Showing papers on "Dengue virus published in 1991"
TL;DR: This work constructed recombinant vaccinia viruses expressing various portions of the NS region of the dengue virus type 4 polyprotein and showed that NS2B was needed, apparently in cis, for NS3/NS4A cleavage and for a series of internal cleavages in NS3.
Abstract: The cleavages at the junctions of the flavivirus nonstructural (NS) proteins NS2A/NS2B, NS2B/NS3, NS3/NS4A, and NS4B/NS5 share an amino acid sequence motif and are presumably catalyzed by a virus-encoded protease. We constructed recombinant vaccinia viruses expressing various portions of the NS region of the dengue virus type 4 polyprotein. By analyzing immune precipitates of 35S-labeled lysates of recombinant virus-infected cells, we could monitor the NS2A/NS2B, NS2B/NS3, and NS3/NS4A cleavages. A polyprotein composed of NS2A, NS2B, and the N-terminal 184 amino acids of NS3 was cleaved at the NS2A/NS2B and NS2B/NS3 junctions, whereas a similar polyprotein containing only the first 77 amino acids of NS3 was not cleaved. This finding is consistent with the proposal that the N-terminal 180 amino acids of NS3 constitute a protease domain. Polyproteins containing NS2A and NS3 with large in-frame deletions of NS2B were not cleaved at the NS2A/NS2B or NS2B/NS3 junctions. Coinfection with a recombinant expressing NS2B complemented these NS2B deletions for NS2B/NS3 cleavage and probably also for NS2A/NS2B cleavage. Thus, NS2B is also required for the NS2A/NS2B and NS2B/NS3 cleavages and can act in trans. Other experiments showed that NS2B was needed, apparently in cis, for NS3/NS4A cleavage and for a series of internal cleavages in NS3. Indirect evidence that NS3 can also act in trans was obtained. Models are discussed for a two-component protease activity requiring both NS2B and NS3.
550 citations
TL;DR: Results indicate (a) T lymphocytes are activated and produce IL-2 and IFN gamma in vivo during DHF and DF, (b) CD4+ T lymphocyte are activated inDHF andDF, and the level of activation is higher in DHF than in DF, and (c) activation of CD8+T lymphocytes is evident in DH, but not in DF.
Abstract: It has been reported that the severe complication of dengue virus infection, dengue hemorrhagic fever (DHF) is much more commonly observed during secondary dengue virus infections than primary infections. In order to elucidate the role of T lymphocytes in the pathogenesis of DHF, we attempted to determine whether T lymphocytes are activated in vivo during dengue virus infections, by examining the levels of soluble IL-2 receptor (sIL-2R), soluble CD4 (sCD4), soluble CD8 (sCD8), interleukin-2 (IL-2) and interferon-gamma (IFN gamma) in the sera of 59 patients with DHF and 41 patients with dengue fever (DF). The levels of sIL-2R, sCD4, sCD8, IL-2, and IFN gamma were significantly higher in the acute sera of patients with DHF than in the sera of healthy children (P less than 0.001 for all markers). The acute sera of patients with DF contained higher levels of sIL-2R, sCD4, IL-2, and IFN gamma than the sera of healthy children (P less than 0.001 for sIL-2R, IL-2, and IFN gamma; P less than 0.05 for sCD4), but did not have elevated levels of sCD8. The levels of sIL-2R (P less than 0.05), sCD4 (P less than 0.001), and sCD8 (P less than 0.001) were higher in DHF than in DF on days 3-4 after the onset of fever. The levels of IL-2 and IFN gamma in patients with DHF were highest 1 d before defervescence. There were no significant differences in the levels of sIL-2R, sCD4, sCD8, IL-2, and IFN gamma among grades 1, 2, and 3 of DHF. These results indicate (a) T lymphocytes are activated and produce IL-2 and IFN gamma in vivo during DHF and DF, (b) CD4+ T lymphocytes are activated in DHF and DF, and the level of activation is higher in DHF than in DF, and (c) activation of CD8+ T lymphocytes is evident in DHF, but not in DF.
326 citations
TL;DR: Evidence is presented that dengue virus recovered from permissive cells transfected with the in vitro RNA transcripts retained a mutation that was engineered into full-length cDNA that should facilitate the development of a safe and effective live vaccine for use in humans.
Abstract: Dengue virus is an enveloped positive-strand RNA virus with a genome approximately 11 kilobases in length. The four serotypes of dengue virus are currently the most important members of the flavivirus family in terms of geographical distribution and the incidence of infection in humans. In this communication we describe successful cloning of a stable full-length cDNA copy of dengue type 4 virus that can be used as the template for in vitro transcription of infectious RNA. Evidence is presented that dengue virus recovered from permissive cells transfected with the in vitro RNA transcripts retained a mutation that was engineered into full-length cDNA. The properties of the virus produced by cells transfected with infectious RNA transcripts of dengue cDNA resembled those of the virus from which the cDNA clone was derived. The dengue virus recombinant DNA system should prove helpful in gaining a better understanding of the molecular biology of dengue viruses and should facilitate the development of a safe and effective live vaccine for use in humans.
259 citations
TL;DR: The amplified sequence size revealed by ethidium bromide-stained agarose gel electrophoresis was unique for each serotype, using infected culture fluid of isolates from d Dengue fever or dengue hemorrhagic fever patients in Thailand, Indonesia, and the Philippines as well as from prototype viruses, thus facilitating simultaneous identification and typing.
Abstract: Four primer pairs were selected on the basis of the published sequence data of four dengue virus serotypes so that each unique target sequence size could be amplified for each serotype by polymerase chain reaction. The procedure consists of (i) RNA preparation, (ii) reverse transcription, and (iii) polymerase chain reaction, all of which could be completed within 2 h in a single tube for each specimen. The amplified sequence size revealed by ethidium bromide-stained agarose gel electrophoresis was unique for each serotype, using infected culture fluid of isolates from dengue fever or dengue hemorrhagic fever patients in Thailand, Indonesia, and the Philippines as well as from prototype viruses, thus facilitating simultaneous identification and typing.
169 citations
TL;DR: Two immunohistochemical techniques to determine the presence of yellow fever and dengue antigens in fixed tissue samples were developed and appeared to be highly reliable for yellow fever diagnosis; however, not enough cases were observed to adequately evaluate the procedures for d Dengue diagnosis.
Abstract: Two immunohistochemical techniques to determine the presence of yellow fever and dengue antigens in fixed tissue samples were developed for the purpose of making retrospective diagnoses of these viral diseases in humans. A horseradish peroxidase label was used for one technique and an alkaline phosphatase label for the other. In the former technique, acid hematin was removed from the tissues, iron-containing pigments were counterstained with Prussian blue, and the product of the diaminobenzidine reaction was enhanced with a dilute solution of osmium tetroxide that differentiated antigen from lipofuscin. In the latter technique, alkaline phosphatase was used as the enzyme labeling system with a red chromogen that contrasted nicely with the pigments in the tissues, as mentioned above. Thus, pigment removal or differentiation from antigen was not required. Replicate sections were cut and mouse polyclonal antibodies for yellow fever and all dengue types were applied to individual sections. On samples positive for dengue antigen, monoclonal antibodies were applied to additional replicate sections to demonstrate antigen of dengue types 1 and 4. In order to test the assay, samples of formalin-fixed liver tissue from Brazilian and Peruvian individuals who had died from a variety of causes as long as eight years earlier were received in a blinded fashion for immunohistochemical analysis. The techniques appeared to be highly reliable for yellow fever diagnosis; however, not enough cases were observed to adequately evaluate the procedures for dengue diagnosis. Both procedures appeared to have similar sensitivity.
155 citations
TL;DR: The results suggest that RT/PCR using degenerate primers is a sensitive and specific method for the detection of dengue viruses in clinical specimens.
Abstract: A set of sense and anti-sense oligomeric DNA primers, degenerate in the third "wobble" base position of codons so as to match all known dengue virus sequences, was evaluated as universal primers in a polymerase chain reaction (PCR) assay for the rapid diagnosis of dengue virus infections. Virus-specific complementary DNA (cDNA) was prepared by reverse transcription (RT) of total RNA extracted from serum. Amplified cDNA was identified by nucleic acid hybridization with four serotype-specific, oligomeric DNA probes. Using sera from patients admitted with dengue fever, RT/PCR followed by nucleic acid hybridization using radiolabeled probes was 68% sensitive (50/74; 95% confidence interval [CI] = 57-78%) and 100% specific. Chemiluminescent detection of hybridized products was 62% sensitive (26/42; 95% CI = 46-75%). Using specimens from which a virus isolate had been obtained, RT/PCR followed by nucleic acid hybridization with radiolabeled probes was 80% sensitive (40/50; 95% CI = 69-91%) and 100% specific. The results suggest that RT/PCR using degenerate primers is a sensitive and specific method for the detection of dengue viruses in clinical specimens.
145 citations
TL;DR: The retardation of replication of the type 2/type 4 chimeric virus suggests that this virus and possibly other intertypic dengue virus chimeras with similar properties should be examined for attenuation in primates and possible usefulness in a live d Dengue virus vaccine for humans.
Abstract: Dengue virus contains an 11-kilobase positive-strand RNA genome that codes for, in one open reading frame, three structural proteins (capsid, premembrane, and envelope), followed by seven nonstructural proteins. The structural protein genes of a full-length cDNA clone of type 4 dengue virus were replaced with the corresponding genes of dengue 1 or dengue 2 to create intertypic chimeric cDNA. The RNA transcripts made from these templates were infectious when transfected into permissive cells in culture. Progeny of chimeric cDNA produced apparently authentic dengue 1 or dengue 2 structural proteins, together with dengue 4 nonstructural proteins, and as a consequence exhibited type 1 or type 2 serological specificity. Both of the chimeras ultimately grew to the same titer as their type 1 or type 2 parent, but the type 2/type 4 chimera grew very slowly. This chimera also produced small plaques; in contrast, the type 1/type 4 chimera produced normal size plaques. The type 2/type 4 chimera retained the mouse neurovirulence of the dengue 2 virus, which was the source of its structural protein genes. Each of the mice inoculated intracerebrally with the chimera died, but survival time was prolonged. The retardation of replication of the type 2/type 4 chimeric virus suggests that this virus and possibly other intertypic dengue virus chimeras with similar properties should be examined for attenuation in primates and possible usefulness in a live dengue virus vaccine for humans.
143 citations
TL;DR: Results indicate that heterogeneous dengue virus-specific CD4+ cytotoxic T cells are stimulated in response to infection with a d Dengue virus and that a nonstructural protein, NS3, contains multiple dominant T-cell epitopes.
Abstract: Thirteen dengue virus-specific, cytotoxic CD4+ CD8- T-cell clones were established from a donor who was infected with dengue virus type 3. These clones were examined for virus specificity and human leukocyte antigen (HLA) restriction in cytotoxic assays. Six patterns of virus specificities were determined. Two serotype-specific clones recognized only dengue virus type 3. Two dengue virus subcomplex-specific clones recognized dengue virus types 2, 3, and 4, and one subcomplex-specific clone recognized dengue virus types 1, 2, and 3. Four dengue virus serotype-cross-reactive clones recognized dengue virus types 1, 2, 3, and 4. One flavivirus-cross-reactive clone recognized dengue virus types 1, 2, 3, and 4 and West Nile virus (WNV), but did not recognize yellow fever virus (YFV), whereas three flavivirus-cross-reactive clones recognized dengue virus types 1, 2, 3, and 4, WNV, and YFV. HLA restriction in the lysis by these T-cell clones was also heterogeneous. HLA-DP, HLA-DQ, and HLA-DR were used as restriction elements by various T-cell clones. We also examined the recognition of viral nonstructural protein NS3, purified from cells infected with dengue virus type 3 or WNV, by these T-cell clones. One serotype-specific clone, two dengue virus subcomplex-specific clones, and three dengue virus serotype-cross-reactive clones recognized NS3 of dengue virus type 3. One flavivirus-cross-reactive clone recognized NS3 of dengue virus type 3 and WNV. These results indicate that heterogeneous dengue virus-specific CD4+ cytotoxic T cells are stimulated in response to infection with a dengue virus and that a nonstructural protein, NS3, contains multiple dominant T-cell epitopes.
141 citations
Patent•
15 Aug 1991
TL;DR: In this paper, a recombinant poxvirus, such as vaccinia virus, fowlpox virus and canarypox virus, containing foreign DNA from flavivirus such as Japanese encephalitis virus, yellow fever virus and Dengue virus, was described.
Abstract: What is described is a recombinant poxvirus, such as vaccinia virus, fowlpox virus and canarypox virus, containing foreign DNA from flavivirus, such as Japanese encephalitis virus, yellow fever virus and Dengue virus. In a preferred embodiment, the recombinant poxvirus generates an extracellular particle containing flavivirus E and M proteins capable of inducing neutralizing antibodies, hemagglutination-inhibiting antibodies and protective immunity against flavivirus infection. What is also described is a vaccine containing the recombinant poxvirus for inducing an immunological response in a host animal inoculated with the vaccine.
122 citations
TL;DR: In this paper, the authors used polyacrylamide gel electrophoresis, Western blotting, and enzyme immunoassay to detect the presence of dengue virus.
Abstract: Antibodies against dengue viral proteins were demonstrated in sera from dengue-infected patients by polyacrylamide gel electrophoresis, Western blotting, and enzyme immunoassay. Primary dengue cases showed low titers of IgG class antibodies to envelope (E) proteins and two non-structural proteins, NS3 and NS5, in sera collected during the convalescent phase. Secondary dengue- infected patients always demonstrated IgG antibodies to E proteins in sera collected during the acute phase, and high titers of IgG antibodies to many other proteins, including NS1, NS3, NS5, and C proteins in sera collected during the convalescent phase. Appearance of antibodies to E, NS3, and NS5 could be detected within five days after the onset of fever. These three dengue viral proteins and their corresponding antibodies may be involved in the immunopathologic mechanism underlying this disease. For diagnostic purposes, identifying the non-structural proteins such as NS3 and NS5 may be the best means for early confirmation of the disease.
113 citations
TL;DR: In this article, the first 392 amino acids of the dengue type 4 virus E sequence, including the Arg-392 following the 79% E C terminus, appeared to be critical for proper antigenic structure required for efficient binding by HMAF.
Abstract: Recombinant vaccinia viruses expressing C-terminally truncated E's that ranged in length from 9 to 99% of the N-terminal sequence were constructed. The overall antigenicity of the E products was analyzed by radioimmunoprecipitation, using dengue virus hyperimmune mouse ascitic fluid (HMAF) or an anti-E peptide serum. Truncated E that was 79% or less in length did not bind HMAF efficiently, whereas E constructs greater than 79% were able to bind HMAF with high efficiency. The first 392 amino acids of the dengue type 4 virus E sequence, including the Arg-392 following the 79% E C terminus, appeared to be critical for proper antigenic structure required for efficient binding by HMAF. Truncated E's ranging from 59 to 81% in length were secreted extracellularly, whereas smaller or larger E's were retained intracellularly. Secreted E's contained carbohydrate side chains that were resistant to endoglycosidase H digestion, suggesting that the transport of E occurs via a pathway from the rough endoplasmic reticulum through the Golgi complex. 79% E-RKG (which possessed the three additional amino acids immediately downstream of 79% E) was expressed at a high concentration on the surface of recombinant virus-infected cells presumably being inserted into the plasma membrane by a hydrophobic C-terminal membrane anchor. Evaluation in mice of the protective efficacy of the various vaccinia virus E recombinants indicated that only truncated E's that were recognized efficiently by HMAF induced a high level of resistance to dengue virus encephalitis. 79% E-RKG which is expressed at a high concentration on the surface of infected cells was highly immunogenic when tested for induction of an E antibody response. This suggests that cell surface expression of 79% E-RKG was responsible for its enhanced immunogenicity. Finally, passive immunization studies indicated that serum antibodies to E played a major role in the complete or nearly complete resistance to dengue virus challenge induced by certain vaccinia virus-truncated E recombinants.
Journal Article•
TL;DR: Results indicate that cell surface molecules other than Fc Gamma R can mediate ADE and suggest that the Fc gamma R does not provide a unique signal necessary for enhanced infection.
Abstract: It is known that antibodies to dengue viruses at subneutralizing concentrations enhance dengue virus infection of Fc gamma R+ cells This phenomenon called antibody-dependent enhancement (ADE) occurs when virus-antibody complexes bind to the Fc gamma R via the Fc portion of the Ig It has been hypothesized that ADE may be responsible for the pathogenesis of the severe manifestations of dengue virus infection including dengue hemorrhagic fever/dengue shock syndrome To further analyze the mechanisms of ADE, we prepared bispecific antibodies by chemically cross-linking antidengue virus antibodies to antibodies specific for Fc gamma RI or Fc gamma RII and the non-Fc R molecules beta2 microglobulin, CD15 or CD33 and examined whether these bispecific antibodies could enhance infection Bispecific antibodies targeting dengue virus to Fc gamma RI or Fc gamma RII enhanced dengue virus infection, consistent with previous reports using conventional antibodies Furthermore, bispecific antibodies targeting dengue virus to beta2 microglobulin, CD15 or CD33 also enhanced dengue virus infection Bispecific antibody mediated ADE was inhibited by pretreating the cells with the appropriate blocking mAb These results indicate that cell surface molecules other than Fc gamma R can mediate ADE and suggest that the Fc gamma R does not provide a unique signal necessary for enhanced infection We hypothesize that directing dengue virus to the cell surface by a bispecific antibody facilitates the interaction between dengue virus and its receptor, thereby increasing its infectivity
TL;DR: Recombinant vaccinia viruses that express the premembrane (pre-M), membrane (M), or the cleaved, residual portion of pre-M (non-M) proteins of dengue 4 virus are constructed to evaluate their ability to induce protective immunity in mice.
TL;DR: This is the first report of the isolation of MAbs which define these determinants and which will allow their further analysis, and several of these MAbs were able to cross-react with other flaviviruses, most notably viruses from the Japanese encephalitis antigenic complex.
Abstract: A panel of mouse monoclonal antibodies (MAbs) raised against the non-structural glycoprotein NS1 of dengue 2 virus (PR159) was studied for cross-reactivity with the NS1 protein of other dengue virus serotypes and other members of the Flaviviridae using immuno-blotting. Most of the 35 anti-NS1 MAbs were found to be specific for dengue 2 virus NS1 (some of which were specific for the native, dimeric form of this protein), but others were found to cross-react within the dengue virus group. This latter group of MAbs, although dominated by MAbs defining a dengue 2 and 4 virus subgroup, also contained some MAbs that were shown to cross-react with both linear (sequential) and conformational epitopes common to the NS1 glycoproteins of all four dengue virus serotypes. Several of these MAbs were also able to cross-react with other flaviviruses, most notably viruses from the Japanese encephalitis antigenic complex. Although cross-reactive epitopes were previously demonstrated on this glycoprotein using polyclonal sera from dengue virus-infected animals and human, this is the first report of the isolation of MAbs which define these determinants and which will allow their further analysis.
TL;DR: Computer analysis revealed a 20-residue region of similarity in amino acid sequence between the dengue type 4 envelope glycoprotein (E) and a family of clotting factors, including plasminogen, the prime mediator of fibrinolysis, that is largely conserved within the currently known flavivirus E sequences.
Abstract: The four serotypes of dengue virus (a mosquito-borne flavivirus) cause an acute febrile illness (dengue fever) or a more prolonged illness with plasma leakage resulting in hypovolemia (dengue hemorrhagic fever). Hemorrhage may accompany either. Epidemiologic data suggest a role for dengue antibodies in pathogenesis. Computer analysis revealed a 20-residue region of similarity in amino acid sequence between the dengue type 4 envelope glycoprotein (E) and a family of clotting factors, including plasminogen, the prime mediator of fibrinolysis. By use of synthetic peptides in ELISA, E antibodies that potentially bind plasminogen were detected in 75% of 40 Thai patients acutely infected with dengue virus type 1, 2, 3, or 4. Plasminogen cross-reactivity of dengue antibodies was shown to be specific for the related sites in E and plasminogen. The dengue E sequence with similarity to plasminogen is largely conserved within the currently known flavivirus E sequences. However, 15 Thai patients hospitalized for illness caused by Japanese encephalitis virus (a flavivirus not associated with hemorrhage) did not develop plasminogen-cross-reactive antibodies, and this finding correlated with failure of Japanese encephalitis virus antibodies to bind to the plasminogen-cross-reactive site in E.
Journal Article•
TL;DR: Higher prevalence of dengue fever was noted among larger families and in families that had two or more patients, the commonest duration between the first and the last patient was often less than 5 days and concomitant entomological studies proved Aedes aegypti breeding.
Abstract: Outbreak of dengue fever in Chikalthana, Pimpalgaon and Waloor villages in Parbhani district of Maharashtra (India) were investigated. Clinically, the illness was typical of dengue fever except for the absence of maculopapular rash. A total of 42 acute, 14 late acute, 73 convalescent and 19 sera from contacts were collected. Of the 15 virus isolates, 12 were identified as dengue virus type 2 and 1 as dengue virus type 1. Serological tests confirmed the etiological role of dengue virus in the outbreak. House-to-house survey was carried out in Chikalthana and Pimpalgaon villages. Overall, 15.09 per cent of the surveyed population was affected during the outbreak and attack rate was higher at Pimpalgaon. A tendency of water storage was observed in the households and concomitant entomological studies proved Aedes aegypti breeding. Higher prevalence of dengue fever was noted among larger families and in families that had two or more patients, the commonest duration between the first and the last patient was often less than 5 days.
TL;DR: Studying the processing of flavivirus polyproteins in vitro by a viral proteinase located within protein NS3 that cleaves at least three sites within the nonstructural region of the polyprotein found that poly Proteins containing the yellow fever virus cleavage sites were processed efficiently and could be altered by site-directed mutagenesis of the proposed substrate-binding pocket.
Abstract: The proteins of flaviviruses are translated as a single long polyprotein which is co- and posttranslationally processed by both cellular and viral proteinases. We have studied the processing of flavivirus polyproteins in vitro by a viral proteinase located within protein NS3 that cleaves at least three sites within the nonstructural region of the polyprotein, acting primarily autocatalytically. Recombinant polyproteins in which part of the polyprotein is derived from yellow fever virus and part from dengue virus were used. We found that polyproteins containing the yellow fever virus cleavage sites were processed efficiently by the yellow fever virus enzyme, by the dengue virus enzyme, and by various chimeric enzymes. In contrast, dengue virus cleavage sites were cleaved inefficiently by the dengue virus enzyme and not at all by the yellow fever virus enzyme. Studies with chimeric proteinases and with site-directed mutants provided evidence for a direct interaction between the cleavage sites and the proposed substrate-binding pocket of the enzyme. We also found that the efficiency and order of processing could be altered by site-directed mutagenesis of the proposed substrate-binding pocket.
Journal Article•
TL;DR: The IgM capture ELISA is compared with the dot enzyme immunoassay and the results are discussed in the context of dengue endemicity.
Abstract: This study describes the use of an IgM capture ELISA using cell culture derived antigens and a polyclonal rabbit antiflavivirus antisera for the detection of dengue positive cases. The IgM capture ELISA is compared with the dot enzyme immunoassay and the results are discussed in the context of dengue endemicity.
TL;DR: In this paper, the authors compared the performance of the DEN-1 and DEN-4 parent (P) and progeny candidate vaccine (CV) viruses in Aedes aegypti and Aedes albopictus mosquitoes.
Abstract: Dengue (DEN-1) and DEN-4 parent (P) and progeny candidate vaccine (CV) viruses were compared in their abilities to infect and to replicate in Aedes aegypti and Aedes albopictus mosquitoes. The DEN CV clones were temperature sensitive (ts) and had small plaque morphology. The DEN-1 and DEN-4 CV viruses differed in their ability to infect, to replicate in, and to be transmitted by mosquitoes. The DEN-1 CV virus was not attenuated for the vector mosquitoes; oral infection rates with the CV virus were as high as or higher than the P virus, and the CV virus replicated efficiently in mosquitoes after oral infection. The DEN-4 CV virus was attenuated; it was less efficient than its P virus in infection and replication in mosquitoes. Thus, the ts phenotype and small plaque morphology are not reliable biological markers for prediction of vector attenuation. Similar results were reported by others for attenuation in man and monkeys. These studies with DEN-1 and DEN-4 viruses, and previously reported studies with DEN-2 virus and with DEN-3 virus suggest that vector and vertebrate host attenuation are genetically linked. Thus, vector attenuation may be a biological marker for human attenuation.
TL;DR: Extracts of Vero cells infected with dengue virus type 2 were digested by trypsin in the presence and absence of detergents to test the models proposed for flavivirus translation in which the glycoproteins prM, E, and NS1 are inserted into the endoplasmic reticulum of the cell whereas certain other nonstructural proteins are not.
Journal Article•
TL;DR: The data obtained show that the DEIA can be effectively used at a serum dilution of 1:1000 to confirm presumptive recent d Dengue in patients with a second dengue infection, however, demonstration of seroconversion proved necessary for patients with primary dengued.
Abstract: 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.
TL;DR: A part of the genome of dengue virus type 2 spanning the coding region from the carboxy terminus of the envelope protein E to the beginning of the NS3 protein was expressed using recombinant vaccinia virus as mentioned in this paper.
Abstract: A part of the genome of dengue virus type 2 spanning the coding region from the carboxy terminus of the envelope protein E to the beginning of the NS3 protein was expressed using recombinant vaccinia virus. Additional constructs which contained open reading frames terminating within the NS1 or NS2A genes were also expressed. NS1 dimers were formed by extended NS1 molecules containing 61 amino acids of NS2A. No dimers were detected when NS1 was shortened by 79 amino acids at its carboxy terminus.
TL;DR: From 1974 to 1989, sera from symptomatic patients with histories of recent travel outside Canada were tested for antibodies to several arboviruses, principally of the alphavirus and flavivirus families, including dengue virus.
Abstract: From 1974 to 1989, sera from symptomatic patients with histories of recent travel outside Canada were tested for antibodies to several arboviruses, principally of the alphavirus and flavivirus families. Diagnostic seroconversions were documented in 84 individuals from six provinces, including one alphavirus (Chikungunya) and 83 flavivirus seroconvertors. Dengue 1 virus was isolated from the blood of one patient. Most flavivirus seroconvertors were likely infected with dengue virus, but infections with tick-borne encephalitis, St Louis encephalitis and Powassan viruses were also recognized. Patients had histories of recent travel to the Caribbean, South America, Asia, Africa, North America (outside Canada), Tahiti, Fiji and Europe. Possible imported infections due to Japanese encephalitis, Ross River, western equine encephalitis and Colorado tick fever viruses were also encountered.
Journal Article•
TL;DR: Testing of the acute and convalescent serum samples obtained from cases showed a serological response to dengue virus, and health education on methods of Aedes control is continuing.
Abstract: In mid 1990, an epidemic of fever affected a single village in Kaniyambadi Block, South India. The illness was characterized by a fever of approximately five days duration, accompanied by headache, chills, sweating and muscle pain. The overall attack rate was 22.5 per cent. The attack rate was uniform across the various age groups and between the sexes. Testing of the acute and convalescent serum samples obtained from cases showed a serological response to dengue virus. The Aedes house index in the village was found to be 36 per cent with toilets serving as active breeding sites. Adjacent villages studied showed similarly high rates of Aedes prevalence, although no cases of the same fever were seen. Since previous exposure to dengue increases the risk for epidemics of dengue hemorrhagic fever and dengue shock syndrome, health education on methods of Aedes control is continuing.
Journal Article•
TL;DR: There probably is far more viral encephalitis due to JEV in Malaysia than the national figures reflect, and titers of antibodies against JEV and dengue virus antigens as determined by DEIA show that.
Abstract: This study describes the status of viral encephalitis in Perak, Malaysia during the year 1990. In addition, 14 cases selected from Penang and Perak during the years 1989 and 1990 are presented, with data showing titers of neutralizing antibodies against Japanese encephalitis virus (JEV) and dengue 2 virus, titers of antibodies against JEV and dengue virus antigens as determined by DEIA, and a comparison of these with the presence of IgM to JEV and dengue virus. These data show that there probably is far more viral encephalitis due to JEV in Malaysia than the national figures reflect.
TL;DR: The recombinant E protein would be especially useful for diagnostic purposes in regions where DEN and JE viruses co-circulate and can clearly differentiate DEN antibody from JE antibody.
Abstract: Truncated dengue-4 E protein was produced as a fusion protein in insect cells using a baculovirus expression vector to examine its usefulness as a diagnostic antigen. A peroxidase-anti-peroxidase (PAP) staining method was used to examine the immunoreactivity of the antigenic determinants in recombinant virus-infected Sf-9 cells with human sera obtained from dengue (DEN) and Japanese encephalitis (JE) endemic areas (41 sera from DEN patients and 39 sera from JE patients or individuals with high JE-antibody titers). The expressed E protein, in which one-third of the carboxy-terminal end was deleted, reacted with sera from DEN patients, but it failed to react or responded only faintly with sera from JE patients. The antibody titers obtained by the staining method correlated with those obtained by enzyme-linked immunosorbent assay (ELISA) (r = 0.64, P < 0.01). Calculation of the ratio (R) of the titer obtained by the PAP staining method to the ELISA titer can clearly differentiate DEN antibody from JE antibody (high R values in DEN sera and low R values in JE sera). The recombinant protein would be especially useful for diagnostic purposes in regions where DEN and JE viruses co-circulate.
Journal Article•
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TL;DR: The pathogenesis of the DHF/DSS can be considered to result from a delayed type hypersensitivity reaction where antigen-activated T lymphocytes release a variety of biologically active chemical mediators (lymphokines) producing the symptoms of shock and hemorrhage seen in these cases.
Abstract: Dengue fever is an acute and infectious disease produced by a togavirus. This clinical syndrome being benign or severe like the Dengue hemorrhagic fever and dengue shock syndrome (DHF/DSS), has been associated with a very high mortality rate specifically in children with different ages and those under 1 year of age from mothers having antibodies to dengue virus. Other groups with potential risk factors are those patients with chronic diseases like asthma, sickle cell anaemia and diabetes mellitus. Dengue virus show a highly tropism for endothelial reticulum system as the bone marrow, spleen, liver and lymph nodes where viral antigens can be demonstrated by several immunological methods. The pathogenesis of the DHF/DSS can be considered to result from a delayed type hypersensitivity reaction where antigen-activated T lymphocytes release a variety of biologically active chemical mediators (lymphokines) with further effects on blood clotting system and vascular permeability producing the symptoms of shock and hemorrhage seen in these cases. The rapid control and hospitalization of the patients allow them to get a fast recovery without any sequelae.
TL;DR: A ribonucleic acid (RNA) hybridization assay to identify cattle infected by bovine viral diarrhea virus (BVDV) is described and cross-reactivity to RNA extracts of border disease virus-infected cells was noted.
Abstract: A ribonucleic acid (RNA) hybridization assay to identify cattle infected by bovine viral diarrhea virus (BVDV) is described. The RNA probe was derived from the coding region at the 3' end of the genome of the NADL strain of BVDV. Total RNA from infected cell cultures or peripheral blood leukocytes from suspect animals was extracted and applied to nylon membranes with a slot blot apparatus. Peripheral blood leukocytes were tested concurrently for BVDV by virus isolation. The results of hybridization and virus isolation were in agreement for 92% of the cases. When compared with virus isolation, hybridization had a sensitivity of detection of 59.5% and a specificity of 95%. Cross-reactivity to RNA extracts of border disease virus-infected cells was noted. No cross-reactivity was detected to other common bovine viruses (bovine herpesvirus-l, bovine respiratory syncytial virus, parainfluenza-3 virus, and bluetongue virus), to viruses classified in related families (equine arteritis virus and Venezuelan equine encephalitis virus), or to viruses having similar genomic orga- nization (dengue virus type 2 and Japanese encephalitis virus). Bovine viral diarrhea virus (BVDV) is a nonarthro- pod-borne member of the Togaviridae, genus Pestivi- rus. It is a small (40-60 nm) enveloped 3,11 positive- sense RNA virus. 8 Bovine viral diarrhea virus has a worldwide distribution with reported serum antibody prevalence in cattle of 50-90%. 1 Infections caused by BVDV result in a significant financial loss to the beef and dairy industries annually. 15