Displaying publications 1 - 20 of 116 in total

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  1. Zueter AM, Mohamed Z, Abdullah AD, Mohamad N, Arifin N, Othman N, et al.
    Singapore Med J, 2014 Jul;55(7):367-71.
    PMID: 25091885
    INTRODUCTION: Strongyloidiasis is one of the most commonly neglected but clinically important parasitic infections worldwide, especially among immunocompromised patients. Evidence of infection among immunocompromised patients in Malaysia is, however, lacking. In this study, microscopy, real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assays (ELISAs) were used to detect Strongyloides stercoralis (S. stercoralis) infection among cancer patients in a Malaysian hospital.

    METHODS: A total of 192 stool and serum samples were collected from cancer patients who were receiving chemotherapy with or without steroid treatment at a hospital in northeastern Malaysia. Stool samples were examined for S. stercoralis using parasitological methods and real-time PCR. Serology by ELISA was performed to detect parasite-specific immunoglobulin G (IgG), IgG4 and immunoglobulin E (IgE) antibodies. For comparison, IgG4- and IgG-ELISAs were also performed on the sera of 150 healthy individuals from the same area.

    RESULTS: Of the 192 samples examined, 1 (0.5%) sample was positive for S. stercoralis by microscopy, 3 (1.6%) by real-time PCR, 8 (4.2%) by IgG-ELISA, 6 (3.1%) by IgG4-ELISA, and none was positive by IgE-ELISA. In comparison, healthy blood donors had significantly lower prevalence of parasite-specific IgG (2.67%, p < 0.05) and IgG4 (2.67%, p < 0.05) responses.

    CONCLUSION: This study showed that laboratory testing may be considered as a diagnostic investigation for S. stercoralis among immunocompromised cancer patients.
  2. Zainudin NS, Othman N, Muhi J, Abdu Sani AA, Noordin R
    Am J Trop Med Hyg, 2015 Dec;93(6):1268-73.
    PMID: 26392156 DOI: 10.4269/ajtmh.15-0333
    This study was performed to identify circulating Plasmodium falciparum proteins in patient serum, which may be useful as diagnostic markers. Depletion of highly abundant proteins from each pooled serum sample obtained from P. falciparum-infected patients and healthy individuals was performed using the Proteoseek Antibody-Based Albumin/IgG Removal Kit (Thermo Scientific, Rockford, IL). In analysis 1, the depleted serum was analyzed directly by NanoLC-MS/MS. In analysis 2, the depleted serum was separated by two-dimensional electrophoresis followed by western blot analysis. Subsequently, the selected band was analyzed by NanoLC-MS/MS. The result of analysis 1 revealed the presence of two mature erythrocyte surface antigen (MESA) proteins and chloroquine resistance transporter protein (PfCRT). In addition, analysis 2 revealed an antigenic 75-kDa band when the membrane was probed with purified IgG from the pooled serum obtained from P. falciparum-infected patients. MS/MS analysis of this protein band revealed fragments of P. falciparum MESA proteins. Thus, in this study, two different analyses revealed the presence of Plasmodium MESA protein in pooled serum from malaria patients; thus, this protein should be further investigated to determine its usefulness as a diagnostic marker.
  3. Zahabiun F, Sadjjadi SM, Yunus MH, Rahumatullah A, Moghaddam MH, Saidin S, et al.
    Am J Trop Med Hyg, 2015 Aug;93(2):319-25.
    PMID: 26033026 DOI: 10.4269/ajtmh.15-0190
    Toxocariasis is a cosmopolitan zoonotic disease caused by the infective larvae of Toxocara canis and T. cati. Diagnosis in humans is usually based on clinical symptoms and serology. Immunoglobulin G (IgG)-enzyme-linked immunosorbent assay kits using T. canis excretory-secretory (TES) larval antigens are commonly used for serodiagnosis. Differences in the antigens of the two Toxocara species may influence the diagnostic sensitivity of the test. In this study, T. cati recombinant TES-120 (rTES-120) was cloned, expressed, and compared with its T. canis homolog in an IgG4-western blot. The diagnostic sensitivity and specificity of T. cati rTES-120 were 70% (33/47) and 100% (39/39), respectively. T. canis rTES-120 showed 57.4% sensitivity and 94.4% specificity. When the results of assays using rTES-120 of both species were considered, the diagnostic sensitivity was 76%. This study shows that using antigens from both Toxocara species may improve the serodiagnosis of toxocariasis.
  4. Yunus MH, Arifin N, Balachandra D, Anuar NS, Noordin R
    Am J Trop Med Hyg, 2019 08;101(2):432-435.
    PMID: 31218996 DOI: 10.4269/ajtmh.19-0053
    The conventional method of detecting Strongyloides stercoralis in fecal samples has poor diagnostic sensitivity. Detection of Strongyloides-specific antibodies increases the sensitivity; however, most tests are ELISAs that use parasite extract which may cross-react with the sera of other helminth infections. To improve the serological diagnosis of strongyloidiasis, this study aimed at developing a sensitive and specific lateral flow rapid dipstick test. Two recombinant proteins, recombinant NIE (rNIE) and recombinant Ss1a (rSs1a), were used in preparing the dipstick, with gold-conjugated antihuman IgG4 as detector reagent. In parallel, the corresponding ELISA was performed. Both assays demonstrated diagnostic sensitivity of 91.3% (21/23) when tested with serum samples of patients with Strongyloides infection, and 100% specificity with 82 sera of asymptomatic (healthy) and those with other parasitic infections. The ELISA and dipstick test results were positively correlated to each other (r = 0.6114, P = 0.0019). The developed lateral flow dipstick test may improve the serodiagnosis of strongyloidiasis and merit further validation studies.
  5. Yunus MH, Tan Farrizam SN, Abdul Karim IZ, Noordin R
    Am J Trop Med Hyg, 2018 Jan;98(1):32-38.
    PMID: 29141740 DOI: 10.4269/ajtmh.17-0632
    Laboratory diagnosis of toxocariasis is still a challenge especially in developing endemic countries with polyparasitism. In this study, three Toxocara canis recombinant antigens, rTES-26, rTES-30, and rTES-120, were expressed and used to prepare lateral flow immunoglobulin G4 (IgG4) dipsticks. The concordance of the results of the rapid test (comprising three dipsticks) with a commercial IgG-enzyme-linked immunosorbent assay (ELISA) (Cypress Diagnostics, Belgium) was compared against the concordance of two other commercial IgG-ELISA kits (Bordier, Switzerland and NovaTec, Germany) with the Cypress kit. Using Toxocara-positive samples, the concordance of the dipstick dotted with rTES-26, rTES-30, and rTES-120 was 41.4% (12/29), 51.7% (15/29), and 72.4% (21/29), respectively. When positivity with any dipstick was considered as an overall positive rapid test result, the concordance with the Cypress kit was 93% (27/29). Meanwhile, when compared with the results of the Cypress kit, the concordance of IgG-ELISA from NovaTec and Bordier was 100% (29/29) and 89.7% (26/29), respectively. Specific IgG4 has been recognized as a marker of active infection for several helminthic diseases; therefore, the two non-concordant results of the rapid test when compared with the NovaTec IgG-ELISA kit may be from samples of people with non-active infection. All the three dipsticks showed 100% (50/50) concordance with the Cypress kit when tested with serum from individuals who were healthy and with other infections. In conclusion, the lateral flow rapid test is potentially a good, fast, and easy test for toxocariasis. Next, further validation studies and development of a test with the three antigens in one dipstick will be performed.
  6. Yogarajah T, Bee YT, Noordin R, Yin KB
    Mol Med Rep, 2015 Jan;11(1):515-20.
    PMID: 25324014 DOI: 10.3892/mmr.2014.2686
    This study was conducted to determine the mRNA and protein expression levels of peroxisome proliferator-activated receptors (PPARs) in visceral adipose tissue, as well as serum adipokine levels, in Sprague Dawley rats. The rats were fed either a normal (control rats) or excessive (experimental rats) intake of food for 8 or 16 weeks, then sacrificed, at which time visceral and subcutaneous adipose tissues, as well as blood samples, were collected. The mRNA and protein expression levels of PPARs in the visceral adipose tissues were determined using reverse transcription-polymerase chain reaction and Western blotting, respectively. In addition, the levels of adipokines in the serum samples were determined using commercial ELISA kits. The results revealed that at 8 weeks, the mass of subcutaneous adipose tissue was higher than that of the visceral adipose tissue in the experimental rats, but the reverse occurred at 16 weeks. Furthermore, at 16 weeks the experimental rats exhibited an upregulation of PPARγ mRNA and protein expression levels in the visceral adipose tissues, and significant increases in the serum levels of CCL2 and interleukin (IL)-6 were observed, compared with those measured at 8 weeks. In conclusion, this study demonstrated that the PPARγ expression level was likely correlated with serum levels of CCL2 and IL-6, molecules that may facilitate visceral adipose tissue accumulation. In addition, the levels of the two adipokines in the serum may be useful as surrogate biomarkers for the expression levels of PPARγ in accumulated visceral adipose tissues.
  7. Yeng C, Osman E, Mohamed Z, Noordin R
    Electrophoresis, 2010 Dec;31(23-24):3843-9.
    PMID: 21080484 DOI: 10.1002/elps.201000038
    Toxoplasma gondii infection in pregnant women may result in abortion and foetal abnormalities, and may be life-threatening in immunocompromised hosts. To identify the potential infection markers of this disease, 2-DE and Western blot methods were employed to study the parasite circulating antigens and host-specific proteins in the sera of T. gondii-infected individuals. The comparisons were made between serum protein profiles of infected (n=31) and normal (n=10) subjects. Antigenic proteins were identified by immunoblotting using pooled sera and monoclonal anti-human IgM-HRP. Selected protein spots were characterised using mass spectrometry. Prominent differences were observed when serum samples of T. gondii-infected individuals and normal controls were compared. A significant up-regulation of host-specific proteins, α(2)-HS glycoprotein and α(1)-B glycoprotein, was also observed in the silver-stained gels of both active and chronic infections. However, only α(2)-HS glycoprotein and α(1)-B glycoprotein in the active infection showed immunoreactivity in Western blots. In addition, three spots of T. gondii proteins were detected, namely (i) hypothetical protein chrXII: 3984434-3 TGME 49, (ii) dual specificity protein phosphatase, catalytic domain TGME 49 and (iii) NADPH-cytochrome p450 reductase TGME 49. Thus, 2-DE approach followed by Western blotting has enabled the identification of five potential infection markers for the diagnosis of toxoplasmosis: three are parasite-specific proteins and two are host-specific proteins.
  8. Yahaya ML, Zakaria ND, Noordin R, Abdul Razak K
    Biotechnol Appl Biochem, 2021 Oct;68(5):1095-1106.
    PMID: 32935878 DOI: 10.1002/bab.2029
    Salmonella and Shigella genera are common pathogens that contaminate foods and beverages. Lateral flow assays (LFA) are commonly used to detect these pathogens. However, most of the developed LFAs are for single detection. Simultaneous detection of pathogens is required to reduce cost and time. In this work, 40 nm gold nanoparticles (AuNPs) were synthesized using the seeding growth method as labeling agent. The AuNPs were characterized and conjugated with mouse anti-Gram negative endotoxin antibody. The nitrocellulose membrane HF135 was immobilized with anti-mouse IgG antibody as a control line and two separate test lines with either anti-Shigella or anti-Salmonella antibody, respectively. Color intensity of test lines was observed for positive samples. A milk sample was used as proof of concept to mimic actual contamination. The limit of detection of the LFA was 3.0 × 106 CFU/mL for multiplex detection of Shigella flexneri and Salmonella Typhi and for both single detections. The result was comparable with the enzyme-linked immunosorbent assay (ELISA) analysis. The produced LFA could differentiate between Shigella flexneri, Shigella boydii, Salmonella Enteritidis, and Salmonella Typhi. The developed LFA was able to identify Shigella flexneri and Salmonella Typhi with good sensitivity in milk samples, thus, beneficial to ensure the safety of food before entering the market.
  9. Wongphutorn P, Noordin R, Anuar NS, Worasith C, Kopolrat KY, Homwong C, et al.
    Am J Trop Med Hyg, 2024 Feb 07;110(2):254-262.
    PMID: 38190756 DOI: 10.4269/ajtmh.23-0518
    Strongyloidiasis, caused by Strongyloides stercoralis, is a neglected tropical disease with a global distribution. The infection can be fatal in immunocompromised individuals, and accurate diagnosis leading to timely treatment can save lives. Serodiagnosis is a sensitive method for diagnosis and is recommended for screening high-risk individuals. A point-of-care rapid test will facilitate the screening activities, especially in low-resource settings. This study aims to apply a new IgG4 immunochromatographic test using S. stercoralis recombinant antigen (SsRapid® cassette test) and to compare it with in-house IgG and IgG4 enzyme-linked immunosorbent assays (IgG- and IgG4-ELISAs) using native Strongyloides ratti antigen to investigate the epidemiology of strongyloidiasis in northeast Thailand. A total of 300 people participated, with 136 males and 164 females of a similar mean age. The reference tests were fecal examinations using the formalin-ethyl acetate concentration technique and an agar plate culture technique. The prevalence of S. stercoralis determined by SsRapid (81.7%) was significantly higher than that by fecal examinations (43.3%) or by antibody detection by IgG-ELISA (53.0%) or IgG4-ELISA (44.0%). The diagnostic sensitivities of SsRapid, IgG-ELISA, and IgG4-ELISA were found to be 93.9%, 77.7%, and 63.1%, respectively. The rate of positive tests by the SsRapid was significantly correlated to the levels of Strongyloides-specific IgG4 and IgG antibodies. By all diagnostic methods, male participants had a significantly higher prevalence of strongyloidiasis than females. Age was significantly associated with the concentration of specific serum IgG but not with the SsRapid grading score. In conclusion, SsRapid was shown to be a sensitive and valuable diagnostic test for the epidemiology study of strongyloidiasis.
  10. Wong WK, Tan ZN, Othman N, Lim BH, Mohamed Z, Olivos Garcia A, et al.
    Clin. Vaccine Immunol., 2011 Nov;18(11):1913-7.
    PMID: 21918120 DOI: 10.1128/CVI.05356-11
    Serodiagnosis of amoebiasis remains the preferred method for diagnosis of amoebic liver abscess (ALA). However, the commercially available kits are problematic in areas of endemicity due to the persistently high background antibody titers. Human serum samples (n = 38) from patients with ALA who live in areas of endemicity were collected from Hospital Universiti Sains Malaysia during the period of 2008 to 2010. Western blots using excretory-secretory antigen (ESA) collected from axenically grown Entamoeba histolytica were probed with the above serum samples. Seven antigenic proteins of ESA with various reactivities were identified, i.e., 152 kDa, 131 kDa, 123 kDa, 110 kDa, 100 kDa, 82 kDa, and 76 kDa. However, only the 152-kDa and 110-kDa proteins showed sensitivities above 80% in the Western blot analysis. All the antigenic proteins showed undetectable cross-reactivity when probed with healthy human serum samples (n = 30) and serum samples from other infections (n = 33). From the matrix-assisted laser desorption ionization-two-stage time of flight (MALDI-TOF/TOF) analysis, the proteins were identified as heavy subunits of E. histolytica lectin and E. histolytica pyruvate phosphate dikinase, respectively. Use of the E. histolytica lectin for diagnosis of ALA has been well reported by researchers and is being used in commercialized kits. However, this is the first report on the potential use of pyruvate phosphate dikinase for diagnosis of ALA; thus, this molecule merits further evaluation on its diagnostic value using a larger panel of serum samples.
  11. Wong WK, Tan ZN, Lim BH, Mohamed Z, Olivos-Garcia A, Noordin R
    Parasitol Res, 2011 Feb;108(2):425-30.
    PMID: 20922423 DOI: 10.1007/s00436-010-2083-8
    Entamoeba histolytica is the etiologic agent for amoebiasis. The excretory-secretory (ES) products of the trophozoites contain virulence factors and antigens useful for diagnostic applications. Contaminants from serum supplements and dead trophozoites impede analysis of ES. Therefore, a protein-free medium that can sustain maximum viability of E. histolytica trophozoites for the longest time duration will enable collection of contaminant-free and higher yield of ES products. In the present study, we compared the efficacy of four types of media in maintaining ≥ 95% trophozoite viability namely Roswell Memorial Park Institute (RPMI-1640), Dulbecco's Modified Eagle Medium (DMEM), phosphate-buffered saline for amoeba (PBS-A), and Hank's balanced salt solution (HBSS). Concurrently, the effect of adding L: -cysteine and ascorbic acid (C&A) to each medium on the parasite viability was also compared. DMEM and RPMI 1640 showed higher viabilities as compared to PBS-A and HBSS. Only RPMI 1640 showed no statistical difference with the control medium for the first 4 h, however the ≥ 95% viability was only maintained for the first 2 h. The other protein-free media showed differences from the serum- and vitamin-free TYI-S-33 control media even after 1 h of incubation. When supplemented with C&A, all media were found to sustain higher trophozoite viabilities than those without the supplements. HBSS-C&A, DMEM-C&A, and RPMI 1640-C&A demonstrated no difference (P>0.05) in parasite viabilities when compared with the control medium throughout the 8-h incubation period. DMEM-C&A showed an eightfold increment in time duration of sustaining ≥ 95% parasite viability, i.e. 8 h, as compared to DMEM alone. Both RPMI 1640-C&A and HBSS-C&A revealed fourfold and threefold increments (i.e., 8 and 6 h, respectively), whereas PBS-A-C&A showed only one fold improvement (i.e., 2 h) as compared to the respective media without C&A. Thus, C&A-supplemented DMEM or RPMI are recommended for collection of ES products.
  12. Wong WK, Mohd-Nor N, Noordin R, Foo PC, Mohamed Z, Haq JA, et al.
    Parasitol Res, 2019 Sep;118(9):2635-2642.
    PMID: 31363922 DOI: 10.1007/s00436-019-06406-7
    The geographical distribution of tuberculosis (TB) overlaps with various parasitic infections. Uncovering the characteristics of coinfecting parasites that potentially affect the host susceptibility to TB is pertinent as it may provide input to current TB therapeutic and prophylactic measures. The present study was aimed at examining the types of parasitic infections in TB patients and healthy TB contacts (HC) in Orang Asli, Malaysian aborigines, who dwelled in the co-endemic areas. Stool and serum samples were collected from Orang Asli who fulfilled the selection criteria and provided written informed consents. Selected parasitic infections in the two study groups were determined by stool examination and commercial serum antibody immunoassays. The prevalence of parasitic infections in TB and HC participants were 100% (n = 82) and 94.6% (n = 55) respectively. The parasitic infections comprised toxocariasis, trichuriasis, amoebiasis, toxoplasmosis, hookworm infection, ascariasis, strongyloidiasis, and brugian filariasis, in decreasing order of prevalence. Overall, helminth or protozoa infection did not show any significant association with the study groups. However, when the species of the parasite was considered, individuals exposed to trichuriasis and toxoplasmosis showed significant odds reduction (odds ratio (OR) 0.338; 95% confidence interval (CI) 0.166, 0.688) and odds increment (OR 2.193; 95% CI 1.051, 4.576) to have active pulmonary TB, respectively. In conclusion, trichuriasis and toxoplasmosis may have distinct negative and positive associations respectively with the increase of host susceptibility to TB.
  13. Wong WK, Foo PC, Olivos-Garcia A, Noordin R, Mohamed Z, Othman N, et al.
    Acta Trop, 2017 Aug;172:208-212.
    PMID: 28506795 DOI: 10.1016/j.actatropica.2017.05.017
    Crude soluble antigen (CSA) produced from Entamoeba histolytica trophozoite is conventionally used for serodiagnosis of invasive amoebiasis. However, high background seropositivities by CSA-assay in endemic areas complicate the interpretation of positive result in clinical settings. Instead, incorporating a second assay which indicates active or recent infection into the routine amoebic serology could possibly complement the limitations of CSA-assay. Hence, the present study aimed to evaluate the diagnostic efficacies of indirect ELISAs using CSA and excretory-secretory antigen (ESA) for serodiagnosis of amoebic liver abscess (ALA). Reference standard for diagnosis of ALA at Hospital Universiti Sains Malaysia is based on clinical presentation, radiological imaging and positive indirect haemagglutination assay (titer ≥256). Five groups of human serum samples collected from the hospital included Group I - ALA diagnosed by the reference standard and pus aspirate analysis using real-time PCR (n=10), Group II - ALA diagnosed by the reference standard only (n=41), Group III - healthy control (n=45), Group IV - other diseases control (n=51) and Group V - other infectious diseases control (n=31). For serodiagnosis of ALA serum samples (Group I and II), CSA-ELISA showed sensitivities of 100% for both groups, while ESA-ELISA showed sensitivities of 100% and 88%, respectively. For serodiagnosis of non-ALA serum samples (Group III, IV and V), CSA-ELISA showed specificities of 91%, 75% and 100%, respectively; while ESA-ELISA showed specificities of 96%, 98% and 100%, respectively. Indirect ELISAs using CSA and ESA have shown distinct strength for serodiagnosis of ALA, in terms of sensitivity and specificity, respectively. In conclusion, parallel analysis by both assays improved the overall efficacies of amoebic serology as compared to either single assay.
  14. Wong MTJ, Anuar NS, Noordin R, Tye GJ
    Acta Trop, 2023 Mar;239:106796.
    PMID: 36586174 DOI: 10.1016/j.actatropica.2022.106796
    It has been tested and proven that vaccination is still the best strategy to combat infectious diseases. However, to date, there are still no vaccines against human soil-transmitted helminthic diseases, despite their high prevalence globally, particularly in developing countries and rural areas with tropical climates and poor sanitation. The development of vaccines against helminths is riddled with obstacles. Helminths have a complex life cycle, multiple stages within the same host with stage-specific antigen expression, and the ability to regulate host immune reactions to evade the immune response. These elements contribute to the main challenge of helminthic vaccines: the identification of effective vaccine candidates. Therefore, this article reviews the current progress and potential future direction of soil-transmitted helminthic vaccines, particularly against Trichuris trichiura, Ascaris lumbricoides, Strongyloides stercoralis, Necator americanus and Ancylostoma duodenale. The study design employed was a systematic review, using qualitative meta-summary synthesis. Preclinical studies and clinical trials on the development of protein subunit vaccines against the five soil-transmitted helminths were searched on PubMed and Scopus. Effectiveness was indicated by a reduction in worm burden or larval output, an increase in specific IgG levels, or an increase in cytokine production. Our findings show that only the hookworm vaccine against N. americanus is in the clinical trial phase, while the rest is still in exploratory research and pre-clinical development phase.
  15. Wong MTJ, Anuar NS, Noordin R, Tye GJ
    Acta Trop, 2024 Mar;251:107122.
    PMID: 38246399 DOI: 10.1016/j.actatropica.2024.107122
    Strongyloidiasis, caused by the nematode Strongyloides stercoralis, remains a threat to global public health, and a vaccine would be useful to control the disease, especially in developing countries. This study aimed to evaluate the efficacy of recombinant proteins, A133 and Ss-IR, as potential vaccine candidates against strongyloidiasis by investigating the humoral and cellular immune responses in immunized mice. Respective antigens were adjuvanted with Complete Freund's Adjuvant (prime) and Incomplete Freund's Adjuvant (boost) and administered intraperitoneally (prime) and subcutaneously (boost) to female BALB/c mice. For antigen-only doses, only antigens were injected without adjuvants. Altogether, 1 prime dose, 4 booster doses, and 2 antigen-only doses were administered successively. ELISAs were conducted to assess the antibody responses, along with flow cytometry and cytokine ELISA to elucidate the cellular immune responses. Results showed that A133 and Ss-IR induced the production of IgG1 and IgG2a, with A133 generating more robust IgG2a responses than Ss-IR. Flow cytometry findings indicated that effector CD8+T-cells and memory B-cells activity were upregulated significantly for A133 only, whereas cytokine ELISA demonstrated that a Th1/Th2/Th17 mixed cell responses were triggered upon vaccination with either antigen. This preliminary study illustrated the good potential of recombinant A133 and Ss-IR as vaccine candidates against S. stercoralis. It provided information on the probable immune mechanism involved in host defence and the elicitation of protection against S. stercoralis.
  16. Won KY, Gass K, Biamonte M, Dagne DA, Ducker C, Hanna C, et al.
    PLoS Negl Trop Dis, 2021 11;15(11):e0009968.
    PMID: 34780503 DOI: 10.1371/journal.pntd.0009968
    As lymphatic filariasis (LF) programs move closer to established targets for validation elimination of LF as a public health problem, diagnostic tools capable of supporting the needs of the programs are critical for success. Known limitations of existing diagnostic tools make it challenging to have confidence that program endpoints have been achieved. In 2019, the World Health Organization (WHO) established a Diagnostic Technical Advisory Group (DTAG) for Neglected Tropical Diseases tasked with prioritizing diagnostic needs including defining use-cases and target product profiles (TPPs) for needed tools. Subsequently, disease-specific DTAG subgroups, including one focused on LF, were established to develop TPPs and use-case analyses to be used by product developers. Here, we describe the development of two priority TPPs for LF diagnostics needed for making decisions for stopping mass drug administration (MDA) of a triple drug regimen and surveillance. Utilizing the WHO core TPP development process as the framework, the LF subgroup convened to discuss and determine attributes required for each use case. TPPs considered the following parameters: product use, design, performance, product configuration and cost, and access and equity. Version 1.0 TPPs for two use cases were published by WHO on 12 March 2021 within the WHO Global Observatory on Health Research and Development. A common TPP characteristic that emerged in both use cases was the need to identify new biomarkers that would allow for greater precision in program delivery. As LF diagnostic tests are rarely used for individual clinical diagnosis, it became apparent that reliance on population-based surveys for decision making requires consideration of test performance in the context of such surveys. In low prevalence settings, the number of false positive test results may lead to unnecessary continuation or resumption of MDA, thus wasting valuable resources and time. Therefore, highly specific diagnostic tools are paramount when used to measure low thresholds. The TPP process brought to the forefront the importance of linking use case, program platform and diagnostic performance characteristics when defining required criteria for diagnostic tools.
  17. Vola A, Tamarozzi F, Noordin R, Yunus MH, Khanbabaie S, De Silvestri A, et al.
    Diagn Microbiol Infect Dis, 2018 Sep;92(1):31-33.
    PMID: 29776711 DOI: 10.1016/j.diagmicrobio.2018.04.007
    Rapid diagnostic tests for cystic echinococcosis (CE) are convenient to support ultrasound diagnosis in uncertain cases, especially in resource-limited settings. We found comparable diagnostic performances of the experimental Hyd Rapid Test and the commercial VIRapid HYDATIDOSIS Test, used in our diagnostic laboratory, using samples from well-characterized hepatic CE cases.
  18. Ujang J, Sani AAA, Lim BH, Noordin R, Othman N
    Proteomics, 2018 12;18(23):e1700397.
    PMID: 30284757 DOI: 10.1002/pmic.201700397
    Entamoeba histolytica membrane proteins are important players toward the pathogenesis of amoebiasis, but the roles of most of the proteins are not fully understood. Since efficient protein extraction method is crucial for a successful MS analysis, three extractions methods are evaluated for the use in studying the membrane proteome of E. histolytica: Two commercial kits (ProteoExtract from Calbiochem and ProteoPrep from Sigma), and a conventional laboratory method. The results show that ProteoExtract and the conventional method gave higher protein yields compared to ProteoPrep. LC-ESI-MS/MS identifies 456, 482, and 551 membrane fraction proteins extracted using ProteoExtract, ProteoPrep, and a conventional method, respectively. In silico analysis predicts 108 (21%), 235 (45%), and 177 (34%) membrane proteins from the extracts of ProteoExtract, ProteoPrep, and the conventional method, respectively. Furthermore, analysis of the cytosolic and membrane fractions shows the highest selectivity of the membrane proteins using the ProteoPrep extraction kit. Overall, this study reports 828 E. histolytica membrane fraction proteins that include 249 predicted membrane proteins. The data are available via ProteomeXchange with identifier PXD010171.
  19. Tommy YB, Lim TS, Noordin R, Saadatnia G, Choong YS
    BMC Struct Biol, 2012 Nov 27;12:30.
    PMID: 23181504 DOI: 10.1186/1472-6807-12-30
    BACKGROUND: Toxoplasma gondii is an intracellular coccidian parasite that causes toxoplasmosis. It was estimated that more than one third of the world population is infected by T. gondii, and the disease is critical in fetuses and immunosuppressed patients. Thus, early detection is crucial for disease diagnosis and therapy. However, the current available toxoplasmosis diagnostic tests vary in their accuracy and the better ones are costly.

    RESULTS: An earlier published work discovered a highly antigenic 12 kDa excretory-secretory (ES) protein of T. gondii which may potentially be used for the development of an antigen detection test for toxoplasmosis. However, the three-dimensional structure of the protein is unknown. Since epitope identification is important prior to designing of a specific antibody for an antigen-detection based diagnostic test, the structural elucidation of this protein is essential. In this study, we constructed a three dimensional model of the 12 kDa ES protein. The built structure possesses a thioredoxin backbone which consists of four α-helices flanking five β-strands at the center. Three potential epitopes (6-8 residues) which can be combined into one "single" epitope have been identified from the built structure as the most potential antibody binding site.

    CONCLUSION: Together with specific antibody design, this work could contribute towards future development of an antigen detection test for toxoplasmosis.

  20. Teh AY, Amerizadeh A, Osman S, Yunus MH, Noordin R
    Pathog Glob Health, 2016 Oct-Dec;110(7-8):277-286.
    PMID: 27697019
    The IgG avidity assay is an important tool in the management of suspected toxoplasmosis in pregnant women. This study aimed to produce new Toxoplasma gondii recombinant proteins and to assess their usefulness in an IgG avidity assay. Toxoplasma positive and negative serum samples were used, the former were categorized into low (LGA) and high (HGA) IgG avidity samples. Immunoblots were performed on 30 T. gondii cDNA clones to determine the reactivity and IgG avidity to the expressed proteins. Two of the clones were found to have diagnostic potential and were analyzed further; AG12b encoded T. gondii apical complex lysine methyltransferase (AKMT) protein and AG18 encoded T. gondii forkhead-associated (FHA) domain-containing protein. The His-tagged recombinant proteins, rAG12b and rAG18, were expressed and tested with LGA and HGA samples using an IgG avidity western blot and ELISA. With the IgG avidity western blot, rAG12b identified 86.4% of LGA and 90.9% of HGA samples, whereas rAG18 identified 81.8% of both LGA and HGA samples. With the IgG avidity ELISA, rAG12b identified 86.4% of both LGA and HGA samples, whereas rAG18 identified 77.3% of LGA and 86.4% of HGA serum samples. This study showed that the recombinant antigens were able to differentiate low avidity and high avidity serum samples, suggesting that they are potential candidates for use in the Toxoplasma IgG avidity assay.
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