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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*
Enzyme-linked amperometric electrochemical genosensor assay for the detection of PCR amplicons on a streptavidin-treated screen-printed carbon electrode

Yean CY, Kamarudin B, Ozkan DA, Yin LS, Lalitha P, Ismail A, et al.

Anal Chem, 2008 Apr 15;80(8):2774-9.
PMID: 18311943 DOI: 10.1021/ac702333x

A general purpose enzyme-based amperometric electrochemical genosensor assay was developed wherein polymerase chain reaction (PCR) amplicons labeled with both biotin and fluorescein were detected with peroxidase-conjugated antifluorescein antibody on a screen-printed carbon electrode (SPCE). As a proof of principle, the response selectivity of the genosensor was evaluated using PCR amplicons derived from lolB gene of Vibrio cholerae. Factors affecting immobilization, hybridization, and nonspecific binding were optimized to maximize sensitivity and reduce assay time. On the basis of the background amperometry signals obtained from nonspecific organisms and positive signals obtained from known V. cholerae, a threshold point of 4.20 microA signal was determined as positive. Under the optimum conditions, the limit of detection (LOD) of the assay was 10 CFU/mL of V. cholerae. The overall precision of this assay was good, with the coefficient of variation (CV) being 3.7% using SPCE and intermittent pulse amperometry (IPA) as an electrochemical technique. The assay is sensitive, safe, and cost-effective when compared to conventional agarose gel electrophoresis, real-time PCR, and other enzyme-linked assays for the detection of PCR amplicons. Furthermore, the use of a hand-held portable reader makes it suitable for use in the field.

Matched MeSH terms: Bacterial Outer Membrane Proteins/genetics
Overexpression, purification and validation of antigenic Salmonella enterica serovar Typhi proteins identified from LC-MS/MS

Chin CF, Teh BA, Anthony AA, Aziah I, Ismail A, Ong EB, et al.

Appl Biochem Biotechnol, 2014 Nov;174(5):1897-906.
PMID: 25149461 DOI: 10.1007/s12010-014-1173-y

In our earlier study, an immunoblot analysis using sera from febrile patients revealed that a 50-kDa band from an outer membrane protein fraction of Salmonella enterica serovar Typhi was specifically recognized only by typhoid sera and not sera from other febrile illnesses. Here, we investigated the identities of the proteins contained in the immunogenic 50-kDa band to pinpoint antigens responsible for its immunogenicity. We first used LC-MS/MS for protein identification, then used the online tool ANTIGENpro for antigenicity prediction and produced recombinant proteins of the lead antigens for validation in an enzyme-linked immunosorbent assay (ELISA). We found that proteins TolC, GlpK and SucB were specific to typhoid sera but react to antibodies differently under native and denatured conditions. This difference suggests the presence of linear and conformational epitopes on these proteins.

Matched MeSH terms: Bacterial Outer Membrane Proteins/immunology*; Bacterial Outer Membrane Proteins/isolation & purification; Bacterial Outer Membrane Proteins/chemistry*
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*
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*
Fulltext Reproductive hormonal variations and adenohypophyseal lesions in pre-pubertal buffalo heifers inoculated with Pasteurella multocida type B: 2 and its immunogens

Jesse FF, Ibrahim HH, Abba Y, Chung EL, Marza AD, Mazlan M, et al.

BMC Vet Res, 2017 Apr 05;13(1):88.
PMID: 28381248 DOI: 10.1186/s12917-017-1010-y

BACKGROUND: Hemorrhagic septicemia is a fatal disease of cattle and buffaloes caused by P. multocida. Although the pathogenesis of the bacteria has been well established in literature, there is a paucity of information on the possible role of the bacteria and its immunogens; lipopolysaccharide (LPS) and outer membrane proteins (OMPs) on the reproductive capacity of buffalo heifers.
METHODS: In this study, twenty one healthy prepubertal female buffaloes aged 8 months were divided into seven groups of 3 buffaloes each (G1-G7). Group 1 (G1) served as the negative control group and were inoculated orally with 10 mL sterile Phosphate Buffer Saline (PBS), groups 2 (G2) and 3 (G3) were inoculated orally and subcutaneously with 10 mL of 10(12) colony forming unit (cfu) of P.multocida type B: 2, while groups 4 (G4) and 5 (G5) received 10 mL of bacterial LPS orally and intravenously, respectively. Lastly, groups 6 (G6) and 7 (G7) were orally and subcutaneously inoculated with 10 mL of bacterial OMPs. Whole blood was collected in EDTA vials at stipulated time points (0, 2, 4, 6, 8, 10, 12, 24, 36, 48, 72, 120, 168, 216, 264, 312, 360, 408, 456 and 504 h), while tissue sections of the pituitary glands were collected and transported to the histopathology laboratory in 10% buffered formalin for processing and Hematoxylin and eosin staining. Plasma levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), progesterone (PG), estradiol (EST) and gonadotrophin releasing hormone (GnRH) were determined.
RESULTS: The histopathological lesions observed in the pituitary gland included hemorrhage, congestion, inflammatory cell infiltration, hydropic degeneration, necrosis and edema. These changes were higher (p

Matched MeSH terms: Bacterial Outer Membrane Proteins/administration & dosage; Bacterial Outer Membrane Proteins/immunology*
Fulltext Serological diagnostic potential of recombinant outer membrane proteins (rOMPs) from Brucella melitensis in mouse model using indirect enzyme-linked immunosorbent assay

Ahmed IM, Khairani-Bejo S, Hassan L, Bahaman AR, Omar AR

BMC Vet Res, 2015;11:275.
PMID: 26530141 DOI: 10.1186/s12917-015-0587-2

Brucella melitensis is the most important pathogenic species of Brucella spp. which affects goats and sheep and causes caprine and ovine brucellosis, respectively. Serological tests for diagnosis of brucellosis such as Rose Bengal plate test (RBPT) and enzyme-linked immunosorbent assay (ELISA) usually utilize smooth lipopolysaccharides (S-LPS) as a diagnostic antigen which could give false positive serological reactions. Outer membrane proteins (OMP) of B. melitensis have been used as alternative diagnostic antigens rather than S-LPS for differential serological diagnosis of brucellosis, mainly in ELISA with single recombinant OMP (rOMP) as a diagnostic antigen. Nevertheless, the use of single format mainly showed lack of sensitivity against the desired rOMP. Therefore, this study aimed to determine whether a newly developed rOMPs indirect ELISA (rOMPs I-ELISA), based on combination of rOMP25, rOMP28 and rOMP31of B. melitensis, has a potential benefit for use in the serodiagnosis of brucellosis.

Matched MeSH terms: Bacterial Outer Membrane Proteins/isolation & purification*
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*
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*
Generation of an RNA aptamer against LipL32 of Leptospira isolated by Tripartite-hybrid SELEX coupled with in-house Python-aided unbiased data sorting

Shien Yeoh T, Yusof Hazrina H, Bukari BA, Tang TH, Citartan M

Bioorg Med Chem, 2023 Mar 01;81:117186.
PMID: 36812779 DOI: 10.1016/j.bmc.2023.117186

Leptospirosis is a potentially life-threatening zoonosis caused by pathogenic Leptospira. The major hurdle of the diagnosis of Leptospirosis lies in the issues associated with current methods of detection, which are time-consuming, tedious and the need for sophisticated, special equipments. Restrategizing the diagnostics of Leptospirosis may involve considerations of the direct detection of the outer membrane protein, which can be faster, cost-saving and require fewer equipments. One such promising marker is LipL32, which is an antigen with high amino acid sequence conservation among all the pathogenic strains. In this study, we endeavored to isolate an aptamer against LipL32 protein via a modified SELEX strategy known as tripartite-hybrid SELEX, based on 3 different partitioning strategies. In this study, we also demonstrated the deconvolution of the candidate aptamers by using in-house Python-aided unbiased data sorting in examining multiple parameters to isolate potent aptamers. We have successfully generated an RNA aptamer against LipL32 of Leptospira, LepRapt-11, which is applicable in a simple direct ELASA for the detection of LipL32. LepRapt-11 can be a promising molecular recognition element for the diagnosis of leptospirosis by targeting LipL32.

Matched MeSH terms: Bacterial Outer Membrane Proteins/metabolism
Helicobacter pylori outer inflammatory protein A (OipA) suppresses apoptosis of AGS gastric cells in vitro

Al-Maleki AR, Loke MF, Lui SY, Ramli NSK, Khosravi Y, Ng CG, et al.

Cell. Microbiol., 2017 12;19(12).
PMID: 28776327 DOI: 10.1111/cmi.12771

Outer inflammatory protein A (OipA) is an important virulence factor associated with gastric cancer and ulcer development; however, the results have not been well established and turned out to be controversial. This study aims to elucidate the role of OipA in Helicobacter pylori infection using clinical strains harbouring oipA "on" and "off" motifs. Proteomics analysis was performed on AGS cell pre-infection and postinfection with H. pylori oipA "on" and "off" strains, using liquid chromatography/mass spectrometry. AGS apoptosis and cell cycle assays were performed. Moreover, expression of vacuolating cytotoxin A (VacA) was screened using Western blotting. AGS proteins that have been suggested previously to play a role or associated with gastric disease were down-regulated postinfection with oipA "off" strains comparing to oipA "on" strains. Furthermore, oipA "off" and ΔoipA cause higher level of AGS cells apoptosis and G0/G1 cell-cycle arrest than oipA "on" strains. Interestingly, deletion of oipA increased bacterial VacA production. The capability of H. pylori to induce apoptosis and suppress expression of proteins having roles in human disease in the absence of oipA suggests that strains not expressing OipA may be less virulent or may even be protective against carcinogenesis compared those expressing OipA. This potentially explains the higher incidence of gastric cancer in East Asia where oipA "on" strains predominates.

Matched MeSH terms: Bacterial Outer Membrane Proteins/genetics; Bacterial Outer Membrane Proteins/metabolism*
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*
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
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*
Fulltext New emm (M protein gene) sequences of group A streptococci isolated from Malaysian patients

Jamal F, Pit S, Facklam R, Beall B

Emerg Infect Dis, 1999 Jan-Feb;5(1):182-3.
PMID: 10081694
Matched MeSH terms: Bacterial Outer Membrane Proteins*
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*
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*
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
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
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*

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