Displaying publications 1 - 20 of 80 in total

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  1. Abd-Jamil J, Cheah CY, AbuBakar S
    Protein Eng. Des. Sel., 2008 Oct;21(10):605-11.
    PMID: 18669522 DOI: 10.1093/protein/gzn041
    A method to map the specific site on dengue virus envelope protein (E) that interacts with cells and a neutralizing antibody is developed using serially truncated dengue virus type 2 (DENV-2) E displayed on M13 phages as recombinant E-g3p fusion proteins. Recombinant phages displaying the truncated E consisting of amino acids 297-423 (EB2) and amino acids 379-423 (EB4) were neutralized by DENV-2 patient sera and the DENV-2 E-specific 3H5-1 monoclonal antibodies suggesting that the phages retained the DENV-2 E antigenic properties. The EB4 followed by EB2 recombinant phages bound the most to human monocytes (THP-1), African green monkey kidney (Vero) cells, mosquito (C6/36) cells, ScFv specific against E and C6/36 cell proteins. Two potential cell attachment sites were mapped to loop I (amino acids 297 to 312) and loop II (amino acids 379-385) of the DENV-2 E using the phage-displayed truncated DENV-2 E fragments and by the analysis of the E structure. Loop II was present only in EB4 recombinant phages. There was no competition for binding to C6/36 cell proteins between EB2 and EB4 phages. Loop I and loop II are similar to the sub-complex specific and type-specific neutralizing monoclonal antibody binding sites, respectively. Hence, it is proposed that binding and entry of DENV involves the interaction of loop I to cell surface glycosaminoglycan-motif and a subsequent highly specific interaction involving loop II with other cell proteins. The phage displayed truncated DENV-2 E is a powerful and useful method for the direct determination of DENV-2 E cell binding sites.
    Matched MeSH terms: Dengue Virus/immunology
  2. 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 Virus/immunology*
  3. 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 Virus/immunology
  4. Al-Alimi AA, Ali SA, Al-Hassan FM, Idris FM, Teow SY, Mohd Yusoff N
    PLoS Negl Trop Dis, 2014 Mar;8(3):e2711.
    PMID: 24625456 DOI: 10.1371/journal.pntd.0002711
    Dengue virus is endemic in peninsular Malaysia. The clinical manifestations vary depending on the incubation period of the virus as well as the immunity of the patients. Glucose-6-phosphate dehydrogenase (G6PD) deficiency is prevalent in Malaysia where the incidence is 3.2%. It has been noted that some G6PD-deficient individuals suffer from more severe clinical presentation of dengue infection. In this study, we aim to investigate the oxidative responses of DENV2-infected monocytes from G6PD-deficient individuals.
    Matched MeSH terms: Dengue Virus/immunology*
  5. 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 Virus/immunology*
  6. Bowen ET, Simpson DI, Platt GS, Way HJ, Bright WF, Day J, et al.
    Trans R Soc Trop Med Hyg, 1975;69(2):182-6.
    PMID: 809868
    449 human sera collected in a Land Dyak village were tested for antibodies to 11 arboviruses. Japanese encephalitis and dengue virus antibodies were particularly prevalent. The rates of infection with these viruses were estimated to be 5-2% per annum for Japanese encephalitis, 8-8% for dengue 1 and 4-3% for dengue 2. Chikungunya virus antibodies were quite common with an annual infection rate of the order of 5% per annum. Infections with other Group A and B and Bunyamwera group viruses were generally at a low level.
    Matched MeSH terms: Dengue Virus/immunology
  7. Cardosa MJ, Tio PH, Nimmannitya S, Nisalak A, Innis B
    PMID: 1298081
    The highly sensitive AFRIMS format IgM capture ELISA for the diagnosis of dengue virus infections requires the use of mouse brain derived hemagglutinins and consequently also the use of 20% acetone extracted normal human serum to eliminate high background. These reagents are not always easily available and we have thus compared the AFRIMS format with another published format which uses cell culture derived antigens (culture fluid, CF, format) in order to determine if it is reasonable to use cell culture derived antigens in situations where hemagglutinins and normal human serum are difficult to obtain. The study shows that using AFRIMS results as the reference point, the CF format described here has a sensitivity of 90% and a specificity of 96%.
    Matched MeSH terms: Dengue Virus/immunology
  8. Cardosa MJ, Tio PH
    Bull World Health Organ, 1991;69(6):741-5.
    PMID: 1786623
    A dot enzyme immunoassay (DEIA) for the detection of antibodies to dengue virus was tested for use as a tool in the presumptive diagnosis of dengue fever and dengue haemorrhagic fever. Paired sera from the following groups of patients were tested using the DEIA and the haemagglutination inhibition (HI) test: those with primary dengue fever; those experiencing a second dengue infection; and febrile patients who did not have dengue. The data obtained show that the DEIA can be effectively used at a serum dilution of 1:1000 to confirm presumptive recent dengue in patients with a second dengue infection. However, demonstration of seroconversion proved necessary for patients with primary dengue. At a serum dilution of 1:1000 the DEIA has a specificity of 97.3%. The role of this simple and rapid test in improving the effectivity of programmes for the control of dengue virus infection is discussed.
    Matched MeSH terms: Dengue Virus/immunology*
  9. Cardosa MJ, Wang SM, Sum MS, Tio PH
    BMC Microbiol, 2002 May 5;2:9.
    PMID: 12019028
    In Southeast Asia, dengue viruses often co-circulate with other flaviviruses such as Japanese encephalitis virus, and due to the presence of shared antigenic epitopes it is often difficult to use serological methods to distinguish between previous infections by these flaviviruses.
    Matched MeSH terms: Dengue Virus/immunology*
  10. 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 Virus/immunology*
  11. Cardosa MJ, Hooi TP, Shaari NS
    J Virol Methods, 1988 Oct;22(1):81-8.
    PMID: 3058737
    Partially purified DEN3 virus was used as antigen in a sensitive dot enzyme immunoassay (DEIA) for the detection of antibodies to flavivirus antigens. We describe here the method used to prepare and optimise the antigen-bearing nitrocellulose membranes and present the results obtained from screening 20 acute phase sera from patients shown to have had recent dengue infections by the haemagglutination inhibition (HI) test. Sixteen pairs of acute and convalescent sera from dengue-negative patients had no detectable antibody to dengue virus by HI. These were shown to have no antibody detectable by DEIA. Sera positive for dengue antibodies by HI had DEIA titers ranging from 10 to several thousand times greater than the titers detected by HI.
    Matched MeSH terms: Dengue Virus/immunology*
  12. Chan SY, Kautner IM, Lam SK
    J Virol Methods, 1994 Oct;49(3):315-22.
    PMID: 7868649
    The potential of RT-PCR to rapidly diagnose dengue infections from both acute and convalescent phase patients' sera was evaluated. The RNA extraction method involved binding of the viral RNA to silica particles in the presence of high concentration of guanidine thiocyanate. The protocol that was established was sensitive enough to detect 40 plaque forming units per 100 microliter of serum and results could be obtained within one day. Results from this study indicate that clinical samples should be collected in the early acute phase of illness when anti-dengue antibodies were undetectable or of low titres to ensure a more reliable diagnosis.
    Matched MeSH terms: Dengue Virus/immunology
  13. Chem YK, Chua KB, Malik Y, Voon K
    Trop Biomed, 2015 Jun;32(2):344-51.
    PMID: 26691263 MyJurnal
    Monoclonal antibody-escape variant of dengue virus type 1 (MabEV DEN-1) was discovered and isolated in an outbreak of dengue in Klang Valley, Malaysia from December 2004 to March 2005. This study was done to investigate whether DEN152 (an isolate of MabEV DEN-1) is a product of recombination event or not. In addition, the non-synonymous mutations that correlate with the monoclonal antibody-escape variant were determined in this study. The genomes of DEN152 and two new DEN-1 isolates, DENB04 and DENK154 were completely sequenced, aligned, and compared. Phylogenetic tree was plotted and the recombination event on DEN152 was investigated. DEN152 is sub-grouped under genotype I and is closely related genetically to a DEN-1 isolated in Japan in 2004. DEN152 is not a recombinant product of any parental strains. Four amino acid substitutions were unique only to DEN 152. These amino acid substitutions were (Ser)[326](Leu), (Ser)[340](Leu) at the deduced E protein, (Ile)[250](Thr) at NS1 protein, and (Thr)[41](Ser) at NS5 protein. Thus, DEN152 is an isolate of the emerging monoclonal antibody-escape variant DEN-1 that escaped diagnostic laboratory detection.
    Matched MeSH terms: Dengue Virus/immunology*
  14. Chen RE, Smith BK, Errico JM, Gordon DN, Winkler ES, VanBlargan LA, et al.
    Cell Host Microbe, 2021 Nov 10;29(11):1634-1648.e5.
    PMID: 34610295 DOI: 10.1016/j.chom.2021.09.006
    Although divergent dengue viruses (DENVs) have been isolated in insects, nonhuman primates, and humans, their relationships to the four canonical serotypes (DENV 1-4) are poorly understood. One virus isolated from a dengue patient, DKE-121, falls between genotype and serotype levels of sequence divergence to DENV-4. To examine its antigenic relationship to DENV-4, we assessed serum neutralizing and protective activity. Whereas DENV-4-immune mouse sera neutralize DKE-121 infection, DKE-121-immune sera inhibit DENV-4 less efficiently. Passive transfer of DENV-4 or DKE-121-immune sera protects mice against homologous, but not heterologous, DENV-4 or DKE-121 challenge. Antigenic cartography suggests that DENV-4 and DKE-121 are related but antigenically distinct. However, DENV-4 vaccination confers protection against DKE-121 in nonhuman primates, and serum from humans immunized with a tetravalent vaccine neutralize DENV-4 and DKE-121 infection equivalently. As divergent DENV strains, such as DKE-121, may meet criteria for serotype distinction, monitoring their capacity to impact dengue disease and vaccine efficacy appears warranted.
    Matched MeSH terms: Dengue Virus/immunology*
  15. Chen WS, Wong CH, Cillekens L
    Med J Malaysia, 2003 Mar;58(1):142-3.
    PMID: 14556343
    Matched MeSH terms: Dengue Virus/immunology*
  16. Chinikar S, Ghiasi SM, Shah-Hosseini N, Mostafavi E, Moradi M, Khakifirouz S, et al.
    Travel Med Infect Dis, 2013 May-Jun;11(3):166-9.
    PMID: 23194952 DOI: 10.1016/j.tmaid.2012.10.001
    Dengue fever is one of the most important arthropod-borne viral diseases of public health significance. It is endemic in most tropical and subtropical parts of the world, many of which are popular tourist destinations. The presence of dengue infection was examined in Iranian patients who were referred to the Arboviruses and Viral Haemorrhagic Fevers Laboratory of the Pasteur Institute of Iran and tested negative for Crimean-Congo Haemorrhagic Fever (CCHF) between 2000 and 2012. Serum samples from these patients were tested for the presence of specific IgG and IgM and viral nucleic acid in blood. Of the 300 sera tested, 15 (5%) were seropositive, and 3 (1%) were both serologically and PCR positive. Of the 15 seropositive cases, 8 (53.3%) had travelled to endemic areas including Malaysia (5, 62.5%), India (2, 25%) and Thailand (1, 12.5%). In contrast, 7 (46.7%) of the cases had not reported travelling abroad. Of these, six cases were from the Sistan and Baluchistan province in southeast Iran and neighbouring Pakistan. Travellers play a key role in the epidemiology of dengue infection in Iran and it is recommended that travellers to endemic areas take precautionary measures to avoid mosquito bites.
    Matched MeSH terms: Dengue Virus/immunology
  17. Chong LC, Khan AM
    BMC Genomics, 2019 Dec 24;20(Suppl 9):921.
    PMID: 31874646 DOI: 10.1186/s12864-019-6311-z
    BACKGROUND: The sequence diversity of dengue virus (DENV) is one of the challenges in developing an effective vaccine against the virus. Highly conserved, serotype-specific (HCSS), immune-relevant DENV sequences are attractive candidates for vaccine design, and represent an alternative to the approach of selecting pan-DENV conserved sequences. The former aims to limit the number of possible cross-reactive epitope variants in the population, while the latter aims to limit the cross-reactivity between the serotypes to favour a serotype-specific response. Herein, we performed a large-scale systematic study to map and characterise HCSS sequences in the DENV proteome.

    METHODS: All reported DENV protein sequence data for each serotype was retrieved from the NCBI Entrez Protein (nr) Database (txid: 12637). The downloaded sequences were then separated according to the individual serotype proteins by use of BLASTp search, and subsequently removed for duplicates and co-aligned across the serotypes. Shannon's entropy and mutual information (MI) analyses, by use of AVANA, were performed to measure the diversity within and between the serotype proteins to identify HCSS nonamers. The sequences were evaluated for the presence of promiscuous T-cell epitopes by use of NetCTLpan 1.1 and NetMHCIIpan 3.2 server for human leukocyte antigen (HLA) class I and class II supertypes, respectively. The predicted epitopes were matched to reported epitopes in the Immune Epitope Database.

    RESULTS: A total of 2321 nonamers met the HCSS selection criteria of entropy  0.8. Concatenating these resulted in a total of 337 HCSS sequences. DENV4 had the most number of HCSS nonamers; NS5, NS3 and E proteins had among the highest, with none in the C and only one in prM. The HCSS sequences were immune-relevant; 87 HCSS sequences were both reported T-cell epitopes/ligands in human and predicted epitopes, supporting the accuracy of the predictions. A number of the HCSS clustered as immunological hotspots and exhibited putative promiscuity beyond a single HLA supertype. The HCSS sequences represented, on average, ~ 40% of the proteome length for each serotype; more than double of pan-DENV sequences (conserved across the four serotypes), and thus offer a larger choice of sequences for vaccine target selection. HCSS sequences of a given serotype showed significant amino acid difference to all the variants of the other serotypes, supporting the notion of serotype-specificity.

    CONCLUSION: This work provides a catalogue of HCSS sequences in the DENV proteome, as candidates for vaccine target selection. The methodology described herein provides a framework for similar application to other pathogens.

    Matched MeSH terms: Dengue Virus/immunology*
  18. Darwish NT, Sekaran SD, Alias Y, Khor SM
    J Pharm Biomed Anal, 2018 Feb 05;149:591-602.
    PMID: 29197806 DOI: 10.1016/j.jpba.2017.11.064
    The sharp increase in incidence of dengue infection has necessitated the development of methods for the rapid diagnosis of this deadly disease. Here we report the design and development of a reliable, sensitive, and specific optical immunosensor for the detection of the dengue nonstructural protein 1 (NS1) biomarker in clinical samples obtained during early stages of infection. The present optical NS1 immunosensor comprises a biosensing surface consisting of specific monoclonal NS1 antibody for immunofluorescence-based NS1 antigen determination using fluorescein isothiocyanate (FITC) conjugated to IgG antibody. The linear range of the optical immunosensor was from 15-500ngmL-1, with coefficient of determination (R2) of 0.92, high reproducibility (the relative standard deviation obtained was 2%), good stability for 21days at 4°C, and low detection limit (LOD) at 15ngmL-1. Furthermore, the optical immunosensor was capable of detecting NS1 analytes in plasma specimens from patients infected with the dengue virus, with low cross-reaction with plasma specimens containing the Japanese encephalitis virus (JEV) and Zika virus. No studies have been performed on the reproducibility and cross-reactivity regarding NS1 specificity, which is thus a limitation for optical NS1 immunosensors. In contrast, the present study addressed these limitations carefully where these two important experiments were conducted to showcase the robustness of our newly developed optical-based fluorescence immunosensor, which can be practically used for direct NS1 determination in any untreated clinical sample.
    Matched MeSH terms: Dengue Virus/immunology*
  19. Dhanoa A, Hassan SS, Jahan NK, Reidpath DD, Fatt QK, Ahmad MP, et al.
    Infect Dis Poverty, 2018 Jan 16;7(1):1.
    PMID: 29335021 DOI: 10.1186/s40249-017-0384-1
    BACKGROUND: The frequency and magnitude of dengue epidemics continue to increase exponentially in Malaysia, with a shift in the age range predominance toward adults and an expansion to rural areas. Despite this, information pertaining to the extent of transmission of dengue virus (DENV) in the rural community is lacking. This community-based pilot study was conducted to establish DENV seroprevalence amongst healthy adults in a rural district in Southern Malaysia, and to identify influencing factors.

    METHODS: In this study undertaken between April and May 2015, a total of 277 adult participants were recruited from households across three localities in the Sungai Segamat subdistrict in Segamat district. Sera were tested for immunoglobulin G (IgG) (Panbio® Dengue Indirect IgG ELISA/high-titer capture) and immunoglobulin M (IgM) (Panbio®) antibodies. The plaque reduction neutralization test (PRNT) was conducted on random samples of IgG-positive sera for further confirmation. Medical history and a recall of previous history of dengue were collected through interviews, whereas sociodemographic information was obtained from an existing database.

    RESULTS: The overall seroprevalence for DENV infection was 86.6% (240/277) (95% CI: 83-91%). Serological evidence of recent infection (IgM/high-titer capture IgG) was noted in 11.2% (31/277) of participants, whereas there was evidence of past infection in 75.5% (209/277) of participants (indirect IgG minus recent infections). The PRNT assay showed that the detected antibodies were indeed specific to DENV. The multivariate analysis showed that the older age group was significantly associated with past DENV infections. Seropositivity increased with age; 48.5% in the age group of <25 years to more than 85% in age group of >45 years (P 

    Matched MeSH terms: Dengue Virus/immunology*
  20. Fry SR, Meyer M, Semple MG, Simmons CP, Sekaran SD, Huang JX, et al.
    PLoS Negl Trop Dis, 2011 Jun;5(6):e1199.
    PMID: 21713023 DOI: 10.1371/journal.pntd.0001199
    BACKGROUND: Serological tests for IgM and IgG are routinely used in clinical laboratories for the rapid diagnosis of dengue and can differentiate between primary and secondary infections. Dengue virus non-structural protein 1 (NS1) has been identified as an early marker for acute dengue, and is typically present between days 1-9 post-onset of illness but following seroconversion it can be difficult to detect in serum.
    AIMS: To evaluate the performance of a newly developed Panbio® Dengue Early Rapid test for NS1 and determine if it can improve diagnostic sensitivity when used in combination with a commercial IgM/IgG rapid test.
    METHODOLOGY: The clinical performance of the Dengue Early Rapid was evaluated in a retrospective study in Vietnam with 198 acute laboratory-confirmed positive and 100 negative samples. The performance of the Dengue Early Rapid in combination with the IgM/IgG Rapid test was also evaluated in Malaysia with 263 laboratory-confirmed positive and 30 negative samples.
    KEY RESULTS: In Vietnam the sensitivity and specificity of the test was 69.2% (95% CI: 62.8% to 75.6%) and 96% (95% CI: 92.2% to 99.8) respectively. In Malaysia the performance was similar with 68.9% sensitivity (95% CI: 61.8% to 76.1%) and 96.7% specificity (95% CI: 82.8% to 99.9%) compared to RT-PCR. Importantly, when the Dengue Early Rapid test was used in combination with the IgM/IgG test the sensitivity increased to 93.0%. When the two tests were compared at each day post-onset of illness there was clear differentiation between the antigen and antibody markers.
    CONCLUSIONS: This study highlights that using dengue NS1 antigen detection in combination with anti-glycoprotein E IgM and IgG serology can significantly increase the sensitivity of acute dengue diagnosis and extends the possible window of detection to include very early acute samples and enhances the clinical utility of rapid immunochromatographic testing for dengue.
    Matched MeSH terms: Dengue Virus/immunology*
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