Displaying publications 1 - 20 of 48 in total

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  1. 3D modelling of the pathogenic Leptospira protein LipL32: A bioinformatics approach
    Kumaran SK, Bakar MFA, Mohd-Padil H, Mat-Sharani S, Sakinah S, Poorani K, et al.
    Acta Trop, 2017 Dec;176:433-439.
    PMID: 28941729 DOI: 10.1016/j.actatropica.2017.09.011
    Leptospirosis is a widespread zoonotic disease caused by pathogenic Leptospira species (Leptospiraceae). LipL32 is an abundant lipoprotein from the outer membrane proteins (OMPs) group, highly conserved among pathogenic and intermediate Leptospira species. Several studies used LipL32 as a specific gene to identify the presence of leptospires. This research was aimed to study the characteristics of LipL32 protein gene code, to fill the knowledge gap concerning the most appropriate gene that can be used as antigen to detect the Leptospira. Here, we investigated the features of LipL32 in fourteen Leptospira pathogenic strains based on comparative analyses of their primary, secondary structures and 3D modeling using a bioinformatics approach. Furthermore, the physicochemical properties of LipL32 in different strains were studied, shedding light on the identity of signal peptides, as well as on the secondary and tertiary structure of the LipL32 protein, supported by 3D modelling assays. The results showed that the LipL32 gene was present in all the fourteen pathogenic Leptospira strains used in this study, with limited diversity in terms of sequence conservation, hydrophobic group, hydrophilic group and number of turns (random coil). Overall, these results add basic knowledge to the characteristics of LipL32 protein, contributing to the identification of potential antigen candidates in future research, in order to ensure prompt and reliable detection of pathogenic Leptospira species.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology; Bacterial Outer Membrane Proteins/chemistry*
  2. A 35 kDa antigenic protein from Shigella flexneri: in silico structural and functional studies
    Yung-Hung RL, Ismail A, Lim TS, Choong YS
    Biochem Biophys Res Commun, 2011 Nov 18;415(2):229-34.
    PMID: 21982766 DOI: 10.1016/j.bbrc.2011.09.116
    Shigella flexneri serotype 2a is a major public health concern in the developing and under-developed countries which contributes to shigellosis endemic and mortality. Thus, there is an urgent need for a rapid diagnostic test for effective therapy and disease management. Previous study showed that a ∼35 kDa antigenic protein from S. flexneri is a potential biomarker. We therefore modelled the three-dimensional structure of the antigen to probe its functionality which could aid in the development of an antigen-based diagnostic. Results showed that the antigen is a transmembrane protein consists of OmpA and OmpA-like domains. The OmpA domain is a beta-barrel embedded in the outer membrane with four surface-exposed extracellular loops. The OmpA-like domain is linked to the OmpA domain with a 17 amino acids linker and located in the periplasmic. Docking of peptidoglycan into the groove of OmpA-like domain might help in catalyzing the bacterial cell wall formation. Both domains are expected to be involved in the virulence, structural stability, pathogenesis and survival of Shigella thus made the 35 kDa protein a suitable shigellosis diagnostic biomarker. This structural elucidation will also enable a better identification of the epitope regions for the development of specific binders to the 35 kDa antigen.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/chemistry*
  3. Fulltext A small RNA decreases the sensitivity of Shigella sonnei to norfloxacin
    Gan IN, Tan HS
    BMC Res Notes, 2019 Feb 21;12(1):97.
    PMID: 30791948 DOI: 10.1186/s13104-019-4124-4
    OBJECTIVES: Shigella is a human pathogen that causes shigellosis, an acute invasive intestinal infection. Recent studies in the model bacterium Escherichia coli (E. coli) provided evidence that small regulatory RNAs (sRNAs) can contribute to antimicrobial resistance or susceptibility. One of the sRNAs is SdsR, which increases sensitivity of E. coli against fluoroquinolone by repressing the drug efflux pump, TolC. However, no reports exist about the effect of SdsR on fluoroquinolone resistance in Shigella sonnei (S. sonnei). In this study, we established the effect of SdsR on the sensitivity of S. sonnei to norfloxacin.

    DATA DESCRIPTION: We tested the effects of SdsR and SdsRv2 on fluoroquinolone resistance in S. sonnei in vivo. SdsRv2 is a synthetic version which promotes higher binding stability to tolC mRNA. Overexpression of either SdsR or SdsRv2 lowers the expression of tolC mRNA. Interestingly, SdsR and SdsRv2 promote the growth of S. sonnei in the presence of a sub-inhibitory concentration of norfloxacin. Mutant carrying SdsRv2 showed the highest growth advantage. This phenotype is opposite to the effect of SdsR reported in E. coli. This study is an example that demonstrates the difference in the phenotypic effect of a highly conserved sRNA in two closely related bacteria.

    Matched MeSH terms: Bacterial Outer Membrane Proteins/drug effects*
  4. Amplification of ST50 gene using dry-reagent-based polymerase chain reaction for the detection of Salmonella typhi
    Aziah I, Ravichandran M, Ismail A
    Diagn Microbiol Infect Dis, 2007 Dec;59(4):373-7.
    PMID: 17964105
    Conventional polymerase chain reaction (PCR) testing requires many pipetting steps and has to be transported and stored in cold chain. To overcome these limitations, we designed a ready-to-use PCR test for Salmonella typhi using PCR reagents, primers against the ST50 gene of S. typhi, a built-in internal amplification control (IAC), and gel loading dye mixed and freeze-dried in a single tube. The 2-step dry-reagent-based assay was used to amplify a 1238-bp target gene and an 810-bp IAC gene from 73 BACTEC blood culture broths (33 true positives for S. typhi and 40 true negatives for non-S. typhi). The sensitivity, specificity, positive predictive value, and negative predictive value of the PCR assay were 87.9%, 100%, 100%, and 90.9%, respectively. We suggest that this rapid 2-step PCR test could be used for the rapid diagnosis of typhoid fever.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/genetics*
  5. Fulltext Assembly and stability of Salmonella enterica ser. Typhi TolC protein in POPE and DMPE
    Leong SW, Lim TS, Tye GJ, Ismail A, Aziah I, Choong YS
    J Biol Phys, 2014 Sep;40(4):387-400.
    PMID: 25011632 DOI: 10.1007/s10867-014-9357-9
    In this work we assessed the suitability of two different lipid membranes for the simulation of a TolC protein from Salmonella enterica serovar Typhi. The TolC protein family is found in many pathogenic Gram-negative bacteria including Vibrio cholera and Pseudomonas aeruginosa and acts as an outer membrane channel for expulsion of drug and toxin from the cell. In S. typhi, the causative agent for typhoid fever, the TolC outer membrane protein is an antigen for the pathogen. The lipid environment is an important modulator of membrane protein structure and function. We evaluated the conformation of the TolC protein in the presence of DMPE and POPE bilayers using molecular dynamics simulation. The S. typhi TolC protein exhibited similar conformational dynamics to TolC and its homologues. Conformational flexibility of the protein is seen in the C-terminal, extracellular loops, and α-helical region. Despite differences in the two lipids, significant similarities in the motion of the protein in POPE and DMPE were observed, including the rotational motion of the C-terminal residues and the partially open extracellular loops. However, analysis of the trajectories demonstrated effects of hydrophobic matching of the TolC protein in the membrane, particularly in the lengthening of the lipids and subtle movements of the protein's β-barrel towards the lower leaflet in DMPE. The study exhibited the use of molecular dynamics simulation in revealing the differential effect of membrane proteins and lipids on each other. In this study, POPE is potentially a more suitable model for future simulation of the S. typhi TolC protein.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/metabolism*; Bacterial Outer Membrane Proteins/chemistry*
  6. CPAF, HSP60 and MOMP antigens elicit pro-inflammatory cytokines production in the peripheral blood mononuclear cells from genital Chlamydia trachomatis-infected patients
    Cheong HC, Lee CYQ, Cheok YY, Shankar EM, Sabet NS, Tan GMY, et al.
    Immunobiology, 2019 01;224(1):34-41.
    PMID: 30477893 DOI: 10.1016/j.imbio.2018.10.010
    BACKGROUND: Persistent inflammation caused by Chlamydia trachomatis in the female genital compartment represents one of the major causes of pelvic inflammatory disease (PID), ectopic pregnancy and infertility in females. Here, we examined the pro-inflammatory cytokine response following stimulation with three different types of C. trachomatis antigens, viz. chlamydial protease-like factor (CPAF), heat shock protein 60 (HSP60) and major outer membrane protein (MOMP).

    METHODS: A total of 19 patients with genital C. trachomatis infection and 10 age-matched healthy controls were recruited for the study. Peripheral blood mononuclear cells (PBMCs) isolated from genital C. trachomatis-infected females were cultured in the presence of CPAF, HSP60 and MOMP antigens, and cytokines were measured by ELISA assay.

    RESULTS: We reported that pro-inflammatory cytokines (TNF-α, IL-1β and IL-6) were robustly secreted following antigenic exposure. Notably, CPAP and MOMP were more potent in triggering IL-1β, as compared to HSP60. Elevated levels of the proinflammatory cytokines were also noted in the samples infected with plasmid-bearing C. trachomatis as compared to those infected with plasmid-free strains.

    CONCLUSIONS: Our study highlights distinct ability of chlamydial antigens in triggering pro-inflammatory response in the host immune cells.

    Matched MeSH terms: Bacterial Outer Membrane Proteins/metabolism*
  7. Characterization of group A streptococci isolated in Kuala Lumpur, Malaysia
    Jamal F, Pit S, Johnson DR, Kaplan EL
    J Trop Med Hyg, 1995 Oct;98(5):343-6.
    PMID: 7563264
    T-agglutination patterns of 190 strains of group A streptococci isolated between January 1989 and December 1993 from body fluids (10), throat culture (56), pus (51) and skin lesions (73) were determined. Mucoid colonial morphology was exhibited by 6.3% (12/190) of the strains on initial isolation. Type T-5,11,27,44 comprised 23.7%, followed by T-1,3,13,B3264 (11.1%), T-4,6 (8.4%) and T-8,25, Imp 19 (7.9%). About 42% (80/190) strains could not be characterized by T agglutination pattern. T-typing of 71 selected strains at WHO Collaborating Center, Minneapolis yielded similar results. Nineteen selected strains were further characterized by M-typing; only three strains were M-typeable. These strains were isolated from throat (M1), sputum (M5) and pus (M12). About 68% (48/71) isolates produced serum opacity factor. These data support the existence of as yet uncharacterized group A streptococcal serotypes in this region.
    Matched MeSH terms: Bacterial Outer Membrane Proteins*
  8. Clinical significance of Helicobacter pylori cagA and iceA genotype status
    Amjad N, Osman HA, Razak NA, Kassian J, Din J, bin Abdullah N
    World J Gastroenterol, 2010 Sep 21;16(35):4443-7.
    PMID: 20845512
    AIM: To study the presence of Helicobacter pylori (H. pylori) virulence factors and clinical outcome in H. pylori infected patients.

    METHODS: A prospective analysis of ninety nine H. pylori-positive patients who underwent endoscopy in our Endoscopy suite were included in this study. DNA was isolated from antral biopsy samples and the presence of cagA, iceA, and iceA2 genotypes were determined by polymerase chain reaction and a reverse hybridization technique. Screening for H. pylori infection was performed in all patients using the rapid urease test (CLO-Test).

    RESULTS: From a total of 326 patients who underwent endoscopy for upper gastrointestinal symptoms, 99 patients were determined to be H. pylori-positive. Peptic ulceration was seen in 33 patients (33%). The main virulence strain observed in this cohort was the cagA gene isolated in 43 patients. cagA was associated with peptic ulcer pathology in 39.5% (17/43) and in 28% (16/56) of non-ulcer patients. IceA1 was present in 29 patients (29%) and iceA2 in 15 patients (15%). Ulcer pathology was seen in 39% (11/29) of patients with iceA1, while 31% (22/70) had normal findings. The corresponding values for iceA2 were 33% (5/15) and 33% (28/84), respectively.

    CONCLUSION: Virulence factors were not common in our cohort. The incidence of factors cagA, iceA1 and iceA2 were very low although variations were noted in different ethnic groups.

    Matched MeSH terms: Bacterial Outer Membrane Proteins/genetics*
  9. Clinico-pathology and hemato-biochemistry responses in buffaloes infected with Pasteurella multocida type B:2 immunogen outer membrane protein
    Chung ELT, Abdullah FFJ, Marza AD, Saleh WMM, Ibrahim HH, Abba Y, et al.
    Microb Pathog, 2017 Jan;102:89-101.
    PMID: 27894962 DOI: 10.1016/j.micpath.2016.11.015
    The aim of this study was to investigate the clinico-pathology and haemato-biochemistry alterations in buffaloes inoculated with Pasteurella multocida type B:2 immunogen outer membrane protein via subcutaneous and oral routes. Nine buffalo heifers were divided equally into 3 treatment groups. Group 1 was inoculated orally with 10 mL of phosphate buffer saline (PBS); Group 2 and 3 were inoculated with 10 mL of outer membrane protein broth subcutaneously and orally respectively. Group 2 buffaloes showed typical haemorrhagic septicaemia clinical signs and were only able to survive for 72 h of the experiment. However, Group 3 buffaloes were able to survive throughout the stipulated time of 21 days of experiment. There were significant differences (p  0.05) in edema between groups except for the lung. This study was a proof that oral route infection of Pasteurella multocida type B:2 immunogen outer membrane protein can be used to stimulate host cell.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology*
  10. Fulltext Cloning, expression and protective capacity of 37 kDa outer membrane protein gene (ompH) of Pasteurella multocida serotype B:2
    Tan HY, Nagoor NH, Sekaran SD
    Trop Biomed, 2010 Dec;27(3):430-41.
    PMID: 21399583 MyJurnal
    The major outer membrane protein (OmpH) of 4 local Malaysian strains of Pasteurella multocida serotype B:2 were characterized in comparison to ATCC strains. Three major peptide bands of MW 26, 32 and 37 kDa were characterized using SDSPAGE. Two of these fragments, the 32 kDa and 37 kDa were observed to be more reactive with a mouse polyclonal antiserum in all of the local isolates as well as the ATCC strains in a Western blot. However, the 32 kDa fragment was found to cross react with other Gram negative bacteria. Therefore, the 37 kDa OmpH was selected as vaccine candidate. The 37 kDa ompH gene of the isolated strain 1710 was cloned into an Escherichia coli expression vector to produce large amounts of recombinant OmpH (rOmpH). The 37 kDa ompH gene of strain 1710 was sequenced. In comparison to a reference strain X-73 of the ompH of P. multocida, 39bp was found deleted in the 37 kDa ompH gene. However, the deletion did not shift the reading frame or change the amino acid sequence. The rOmpH was used in a mice protection study. Mice immunized and challenged intraperitoneally resulted 100% protection against P. multocida whilst mice immunized subcutaneously and challenged intraperitoneally only resulted 80% protection. The rOmpH is therefore a suitable candidate for vaccination field studies. The same rOmpH was also used to develop a potential diagnostic kit in an ELISA format.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/genetics; Bacterial Outer Membrane Proteins/immunology*; Bacterial Outer Membrane Proteins/chemistry
  11. Comparative study of immunopathophysiological responses induced by B. melitensis and its lipopolysaccharide in mouse model infected via intranasal route of exposure
    Osman AY, Saharee AA, Jesse FF, Kadir AA
    Microb Pathog, 2017 Sep;110:365-374.
    PMID: 28710016 DOI: 10.1016/j.micpath.2017.07.014
    In this study, we developed a mouse model and characterized the effects of intranasal inoculation of virulent Brucella melitensis strain 16M and its lipopolysaccharide (LPS). The effects of the exposure were compared with respective control groups. Both Brucella melitensis-infected and LPS-infected groups showed no significant clinical presentation with minor relevance in the mortality associated with the infection. In Brucella melitensis-infected group, significant histopathological changes in comparison to the LPS infected group with increase bacterial burden in the lungs, reproductive and reticuloendothelial organs were observed. However, both infected groups showed elevated levels of pro-inflammatory cytokine expression (IL-1β and IL6) and antibody production (IgM an IgG) as early as 3 days post-infection with predominance in LPS infected group. In contrast, low levels of sex related hormonal changes was recorded in both infected groups throughout the experimental period. This is the first detailed investigation comparing the infection progression and host responses in relation to the immunopathophysiological aspects in mouse model after intranasal inoculation with B. melitensis and its lipopolysaccharide. The study revealed a significant difference between infected and control groups with overlap in clinical, pathological, and immunological responses as well as sex related hormonal changes resulting from the infections.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology
  12. Fulltext Crystal structure of an antigenic outer-membrane protein from Salmonella Typhi suggests a potential antigenic loop and an efflux mechanism
    Guan HH, Yoshimura M, Chuankhayan P, Lin CC, Chen NC, Yang MC, et al.
    Sci Rep, 2015 Nov 13;5:16441.
    PMID: 26563565 DOI: 10.1038/srep16441
    ST50, an outer-membrane component of the multi-drug efflux system from Salmonella enterica serovar Typhi, is an obligatory diagnostic antigen for typhoid fever. ST50 is an excellent and unique diagnostic antigen with 95% specificity and 90% sensitivity and is used in the commercial diagnosis test kit (TYPHIDOT(TM)). The crystal structure of ST50 at a resolution of 2.98 Å reveals a trimer that forms an α-helical tunnel and a β-barrel transmembrane channel traversing the periplasmic space and outer membrane. Structural investigations suggest significant conformational variations in the extracellular loop regions, especially extracellular loop 2. This is the location of the most plausible antibody-binding domain that could be used to target the design of new antigenic epitopes for the development of better diagnostics or drugs for the treatment of typhoid fever. A molecule of the detergent n-octyl-β-D-glucoside is observed in the D-cage, which comprises three sets of Asp361 and Asp371 residues at the periplasmic entrance. These structural insights suggest a possible substrate transport mechanism in which the substrate first binds at the periplasmic entrance of ST50 and subsequently, via iris-like structural movements to open the periplasmic end, penetrates the periplasmic domain for efflux pumping of molecules, including poisonous metabolites or xenobiotics, for excretion outside the pathogen.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/genetics; Bacterial Outer Membrane Proteins/metabolism; Bacterial Outer Membrane Proteins/chemistry*
  13. Demonstration of an antigenic protein specific for Salmonella typhi
    Ismail A, Hai OK, Kader ZA
    Biochem Biophys Res Commun, 1991 Nov 27;181(1):301-5.
    PMID: 1958200
    Current studies were undertaken to determine the presence of a specific antigenic protein on the outer membrane of Salmonella typhi. Immunoblot analysis using sera from patients with fevers revealed that the 50 kD band was specifically recognized only by typhoid sera. The 50 kD band located on the outer membrane is protein by nature and is not a Vi (capsular), dH (flagellar), or O9 (somatic) antigen of S. typhi. These results indicate the usefulness of the specific antigen in the development of a serodiagnostic test for typhoid fever since antibodies of both the IgM and IgG class responses were obtained.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/analysis*
  14. Demonstration of an outer membrane protein that is antigenically specific for Acinetobacter baumannii
    Islam AH, Singh KK, Ismail A
    Diagn Microbiol Infect Dis, 2011 Jan;69(1):38-44.
    PMID: 21146712 DOI: 10.1016/j.diagmicrobio.2010.09.008
    Acinetobacter baumannii is an emerging nosocomial pathogen that is resistant to many types of antibiotics, and hence, a fast, sensitive, specific, and economical test for its rapid diagnosis is needed. Development of such a test requires a specific antigen, and outer membrane proteins (OMPs) are the prime candidates. The goal of this study was to find a specific OMP of A. baumannii and demonstrate the presence of specific IgM, IgA, and IgG against the candidate protein in human serum. OMPs of A. baumannii ATCC 19606 and 16 other clinical isolates of A. baumannii were extracted from an overnight culture grown at 37 °C. Protein profiles were obtained using sodium dodecyl sulfate polyacrylamide gel electrophoresis, and Western blot analysis was performed to detect the presence of IgM, IgA, and IgG against the OMP in host serum. An antigenic 34.4-kDa OMP was uniquely recognized by IgM, IgA, and IgG from patients with A. baumannii infection, and it did not cross-react with sera from patients with other types of infection. The band was also found in the other 16 A. baumannii isolates. This 34.4-kDa OMP is a prime candidate for development of a diagnostic test for the presence of A. baumannii.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology*; Bacterial Outer Membrane Proteins/isolation & purification
  15. Designing and evaluation of an antibody-targeted chimeric recombinant vaccine encoding Shigella flexneri outer membrane antigens
    Kazi A, Hisyam Ismail CMK, Anthony AA, Chuah C, Leow CH, Lim BH, et al.
    Infect Genet Evol, 2020 06;80:104176.
    PMID: 31923724 DOI: 10.1016/j.meegid.2020.104176
    Shigellosis is one of the most common diseases found in the developing countries, especially those countries that are prone flood. The causative agent for this disease is the Shigella species. This organism is one of the third most common enteropathogens responsible for childhood diarrhea. Since Shigella can survive gastric acidity and is an intracellular pathogen, it becomes difficult to treat. Also, uncontrolled use of antibiotics has led to development of resistant strains which poses a threat to public health. Therefore, there is a need for long term control of Shigella infection which can be achieved by designing a proper and effective vaccine. In this study, emphasis was made on designing a candidate that could elicit both B-cell and T-cell immune response. Hence B- and T-cell epitopes of outer membrane channel protein (OM) and putative lipoprotein (PL) from S. flexneri 2a were computationally predicted using immunoinformatics approach and a chimeric construct (chimeric-OP) containing the immunogenic epitopes selected from OM and PL was designed, cloned and expressed in E. coli system. The immunogenicity of the recombinant chimeric-OP was assessed using Shigella antigen infected rabbit antibody. The result showed that the chimeric-OP was a synthetic peptide candidate suitable for the development of vaccine and immunodiagnostics against Shigella infection.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/genetics; Bacterial Outer Membrane Proteins/immunology*; Bacterial Outer Membrane Proteins/chemistry
  16. Detection of Chlamydia trachomatis in urine samples by polymerase chain reaction and enzyme immunoassay
    Ngeow YF, Hema V, Zakaria M, Lee CH, Ramachandran S
    Malays J Pathol, 1997 Dec;19(2):127-32.
    PMID: 10879253
    First-void urine samples collected from sexually transmitted diseases (STD) clinic patients were examined by a nested polymerase chain reaction (PCR) and a commercial enzyme immunoassay (IDEIA Chlamydia) for the diagnosis of Chlamydia trachomatis urethritis or cervicitis. The primers for the PCR amplified a target in the major outer membrane protein (MOMP) gene in C trachomatis while the IDEIA detected genus-specific chlamydial lipopolysaccharide. Discrepant results were resolved by retesting urine specimens with a second (plasmid-based) PCR and taking urethral or endocervical swab results into consideration. For 231 men (chlamydial prevalence 20.4%), the sensitivity, specificity, positive and negative predictive values were 59.6%, 99.5%, 96.6% and 90.6% for urine IDEIA, 68.1%, 99.5%, 97% and 92.4% for urethral swab IDEIA and 97.9%, 99.5%, 97.9% and 99.5% for urine PCR. The corresponding rates for 66 women (chlamydial prevalence 54.6%) were 19.4%, 100%, 100% and 50.8% for urine IDEIA, 86.1%, 96.7%, 96.9% and 85.3% for endocervical swab IDEIA and 91.7%, 93.3%, 94.3% and 90.3% for urine PCR. Hence, in a high prevalence population, the urine IDEIA was a suitable alternative to the male urethral swab IDEIA but significantly less sensitive than the endocervical swab IDEIA. The urine PCR was, however, much more sensitive than the urine IDEIA for both men and women and could replace the endocervical swab IDEIA for the diagnosis of chlamydial cervicitis.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/analysis
  17. 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*
  18. Development of a dry reagent-based triplex PCR for the detection of toxigenic and non-toxigenic Vibrio cholerae
    Chua AL, Elina HT, Lim BH, Yean CY, Ravichandran M, Lalitha P
    J Med Microbiol, 2011 Apr;60(Pt 4):481-485.
    PMID: 21183596 DOI: 10.1099/jmm.0.027433-0
    Vibrio cholerae has caused severe outbreaks of cholera worldwide with thousands of recorded deaths annually. Molecular diagnosis for cholera has become increasingly important for rapid detection of cholera as the conventional methods are time-consuming and labour intensive. However, traditional PCR tests still require cold-chain transportation and storage as well as trained personnel to perform, which makes them user-unfriendly. The aim of this study was to develop a thermostabilized triplex PCR test for cholera which is in a ready-to-use form and requires no cold chain. The PCR test specifically detects both toxigenic and non-toxigenic strains of V. cholerae based on the cholera toxin A (ctxA) and outer-membrane lipoprotein (lolB) genes. The thermostabilized triplex PCR also incorporates an internal amplification control that helps to check for PCR inhibitors in samples. PCR reagents and the specific primers were lyophilized into a pellet form in the presence of trehalose, which acts as an enzyme stabilizer. The triplex PCR was validated with 174 bacteria-spiked stool specimens and was found to be 100 % sensitive and specific. The stability of the thermostabilized PCR was evaluated using the Q10 method and it was found to be stable for approximately 7 months at 24 °C. The limit of detection of the thermostabilized triplex PCR assay was 2×10(4) c.f.u. at the bacterial cell level and 100 pg DNA at the genomic DNA level, comparable to conventional PCR methods. In conclusion, a rapid thermostabilized triplex PCR assay was developed for detecting toxigenic and non-toxigenic V. cholerae which requires minimal pipetting steps and is cold chain-free.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/genetics*
  19. Development of monoclonal antibodies against recombinant LipL21 protein of pathogenic Leptospira through phage display technology
    Mohd Ali MR, Sum JS, Aminuddin Baki NN, Choong YS, Nor Amdan NA, Amran F, et al.
    Int J Biol Macromol, 2021 Jan 31;168:289-300.
    PMID: 33310091 DOI: 10.1016/j.ijbiomac.2020.12.062
    Leptospirosis is a potentially fatal zoonosis that is caused by spirochete Leptospira. The signs and symptoms of leptospirosis are usually varied, allowing it to be mistaken for other causes of acute febrile syndromes. Thus, early diagnosis and identification of a specific agent in clinical samples is crucial for effective treatment. This study was aimed to develop specific monoclonal antibodies against LipL21 antigen for future use in leptospirosis rapid and accurate immunoassay. A recombinant LipL21 (rLipL21) antigen was optimized for expression and evaluated for immunogenicity. Then, a naïve phage antibody library was utilized to identify single chain fragment variable (scFv) clones against the rLipL21 antigen. A total of 47 clones were analysed through monoclonal phage ELISA. However, after taking into consideration the background OD405 values, only 4 clones were sent for sequencing to determine human germline sequences. The sequence analysis showed that all 4 clones are identical. The in silico analysis of scFv-lip-1 complex indicated that the charged residues of scFv CDRs are responsible for the recognition with rLipL21 epitopes. The generated monoclonal antibody against rLipL21 will be evaluated as a detection reagent for the diagnosis of human leptospirosis in a future study.
    Matched MeSH terms: Bacterial Outer Membrane Proteins/genetics; Bacterial Outer Membrane Proteins/immunology*; Bacterial Outer Membrane Proteins/isolation & purification; Bacterial Outer Membrane Proteins/metabolism
  20. 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*
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