Displaying publications 1 - 20 of 66 in total

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  1. Thiha A, Ibrahim F
    Sensors (Basel), 2015;15(5):11431-41.
    PMID: 25993517 DOI: 10.3390/s150511431
    The enzyme-linked Immunosorbent Assay (ELISA) is the gold standard clinical diagnostic tool for the detection and quantification of protein biomarkers. However, conventional ELISA tests have drawbacks in their requirement of time, expensive equipment and expertise for operation. Hence, for the purpose of rapid, high throughput screening and point-of-care diagnosis, researchers are miniaturizing sandwich ELISA procedures on Lab-on-a-Chip and Lab-on-Compact Disc (LOCD) platforms. This paper presents a novel integrated device to detect and interpret the ELISA test results on a LOCD platform. The system applies absorption spectrophotometry to measure the absorbance (optical density) of the sample using a monochromatic light source and optical sensor. The device performs automated analysis of the results and presents absorbance values and diagnostic test results via a graphical display or via Bluetooth to a smartphone platform which also acts as controller of the device. The efficacy of the device was evaluated by performing dengue antibody IgG ELISA on 64 hospitalized patients suspected of dengue. The results demonstrate high accuracy of the device, with 95% sensitivity and 100% specificity in detection when compared with gold standard commercial ELISA microplate readers. This sensor platform represents a significant step towards establishing ELISA as a rapid, inexpensive and automatic testing method for the purpose of point-of-care-testing (POCT) in resource-limited settings.
    Matched MeSH terms: Dengue/immunology
  2. Hu D, Zhu Z, Li S, Deng Y, Wu Y, Zhang N, et al.
    PLoS Pathog, 2019 06;15(6):e1007836.
    PMID: 31242272 DOI: 10.1371/journal.ppat.1007836
    Dengue is the most widespread vector-borne viral disease caused by dengue virus (DENV) for which there are no safe, effective drugs approved for clinical use. Here, by using sequential antigen panning of a yeast antibody library derived from healthy donors against the DENV envelop protein domain III (DIII) combined with depletion by an entry defective DIII mutant, we identified a cross-reactive human monoclonal antibody (mAb), m366.6, which bound with high affinity to DENV DIII from all four DENV serotypes. Immunogenetic analysis indicated that m366.6 is a germline-like mAb with very few somatic mutations from the closest VH and Vλ germline genes. Importantly, we demonstrated that it potently neutralized DENV both in vitro and in the mouse models of DENV infection without detectable antibody-dependent enhancement (ADE) effect. The epitope of m366.6 was mapped to the highly conserved regions on DIII, which may guide the design of effective dengue vaccine immunogens. Furthermore, as the first germline-like mAb derived from a naïve antibody library that could neutralize all four DENV serotypes, the m366.6 can be a tool for exploring mechanisms of DENV infection, and is a promising therapeutic candidate.
    Matched MeSH terms: Dengue/immunology
  3. Wahid SF, Sanusi S, Zawawi MM, Ali RA
    PMID: 11127322
    The impact of dengue on liver function was studied on fifty serologically confirmed dengue cases admitted to Hospital Universiti Kebangsaan Malaysia (HUKM). Twenty-five of these patients had classic dengue fever (DF) and 25 had grade 1 or 2 dengue hemorrhagic fever (DHF). There were more (60%) DHF patients with hepatomegaly compared to DF (40%) but the difference was not statistically significant. Analysis of the liver profile showed that liver dysfunction was commoner in DHF compared to DF, indicating that the degree of liver impairment may be related to the severity of DHF. Hyperbilirubinemia was noted in 3 (12%) DHF and 2 (8%) DF patients. The mean (range) serum bilirubin was higher in DHF [14.2(5-50) micromol/l] compared to DF [10.9(5-30) micromol/l)] (p > 0.05). Elevated levels of serum alanine aminotransferase (ALT) and alkaline phosphatase (ALP) were observed more frequently in DHF (20 and 12 patients respectively) compared to DF (16 and 8 patients respectively). Nine (36%) DHF and 6 (24%) DF patients had concomitant elevation of ALT and ALP levels. The mean (range) serum ALT levels were 109.3(23-325) U/l in DHF and 90.8(13-352) U/l in DF (p > 0.05). The mean (range) serum ALP levels were 102.2(15-319) U/l in DHF and 93.3(34-258) U/l in DF (p > 0.05). The ALT and ALP levels were significantly higher in DHF patients with spontaneous bleeding than those without bleeding (p < 0.05) None of the patients developed fulminant hepatitis. The immunoregulatory cells, which include the T (CD3), B (CD 19), CD4, CD8, CD5 and natural killer (NK) cells were significantly lower in DHF compared to DF patients (p < 0.05). However, the reduction in these cell counts did not correlate with the liver dysfunction seen in DHF patients. In conclusion, hepatomegaly and liver dysfunction were commoner in DHF compared to DF.
    Matched MeSH terms: Dengue/immunology; Severe Dengue/immunology
  4. Osman O, Fong MY, Devi S
    Jpn J Infect Dis, 2007 Jul;60(4):205-8.
    PMID: 17642533
    The purpose of this study was to examine the extent of dengue infection in Brunei and to determine the predominant serotype circulating in the country. The study generated useful epidemiological data on dengue infection in Brunei. A total of 271 samples from patients suspected of having dengue infections were selected and analyzed. All patients were seen in clinics and hospitals in Brunei. The samples were collected from April 2005 to April 2006 and transported to the WHO Collaborating Centre for Arbovirus Reference and Research, University of Malaya, Malaysia. The following tests were used to achieve the objectives: in-house IgM-capture enzyme-linked immunosorbent assay, virus isolation in mosquito albopictus cell line (C6/36), and viral RNA detection and serotyping by reverse transcriptase-polymerase chain reaction (RT-PCR). The results show that 45 people were positive for dengue-specific IgM (27 males and 18 females), while RT-PCR detected dengue viral RNA in 12 patients, 3 identified as DEN-1 and 9 as DEN-2. Dengue virus was isolated from 6 patients using the C6/36 cell line; 3 were DEN-2 isolates and 3 were DEN-1 isolates. These data show that dengue virus is circulating in Brunei and the predominant infecting serotype for that period was DEN-2 followed by DEN-1. This study is the first to report the detection and isolation of dengue virus from Brunei using RT-PCR and culture in the C6/36 albopictus mosquito cell line.
    Matched MeSH terms: Dengue/immunology
  5. Yong YK, Tan HY, Jen SH, Shankar EM, Natkunam SK, Sathar J, et al.
    J Transl Med, 2017 05 31;15(1):121.
    PMID: 28569153 DOI: 10.1186/s12967-017-1226-4
    BACKGROUND: Currently, several assays can diagnose acute dengue infection. However, none of these assays can predict the severity of the disease. Biomarkers that predicts the likelihood that a dengue patient will develop a severe form of the disease could permit more efficient patient triage and allows better supportive care for the individual in need, especially during dengue outbreaks.

    METHODS: We measured 20 plasma markers i.e. IFN-γ, IL-10, granzyme-B, CX3CL1, IP-10, RANTES, CXCL8, CXCL6, VCAM, ICAM, VEGF, HGF, sCD25, IL-18, LBP, sCD14, sCD163, MIF, MCP-1 and MIP-1β in 141 dengue patients in over 230 specimens and correlate the levels of these plasma markers with the development of dengue without warning signs (DWS-), dengue with warning signs (DWS+) and severe dengue (SD).

    RESULTS: Our results show that the elevation of plasma levels of IL-18 at both febrile and defervescence phase was significantly associated with DWS+ and SD; whilst increase of sCD14 and LBP at febrile phase were associated with severity of dengue disease. By using receiver operating characteristic (ROC) analysis, the IL-18, LBP and sCD14 were significantly predicted the development of more severe form of dengue disease (DWS+/SD) (AUC = 0.768, P 

    Matched MeSH terms: Dengue/immunology*; Severe Dengue/immunology*
  6. Ellan K, Thayan R, Phan CW, Sabaratnam V
    Trop Biomed, 2019 Dec 01;36(4):1087-1098.
    PMID: 33597478
    Pathogenesis of dengue fever has been associated with the activation of the cytokine cascade that triggered inflammatory responses. The inflammatory reactions in dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS) are the main cause of haemorrhagic manifestations, coagulation disorders, vascular permeability, hypotension and shock which could exacerbate the condition of the disease. In an earlier study, extracts belonging to Lignosus rhinocerotis, Pleurotus giganteus, Hericium erinaceus, Schizophyllum commune and Ganoderma lucidium mushrooms were screened for antidengue virus activities. We found that hot aqueous extract (HAE) and aqueous soluble separated from ethanol extract (ASE) exhibited their potential to reduce dengue viral load which were observed in plaque reduction assay and real-time RT-PCR. In continuation of our previous findings, this study was initiated to further investigate the other aspect; the anti-inflammatory activities of HAE and ASE of L. rhinocerotis, P. giganteus, H. erinaceus, S. commune and G. lucidium on human monocytes infected with dengue virus-2 (DENV-2) New guinea C strain. Human monocytes infected with DENV-2 were treated with mushroom extracts for 48 hours. The cytokine profile coincides with dengue infection, i.e. IFN-γ, TNF-α, IL-1β, IL-6, IL-8, and IL-10 were measured by BD OptEIATM Elisa Kit. The expression of these cytokines was significantly elevated in untreated infected cells two days after infection. However, after treated with mushroom extracts prominent anti-inflammatory effect were detected towards IFN-γ, IL-10, TNF-α, IL-6, and IL-1β. The most significant anti-inflammatory effects were detected in HAE of G. lucidium, S. commune, P. giganteus and ASE of L. rhinocerotis and the effects were comparable with dexamethasone, the reference inhibitor. These results demonstrated that mushroom HAE or ASE could successfully have suppressed cytokine production in dengue-infected monocytes and has a great potential to develop an antiinflammatory agent from mushroom extract for the treatment of dengue infection.
    Matched MeSH terms: Dengue/immunology*
  7. Wong SS, Abd-Jamil J, Abubakar S
    Viral Immunol, 2007 Sep;20(3):359-68.
    PMID: 17931106
    Outbreaks involving dengue viruses (DENV) of the same genotype occur in a cyclical pattern in Malaysia. Two cycles of outbreaks involving dengue virus type 2 (DENV-2) of the same genotype occurred in the 1990s in the Klang Valley, Malaysia. Sera of patients from the first outbreak and sera of mice inoculated with virus from the same outbreak had poorer neutralization activity against virus of the second outbreak. Conversely, patient sera from the second outbreak showed higher neutralization titer against virus of the early outbreak. At subneutralizing concentrations, sera of mice immunized with second outbreak virus did not significantly enhance infection with viruses from the earlier outbreak. Amino acid substitution from valine to isoleucine at position 129 of the envelope protein (E), as well as threonine to alanine at position 117 and lysine to arginine at position 272 of the NS1 protein, differentiated viruses of the two outbreaks. These findings highlight the potential influence of specific intragenotypic variations in eliciting varied host immune responses against the different DENV subgenotypes. This could be an important contributing factor in the recurring homogenotypic dengue virus outbreaks seen in dengue-endemic regions.
    Matched MeSH terms: Dengue/immunology*
  8. AbuBakar S, Azmi A, Mohamed-Saad N, Shafee N, Chee HY
    Malays J Pathol, 1997 Jun;19(1):41-51.
    PMID: 10879241
    The present study was undertaken to investigate the antibody responses of dengue fever (DF) patients to specific dengue virus proteins. Partially purified dengue 2 New Guinea C (NGC) strain virus was used as antigen. Under the present experimental protocols, it was observed that almost all DF patients' sera had detectable presence of antibodies which recognize the dengue 2 envelope (E) protein. The convalescent-phase sera especially had significant detectable IgG, IgM and IgE against the protein. In addition, IgGs specific against the NS1 dimer and PrM were also detected. Antibody against the core (C) protein, however, was not detectable in any of the DF patients' sera. The substantial presence of IgG against the PrM in the convalescent-phase sera, and the presence of IgE specific for the E, reflect the potential importance of these antibody responses in the pathogenesis of dengue.
    Matched MeSH terms: Dengue/immunology*
  9. Abubakar S, Azila A, Suzana M, Chang LY
    Malays J Pathol, 2002 Jun;24(1):29-36.
    PMID: 16329553
    At least three major antigenic dengue 2 virus proteins were recognized by pooled dengue fever patients' sera in infected Aedes albopictus (C6/36) mosquito cells. Dengue virus envelope (E), premembrane (PrM) and non-structural protein 1 (NS 1) dimer were detected beginning on day 3 postinfection in both the cell membrane and cytosolic fractions. Using the patients' sera, the presence of antigenic intermediate core protein (C)-PrM and NS1-non-structural protein 2a (NS2a) in the cytoplasmic fraction of dengue 2 virus infected cells was revealed. The presence of a approximately 92 and approximately 84 kDa NS 1 dimer in the membrane (NS 1m) and cytosolic (NS 1c) fractions of C6/36 cells, respectively, was also recognized. Using individual patient's serum, it was further confirmed that all patients' sera contained antibodies that specifically recognized E, NS 1 and PrM present in the dengue 2 virus-infected cell membrane fractions, suggesting that these glycosylated virus proteins were the main antigenic proteins recognized in vivo. Detection of dengue 2 virus C antibody in some patients further suggested that C could be antigenic if presented in vivo.
    Matched MeSH terms: Dengue/immunology*
  10. Muhamad M, Kee LY, Rahman NA, Yusof R
    Int J Biol Sci, 2010 May 23;6(3):294-302.
    PMID: 20567498
    Dengue viruses, mosquito-borne members of the Flaviviridae family, are the causative agents of dengue fever and its associated complications, dengue haemorrhagic fever and dengue shock syndrome. To date, more than 2.5 billion people in over 100 countries are at risk of infection, and approximately 20 million infections were reported annually. There is currently no treatment or vaccine available for dengue infection. This study employed a whole-cell organism model or in vitro methods to study the inhibitory property of the flavanoid-derived compounds against DENV2 activity. Results showed that at concentration not exceeding the maximum non-toxic dose (MNTD), these compounds completely prevented DENV2 infection in HepG2 cells as indicated by the absence of cytophatic effects. The in vitro antiviral activity assessed in HepG2 cells employing virus inhibition assay showed high inhibitory activity in a dose dependent manner. At concentration below MNTD, compounds exhibited inhibitory activity against DENV2 with a range of potency strengths of 72% to 100%. The plaque forming unit per ml (pfu/ml) was reduced prominently with a maximum reduction of 98% when the infected HepG2 cells were treated with the highest non-toxic dose of compounds. The highly potent activity of the compounds against DENV2 infection strongly suggests their potential as a lead antiviral agent for dengue.
    Matched MeSH terms: Dengue/immunology
  11. Rathakrishnan A, Klekamp B, Wang SM, Komarasamy TV, Natkunam SK, Sathar J, et al.
    PLoS One, 2014;9(3):e92021.
    PMID: 24647042 DOI: 10.1371/journal.pone.0092021
    With its elusive pathogenesis, dengue imposes serious healthcare, economic and social burden on endemic countries. This study describes the clinical and immunological parameters of a dengue cohort in a Malaysian city, the first according to the WHO 2009 dengue classification.
    Matched MeSH terms: Dengue/immunology*
  12. Hoh BP, Umi-Shakina H, Zuraihan Z, Zaiharina MZ, Rafidah-Hanim S, Mahiran M, et al.
    Hum Immunol, 2015 Jun;76(6):421-6.
    PMID: 25858769 DOI: 10.1016/j.humimm.2015.03.019
    Dengue causes significantly more human disease than any other arboviruses. It causes a spectrum of illness, ranging from mild self-limited fever, to severe and fatal dengue hemorrhagic fever, as evidenced by vascular leakage and multifactorial hemostatic abnormalities. There is no specific treatment available till date. Evidence shows that chemokines CXCL10, CXCL11 and their receptor CXCR3 are involved in severity of dengue, but their genetic association with the susceptibility of vascular leakage during dengue infection has not been reported. We genotyped 14 common variants of these candidate genes in 176 patients infected with dengue. rs4859584 and rs8878 (CXCL10) were significantly associated with vascular permeability of dengue infection (P<0.05); while variants of CXCL11 showed moderate significance of association (P=0.0527). Haplotype blocks were constructed for genes CXCL10 and CXCL11 (5 and 7 common variants respectively). Haplotype association tests performed revealed that, "CCCCA" of gene CXCL10 and "AGTTTAC" of CXCL11 were found to be significantly associated with vascular leakage (P=0.0154 and 0.0366 respectively). In summary, our association study further strengthens the evidence of the involvement of CXCL10 and CXCL11 in the pathogenesis of dengue infection.
    Matched MeSH terms: Dengue/immunology
  13. Wong LP, AbuBakar S, Chinna K
    PLoS Negl Trop Dis, 2014 May;8(5):e2789.
    PMID: 24853259 DOI: 10.1371/journal.pntd.0002789
    Demographic, economic and behavioural factors are central features underpinning the successful management and biological control of dengue. This study aimed to examine these factors and their association with the seroprevalence of this disease.
    Matched MeSH terms: Dengue/immunology
  14. Soe HJ, Manikam R, Raju CS, Khan MA, Sekaran SD
    PLoS One, 2020;15(8):e0237141.
    PMID: 32764789 DOI: 10.1371/journal.pone.0237141
    Severe dengue can be lethal caused by manifestations such as severe bleeding, fluid accumulation and organ impairment. This study aimed to investigate the role of dengue non-structural 1 (NS1) protein and host factors contributing to severe dengue. Electrical cell-substrate impedance sensing system was used to investigate the changes in barrier function of microvascular endothelial cells treated NS1 protein and serum samples from patients with different disease severity. Cytokines and metabolites profiles were assessed using a multiplex cytokine assay and liquid chromatography mass spectrometry respectively. The findings showed that NS1 was able to induce the loss of barrier function in microvascular endothelium in a dose dependent manner, however, the level of NS1 in serum samples did not correlate with the extent of vascular leakage induced. Further assessment of host factors revealed that cytokines such as CCL2, CCL5, CCL20 and CXCL1, as well as adhesion molecule ICAM-1, that are involved in leukocytes infiltration were expressed higher in dengue patients in comparison to healthy individuals. In addition, metabolomics study revealed the presence of deregulated metabolites involved in the phospholipid metabolism pathway in patients with severe manifestations. In conclusion, disease severity in dengue virus infection did not correlate directly with NS1 level, but instead with host factors that are involved in the regulation of junctional integrity and phospholipid metabolism. However, as the studied population was relatively small in this study, these exploratory findings should be confirmed by expanding the sample size using an independent cohort to further establish the significance of this study.
    Matched MeSH terms: Severe Dengue/immunology
  15. Appanna R, Huat TL, See LL, Tan PL, Vadivelu J, Devi S
    Clin. Vaccine Immunol., 2007 Aug;14(8):969-77.
    PMID: 17567768
    Dengue virus infections are a major cause of morbidity and mortality in tropical and subtropical areas in the world. Attempts to develop effective vaccines have been hampered by the lack of understanding of the pathogenesis of the disease and the absence of suitable experimental models for dengue viral infection. The magnitude of T-cell responses has been reported to correlate with dengue disease severity. Sixty Malaysian adults with dengue viral infections were investigated for their dengue virus-specific T-cell responses to 32 peptides antigens from the structural and nonstructural regions from a dengue virus isolate. Seventeen different peptides from the C, E, NS2B, NS3, NS4A, NS4B, and NS5 regions were found to evoke significant responses in a gamma interferon enzyme-linked immunospot (ELISPOT) assay of samples from 13 selected patients with dengue fever (DF) and dengue hemorrhagic fever (DHF). NS3 and predominantly NS3(422-431) were found to be important T-cell targets. The highest peaks of T-cell responses observed were in responses to NS3(422-431) and NS5(563-571) in DHF patients. We also found almost a sevenfold increase in T-cell response in three DHF patients compared to three DF patient responses to peptide NS3(422-431). A large number of patients' T cells also responded to the NS2B(97-106) region. The ELISPOT analyses also revealed high frequencies of T cells that recognize both serotype-specific and cross-reactive dengue virus antigens in patients with DHF.
    Matched MeSH terms: Dengue/immunology*; Severe Dengue/immunology*
  16. Wallace HG, Lim TW, Rudnick A, Knudsen AB, Cheong WH, Chew V
    PMID: 6105712
    The first major Malaysian epidemic of dengue hemorrhagic fever with severe manifestations occurred in 1973, with 969 reported cases and 54 deaths. In a detailed study of 138 clinically diagnosed and laboratory confirmed cases at the General Hospital in Kuala Lumpur, hemorrhagic manifestations were observed in 68.7% and shock in 18.1% of the patients. The cases occurred mainly from May to September, largely in urban and suburban areas of the majority of the states in the country. A main focus of infection was Jinjang, a heavily populated outlying district of Kuala Lumpur, where unusually high incidences of morbidity, severe disease and mortality were seen. Severe disease was seen mostly in children under the age of 15 years, although a significant number of adults suffered milder illnesses. The Chinese population was chiefly affected, due to their living in crowded, low-income housing where the vector, Aedes aegypti, occurred in the greatest numbers. All four dengue types were recovered during the epidemic period, although dengue 3 (DEN-3) was incriminated as the major epidemic type. Entomological data revealed high indices of A. aegypti throughout the country and left little doubt that this epidemic was aegypti transmitted. Spraying and fogging operations were carried out in attempts to control vector populations.
    Matched MeSH terms: Dengue/immunology
  17. Yeo AS, Rathakrishnan A, Wang SM, Ponnampalavanar S, Manikam R, Sathar J, et al.
    Biomed Res Int, 2015;2015:420867.
    PMID: 25815314 DOI: 10.1155/2015/420867
    Dengue virus infection is a common tropical disease which often occurs without being detected. These asymptomatic cases provide information in relation to the manifestation of immunological aspects. In this study, we developed an ELISA method to compare neutralizing effects of dengue prM and E antibodies between dengue patients and their asymptomatic household members. Recombinant D2 premembrane (prM) was constructed, cloned, and tested for antigenicity. The recombinant protein was purified and tested with controls by using an indirect ELISA method. Positive dengue serum samples with their asymptomatic pair were then carried out onto the developed ELISA. In addition, commercially available recombinant envelope (E) protein was used to develop an ELISA which was tested with the same set of serum samples in the prM ELISA. Asymptomatic individuals showed preexisting heterotypic neutralizing antibodies. The recombinant prM was antigenically reactive in the developed ELISA. Dengue patients had higher prM and E antibodies compared to their household members. Our study highlights the neutralizing antibodies levels with respect to dengue prM and E between dengue patients and asymptomatic individuals.
    Matched MeSH terms: Dengue/immunology*
  18. Cardosa MJ
    Br Med Bull, 1998;54(2):395-405.
    PMID: 9830205 DOI: 10.1093/oxfordjournals.bmb.a011696
    Dengue virus infection is now a global problem affecting tens of millions of people. The spread of the four dengue virus serotypes had led to increased incidence of dengue haemorrhagic fever (DHF) reported and with 2.5 billion people at risk, efforts towards the development of safe and effective vaccines against dengue must be accelerated. This chapter reviews some of the important lessons of pathogenesis which may be learnt from classical studies in the field and place these in the context of current knowledge about the molecular biology of the virus. The issues which have to be addressed in designing a safe vaccine against dengue are raised and the problems of designing subunit as well as whole virus vaccines are pointed out, particularly with regard to the phenomenon of antibody dependent enhancement and, more generally, the problem of immune potentiation of disease. More efforts must be made to understand the basis of pathogenesis in DHF and in finding out what nature has to teach about protection against and recovery from dengue virus infection.
    Matched MeSH terms: Dengue/immunology; Severe Dengue/immunology
  19. Cardosa MJ
    Lancet, 1987 Jan 24;1(8526):193-4.
    PMID: 2880019
    Acute-phase serum samples collected during an outbreak of dengue fever and dengue haemorrhagic fever in Penang, Malaysia, were tested by a method involving antibody-dependent enhancement of infectivity in the mouse macrophage-like cell line, P388D1. 58 of 71 (81.7%) serologically positive cases yielded virus.
    Matched MeSH terms: Dengue/immunology*
  20. Lam SK, Devi S, Pang T
    PMID: 3329413
    A modification of the IgM-capture ELISA which can provide an early diagnosis for dengue infection is presented. The test is technically simple compared to HI and appears to be more sensitive. It has the advantage over HIT for the detection of specific IgM in that it is more sensitive and the reading of the result is not subjective. There is the possibility of the test being able to replace HI and HIT in the future.
    Matched MeSH terms: Dengue/immunology
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