome sequence, we undertook to identify genes encoding the known immunogenic outer membrane protein A (OmpA). Twelve OmpA domains were identified and ORFs containing these domains were fully annotated. Of the 12 ORFs, two of these OmpAs, Omp3 and Omp7, were successfully cloned, expressed as soluble protein and purified. Both proteins were recognised by antibodies in melioidosis patients' sera by Western blot analysis. Purified soluble fractions of Omp3 and Omp7 were assessed for their ability to protect BALB/c mice against B. pseudomallei infection. Mice were immunised with either Omp3 or Omp7, subsequently challenged with 1x10(6) colony forming units (cfu) of B. pseudomallei via the intraperitoneal route, and examined daily for 21 days post-challenge. This pilot study has demonstrated that whilst all control unimmunised mice died by day 9 post-challenge, two mice (out of 4) from both immunised groups survived beyond 21 days post-infection.
CONCLUSIONS/SIGNIFICANCE: We have demonstrated that B. pseudomallei OmpA proteins are immunogenic in mice as well as melioidosis patients and should be further assessed as potential vaccine candidates against B. pseudomallei infection.

Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology*
Fulltext The detection and characterization of pathogenic Leptospira and the use of OMPs as potential antigens and immunogens

Gebriel AM, Subramaniam G, Sekaran SD

Trop Biomed, 2006 Dec;23(2):194-207.
PMID: 17322822 MyJurnal

The detection of leptospires in patient blood in the first week of the disease using PCR provides an early diagnostic tool. PCR using two sets of primers (G1/G2 and B64-I/B64-II) tested with samples seeded with 23 leptospiral strains from pathogenic and non-pathogenic strains was able to amplify leptospiral DNA from pathogenic strains only. Of the 39 antibody negative samples collected from patients suspected for leptospirosis, only 1 sample (2.6%) was PCR positive. Using LSSP-PCR, the G2 primers allowed the characterization of Leptopira species to 10 different genetic signatures which may have epidemiological value in determining species involved in outbreaks. Leptospiral outer membrane proteins from three strains were purified and reacted against patients sera and gave rise to different profiles for pathogenic and non-pathogenic strains. Lymphocytes of mice injected with OMPs proliferated and released IFN(-3) when stimulated in vitro using Leptospira OMP as antigens. This suggests that an immune response could be established using leptospiral OMPs as a putative vaccine. OMPs were also used in a Dot-ELISA to detect antibodies against Leptospira pathogens in humans.

Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology*
Construction and characterization of recombinant single-chain variable fragment antibodies against Toxoplasma gondii MIC2 protein

Hoe LN, Wan KL, Nathan S

Parasitology, 2005 Dec;131(Pt 6):759-68.
PMID: 16336729

The protozoan parasite Toxoplasma gondii produces a family of microneme proteins that are thought to play diverse roles in aiding the parasite's intracellular existence. Among these, TgMIC2 has a putative function in parasite adhesion to the host cell to initiate the invasion process. The invasion process may be localized and inhibited by monoclonal antibodies against the protein(s) involved. Here we report on the construction of a phage-displayed single-chain variable fragment (scFv) library from mice immunized with whole T. gondii parasites. The library was subsequently panned against recombinant TgMIC2 (rpTgMIC2) and 2 different groups of antibody clones were obtained, based on fingerprinting and sequencing data. The expressed recombinant scFv antibody was able to recognize rpTgMIC2 in a Western blot detection experiment. These results show that the phage display technology allows quick and effective production of monoclonal antibodies against parasite antigens. By panning the scFv-displayed library, we should be able to obtain a plethora of multi-functional scFv antibodies towards T. gondii proteins.

Matched MeSH terms: Membrane Proteins/immunology*
The role of CD4+ cells in vivo on the induction of the immune response to Porphyromonas gingivalis in mice

Sosroseno W, Bird PS, Gemmell E, Seymour GJ

J. Periodontol., 2002 Oct;73(10):1133-40.
PMID: 12416770

It has previously been suggested that CD4+ T cells play a pivotal role in regulating the immune response to periodontal pathogens. The aim of the present study therefore was to determine delayed type hypersensitivity (DTH), spleen cell proliferation, serum and splenic anti-Porphyromonas gingivalis antibody levels, and lesion sizes following challenge with viable P. gingivalis in CD4-depleted BALB/c mice immunized with P. gingivalis outer membrane proteins (OMP).

Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology
Efficacy of an outer membrane protein of Pasteurella haemolytica A2, A7 or A9-enriched vaccine against intratracheal challenge exposure in sheep

Sabri MY, Zamri-Saad M, Mutalib AR, Israf DA, Muniandy N

Vet Microbiol, 2000 Apr 04;73(1):13-23.
PMID: 10731614

The outer membrane proteins (OMP) were extracted from the P. haemolytica A2, A7 and A9 to determine their potential as immunogens and their capability for cross-protection. Sixty lambs of approximately 9 months old were divided into four main groups. Animals in Group 1 were vaccinated with 2ml vaccine containing 100microg/ml of the outer membrane proteins of P. haemolytica A2. Animals in Group 2 were similarly vaccinated with the OMPs of P. haemolytica A7 while Group 3 with OMPs of P. haemolytica A9. Animals in Group 4 were unvaccinated control. During the course of the study, serum was collected to evaluate the antibody levels toward each OMP. There appeared to be good immune responses. However, high antibody levels did not necessarily result in good protection of the animals, particularly against cross-infection with P. haemolytica A9 in animals vaccinated with the OMPs of P. haemolytica A2. It seemed that the antibody responses were more specific toward the homologous challenge but generally did not cross-protect against heterologous serotype challenge. However, the OMPs of P. haemolytica A7 produced good in vivo cross-protection and excellent correlations when good antibody responses against all serotypes led to successful reductions of the extent of lung lesions following homologous and heterologous challenge exposures. Thus, the OMPs of P. haemolytica A7 was effective in protecting animals against homologous and heterologous infection by live P. haemolytica A2, A7 and A9.

Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology*
Rapid serologic diagnosis of pediatric typhoid fever in an endemic area: a prospective comparative evaluation of two dot-enzyme immunoassays and the Widal test

Bhutta ZA, Mansurali N

Am J Trop Med Hyg, 1999 Oct;61(4):654-7.
PMID: 10548305

We evaluated the diagnostic sensitivity and specificity of two dot-enzyme-linked immunoassays (Typhidot and Typhidot-M; Malaysian Biodiagnostic Research SDN BHD, Kuala Lumpur, Malaysia), assessing IgG and IgM antibodies against the outer membrane protein (OMP) of Salmonella typhi, and the Widal test in comparison with blood culture in a consecutive group of children with suspected typhoid fever. Of 97 children with suspected typhoid fever, the disease was confirmed bacteriologically in 46 (47%), whereas 25 (26%) were considered to have typhoid fever on clinical grounds. An alternative diagnosis was made in 26 (27%). The Typhidot and Typhidot-M were superior to the Widal test in their diagnostic sensitivity and specificity, although values (sensitivity = 85-94% and specificity = 77-89%) were significantly lower than in other regional reports. The lower specificity of the Typhidot in our series may represent regional differences in the genomic structure and plasticity of the OMP of S. typhi and merits further evaluation of these tests in diverse geographic locations.

Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology
Longevity of antibody responses to a Salmonella typhi-specific outer membrane protein: interpretation of a dot enzyme immunosorbent assay in an area of high typhoid fever endemicity

Choo KE, Davis TM, Ismail A, Ong KH

Am J Trop Med Hyg, 1997 Dec;57(6):656-9.
PMID: 9430522

The objective of this study was to investigate the longevity of positive dot enzyme immunosorbent assay (dot EIA) results for IgM and IgG to a Salmonella typhi outer membrane protein in Malaysian children with enteric fever. The patients were children one month to 12 years of age with clinical evidence of typhoid fever, positive blood or stool cultures for S. typhi, and/or a positive Widal test result who were admitted over a two-year period to General Hospital (Kota Bharu, Malaysia). These patients received standard inpatient treatment for enteric fever including chloramphenicol therapy for 14 days. Dot EIA tests were performed as part of clinical and laboratory assessments on admission, at two weeks, and then at 3, 6, 9, 12, 15, 18, and 21 months postdischarge. Assessment of the longevity of positive dot EIA IgM and IgG titers was done by Kaplan-Meier analysis. In 94 evaluable patients, 28% were dot EIA IgM positive but IgG negative on admission, 50% were both IgM and IgG positive, and 22% were IgM negative and IgG positive. Mean persistence of IgM dot EIA positivity was 2.6 months (95% confidence interval = 2.0-3.1 months) and that of IgG was 5.4 months (4.5-6.3 months). There were no significant differences between the three subgroups. Thus, positive IgM and IgG results determined by dot EIA within four and seven months, respectively, following documented or suspected enteric fever in a child from an endemic area should be interpreted with caution. In other clinical situations, the dot EIA remains a rapid and reliable aid to diagnosis.

Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology*
Rapid serodiagnosis of typhoid fever by dot enzyme immunoassay in an endemic area

Choo KE, Oppenheimer SJ, Ismail AB, Ong KH

Clin Infect Dis, 1994 Jul;19(1):172-6.
PMID: 7948526

A dot enzyme immunoassay (EIA) using 50-kD outer-membrane proteins (OMPs) of Salmonella typhi was compared with the Widal test for the serodiagnosis of typhoid fever in 109 febrile children admitted to a hospital in an endemic area. In the culture-positive typhoid group, the initial dot EIA was positive in 40 of 42 cases and the initial Widal test was positive in 41. In the culture-negative clinical typhoid group, both the dot EIA and the Widal test were positive in 17 of 18 cases. In the nontyphoidal fever group, the dot EIA was negative in all of 49 cases and the Widal test was negative in 44. With culture used as the gold standard, the dot EIA is as sensitive as the Widal test (95% vs. 98%), has a similar high negative predictive value (96% vs. 98%), and is more specific (75% vs. 67%). In addition, the dot EIA offers the advantages of simplicity, speed, early diagnosis, economy, and flexibility (i.e., other diagnostic tests can be conducted simultaneously).

Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology*
Epitope mapping of the Sta58 major outer membrane protein of Rickettsia tsutsugamushi

Lachumanan R, Devi S, Cheong YM, Rodda SJ, Pang T

Infect Immun, 1993 Oct;61(10):4527-31.
PMID: 7691753

Binding studies of 160 overlapping, synthetic octapeptides from the hydrophilic regions of the Sta58 major outer membrane protein of Rickettsia tsutsugamushi with sera from patients with scrub typhus revealed 15 immunodominant peptides which are recognized by all the sera tested. Further analysis of the specificity of peptide binding with five of these peptides indicated that the peptides showed significantly stronger binding to scrub typhus patients' sera than they did to sera from patients with other febrile illnesses common in the region, i.e., malaria, dengue fever, typhoid fever, and leptospirosis. The main antibody class binding to these peptides appears to be immunoglobulin M, and there appears to be little correlation between reactivity with peptides and antibody titers measured by the indirect immunoperoxidase test.

Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology*
Detection of antibodies against Salmonella typhi outer membrane protein (OMP) preparation in typhoid fever patients

Verdugo-Rodriguez A, Gam LH, Devi S, Koh CL, Puthucheary SD, Calva E, et al.

Asian Pac J Allergy Immunol, 1993 Jun;11(1):45-52.
PMID: 8216558

An indirect ELISA was used to detect antibodies against outer membrane protein preparations (OMPs) from Salmonella typhi. Sera from patients with a definitive diagnosis of typhoid fever (TF) gave a mean absorbance reading, at 414 nm, of 1.52 +/- 0.23 as compared to 0.30 +/- 0.11 for sera from healthy individuals. This gave a positive to negative ratio of absorbance readings of approximately 5.1. Suspected TF patients (no isolation of S. typhi), with positive and negative Widal titers had mean absorbance readings of 1.282 +/00.46 and 0.25 +/- 0.19, respectively. Sera from patients with leptospirosis, rickettsial typhus, dengue fever, and other infections gave mean absorbances of 0.20 +/- 0.08, 0.24 +/- 0.08, 0.27 +/- 0.08, and 0.31 +/- 0.16, respectively. The sensitivity, specificity, positive and negative predictive values were 100%, 94%, 80% and 100%, respectively. The antibody response detected in the definitive TF cases was predominantly IgG in nature and no cross-reactivity was seen with OMP preparations extracted from E. coli. Variable reactivity was noted with OMP preparations obtained from other Salmonella spp. Three major OMPs are presented in the antigen preparation and strong binding of positive sera was detected to all three bands.

Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology*