Displaying publications 41 - 60 of 177 in total

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  1. A simple adherence test for detection of IgM antibodies in typhoid
    Ong LY, Pang T, Lim SH, Tan EL, Puthucheary SD
    J Med Microbiol, 1989 Jul;29(3):195-8.
    PMID: 2473209
    A simple adherence test to detect IgM antibodies in patients with typhoid is described. The test utilises the IgM-"capture" approach, in which the test serum is applied to microtitration plate wells previously coated with anti-human IgM, followed by application of a stained Salmonella typhi antigen suspension which shows adherence in positive cases. By this test, 58 (95%) of 61 sera from confirmed cases of typhoid possessed IgM antibodies to the H or O or both antigens of S. typhi. In patients for whom a diagnosis of typhoid was based only on a significant Widal-test titre, 31 (41%) of 76 sera had IgM antibodies to the H or O or both antigens of S. typhi. Some cross-reactivity of the IgM antibodies was detected, especially with the O antigens of S. paratyphi A and B. A total of 82 sera from non-typhoidal fevers (leptospirosis, typhus, dengue fever) showed no reactivity in this test. In normal sera there was no detectable IgM to the O antigen of S. typhi and only a small number (3.9%) had low levels of IgM to the H antigen. The significance and potential importance of this simple, sensitive, specific and economical test is discussed.
    Matched MeSH terms: Antibodies, Bacterial/analysis
  2. Distribution of immunoglobulin classes and IgG subclasses against a culture filtrate antigen of Burkholderia pseudomallei in melioidosis patients
    Chenthamarakshan V, Kumutha MV, Vadivelu J, Puthucheary SD
    J Med Microbiol, 2001 Jan;50(1):55-61.
    PMID: 11192506 DOI: 10.1099/0022-1317-50-1-55
    The class and subclass distribution of antibody response to the culture filtrate antigen (CFA) of Burkholderia pseudomallei was examined in the sera of 45 septicaemic and 17 localised melioidosis cases and 40 cases clinically suspected of melioidosis and the results were compared with those from high-risk and healthy control groups. The geometric mean titre index (GMTI) values for all classes and subclasses of immunoglobulins examined were higher for sera from the proven and clinically suspected melioidosis cases than for the control groups. However, the highest response in the three patient groups was that of IgG with GMTIs ranging from 219.4 to 291.6 and the lowest was for IgM with GMTIs of 22.5, 24.3 and 28.7. The IgA response was intermediate with GMTIs ranging from 119.2 to 170. The GMTIs were highest for IgG in septicaemic and localised infections and for IgA and IgM in localised infections. As regards IgG subclass distribution, IgG1 and IgG2 were the predominant subclasses produced against the CFA in contrast to IgG3 and IgG4, which were produced in low amounts. None of the sera from the control groups had any significant titres of antibodies.
    Matched MeSH terms: Antibodies, Bacterial/blood*
  3. Fulltext Prevalence of canine ehrlichiosis in Perak State, peninsular Malaysia
    Rahman WA, Ning CH, Chandrawathani P
    Trop Biomed, 2010 Apr;27(1):13-8.
    PMID: 20562808 MyJurnal
    The Indirect Fluorescent Antibody Test (IFAT) and thin blood smears were conducted to establish the prevalence of Ehrlichia canis infection in dogs presented for treatment by pet owners at five private and one government veterinary clinic. Results showed that 15% of the dogs were positive for the parasite via IFAT, but none using blood smears. However, infected dogs did not show severe clinical symptoms of canine monocytic ehrlichiosis (CME).
    Matched MeSH terms: Antibodies, Bacterial/blood
  4. Evaluation of IgM LAT and IgM ELISA as compared to microscopic agglutination test (MAT) for early diagnosis of Leptospira sp
    Zin NM, Othman SN, Abd Rahman FR, Abdul Rachman AR
    Trop Biomed, 2019 Dec 01;36(4):1071-1080.
    PMID: 33597476
    Leptospirosis is a worldwide zoonotic disease caused by spirochetes of the genus Leptospira. The clinical manifestation of leptospirosis is non-specific and frequently misdiagnosed as other illnesses. The aim of this study was to compare the diagnostic accuracies of two commercial tests for early diagnosis of Leptospira species: the IgM latex agglutination test (IgM LAT) and the IgM enzyme-linked immunosorbent assay (IgM ELISA). A total of 140 serum samples were obtained from patients suspected of leptospirosis at the Universiti Kebangsaan Malaysia Medical Centre (UKMMC). These serum samples were tested for the presence of Leptospira sp. using IgM LAT, IgM ELISA and MAT. From Table 1, IgM LAT showed 21% (n = 29) positive, 18% (n = 25) inconclusive and 61% (n = 86) negative, while IgM ELISA showed 6% (n = 8) positive, 6% (n = 8) inconclusive, 88% (n = 124) negative and MAT showed 11% (n = 16) positive, 47% (n = 65) inconclusive, 42% (n = 59) negative. The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of IgM LAT were 68.8%, 57.6%, 30.6% and 87.2% respectively, while for IgM ELISA they were 37.5%, 89.8%, 50% and 84.1%, respectively as compared to MAT (Table 2). The results showed that IgM LAT had higher sensitivity but lower specificity compared to IgM ELISA. In conclusion, IgM LAT can be useful as an early screening test for early diagnosis of Leptospira sp., while IgM ELISA is a suitable method for reducing false negative detection of Leptospira sp. As both tests show moderate percentages (~65%) in accuracy, an additional test is required for better detection of Leptospira sp.
    Matched MeSH terms: Antibodies, Bacterial/blood*
  5. Serological evidence for a high incidence of transmission of Rickettsia tsutsugamushi in two Orang Asli settlements in Peninsular Malaysia
    Brown GW, Robinson DM, Huxsoll DL
    Am J Trop Med Hyg, 1978 Jan;27(1 Pt 1):121-3.
    PMID: 415625
    Two communities of Orang Asli (aborigines) in Peninsular Malaysia were observed for evidence of Rickettsia tsutsugamushi infection over periods of 1-8 mo. Sequential sera were examined for antibody by the indirect immunofluorescence test. The incidence of infection in the two self-selected populations in the two communities was calculated to be 3.9% per month and 3.2% per month.
    Matched MeSH terms: Antibodies, Bacterial/analysis*
  6. Melioidosis antibodies in Commonwealth soldiers
    Thin RN
    Lancet, 1976 Jan 3;1(7949):31-3.
    PMID: 54528 DOI: 10.1016/s0140-6736(76)92922-6
    Titres of melioidosis haemagglutinating antibodies of 1/40 or more were found in 18 of 905 British, Australian, and New Zealand soldiers serving in West Malaysia. Previous mild unsuspected melioidosis seemed to be responsible for these positive titres, which were more common in men exposed to surface water at work and during recreation. This accords with the current view that soil and surface water is the normal habitat of Pseudomonas pseudomallei, the causal organism. Pyrexia of unknown origin after arriving in Malaysia was significantly more common in men with titres of 1/40 or more than in the remainder. It is suggested that mild melioidosis may present as pyrexia of unknown origin. Pyrexias of unknown origin should be investigated vigorously in patients who are in or who have visited endemic areas.
    Matched MeSH terms: Antibodies, Bacterial/isolation & purification*
  7. Scrub typhus: a common cause of illness in indigenous populations
    Brown GW, Robinson DM, Huxsoll DL, Ng TS, Lim KJ
    Trans R Soc Trop Med Hyg, 1976;70(5-6):444-8.
    PMID: 402722
    An explanation was sought for the disparity between the low reported incidence of scrub typhus and the high prevalence of antibody to Rickettsia tsutsugamushi in the rural population of Malaysia. A combination of isolation of the organism, titration of antibody by indirect immunofluorescence, and the Weil-Felix test was used to confirm infections. Scrub typhus was found to be very common, causing 23% of all febrile illnesses at one hospital. The infection was particularly prevalent in oil-palm workers, causing an estimated 400 cases annually in a population of 10,000 people living on one plantation. The clinical syndrome, whether mild or severe, was difficult to distinguish from that due to other infections. Eschars, rashes and adenopathy were uncommon. When used to examine early sera, the Weil-Felix test failed to confirm the diagnosis in most infections.20
    Matched MeSH terms: Antibodies, Bacterial/analysis
  8. Interactions of domain antibody (dAbκ11) with Mycobacterium tuberculosis Ac2SGL in complex with CD1b
    Law CT, Camacho F, Garcia-Alles LF, Gilleron M, Sarmiento ME, Norazmi MN, et al.
    Tuberculosis (Edinb), 2019 01;114:9-16.
    PMID: 30711162 DOI: 10.1016/j.tube.2018.11.002
    Tuberculosis (TB) is the main cause of mortality among all infectious diseases. The presentation of lipids by CD1b molecules and the interactions of the CD1b-lipid complexes with the immune receptors are important for the understanding of the immune response to Mycobacterium tuberculosis (Mtb), and to develop TB control methods. A specific domain antibody (dAbk11) recognizing the complex of CD1b with Mtb sulphoglycolipid (Ac2SGL) had been previously developed. In order to study the interactions of dAbk11 with Ac2SGL:CD1b, the conformation of Ac2SGL within CD1b was first modelled. The orientation of dAbκ11 with Ac2SGL:CD1b was then predicted by a docking experiment and the complex was sampled using molecular dynamics simulation. Data showed that dAbκ11 Tyr32 OH plays a decisive role in interacting with Ac2SGL alkyl tail HO17. The binding free energy calculation showed that Ac2SGL establish strong hydrophobic interactions with dAbκ11. The model also predicted a higher affinity for the natural sulfoglycolipid (Ac2SGL) than the synthetic analogue (SGL12), which was supported by the ELISA data. These results shed light on the likely mechanism of interactions between Ac2SGL:CD1b and dAbκ11, thus making possible to envision the strategies for dAbκ11 optimization for possible future applications.
    Matched MeSH terms: Antibodies, Bacterial/immunology
  9. Cellulitis in human brucellosis: An atypical presentation
    Subramaniam K, Ali SU
    Malays J Pathol, 2019 Dec;41(3):359-364.
    PMID: 31901923
    INTRODUCTION: Brucellosis is a zoonotic disease with variable clinical manifestations and atypical presentation in humans. Human brucellosis cases are not seen often in Malaysia.

    CASE REPORT: This is a case report of 19 years old gentleman who presented with fever, lower limb redness, pain and swelling. He was initially treated as cellulitis. However, based on the recovery of Brucella melitensis from his blood culture, he was later diagnosed to have brucellosis. He had a history of consumption of fresh goat's milk and uncooked meat which could have been the possible modes of transmission. Brucella serology IgM and IgG were both positive, and anti-Brucella immunocapture agglutination test (BrucellaCapt) was also positive with a titer of 1:2560. He was treated with six weeks of oral doxycycline 100 mg twice daily and oral rifampin 450 mg twice daily.

    DISCUSSION: This is a case of human brucellosis with atypical cutaneous involvement.

    Matched MeSH terms: Antibodies, Bacterial/therapeutic use
  10. Comparative evaluation of the indirect immunoperoxidase test for the serodiagnosis of rickettsial disease
    Kelly DJ, Wong PW, Gan E, Lewis GE
    Am J Trop Med Hyg, 1988 Mar;38(2):400-6.
    PMID: 3128129 DOI: 10.4269/ajtmh.1988.38.400
    An indirect immunoperoxidase test was compared with an indirect fluorescent antibody test and the Weil-Felix OXK test for serodiagnosis of scrub typhus by measuring the rickettsial antigen specific activity of IgG, IgM, and whole globulin. Acute and convalescent sera from 50 Rickettsia tsutsugamushi isolate-positive scrub typhus patients and from 45 febrile patients diagnosed as having diseases other than scrub typhus were tested. The receiver operating characteristic for each test showed that the indirect immunoperoxidase and indirect fluorescent antibody tests were more sensitive and specific than the Weil-Felix test using convalescent and acute as well as paired sera. The indirect immunoperoxidase test showed no cross-reactivity when R. tsutsugamushi antigen was tested against sera collected from patients living outside the scrub typhus-endemic area with diseases other than scrub typhus. The indirect immunoperoxidase and indirect fluorescent antibody tests were comparable in measured response to R. tsutsugamushi, R. typhi, and TT-118 (spotted fever group) antigen. Thus the indirect immunoperoxidase test represents a sensitive, specific, reproducible, and practical semiquantitative test for rickettsial disease diagnosis.
    Matched MeSH terms: Antibodies, Bacterial/analysis*
  11. Immune TB Antibody Phage Display Library as a Tool To Study B Cell Immunity in TB Infections
    Hamidon NH, Suraiya S, Sarmiento ME, Acosta A, Norazmi MN, Lim TS
    Appl Biochem Biotechnol, 2018 Mar;184(3):852-868.
    PMID: 28884285 DOI: 10.1007/s12010-017-2582-5
    B cells and in particular antibodies has always played second fiddle to cellular immunity in regard to tuberculosis (TB). However, recent studies has helped position humoral immunity especially antibodies back into the foray in relation to TB immunity. Therefore, the ability to correlate the natural antibody responses of infected individuals toward TB antigens would help strengthen this concept. Phage display is an intriguing approach that can be utilized to study antibody-mediated responses against a particular infection via harvesting the B cell repertoire from infected individuals. The development of disease-specific antibody libraries or immune libraries is useful to better understand antibody-mediated immune responses against specific disease antigens. This study describes the generation of an immune single-chain variable fragment (scFv) library derived from TB-infected individuals. The immune library with an estimated diversity of 109 independent clones was then applied for the identification of monoclonal antibodies against Mycobacterium tuberculosis α-crystalline as a model antigen. Biopanning of the library isolated three monoclonal antibodies with unique gene usage. This strengthens the role of antibodies in TB immunity in addition to the role played by cellular immunity. The developed library can be applied against other TB antigens and aid antibody-derived TB immunity studies in the future.
    Matched MeSH terms: Antibodies, Bacterial/immunology*
  12. Fulltext The increasing prevalence of endemic typhus in Kuala Lumpur and an evaluation of a diagnostic ELISA dot test for the detection of antibodies to Rickettsia typhi
    Sekhar WY, Devi S
    Singapore Med J, 2000 May;41(5):226-31.
    PMID: 11063173
    A seroepidemiology study was done in response to the recent increase of Endemic Typhus cases diagnosed at University Hospital. The serosurvey was based on doctors' request for the Weil Felix (WF) or the Indirect Immunoperoxidase (IIP) test in Pyrexia of Unknown Origin (PUO) patients for the years 1991 to 1997. Over the 7 years, we found that the incidence of Endemic typhus is increasing with gender (male:female = 2:1), age (20-40 years) and race distribution (Indians > Malay > Chinese) that reflects socioeconomic circumstances. A commercially available ELISA dot assay [INDX (E2R3) Dip-S-Ticks], for the detection of antibodies against R. typhi was compared with the indirect immunoperoxidase test (IIP). The ELISA assay was done against 219 IIP tested sera. The Dip-S-Ticks was found to be comparable to the IIP with a sensitivity of 91.7% and specificity of 92.8% at cut-off titres of > 1:80 IIP.
    Matched MeSH terms: Antibodies, Bacterial/analysis*
  13. A large exposure to Brucella melitensis in a diagnostic laboratory
    Sam IC, Karunakaran R, Kamarulzaman A, Ponnampalavanar S, Syed Omar SF, Ng KP, et al.
    J Hosp Infect, 2012 Apr;80(4):321-5.
    PMID: 22237130 DOI: 10.1016/j.jhin.2011.12.004
    Brucella species are easily transmitted by aerosols and can be acquired in the laboratory.
    Matched MeSH terms: Antibodies, Bacterial/blood
  14. An immunogenic epitope of Chlamydia pneumoniae from a random phage display peptide library is reactive with both monoclonal antibody and patients sera
    Naidu BR, Ngeow YF, Wang LF, Chan L, Yao ZJ, Pang T
    Immunol Lett, 1998 Jun;62(2):111-5.
    PMID: 9698107
    Random 15-mer peptides displayed on filamentous phages were screened in binding studies using a Chlamydia pneumoniae-specific monoclonal antibody (RR-402) and affinity-purified, polyclonal sera from patients seropositive for C. pneumoniae infections by the microimmunofluorescence (MIF) test. One 15-mer epitope, epitope Cpnl5A (LASLCNPKPSDAPVT) was identified in both the monoclonal and polyclonal screenings, and showed higher ELISA reactivity with C. pneumoniae MIF-positive sera compared to patients with other chlamydial infections, non-chlamydial respiratory infections and normal healthy sera (MIF-negative). Interestingly, epitope Cpnl5A also showed significant (52%) amino acid sequence homology to the 56 kDa type-specific antigen of Rickettsia tsutsugamushi, a protein implicated in the virulence of this organism.
    Matched MeSH terms: Antibodies, Bacterial/immunology*
  15. Fulltext Evaluation of Elecsys Syphilis Assay for Routine and Blood Screening and Detection of Early Infection
    Kremastinou J, Polymerou V, Lavranos D, Aranda Arrufat A, Harwood J, Martínez Lorenzo MJ, et al.
    J Clin Microbiol, 2016 09;54(9):2330-6.
    PMID: 27358468 DOI: 10.1128/JCM.02544-15
    Treponema pallidum infections can have severe complications if not diagnosed and treated at an early stage. Screening and diagnosis of syphilis require assays with high specificity and sensitivity. The Elecsys Syphilis assay is an automated treponemal immunoassay for the detection of antibodies against T. pallidum The performance of this assay was investigated previously in a multicenter study. The current study expands on that evaluation in a variety of diagnostic settings and patient populations, at seven independent laboratories. The samples included routine diagnostic samples, blood donation samples, samples from patients with confirmed HIV infections, samples from living organ or bone marrow donors, and banked samples, including samples previously confirmed as syphilis positive. This study also investigated the seroconversion sensitivity of the assay. With a total of 1,965 syphilis-negative routine diagnostic samples and 5,792 syphilis-negative samples collected from blood donations, the Elecsys Syphilis assay had specificity values of 99.85% and 99.86%, respectively. With 333 samples previously identified as syphilis positive, the sensitivity was 100% regardless of disease stage. The assay also showed 100% sensitivity and specificity with samples from 69 patients coinfected with HIV. The Elecsys Syphilis assay detected infection in the same bleed or earlier, compared with comparator assays, in a set of sequential samples from a patient with primary syphilis. In archived serial blood samples collected from 14 patients with direct diagnoses of primary syphilis, the Elecsys Syphilis assay detected T. pallidum antibodies for 3 patients for whom antibodies were not detected with the Architect Syphilis TP assay, indicating a trend for earlier detection of infection, which may have the potential to shorten the time between infection and reactive screening test results.
    Matched MeSH terms: Antibodies, Bacterial/blood
  16. Fulltext A randomised trial to evaluate the immunogenicity, reactogenicity, and safety of the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) co-administered with routine childhood vaccines in Singapore and Malaysia
    Lim FS, Koh MT, Tan KK, Chan PC, Chong CY, Shung Yehudi YW, et al.
    BMC Infect Dis, 2014;14:530.
    PMID: 25278086 DOI: 10.1186/1471-2334-14-530
    BACKGROUND: The immunogenicity, reactogenicity, and safety of the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV) co-administered with routine childhood vaccines were evaluated among infants from Singapore and Malaysia, where PHiD-CV has been licensed.
    METHODS: In the primary vaccination phase, 298 infants from Singapore and 168 infants from Malaysia were randomised to receive the Phase III Clinical (Clin) or the Commercial (Com) lot of PHiD-CV at 2, 3, and 5 months of age. In the booster vaccination phase, 238 toddlers from Singapore received one dose of the PHiD-CV Commercial lot at 18-21 months of age. Immune responses to pneumococcal polysaccharides were measured using 22F-inhibition enzyme-linked immunosorbent assay (ELISA) and functional opsonophagocytic activity (OPA) assay and to protein D, using ELISA.
    RESULTS: Immune responses induced by primary vaccination with the PHiD-CV Commercial lot were non-inferior to the Phase III Clinical lot in terms of adjusted antibody geometric mean concentration (GMC) ratios for each vaccine pneumococcal serotype and protein D. For each vaccine pneumococcal serotype, ≥93.6% and ≥88.5% of infants from Malaysia and Singapore had post-primary vaccination antibody concentrations ≥0.2 μg/mL and OPA titres ≥8, in the Clin and Com groups, respectively. For each vaccine pneumococcal serotype, ≥60.8% and ≥98.2% of toddlers from Singapore had pre- and post-booster antibody concentrations ≥0.2 μg/mL, in the Clin and Com groups, respectively. All children, except one, had measurable anti-protein D antibodies and the primary and booster doses of the co-administered vaccines were immunogenic. The incidence of each grade 3 solicited symptom was ≤11.1% in both study phases. No serious adverse events considered causally related to vaccination were reported throughout the study.
    CONCLUSIONS: PHiD-CV given as three-dose primary vaccination to infants in Singapore and Malaysia and booster vaccination to toddlers in Singapore was shown to be immunogenic with a clinically acceptable-safety profile.This study has been registered at http://www.clinicaltrials.govNCT00808444 and NCT01119625.
    Matched MeSH terms: Antibodies, Bacterial/blood; Antibodies, Bacterial/immunology
  17. A genome level survey of Burkholderia pseudomallei immunome expressed during human infection
    Su YC, Wan KL, Mohamed R, Nathan S
    Microbes Infect., 2008 Oct;10(12-13):1335-45.
    PMID: 18761419 DOI: 10.1016/j.micinf.2008.07.034
    Burkholderia pseudomallei is the etiological agent of melioidosis, a severe infectious disease of humans and animals. The role of the bacterium's proteins expressed in vivo during human melioidosis continues to remain an enigma. This study's aim was to identify B. pseudomallei target proteins that elicit the humoral immune response in infected humans. A small insert genomic expression library was constructed and immunoscreened to identify peptides that reacted exclusively with melioidosis patients' sera. Sero-positive clones expressing immunogenic peptides were sequenced and annotated, and shown to represent 109 proteins involved in bacterial cell envelope biogenesis, cell motility and secretion, transcription, amino acid, ion and protein metabolism, energy production, DNA repair and unknown hypothetical proteins. Western blot analysis of three randomly selected full-length immunogenic polypeptides with patients' sera verified the findings of the immunome screening. The patients' humoral immune response to the 109 proteins suggests the induction or significant upregulation of these proteins in vivo during human infection and thus may play a role in the pathogenesis of B. pseudomallei. Identification of B. pseudomallei immunogens has shed new light on the elucidation of the bacterium's pathogenesis mechanism and disease severity. These immunogens can be further evaluated as prophylactic and serodiagnostic candidates as well as drug targets.
    Matched MeSH terms: Antibodies, Bacterial/blood; Antibodies, Bacterial/immunology
  18. Phage display of recombinant antibodies toward Burkholderia pseudomallei exotoxin
    Nathan S, Li H, Mohamed R, Embi N
    J. Biochem. Mol. Biol. Biophys., 2002 Feb;6(1):45-53.
    PMID: 12186782
    We have used the phagemid pComb3H to construct recombinant phages displaying the single chain variable fragment (ScFv) towards exotoxin of Burkholderia pseudomallei. Variable heavy and light chain fragments were amplified from the hybridoma 6E6A8F3B line, with a wide spectrum of primers specific to mouse antibody genes. Through overlapping extension polymerase chain reaction, the heavy and light chain fragments were linked to form the ScFv which was subsequently cloned into the phage display vector and transformed into ER2537 cells to yield a complexity of 10(8) clones. The transformants were screened by four rounds of biopanning against the exotoxin and resulted in selective enrichment of exotoxin-binding antibodies by 301 fold. The phage pool from the final round of selection displayed antibodies of high-affinity to the exotoxin as demonstrated by ELISA. Several clones were selected randomly from this pool and analysed by restriction enzyme digestion, fingerprinting and sequencing. Restriction analysis confirmed that all clones carried a 700-800 bp insert whose sequences, in general, corresponded to that of mouse IgG. Fingerprinting profiles delineated the antibodies into two families with different CDR sequences.
    Matched MeSH terms: Antibodies, Bacterial/genetics*; Antibodies, Bacterial/immunology
  19. Immunogenicity of purified lipopolysaccharide or protein-oligosaccharide conjugates of Pasteurella multocida type 6:B in mice
    Muniandy N, Love DN, Mukkur TK
    Comp Immunol Microbiol Infect Dis, 1998 Oct;21(4):257-79.
    PMID: 9775357
    Purified lipopolysaccharide (LPS) of Pasteurella multocida type 6:B, while toxic at higher doses, was protective at lower dose levels against experimentally-induced pasteurellosis in mice. However, the observed protection was abrogated if such LPS was digested with proteinase K prior to use in immunisation. The O-antigen polysaccharide side-chain (OS) of LPS did not appear to contribute to the observed protection as judged by the fact that immunisation of mice with purified OS or OS-protein conjugates, all of which were nontoxic, failed to confer protection against challenge with homologous virulent organisms. This was despite generation of significant levels of OS-specific antibodies, predominantly either of the IgM or IgG isotypes, in immunised mice.
    Matched MeSH terms: Antibodies, Bacterial/biosynthesis; Antibodies, Bacterial/immunology
  20. Fulltext Delineation of B-cell Epitopes of Salmonella enterica serovar Typhi Hemolysin E: Potential antibody therapeutic target
    Chin CF, Lai JY, Choong YS, Anthony AA, Ismail A, Lim TS
    Sci Rep, 2017 05 19;7(1):2176.
    PMID: 28526816 DOI: 10.1038/s41598-017-01987-8
    Hemolysin E (HlyE) is an immunogenic novel pore-forming toxin involved in the pathogenesis of typhoid fever. Thus, mapping of B-cell epitopes of Salmonella enterica serovar Typhi (S. Typhi) is critical to identify key immunogenic regions of HlyE. A random 20-mer peptide library was used for biopanning with enriched anti-HlyE polyclonal antibodies from typhoid patient sera. Bioinformatic tools were used to refine, analyze and map the enriched peptide sequences against the protein to identify the epitopes. The analysis identified both linear and conformational epitopes on the HlyE protein. The predicted linear GAAAGIVAG and conformational epitope PYSQESVLSADSQNQK were further validated against the pooled sera. The identified epitopes were then used to isolate epitope specific monoclonal antibodies by antibody phage display. Monoclonal scFv antibodies were enriched for both linear and conformational epitopes. Molecular docking was performed to elucidate the antigen-antibody interaction of the monoclonal antibodies against the epitopes on the HlyE monomer and oligomer structure. An in-depth view of the mechanistic and positional characteristics of the antibodies and epitope for HlyE was successfully accomplished by a combination of phage display and bioinformatic analysis. The predicted function and structure of the antibodies highlights the possibility of utilizing the antibodies as neutralizing agents for typhoid fever.
    Matched MeSH terms: Antibodies, Bacterial/immunology; Antibodies, Bacterial/chemistry
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