Displaying publications 1 - 20 of 109 in total

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  1. Plasma interleukin-18 levels are a biomarker of innate immune responses that predict and characterize tuberculosis-associated immune reconstitution inflammatory syndrome
    Tan HY, Yong YK, Andrade BB, Shankar EM, Ponnampalavanar S, Omar SF, et al.
    AIDS, 2015 Feb 20;29(4):421-31.
    PMID: 25565499 DOI: 10.1097/QAD.0000000000000557
    Tuberculosis-associated immune reconstitution inflammatory syndrome (TB-IRIS) is a substantial problem in HIV/TB coinfected patients commencing antiretroviral therapy (ART). The immunopathogenesis of TB-IRIS includes increased production of proinflammatory chemokines and cytokines, including interleukin-18, which is a signature cytokine of the nucleotide-binding domain and leucine-rich repeat pyrin containing protein-3 inflammasome. We compared plasma levels of interleukin-18 and other biomarkers of monocyte/macrophage activation in the prediction and characterization of TB-IRIS.
    Matched MeSH terms: Antigens, Bacterial/immunology
  2. Fulltext Experimental exposure of Burkholderia pseudomallei crude culture filtrate upregulates PD-1 on T lymphocytes
    Menon N, Mariappan V, Vellasamy KM, Samudi C, See JX, Ganesh PS, et al.
    Access Microbiol, 2020;2(5):acmi000110.
    PMID: 32974575 DOI: 10.1099/acmi.0.000110
    Burkholderia pseudomallei is the causative agent for melioidosis. Because of its intracellular nature, the bacterium is capable of replicating within a plethora of eukaryotic cell lines. B. pseudomallei can remain dormant within host cells without symptoms for years, causing recrudescent infections. Here, we investigated the pathogenesis mechanism behind the suppression of T cell responses by B. pseudomallei . Peripheral blood mononuclear cells (1×106 cells/well) isolated by Ficoll Paque (Sigma-Aldrich) density gradient centrifugation were incubated with optimized concentrations of bacterial crude culture filtrate antigens (CFAs) (10 ug ml-1) and heat-killed bacteria [1 : 10 multiplicity of infection (m.o.i.)]. Following incubation, cells were investigated for surface expression of coinhibitory molecules by flow cytometry. We found that B. pseudomallei induced the upregulation of programmed death 1 (PD-1), a molecule responsible for T cell exhaustion, on T cells in vitro following exposure to crude CFAs of B. pseudomallei . This upregulation of PD-1 probably contributes to poor immune surveillance and disease pathogenesis.
    Matched MeSH terms: Antigens, Bacterial
  3. 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: Antigens, Bacterial/immunology; Antigens, Bacterial/chemistry*
  4. Studies on variation in Lancefield group A type 50 streptococcal cell-wall carbohydrate
    Kurl DN
    Adv Exp Med Biol, 1997;418:607-10.
    PMID: 9331725
    Matched MeSH terms: Antigens, Bacterial/biosynthesis; Antigens, Bacterial/genetics; Antigens, Bacterial/chemistry
  5. Limitations of serodiagnosis in chlamydial genital tract infections
    Ngeow YF
    Ann Acad Med Singap, 1996 Mar;25(2):300-4.
    PMID: 8799029
    Infection with Chlamydia trachomatis results in the formation of a variety of antibodies with group, species, subspecies and serovarspecificity. Sera from patients with genital tract infections often show broad reactivity in serological tests. This may be due to the presence of cross-reacting antibodies, repeated infections by different serotypes or concurrent genital and respiratory infections by different chlamydial species. Other factors contributing to difficulties in interpretation include how antibody titres in acute mucosal infections, the occurrence of latent infections and reactivations, and the persistence of IgG which does not allow the differentiation of past from current infections. For these reasons, serology alone is inadequate for the diagnosis of uncomplicated lower genital tract infections. In upper genital tract infections, however, because of difficulties with sampling from the infected site, a positive serology may be the only indications of chlamydial involvement. This paper discusses the principles of chlamydial antibody assays, difficulties with their interpretation and their role in the diagnosis of upper and lower genital tract infections.
    Matched MeSH terms: Antigens, Bacterial/analysis*
  6. Evaluation of the Atlas Helicobacter pylori stool antigen test for diagnosis of infection in adult patients
    Osman HA, Hasan H, Suppian R, Bahar N, Hussin NS, Rahim AA, et al.
    Asian Pac J Cancer Prev, 2014;15(13):5245-7.
    PMID: 25040982
    BACKGROUND: Helicobacter pylori (H. pylori) is one of the most important causes of dyspepsia and gastric cancer and diagnosis can be made by invasive or non-invasive methods. The Atlas Helicobacter pylori antigen test is a new rapid non-invasive method which is simple to conduct. The aim of this study was to determine its sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy.

    MATERIALS AND METHODS: This prospective study was conducted between July 2012 and December 2013. Stool samples of 59 dyspeptic patients who underwent upper endoscopy were evaluated for H. pylori stool antigen.

    RESULTS: From the 59 patients who participated in this study, there were 36 (61%) males and 23 (39%) females. H. pylori was diagnosed in 24 (40.7%) gastric biopsies, 22 (91.7 %) of these being positive for the Atlas H. pylori antigen test. The sensitivity, specificity, PPV, NPV and accuracy were 91.7%, 100%, 100%, 94.6% and 96.6% respectively.

    CONCLUSIONS: The Atlas H. pylori antigen test is a new non-invasive method which is simple to perform and avails reliable results in a few minutes. Thus it can be the best option for the diagnosis of H. pylori infection due to its high sensitivity and specificity.

    Matched MeSH terms: Antigens, Bacterial/immunology*
  7. Antigenic proteins of Helicobacter pylori of potential diagnostic value
    Khalilpour A, Santhanam A, Wei LC, Saadatnia G, Velusamy N, Osman S, et al.
    Asian Pac J Cancer Prev, 2013;14(3):1635-42.
    PMID: 23679248
    Helicobacter pylori antigen was prepared from an isolate from a patient with a duodenal ulcer. Serum samples were obtained from culture-positive H. pylori infected patients with duodenal ulcers, gastric ulcers and gastritis (n=30). As controls, three kinds of sera without detectable H. pylori IgG antibodies were used: 30 from healthy individuals without history of gastric disorders, 30 from patients who were seen in the endoscopy clinic but were H. pylori culture negative and 30 from people with other diseases. OFF-GEL electrophoresis, SDS-PAGE and Western blots of individual serum samples were used to identify protein bands with good sensitivity and specificity when probed with the above sera and HRP-conjugated anti-human IgG. Four H. pylori protein bands showed good (≥ 70%) sensitivity and high specificity (98-100%) towards anti-Helicobacter IgG antibody in culture- positive patients sera and control sera, respectively. The identities of the antigenic proteins were elucidated by mass spectrometry. The relative molecular weights and the identities of the proteins, based on MALDI TOF/ TOF, were as follows: CagI (25 kDa), urease G accessory protein (25 kDa), UreB (63 kDa) and proline/pyrroline- 5-carboxylate dehydrogenase (118 KDa). These identified proteins, singly and/or in combinations, may be useful for diagnosis of H. pylori infection in patients.
    Matched MeSH terms: Antigens, Bacterial/immunology*; Antigens, Bacterial/metabolism
  8. Fulltext Recovery of recombinant Mycobacterium tuberculosis antigens fused with cell wall-anchoring motif (LysM) from inclusion bodies using non-denaturing reagent (N-laurylsarcosine)
    Mustafa AD, Kalyanasundram J, Sabidi S, Song AA, Abdullah M, Abdul Rahim R, et al.
    BMC Biotechnol, 2019 05 14;19(1):27.
    PMID: 31088425 DOI: 10.1186/s12896-019-0522-x
    BACKGROUND: The current limitations of conventional BCG vaccines highlights the importance in developing novel and effective vaccines against tuberculosis (TB). The utilization of probiotics such as Lactobacillus plantarum for the delivery of TB antigens through in-trans surface display provides an effective and safe vaccine approach against TB. Such non-recombinant probiotic surface display strategy involves the fusion of candidate proteins with cell wall binding domain such as LysM, which enables the fusion protein to anchor the L. plantarum cell wall externally, without the need for vector genetic modification. This approach requires sufficient production of these recombinant fusion proteins in cell factory such as Escherichia coli which has been shown to be effective in heterologous protein production for decades. However, overexpression in E. coli expression system resulted in limited amount of soluble heterologous TB-LysM fusion protein, since most of it are accumulated as insoluble aggregates in inclusion bodies (IBs). Conventional methods of denaturation and renaturation for solubilizing IBs are costly, time-consuming and tedious. Thus, in this study, an alternative method for TB antigen-LysM protein solubilization from IBs based on the use of non-denaturating reagent N-lauroylsarcosine (NLS) was investigated.

    RESULTS: Expression of TB antigen-LysM fusion genes was conducted in Escherichia coli, but this resulted in IBs deposition in contrast to the expression of TB antigens only. This suggested that LysM fusion significantly altered solubility of the TB antigens produced in E. coli. The non-denaturing NLS technique was used and optimized to successfully solubilize and purify ~ 55% of the recombinant cell wall-anchoring TB antigen from the IBs. Functionality of the recovered protein was analyzed via immunofluorescence microscopy and whole cell ELISA which showed successful and stable cell wall binding to L. plantarum (up to 5 days).

    CONCLUSION: The presented NLS purification strategy enables an efficient and rapid method for obtaining higher yields of soluble cell wall-anchoring Mycobacterium tuberculosis antigens-LysM fusion proteins from IBs in E. coli.

    Matched MeSH terms: Antigens, Bacterial/genetics; Antigens, Bacterial/metabolism*
  9. Fulltext Proof of concept in utilizing in-trans surface display system of Lactobacillus plantarum as mucosal tuberculosis vaccine via oral administration in mice
    Mustafa AD, Kalyanasundram J, Sabidi S, Song AA, Abdullah M, Abdul Rahim R, et al.
    BMC Biotechnol, 2018 10 11;18(1):63.
    PMID: 30309359 DOI: 10.1186/s12896-018-0461-y
    BACKGROUND: Tuberculosis is one of the most common and deadliest infectious diseases worldwide affecting almost a third of the world's population. Although this disease is being prevented and controlled by the Bacille Calmette Guérin (BCG) vaccine, the protective efficacy is highly variable and substandard (0-80%) in adults. Therefore, novel and effective tuberculosis vaccine that can overcome the limitations from BCG vaccine need to be developed.

    RESULTS: A novel approach of utilizing an in-trans protein surface display system of Lactobacillus plantarum carrying and displaying combination of Mycobacterium tuberculosis subunit epitope antigens (Ag85B, CFP-10, ESAT-6, Rv0475 and Rv2031c) fused with LysM anchor motif designated as ACERL was constructed, cloned and expressed in Esherichia coli Rossetta expression host. Subsequently the binding capability of ACERL to the cell wall of L. plantarum was examined via the immunofluorescence microscopy and whole cell ELISA where successful attachment and consistent stability of cell wall binding up to 4 days was determined. The immunization of the developed vaccine of L. plantarum surface displaying ACERL (Lp ACERL) via the oral route was studied in mice for its immunogenicity effects. Lp ACERL immunization was able to invoke significant immune responses that favor the Th1 type cytokine response of IFN-γ, IL-12 and IL-2 as indicated by the outcome from the cytokine profiling of spleen, lung, gastrointestinal tract (GIT), and the re-stimulation of the splenocytes from the immunized mice. Co-administration of an adjuvant consisting of Lactococcus lactis secreting mouse IL-12 (LcIL-12) with Lp ACERL was also investigated. It was shown that the addition of LcIL-12 was able to further generate significant Th1 type cytokines immune responses, similar or better than that of Lp ACERL alone which can be observed from the cytokine profiling of the immunized mice's spleen, lung and GIT.

    CONCLUSIONS: This study represents a proof of concept in the development of L. plantarum as a carrier for a non-genetically modified organism (GMO) tuberculosis vaccine, which may be the strategy in the future for tuberculosis vaccine development.

    Matched MeSH terms: Antigens, Bacterial/administration & dosage; Antigens, Bacterial/genetics; Antigens, Bacterial/immunology
  10. Fulltext Immunogenicity of recombinant Mycobacterium bovis bacille Calmette-Guèrin clones expressing T and B cell epitopes of Mycobacterium tuberculosis antigens
    Mohamud R, Azlan M, Yero D, Alvarez N, Sarmiento ME, Acosta A, et al.
    BMC Immunol, 2013;14 Suppl 1:S5.
    PMID: 23458635 DOI: 10.1186/1471-2172-14-S1-S5
    Recombinant Mycobacterium bovis bacille Calmette-Guèrin (rBCG) expressing three T cell epitopes of Mycobacterium tuberculosis (MTB) Ag85B antigen (P1, P2, P3) fused to the Mtb8.4 protein (rBCG018) or a combination of these antigens fused to B cell epitopes from ESAT-6, CFP-10 and MTP40 proteins (rBCG032) were used to immunize Balb/c mice. Total IgG responses were determined against Mtb8.4 antigen and ESAT-6 and CFP-10 B cell epitopes after immunization with rBCG032. Mice immunized with rBCG032 showed a significant increase in IgG1 and IgG2a antibodies against ESAT-6 and MTP40 (P1) B cell epitopes and IgG3 against both P1 and P2 B cell epitopes of MPT40. Splenocytes from mice immunized with rBCG018 proliferated against Ag85B P2 and P3 T cell epitopes and Mtb8.4 protein whereas those from mice-immunized with rBCG032 responded against all Ag85B epitopes and the ESAT-6 B cell epitope. CD4⁺ and CD8⁺ lymphocytes from mice immunized with rBCG018 produced primarily Th1 type cytokines in response to the T cell epitopes. Similar pattern of recognition against the T cell epitopes were obtained with rBCG032 with the additional recognition of ESAT-6, CFP-10 and one of the MTP40 B cell epitopes with the same pattern of cytokines. This study demonstrates that rBCG constructs expressing either T or T and B cell epitopes of MTB induced appropriate immunogenicity against MTB.
    Matched MeSH terms: Antigens, Bacterial/immunology*; Antigens, Bacterial/metabolism
  11. Fulltext In Silico identification of M. TB proteins with diagnostic potential
    Calero R, Mirabal M, Bouza J, Guzmán MV, Carrillo H, López Y, et al.
    BMC Immunol, 2013;14 Suppl 1:S9.
    PMID: 23458073 DOI: 10.1186/1471-2172-14-S1-S9
    TB, caused by Mycobacterium tuberculosis (MTB), is one of the major global infectious diseases. For the pandemic control, early diagnosis with sensitive and specific methods is fundamental. With the advent of bioinformatics' tools, the identification of several proteins involved in the pathogenesis of TB (TB) has been possible. In the present work, the MTB genome was explored to look for molecules with possible antigenic properties for their evaluation as part of new generation diagnostic kits based on the release of cytokines. Seven proteins from the MTB proteome and some of their combinations suited the computational test and the results suggested their potential use for the diagnosis of infection in the following population groups: Cuba, Mexico, Malaysia and sub-Saharan Africa. Our predictions were performed using public bioinformatics tools plus three computer programs, developed by our group, to facilitate information retrieval and processing.
    Matched MeSH terms: Antigens, Bacterial/immunology
  12. Fulltext Multiple-antigen ELISA for melioidosis--a novel approach to the improved serodiagnosis of melioidosis
    Hara Y, Chin CY, Mohamed R, Puthucheary SD, Nathan S
    BMC Infect Dis, 2013;13:165.
    PMID: 23556548 DOI: 10.1186/1471-2334-13-165
    Burkholderia pseudomallei, the causative agent of melioidosis, is endemic to Southeast Asia and northern Australia. Clinical manifestations of disease are diverse, ranging from chronic infection to acute septicaemia. The current gold standard of diagnosis involves bacterial culture and identification which is time consuming and often too late for early medical intervention. Hence, rapid diagnosis of melioidosis is crucial for the successful management of melioidosis.
    Matched MeSH terms: Antigens, Bacterial*
  13. Detection of virulence genes in Malaysian Shigella species by multiplex PCR assay
    Thong KL, Hoe SL, Puthucheary SD, Yasin R
    BMC Infect Dis, 2005 Feb 14;5:8.
    PMID: 15707504
    In Malaysia, Shigella spp. was reported to be the third commonest bacterial agent responsible for childhood diarrhoea. Currently, isolation of the bacterium and confirmation of the disease by microbiological and biochemical methods remain as the "gold standard". This study aimed to detect the prevalence of four Shigella virulence genes present concurrently, in randomly selected Malaysian strains via a rapid multiplex PCR (mPCR) assay.
    Matched MeSH terms: Antigens, Bacterial/genetics; Antigens, Bacterial/isolation & purification
  14. An investigative study on the zoonotic potential of Helicobacter pylori
    Shaaban SI, Talat D, Khatab SA, Nossair MA, Ayoub MA, Ewida RM, et al.
    BMC Vet Res, 2023 Jan 21;19(1):16.
    PMID: 36670434 DOI: 10.1186/s12917-023-03572-w
    BACKGROUND: Helicobacter pylori is one of the most common bacterial infections and is widespread globally. It causes a variety of gastrointestinal disorders, though a great proportion of infections are asymptomatic. A total of 143 fresh stool samples were collected from apparently healthy farm and pet animals (43 cattle, 50 buffaloes, 50 sheep, 50 dogs, and 50 cats), in addition to 768 human stool samples. The samples were examined using stool antigen and rapid antibody tests, and further confirmation of glmM "human antigen-positive samples and animal milk samples" was conducted by polymerase chain reaction (PCR).

    RESULTS: The prevalence rates of H. pylori infection in animals were 22.2% and 16% in antibody and stool antigen tests, respectively. The detection rates were 28%, 24%, 12%, 10%, and 4.7% in cats, dogs, buffaloes, sheep, and cattle, respectively. On the other hand, the prevalence rate of H. pylori infection in human stool samples was 74.8%, and a statistically significant association was observed between prevalence and several factors, such as sex, age, and locality. PCR was performed to detect the glmM gene of H. pylori, and this gene was found in 21 of 27 human antigen-positive samples and 5 of 13 animal milk samples.

    CONCLUSIONS: H. pylori was detected in both human and animal samples. Furthermore, glmM was found in milk and human samples. Our findings suggest that pet and farm animals could transmit H. pylori infection to humans.

    Matched MeSH terms: Antigens, Bacterial/genetics
  15. Fulltext Protective effect of a lipid-based preparation from Mycobacterium smegmatis in a murine model of progressive pulmonary tuberculosis
    García Mde L, Borrero R, Lanio ME, Tirado Y, Alvarez N, Puig A, et al.
    Biomed Res Int, 2014;2014:273129.
    PMID: 25548767 DOI: 10.1155/2014/273129
    A more effective vaccine against tuberculosis (TB) is urgently needed. Based on its high genetic homology with Mycobacterium tuberculosis (Mtb), the nonpathogenic mycobacteria, Mycobacterium smegmatis (Ms), could be an attractive source of potential antigens to be included in such a vaccine. We evaluated the capability of lipid-based preparations obtained from Ms to provide a protective response in Balb/c mice after challenge with Mtb H37Rv strain. The intratracheal model of progressive pulmonary TB was used to assess the level of protection in terms of bacterial load as well as the pathological changes in the lungs of immunized Balb/c mice following challenge with Mtb. Mice immunized with the lipid-based preparation from Ms either adjuvanted with Alum (LMs-AL) or nonadjuvanted (LMs) showed significant reductions in bacterial load (P < 0.01) compared to the negative control group (animals immunized with phosphate buffered saline (PBS)). Both lipid formulations showed the same level of protection as Bacille Calmette and Guerin (BCG). Regarding the pathologic changes in the lungs, mice immunized with both lipid formulations showed less pneumonic area when compared with the PBS group (P < 0.01) and showed similar results compared with the BCG group. These findings suggest the potential of LMs as a promising vaccine candidate against TB.
    Matched MeSH terms: Antigens, Bacterial/immunology; Antigens, Bacterial/therapeutic use
  16. Fulltext Production and characterization of a polyclonal antibody of anti-rLipL21-IgG against leptospira for early detection of acute leptospirosis
    Seenichamy A, Bahaman AR, Mutalib AR, Khairani-Bejo S
    Biomed Res Int, 2014;2014:592858.
    PMID: 24860824 DOI: 10.1155/2014/592858
    Leptospirosis is one of the zoonotic diseases in animals and humans throughout the world. LipL21 is one of the important surface-exposed lipoproteins in leptospires and the most effective cross protective immunogenic antigen. It is widely considered as a diagnostic marker for leptospirosis. In this study, we evaluated the serodiagnostic potential of LipL21 protein of Leptospira interrogans serovar Pomona. We have successfully amplified, cloned, and expressed LipL21 in E. coli and evaluated its specificity by immunoblotting. Purified recombinant LipL21 (rLipL21) was inoculated into rabbits for the production of polyclonal antibody. Characterization of the purified IgG antibody against rLipL21 was performed by cross reactivity assay. Only sera from leptospirosis patients and rabbit hyperimmune sera recognized rLipL21 while the nonleptospirosis control sera showed no reaction in immunoblotting. We confirmed that anti-rLipL21-IgG antibody cross reacted with and detected only pathogenic leptospiral species and it did not react with nonpathogenic leptospires and other bacterial species. Results observed showed that anti-rLipL21-IgG antibody has high specificity and sensitivity to leptospires. The findings indicated that the antibody could be used in a diagnostic assay for detection of leptospires or their proteins in the early phase of infection.
    Matched MeSH terms: Antigens, Bacterial/immunology*
  17. 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: Antigens, Bacterial/chemistry*
  18. 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: Antigens, Bacterial/analysis*
  19. Mimotopes of the Vi antigen of Salmonella enterica serovar typhi identified from phage display peptide library
    Tang SS, Tan WS, Devi S, Wang LF, Pang T, Thong KL
    Clin Diagn Lab Immunol, 2003 Nov;10(6):1078-84.
    PMID: 14607870
    The capsular polysaccharide Vi antigen (ViCPS) is an essential virulence factor and also a protective antigen of Salmonella enterica serovar Typhi. A random 12-mer phage-displayed peptide library was used to identify mimotopes (epitope analogues) of this antigen by panning against a ViCPS-specific monoclonal antibody (MAb) ATVi. Approximately 75% of the phage clones selected in the fourth round carried the peptide sequence TSHHDSHGLHRV, and the rest of the clones harbored ENHSPVNIAHKL and other related sequences. These two sequences were also obtained in a similar panning process by using pooled sera from patients with a confirmed diagnosis of typhoid fever, suggesting they mimic immunodominant epitopes of ViCPS antigens. Binding of MAb ATVi to the mimotopes was specifically blocked by ViCPS, indicating that they interact with the same binding site (paratope) of the MAb. Data and reagents generated in this study have important implications for the development of peptide-base diagnostic tests and peptide vaccines and may also provide a better understanding of the pathogenesis of typhoid fever.
    Matched MeSH terms: Antigens, Bacterial/immunology*
  20. 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: Antigens, Bacterial/immunology*
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