Dear Editor,Dengue virus(DENV,family Flaviviridae,genus Flavivirus)serotypes 1 to 4(DENV-1,-2,-3,and-4)are responsible for more than 100 million infections per year worldwide.Symptoms of DENV infection can be diverse,...Dear Editor,Dengue virus(DENV,family Flaviviridae,genus Flavivirus)serotypes 1 to 4(DENV-1,-2,-3,and-4)are responsible for more than 100 million infections per year worldwide.Symptoms of DENV infection can be diverse,reaching from an acute febrile illness to the more severe,sometimes fatal dengue haemorrhagic fever/dengue shock syndrome.展开更多
Dengue fever is a mosquito-borne disease caused by four related but antigenically distinct dengue viruses. In the last half-century, the prevalence of dengue fever has increased dramatically (up to 30%) worldwide, esp...Dengue fever is a mosquito-borne disease caused by four related but antigenically distinct dengue viruses. In the last half-century, the prevalence of dengue fever has increased dramatically (up to 30%) worldwide, especially in Sub-Saharan Africa. In Burkina Faso, the last dengue epidemic occurred in 2016, and the epidemiological situation is still poorly documented at the national level. Therefore, the present study aimed to conduct a sentinel seroepidemiology of suspected dengue virus infections from 2017 to 2020 at Charles de Gaulle University Pediatric Hospital Center of Ouagadougou. This investigation was designed to be a descriptive and analytical study. Patients with suspected cases of dengue fever were recruited from January 2017 to December 2020 during general medicine consultation and referred to Charles de Gaulle University Pediatric Hospital Center of Ouagadougou for the serological diagnosis of dengue. Venous blood was collected in dry or EDTA tubes and tested for DENV NS1 antigen, anti-dengue IgM, and anti-dengue IgG using SD Bioline Dengue Duo Rapid Detection Kit (Standard Diagnostic Inc., Korea). A total of 3400 blood samples from clinically suspected dengue cases were analyzed, of which 1784 (52.5%) were males, and 1616 (47.5%) were females. Among the 3400 patients included in the study, 661 (19.4%) were tested at least positive for NS1 antigen, anti-dengue IgM or anti-IgG. Among them, individuals positive for IgG suggesting past dengue virus infection were found in more than a third of 262 (7.7%) of the cases. Approximately, 80.0% (2705/3400) dengue suspected cases and 85.5% (341/399) early or primary dengue infections were recorded in the last four months of the study (September to December 2020), with a peak in mid-October and mid-November. There was no statistically significant difference in seroprevalence between males and females (p = 0.7), but an increasing seropositivity trend with age, from 11.6% for the patient under 5 years group to 39.7% for 30 years and over age group were noted. This study puts in evidence a considerable level of transmission of dengue viruses in Burkina Faso and provides baseline seroprevalence data. The recurrent outbreaks of dengue infection in multiple geographical areas need comprehensive surveillance and a diagnostic system to identify the actual burden and pinpoint the risk factors. A larger study is, therefore, needed to determine the actual prevalence of dengue in Burkina Faso and map the serotypes.展开更多
Objective: To investigate the inhibitory effects against dengue virus serotype 2(DENV-2) by five different fractions(extracted by methanol, ethanol, benzene, chloroform and n-hexane) of Rumex dentatus, Commelina bengh...Objective: To investigate the inhibitory effects against dengue virus serotype 2(DENV-2) by five different fractions(extracted by methanol, ethanol, benzene, chloroform and n-hexane) of Rumex dentatus, Commelina benghalensis, Ajuga bracteosa and Ziziphus mauritiana, as well as their constituents(gallic acid, emodin, and isovanillic acid). Methods: All the samples were tested for cytotoxicity on baby hamster kidney cells by MTT assay and for anti-DENV-2 activity by plaque reduction neutralization assay using two DENV-2 doses(45 and 90 plaqueforming units or PFU). Results: All the samples except isovanillic acid exhibited significant prophylactic effects against DENV-2 infectivity(without cytotoxicity) when administered to cells before infection, but were not effective when given 6 h post-infection. The methanol extract of Rumex dentatus demonstrated the highest antiviral efficacy by inhibiting DENV-2 replication, with IC_(50) of 0.154 μg/mL and 0.234 μg/mL, when added before infection with 45 and 90 PFU of virus, respectively. Gallic acid also exhibited significant antiviral effects by prophylactic treatment prior to virus adsorption on cells, with IC_(50) of 0.191 μg/mL and 0.522 μg/mL at 45 and 90 PFU of DENV-2 infection, respectively. Conclusions: The highly potent activities of the extracts and constituent compounds of these plants against DENV-2 infectivity highlight their potential as targets for further research to identify novel antiviral agents against dengue.展开更多
Dengue virus(DENV)is one of the most important arboviral pathogens in the tropics and subtropics,and nearly one-third of the world's population is at risk of infection.The transmission of DENV involves a sylvatic ...Dengue virus(DENV)is one of the most important arboviral pathogens in the tropics and subtropics,and nearly one-third of the world's population is at risk of infection.The transmission of DENV involves a sylvatic cycle between nonhuman primates(NHP)and Aedes genus mosquitoes,and an endemic cycle between human hosts and predominantly Aedes aegypti.DENV belongs to the genus Flavivirus of the family Flaviviridae and consists of four antigenically distinct serotypes(DENV-1-4).Phylogenetic analyses of DENV have revealed its origin,epidemiology,and the drivers that determine its molecular evolution in nature.This review discusses how phyloge-netic research has improved our understanding of DENV evolution and how it affects viral ecology and improved our ability to analyze and predict future DENV emergence.展开更多
Dengue is a significant public health concern across tropical and subtropical regions worldwide,principally causing disease in children.Very young children are at increased risk of severe manifestations of dengue infe...Dengue is a significant public health concern across tropical and subtropical regions worldwide,principally causing disease in children.Very young children are at increased risk of severe manifestations of dengue infection.The mechanism of dengue disease in this population is not fully understood.In this study,we present a murine model of dengue virus primary infection in suckling C57BL/6 and BALB/c mice in order to investigate disease pathogenesis.Three-day-old C57BL/6 mice intraperitoneally infected with DENV-2 NGC were more susceptible to infection than BALB/c mice,showing increased liver enzymes,extended viremia,dissemination to organs and histological alterations in liver and small intestine.Furthermore,the immune response in DENV-infected C57BL/6 mice exhibited a marked Th1 bias compared to BALB/c mice.These findings highlight the possibility of establishing an immunocompetent mouse model of DENV-2 infection in suckling mice that reproduces certain signs of disease observed in humans and that could be used to further study agerelated mechanisms of dengue pathogenesis.展开更多
Objective: To identify the changes in the proteome of U937 cells infected with dengue virus(DENV).Methods: In this study, differentiated U937 cultures were infected with two DENV-2strains, one of which was associated ...Objective: To identify the changes in the proteome of U937 cells infected with dengue virus(DENV).Methods: In this study, differentiated U937 cultures were infected with two DENV-2strains, one of which was associated with dengue(DENV-2/NG) and the other one with severe dengue(DENV-2/16681), with the aim of determining the cellular proteomic profiles under different infection conditions. Cellular proteins were extracted and separated by two-dimensional electrophoresis, and those proteins with differential expression profiles were identified by mass spectrometry. The obtained results were correlated with cellular viability, the number of infectious viral particles, and the viral DNA/protein quantity.Results: In comparison with non-infected cultures, in the cells infected with the DENV-2/NG strain, nine proteins were expressed differentially(five were upregulated and four were downregulated); in those cultures infected with the DENV-2/16681 strain, six proteins were differentially expressed(two were downregulated and four were upregulated). The downregulated proteins included fatty acid-binding protein, heterogeneous nuclear ribonucleoprotein 1, protein disulfide isomerase, enolase 1, heat shock 70 k Da protein 9, phosphotyrosyl phosphatase, and annexin IV. The upregulated proteins included heat shock 90 k Da protein AA1, tubulin beta, enolase 1, pyruvate kinase,transaldolase and phospholipase C-alpha.Conclusions: Because the monocyte/macrophage lineage is critical for disease pathogenicity, additional studies on these proteins could provide a better understanding of the cellular response to DENV infection and could help identify new therapeutic targets against infection.展开更多
Objective:To investigate the involvement of Ca^(2+)in dengue virus(DENV)-infected human umbilical vein endothelial cells(HUVECs)and the disruption of endothelial integrity.Methods:HUVECs were infected with DENV-2 in t...Objective:To investigate the involvement of Ca^(2+)in dengue virus(DENV)-infected human umbilical vein endothelial cells(HUVECs)and the disruption of endothelial integrity.Methods:HUVECs were infected with DENV-2 in the presence of intracellular Ca^(2+)or endoplasmic reticulum Ca^(2+)chelators.Virus infectivity was measured by focus-forming assay and quantitative RT-PCR.Intracellular Ca^(2+)was measured using Fluo-4-AM dye.VE-cadherin and focal adhesion kinase(FAK)expressions were investigated by immunofluorescence and immunoblotting assays,respectively.Results:DENV infection increased intracellular cytosolic Ca^(2+)levels and caused disassembly of the adherens junction protein,VEcadherin as evidenced by decreased VE-cadherin expression at the periphery of DENV-2 infected HUVECs.Depletion of intracellular Ca^(2+)stores,particularly those of the endoplasmic reticulum Ca^(2+),significantly decreased DENV yield in HUVECs.Decreased virus yield following the depletion of intracellular Ca^(2+)was caused by the inhibition of viral entry into HUVECs and not the inhibition of viral binding or attachment.DENV-2 infection also resulted in Ca^(2+)-dependent activation of FAK.Conclusions:Intracellular Ca^(2+)is required for the early phases of DENV infection in endothelial cells.Increased cytosolic Ca^(2+)levels in endothelial cells during DENV infection activated FAK,disrupted adherens junctions and compromised barrier integrity.Thus,Ca^(2+)plays an important role in DENV infection in endothelial cells.展开更多
Objective: To evaluate the expression of DNA plasmid-harboring modified antibody gene that produces neutralizing human monoclonal antibodies against four serotypes of dengue virus(DENV) without enhancing activity in B...Objective: To evaluate the expression of DNA plasmid-harboring modified antibody gene that produces neutralizing human monoclonal antibodies against four serotypes of dengue virus(DENV) without enhancing activity in BALB/c mice. Methods: We constructed pFUSE-based vectors(pFUSE1 G7 C2hVH and pFUSE1 G7 C2hVL) containing genes encoding the variable domains of the heavy or light chain of the anti-dengue virus antibody 1 G7 C2, a human IgG1 that has been characterized for its neutralizing activity to DENV-1-4. Leucine(L) at positions 234 and 235 on the Fc CH2 domain in pFUSE1 G7 C2hVH was mutated to alanine(A)(LALA mutation) by site direct mutagenesis, and the new plasmid was termed pFUSE1 G7 C2hVHLALA. An equal amount of pFUSE1 G7 C2hVL and 1 G7 C2hG1-LALA plasmids were co-transfected into Chinese hamster ovary cells(CHO-K1) and a single dose of 100 μg 1 G7 C2hG1-LALA plasmid was intramuscularly injected, followed by electroporation in BALB/c mice. The secreted 1 G7 C2hG1-LALA antibodies in cell culture supernatant and mouse serum were examined for their biological functions, neutralization and enhancing activity. Results: The co-transfection of heavy-and light-chain 1 G7 C2hG1-LALA plasmids in CHO-K1 cells produced approximately 3 900 ng/mL human IgG and neutralized 90%-100% all four DENV, with no enhancing activity. Furthermore, the modified human IgG was produced more than 1 000 ng/mL in mouse serum on day 7 post plasmid injection and showed cross-neutralization to four DENV serotypes. Subsequently, antibody production and neutralization decreased rapidly. Nevertheless, the secreted neutralizing 1 G7 C2hG1-LALA in mouse serum demonstrated complete absence of enhancing activities to all DENV serotypes. Conclusions: These findings reveal that a new modified 1 G7 C2h G1-LALA expressing plasmid based on gene transfer is a possible therapeutic antibody candidate against DENV infection.展开更多
Dengue virus infections are increasing worldwide generally and in Asia,Central and South America and Africa,particularly.It poses a serious threat to the children population.The rapid and accurate diagnostic systems a...Dengue virus infections are increasing worldwide generally and in Asia,Central and South America and Africa,particularly.It poses a serious threat to the children population.The rapid and accurate diagnostic systems are essentially required due to lack of effective vaccine against dengue virus and the progressive spread of the dengue virus infection.The recent progress in developing micro-and nano-fabrication techniques has led to low cost and scale down the biomedical point-of-care devices.Starting from the conventional and modern available methods for the diagnosis of dengue infection,this review examines several emerging rapid and point-of-care diagnostic devices that hold significant potential for the progress in smart diagnosis tools.The given review revealed that an effective vaccine is required urgently against all the dengue virus serotypes.However,the rapid detection methods of dengue virus help in early treatment and significantly reduce the dengue virus outbreak.展开更多
Objectives: Dengue virus (DENV) infection is a mosquito-borne disease that stands out as one of the major public health issues and has a wide-ranging geographical distribution throughout the tropics and subtropics. Th...Objectives: Dengue virus (DENV) infection is a mosquito-borne disease that stands out as one of the major public health issues and has a wide-ranging geographical distribution throughout the tropics and subtropics. The general alarming increase in the number of cases over the last two decades can be attributed to an extent by the change in national practices to keeping records and reporting dengue to the Ministries of Health, and WHO. Dengue diagnosis is routinely carried out by detection of dengue virus (DENV) antigen NS1 (Non-structural Antigen 1) and/or anti-DENV IgM/IgG antibodies using enzyme-linked immunosorbent assays (ELISAs) and rapid diagnostic tests (RDTs). This study compared the performance of three RDTs and one ELISA used for dengue diagnosis in southeastern, Nigeria. Design: This study adopted a cross-sectional design that included prospective hospital-based surveillance of cases among febrile participants attending two major health facilities within the southeastern region of Nigeria. In this study, 338 HIV-infected participants from two teaching hospitals in Nigeria’s southeast were systematically tested for Dengue with four methods: NS1 RDT, IgG RDT, IgM RDT, and NS1 ELISA. Their specificities and sensitivities were compared, as well as their level of concordance. Their respective performances were also evaluated using the Receivers Operational curve (ROC). Results: Out of the 338 patients, the dengue prevalence from the four dengue diagnostic methods Dengue virus NS1 ELISA, NS1 RDT, IgM and IgG seropositivity were 8.9%, 0.6%, 5.6%, and 8.0%, respectively. The Dengue IgM RDT test indicated 36.8% sensitivity, 92.8% specificity, the IgG anti-dengue specific test indicated 29.6% sensitivity, 92.9% specificity and the dengue NS1 RDT test indicated 3.3% sensitivity, 99.4% specificity when compared with the Dengue NSI Elisa test method as a reference method. Conclusion: The use of NSI ELISA for DENV diagnosis showed good performance and the RDTs showed, to an extent, reliable results compared with ELISA. However, diagnostic laboratories should be aware of performance variations across tests and the possibilities of cross-reactivity that may affect results.展开更多
Obejective The domainⅢof dengue virus type 2 envelope was cloned and expressed in Escherichia coli and the inhibited effects of recombinant protein on virus was detected. Methods In this study, the domainⅢ(DⅢ) pro...Obejective The domainⅢof dengue virus type 2 envelope was cloned and expressed in Escherichia coli and the inhibited effects of recombinant protein on virus was detected. Methods In this study, the domainⅢ(DⅢ) protein of the dengue virus type-2 (DENV-2) envelope (E) antigen was expressed in Escherichia coli by fusion with a carrier protein. The protein was puriifed using enzymatic cleavage and afifnity puriifcation. Rabbit immunization and antibody detection was carried out. Inhibition of DENV-2 infection was observed by DENV-2 EDⅢprotein and its immunity rabbits serum. Results The recombinant expression DENV-2 EDⅢ protein plasmid was constructed successfully. After isopropyl thiogalactoside induction, a speciifc soluble 29 kD protein was obtained, and the expression product accounted for 68.87%of the total protein of the cell lysate. Western blot demonstrated the reactivity of the recombinant protein with his-tag and DENV (Ⅰ-Ⅳ) monoclonal antibodies. The protein was puriifed using enzymatic cleavage and affinity purification. The purified recombinant EDⅢ protein inhibited the entry of DENV-2 into BHK-21 cells. DENV-2 plaque neutralization assays were carried out using serially diluted antibodies against EDⅢprotein. At a 1︰16 dilution, the antibodies produced at least 90%neutralization of the DENV-2 virus. Furthermore, the antibodies continued to exhibit high neutralization effects (approximately 80%) until the anti-EDⅢantibody titer reached 1︰1 024. Conclusions DENV-2 EDⅢwas cloned and expressed successfully. DENV-2 EDⅢprotein could be useful in the development of inexpensive dengue vaccine. The data also suggested that DENV-2 employed an attachment molecule or receptor for its entry into C6/36 mosquito cells.展开更多
Objective:To evaluate the in vitro activities of the ethyl acetate(EA) fraction of Houttuynia cordata(H.cordata) Thunb.(Saururaceae) and three of its constituent flavonoids(quercetin.quercitrin and rutin) against muri...Objective:To evaluate the in vitro activities of the ethyl acetate(EA) fraction of Houttuynia cordata(H.cordata) Thunb.(Saururaceae) and three of its constituent flavonoids(quercetin.quercitrin and rutin) against murine coronavirus and dengue virus(DENV).Methods:The antiviral activities of various concentrations of the EA fraction of H.cordata and flavonoids were assessed using virus neutralization tests against mouse hepatitis virus(MHV) and DENV type 2(DENV-2).Cinanserin hydrochloride was also tested against MHV.The EA fraction of H.cordata was tested for acute oral toxicity in C57BL/6 mice.Results:The EA fraction of H.cordata inhibited viral infectivity up to 6 d.Cinanserin hydrochloride was able to inhibit MHV for only 2 d.The 50%inhibitory concentrations(IC_(50)) of the EA fraction of H.cordata added before the viral adsorption stage were 0.98 μg/mL for MHV and 7.50 μg/mL for DENV-2with absence of cytotoxicity.The mice fed with the EA fraction up to 2 000 mg/kg did not induce any signs of acute toxicity,with normal histological features of major organs.Certain flavonoids exhibited comparatively weaker antiviral activity,notably quercetin which could inhibit both MHV and DENV-2.This was followed by quercitrin which could inhibit DENV-2but not MHV,whereas rutin did not exert any inhibitory effect on either virus.When quercetin was combined with quercitrin,enhancement of anti-DENV-2 activity and reduced cytotoxicity were observed.However,the synergistic efficacy of the flavonoid combination was still less than that of the EA fraction.Conclusions:The compounds in H.cordata contribute to the superior antiviral efficacy of the EA fraction which lacked cytotoxicity in vitro and acute toxicity in vim.H.cordata has much potential for the development of antiviral agents against coronavirus and dengue infections.展开更多
Dengue virus infection has become a global threat affecting around 100 countries in the world.Currently,there is no licensed antiviral agent available against dengue.Thus,there is a strong need to develop therapeutic ...Dengue virus infection has become a global threat affecting around 100 countries in the world.Currently,there is no licensed antiviral agent available against dengue.Thus,there is a strong need to develop therapeutic strategies that can tackle this life threatening disease.RNA interference is an important and effective gene silencing process which degrades targeted RNA by a sequence specific process.Several studies have been conducted during the last decade to evaluate the efficiency of siRNA in inhibiting dengue virus replication.This review summarizes siRNAs as a therapeutic approach against dengue virus serotypes and concludes that siRNAs against virus and host genes can be next generation treatment of dengue virus infection.展开更多
Objective:To develop diagnostic test for detection chikungunya virus(CHIKV and Dengue virus (DENV) infection.Methods:We have performed a rapid,accurate laboratory confirmative method to simultaneously detect,quantify ...Objective:To develop diagnostic test for detection chikungunya virus(CHIKV and Dengue virus (DENV) infection.Methods:We have performed a rapid,accurate laboratory confirmative method to simultaneously detect,quantify and differentiate CHIKV and DENV infection by single-step multiplex real-time RT-PCR.Results:The assay’s sensitivity was 97.65%,specificity was 92.59% and accuracy was 95.82%when compared to conventional RT-PCR.Additionally,there was no cross-reaction between CHIKV,DENV,Japanese encephalitis virus,hepatitis C,hepatitis A or hepatitis E virus.Conclusions:This rapid and reliable assay provides a means for simultaneous early diagnosis of CHIKV and DENV in a single-step reaction.展开更多
Objective: To describe the clinical manifestation of patient with severe dengue, to identify the serotypes and genotypes of dengue viruses(DENV) which concurrently infecting the patient, and to explore the possible re...Objective: To describe the clinical manifestation of patient with severe dengue, to identify the serotypes and genotypes of dengue viruses(DENV) which concurrently infecting the patient, and to explore the possible relationship of severe dengue with the concurrent infection of DENV. Methods: Dengue diagnosis was performed using NS1 antigen detection and Ig G/Ig M ELISA. Standard clinical and laboratory examinations were performed to obtain the clinical and hematological data. DENV concurrent infections were detected and confirmed using RT-PCR and DENV Envelope gene sequencing. Phylogenetic analyses were performed to determine the genotypes of the viruses. Results: The patient was classified as having severe dengue characterized by severe plasma leakage, hemorrhage, and organ damage involving lung, liver, and kidney. Concurrent infection of DENV serotype 2 and 3 was observed. The infecting DENV-2 virus was grouped into Cosmopolitan genotype while DENV-3 virus was classified into Genotype Ⅰ. Both viruses were closely related to isolates that were endemic in Jakarta. Viremia measurement was conducted and revealed a significantly higher virus titer of DENV-3 compared to DENV-2. Conclusions: The occurrence of multi-serotype DENV infections was presented in a patient with severe clinical manifestation in Indonesia. The hyperendemicity of dengue in Indonesia may contribute to the DENV concurrent infections cases and may underlie the severity of the disease.展开更多
Dengue virus(DENV) has emerged as a major virus that is spread by mosquitoes. Recently, it has spread to more than a hundred nations but continues to lack specific treatable medication. Many traditional Chinese medici...Dengue virus(DENV) has emerged as a major virus that is spread by mosquitoes. Recently, it has spread to more than a hundred nations but continues to lack specific treatable medication. Many traditional Chinese medicinal(TCM) plants are in practice for dengue fever in dengue endemic regions. These traditional medicines persevere with treatments, which modern medicines lack. The study aims to substantiate the anti-dengue potential of some traditional herbs and make them available for further studies to facilitate TCM users. Twelve TCM plants aqueous extracts were evaluated, which are described as cool herbs used for the diseases with high fever. Lead plants were established through detailed in vitro foci forming unit reduction analysis(FFURA) against all four serotypes and validated through quantitative real-time RT-PCR(q RT-PCR). Four plants potentially inhibited the virus in primary phenotypic in vitro evaluation. Two lead plants Dryopteris crassirhizoma(DC) and Morus alba(MA) were identified with half minimal inhibitory concentration(IC50) 130 and 221 μg m L^-1, respectively, while the selectivity indices(SI) were 4.21 and 4.62, respectively. Lead plants equally inhibited all four serotypes of DENV. Time-of-addition analysis suggested that, DC was active at later stages of viral replication, whereas MA was active during the early stages and even showed some prophylactic activity. Liquid chromatography-mass spectrometry(HPLC/MS) analysis revealed presence of flavonoids. DC and MA are identified as potential anti-dengue plants, active against varied stages of dengue virus replication cycle. These results may serve as the base knowledge for further investigation on their combined treatments or integrative treatment with western medicines, which may improve the overall anti-dengue activity in future.展开更多
The risk of dengue virus transmission via blood transfusion is confirmed.As a similar virus,the risk for the case of Zika virus should be mentioned.Here,the authors calculated for the risk of Zika virus transmission v...The risk of dengue virus transmission via blood transfusion is confirmed.As a similar virus,the risk for the case of Zika virus should be mentioned.Here,the authors calculated for the risk of Zika virus transmission via blood transmission referring to the previous data on the risk in case of dengue virus.展开更多
Dengue virus(DENV) nonstructural protein 1(NS1) is a highly conserved 46-kDa protein that contains 2 glycosylation sites(Asn-130 and Asn-207) and 12 conserved cysteine(Cys) residues. Here, we performed site-directed m...Dengue virus(DENV) nonstructural protein 1(NS1) is a highly conserved 46-kDa protein that contains 2 glycosylation sites(Asn-130 and Asn-207) and 12 conserved cysteine(Cys) residues. Here, we performed site-directed mutagenesis to generate systematic mutants of viral strain TSV01. The results of the subsequent analysis showed that an alanine substitution at the second N-linked glycan Asn-207 in NS1 delayed viral RNA synthesis, reduced virus plaque size, and weakened the cytopathic effect. Three mutants at Cys sites(Cys-4, Cys-55, Cys-291) and a C-terminal deletion(ΔC) mutant significantly impaired RNA synthesis, and consequently abolished viral growth, whereas alanine mutations at Asn-130 and Glu-173 resulted in phenotypes that were similar to the wild-type(WT) virus. Further analysis showed that the Asn-207 mutation slightly delayed viral replication. These results suggest that the three conserved disulfide bonds and the second N-linked glycan in NS1 are required for DENV-2 replication.展开更多
The major envelope glycoprotein E of dengue (DEN) virus plays a central role in the biology of flaviviruses. It is capable of inducing a protective immune response in vivo and responsible for the viral binding to the ...The major envelope glycoprotein E of dengue (DEN) virus plays a central role in the biology of flaviviruses. It is capable of inducing a protective immune response in vivo and responsible for the viral binding to the cellular receptor. The crystal structures of glycoprotein E ectodomains have already been determined. However, it is still un-clear where the well-defined B-cell epitopes for glycoprotein E which induce the neutralizing an-tibodies locates. Thus, in order to characterize the role of glycoprotein E in the pathogenesis of dengue virus infection, we first used network servers (http://bio.dfci. harvard.edu/Tools/ &http://www. imtech. res. in) to predict and analyze the well defined B-cell and T-cell epitopes of the glycoprotein of the DEN-1 HAWAII strain. Then based on the highly conserved envelop glyco-protein amino acids, the hydrophilicity, antigenic-ity, accessibility and flexibility of envelop glyco-protein E were further predicted by using Biotic softwares (DNASTAR) and network servers (http://bio. dfci.harvard.edu/Tools/), the secondary structure was putatively obtained. In our study, the sequence at 281-295 amino acid (aa) for den-gue virus type 1 HAWAII strain and the sequence at 345-359, 383-397 for dengue virus type 2 NGC strain were predicted as the more prevalent epi-topes by using multiple parameters and different analysis softwares, respectively. Two epitopes of DEN-2 and one of DEN-1 locate on the domain Ш and domainⅡ of the protein E, respectively. Sub-sequently, further studies will be carried out to examine the antigenicity and protection of the synthetic peptides with higher scores in the av-erage antigen index (AI) and better hydrophilic properties determined by our data.展开更多
Global incidence of dengue, a vector-borne tropical disease, has seen a dramatic increase with several major outbreaks in the past few decades. We formulate and analyze a stochastic epidemic model for the transmission...Global incidence of dengue, a vector-borne tropical disease, has seen a dramatic increase with several major outbreaks in the past few decades. We formulate and analyze a stochastic epidemic model for the transmission dynamics of a single strain of dengue virus. The stochastic model is constructed using a continuous time Markov chain (CTMC) and is based on an existing deterministic model that suggests the existence of a backward bifurcation for some values of the model parameters. The dynamics of the stochastic model are explored through numerical simulations in this region of bistability. The mean of each random variable is numerically estimated and these are compared to the dynamics of the deterministic model. It is observed that the stochastic model also predicts the co-existence of a locally asymptotically stable disease-free equilibrium along with a locally stable endemic equilibrium. This co-existence of equilibria is important from a public health perspective because it implies that dengue can persist in populations even if the value of the basic reproduction number is less than unity.展开更多
基金Supported by the German Research Foundation (JO 1276/5-1)the Federal Ministry of Education and Research of Germany (BMBF) under the project NEED (01Kl2022).
文摘Dear Editor,Dengue virus(DENV,family Flaviviridae,genus Flavivirus)serotypes 1 to 4(DENV-1,-2,-3,and-4)are responsible for more than 100 million infections per year worldwide.Symptoms of DENV infection can be diverse,reaching from an acute febrile illness to the more severe,sometimes fatal dengue haemorrhagic fever/dengue shock syndrome.
文摘Dengue fever is a mosquito-borne disease caused by four related but antigenically distinct dengue viruses. In the last half-century, the prevalence of dengue fever has increased dramatically (up to 30%) worldwide, especially in Sub-Saharan Africa. In Burkina Faso, the last dengue epidemic occurred in 2016, and the epidemiological situation is still poorly documented at the national level. Therefore, the present study aimed to conduct a sentinel seroepidemiology of suspected dengue virus infections from 2017 to 2020 at Charles de Gaulle University Pediatric Hospital Center of Ouagadougou. This investigation was designed to be a descriptive and analytical study. Patients with suspected cases of dengue fever were recruited from January 2017 to December 2020 during general medicine consultation and referred to Charles de Gaulle University Pediatric Hospital Center of Ouagadougou for the serological diagnosis of dengue. Venous blood was collected in dry or EDTA tubes and tested for DENV NS1 antigen, anti-dengue IgM, and anti-dengue IgG using SD Bioline Dengue Duo Rapid Detection Kit (Standard Diagnostic Inc., Korea). A total of 3400 blood samples from clinically suspected dengue cases were analyzed, of which 1784 (52.5%) were males, and 1616 (47.5%) were females. Among the 3400 patients included in the study, 661 (19.4%) were tested at least positive for NS1 antigen, anti-dengue IgM or anti-IgG. Among them, individuals positive for IgG suggesting past dengue virus infection were found in more than a third of 262 (7.7%) of the cases. Approximately, 80.0% (2705/3400) dengue suspected cases and 85.5% (341/399) early or primary dengue infections were recorded in the last four months of the study (September to December 2020), with a peak in mid-October and mid-November. There was no statistically significant difference in seroprevalence between males and females (p = 0.7), but an increasing seropositivity trend with age, from 11.6% for the patient under 5 years group to 39.7% for 30 years and over age group were noted. This study puts in evidence a considerable level of transmission of dengue viruses in Burkina Faso and provides baseline seroprevalence data. The recurrent outbreaks of dengue infection in multiple geographical areas need comprehensive surveillance and a diagnostic system to identify the actual burden and pinpoint the risk factors. A larger study is, therefore, needed to determine the actual prevalence of dengue in Burkina Faso and map the serotypes.
基金support of the National University of SingaporeQuaid-i-Azam University
文摘Objective: To investigate the inhibitory effects against dengue virus serotype 2(DENV-2) by five different fractions(extracted by methanol, ethanol, benzene, chloroform and n-hexane) of Rumex dentatus, Commelina benghalensis, Ajuga bracteosa and Ziziphus mauritiana, as well as their constituents(gallic acid, emodin, and isovanillic acid). Methods: All the samples were tested for cytotoxicity on baby hamster kidney cells by MTT assay and for anti-DENV-2 activity by plaque reduction neutralization assay using two DENV-2 doses(45 and 90 plaqueforming units or PFU). Results: All the samples except isovanillic acid exhibited significant prophylactic effects against DENV-2 infectivity(without cytotoxicity) when administered to cells before infection, but were not effective when given 6 h post-infection. The methanol extract of Rumex dentatus demonstrated the highest antiviral efficacy by inhibiting DENV-2 replication, with IC_(50) of 0.154 μg/mL and 0.234 μg/mL, when added before infection with 45 and 90 PFU of virus, respectively. Gallic acid also exhibited significant antiviral effects by prophylactic treatment prior to virus adsorption on cells, with IC_(50) of 0.191 μg/mL and 0.522 μg/mL at 45 and 90 PFU of DENV-2 infection, respectively. Conclusions: The highly potent activities of the extracts and constituent compounds of these plants against DENV-2 infectivity highlight their potential as targets for further research to identify novel antiviral agents against dengue.
基金National Key Research and Development Plan of China,Grant/Award Number:2018YFA0507202,2020YFC1200100 and 2021YFC2300200National Natural Science Foundation of China,Grant/Award Number:31825001,32188101,81730063,81961160737 and 82102389+5 种基金Provincial Innovation Team for the Prevention and Control of Highly Pathogenic Pathogens,Institute of Medical Biology,Chinese Academy of Medical Sciences,Grant/Award Number:202105AE160020Shenzhen San-Ming Project for Prevention and Research on Vector-borne Diseases,Grant/Award Number:SZSM201611064Shenzhen Science and Technology Project,Grant/Award Number:JSGG20191129144225464Tsinghua University Spring Breeze Fund,Grant/Award Number:2020Z99CFG017Young Elite Scientists Sponsorship Program,Grant/Award Number:2021QNRC001Yunnan Cheng Gong Expert Work-Station,Grant/Award Number:202005AF150034。
文摘Dengue virus(DENV)is one of the most important arboviral pathogens in the tropics and subtropics,and nearly one-third of the world's population is at risk of infection.The transmission of DENV involves a sylvatic cycle between nonhuman primates(NHP)and Aedes genus mosquitoes,and an endemic cycle between human hosts and predominantly Aedes aegypti.DENV belongs to the genus Flavivirus of the family Flaviviridae and consists of four antigenically distinct serotypes(DENV-1-4).Phylogenetic analyses of DENV have revealed its origin,epidemiology,and the drivers that determine its molecular evolution in nature.This review discusses how phyloge-netic research has improved our understanding of DENV evolution and how it affects viral ecology and improved our ability to analyze and predict future DENV emergence.
基金Consejo Nacional de Investigaciones Científicas y Técnicas,Grant/Award Number:PIP0118UBS Optimus Foundation,Grant/Award Number:ID 2007-00206+1 种基金Fundación Bunge y BornFondo para la Investigación Científica y Tecnológica,Grant/Award Number:PICT2008-1073。
文摘Dengue is a significant public health concern across tropical and subtropical regions worldwide,principally causing disease in children.Very young children are at increased risk of severe manifestations of dengue infection.The mechanism of dengue disease in this population is not fully understood.In this study,we present a murine model of dengue virus primary infection in suckling C57BL/6 and BALB/c mice in order to investigate disease pathogenesis.Three-day-old C57BL/6 mice intraperitoneally infected with DENV-2 NGC were more susceptible to infection than BALB/c mice,showing increased liver enzymes,extended viremia,dissemination to organs and histological alterations in liver and small intestine.Furthermore,the immune response in DENV-infected C57BL/6 mice exhibited a marked Th1 bias compared to BALB/c mice.These findings highlight the possibility of establishing an immunocompetent mouse model of DENV-2 infection in suckling mice that reproduces certain signs of disease observed in humans and that could be used to further study agerelated mechanisms of dengue pathogenesis.
基金Supported by the Administrative Department of Science,Technology,and Research-COLCIENCIAS(Projects 111549326092 and 111549326083)
文摘Objective: To identify the changes in the proteome of U937 cells infected with dengue virus(DENV).Methods: In this study, differentiated U937 cultures were infected with two DENV-2strains, one of which was associated with dengue(DENV-2/NG) and the other one with severe dengue(DENV-2/16681), with the aim of determining the cellular proteomic profiles under different infection conditions. Cellular proteins were extracted and separated by two-dimensional electrophoresis, and those proteins with differential expression profiles were identified by mass spectrometry. The obtained results were correlated with cellular viability, the number of infectious viral particles, and the viral DNA/protein quantity.Results: In comparison with non-infected cultures, in the cells infected with the DENV-2/NG strain, nine proteins were expressed differentially(five were upregulated and four were downregulated); in those cultures infected with the DENV-2/16681 strain, six proteins were differentially expressed(two were downregulated and four were upregulated). The downregulated proteins included fatty acid-binding protein, heterogeneous nuclear ribonucleoprotein 1, protein disulfide isomerase, enolase 1, heat shock 70 k Da protein 9, phosphotyrosyl phosphatase, and annexin IV. The upregulated proteins included heat shock 90 k Da protein AA1, tubulin beta, enolase 1, pyruvate kinase,transaldolase and phospholipase C-alpha.Conclusions: Because the monocyte/macrophage lineage is critical for disease pathogenicity, additional studies on these proteins could provide a better understanding of the cellular response to DENV infection and could help identify new therapeutic targets against infection.
基金funding from the Ministry of Higher Education Malaysia via the Higher Institution Centre of Excellence(HICo E)program(MO002-2019)Development of Research Institute for Excellent Enterprises(ATC+)Project,Republic of Korea(IF001-2021)
文摘Objective:To investigate the involvement of Ca^(2+)in dengue virus(DENV)-infected human umbilical vein endothelial cells(HUVECs)and the disruption of endothelial integrity.Methods:HUVECs were infected with DENV-2 in the presence of intracellular Ca^(2+)or endoplasmic reticulum Ca^(2+)chelators.Virus infectivity was measured by focus-forming assay and quantitative RT-PCR.Intracellular Ca^(2+)was measured using Fluo-4-AM dye.VE-cadherin and focal adhesion kinase(FAK)expressions were investigated by immunofluorescence and immunoblotting assays,respectively.Results:DENV infection increased intracellular cytosolic Ca^(2+)levels and caused disassembly of the adherens junction protein,VEcadherin as evidenced by decreased VE-cadherin expression at the periphery of DENV-2 infected HUVECs.Depletion of intracellular Ca^(2+)stores,particularly those of the endoplasmic reticulum Ca^(2+),significantly decreased DENV yield in HUVECs.Decreased virus yield following the depletion of intracellular Ca^(2+)was caused by the inhibition of viral entry into HUVECs and not the inhibition of viral binding or attachment.DENV-2 infection also resulted in Ca^(2+)-dependent activation of FAK.Conclusions:Intracellular Ca^(2+)is required for the early phases of DENV infection in endothelial cells.Increased cytosolic Ca^(2+)levels in endothelial cells during DENV infection activated FAK,disrupted adherens junctions and compromised barrier integrity.Thus,Ca^(2+)plays an important role in DENV infection in endothelial cells.
基金supported by the Faculty of Tropical Medicine,Mahidol University,Thailand,Research Fund through a Research and Researcher for Industry(RRi,Grant Number PHD59I0063 for SB)TRF Grant for New Researcher(TRG,Grant Number TRG5980015 for CP)the Office of the National Research Council of Thailand-Japan Society for the Promotion of Science(JSPS)or NRCT-JSPS
文摘Objective: To evaluate the expression of DNA plasmid-harboring modified antibody gene that produces neutralizing human monoclonal antibodies against four serotypes of dengue virus(DENV) without enhancing activity in BALB/c mice. Methods: We constructed pFUSE-based vectors(pFUSE1 G7 C2hVH and pFUSE1 G7 C2hVL) containing genes encoding the variable domains of the heavy or light chain of the anti-dengue virus antibody 1 G7 C2, a human IgG1 that has been characterized for its neutralizing activity to DENV-1-4. Leucine(L) at positions 234 and 235 on the Fc CH2 domain in pFUSE1 G7 C2hVH was mutated to alanine(A)(LALA mutation) by site direct mutagenesis, and the new plasmid was termed pFUSE1 G7 C2hVHLALA. An equal amount of pFUSE1 G7 C2hVL and 1 G7 C2hG1-LALA plasmids were co-transfected into Chinese hamster ovary cells(CHO-K1) and a single dose of 100 μg 1 G7 C2hG1-LALA plasmid was intramuscularly injected, followed by electroporation in BALB/c mice. The secreted 1 G7 C2hG1-LALA antibodies in cell culture supernatant and mouse serum were examined for their biological functions, neutralization and enhancing activity. Results: The co-transfection of heavy-and light-chain 1 G7 C2hG1-LALA plasmids in CHO-K1 cells produced approximately 3 900 ng/mL human IgG and neutralized 90%-100% all four DENV, with no enhancing activity. Furthermore, the modified human IgG was produced more than 1 000 ng/mL in mouse serum on day 7 post plasmid injection and showed cross-neutralization to four DENV serotypes. Subsequently, antibody production and neutralization decreased rapidly. Nevertheless, the secreted neutralizing 1 G7 C2hG1-LALA in mouse serum demonstrated complete absence of enhancing activities to all DENV serotypes. Conclusions: These findings reveal that a new modified 1 G7 C2h G1-LALA expressing plasmid based on gene transfer is a possible therapeutic antibody candidate against DENV infection.
基金supported by the Scientific Research Fund of the Shenzhen International cooperation projects under Grant Nos.(GJHZ20190819151403615)the Natural Science Youth Foundation of China(61801307).
文摘Dengue virus infections are increasing worldwide generally and in Asia,Central and South America and Africa,particularly.It poses a serious threat to the children population.The rapid and accurate diagnostic systems are essentially required due to lack of effective vaccine against dengue virus and the progressive spread of the dengue virus infection.The recent progress in developing micro-and nano-fabrication techniques has led to low cost and scale down the biomedical point-of-care devices.Starting from the conventional and modern available methods for the diagnosis of dengue infection,this review examines several emerging rapid and point-of-care diagnostic devices that hold significant potential for the progress in smart diagnosis tools.The given review revealed that an effective vaccine is required urgently against all the dengue virus serotypes.However,the rapid detection methods of dengue virus help in early treatment and significantly reduce the dengue virus outbreak.
文摘Objectives: Dengue virus (DENV) infection is a mosquito-borne disease that stands out as one of the major public health issues and has a wide-ranging geographical distribution throughout the tropics and subtropics. The general alarming increase in the number of cases over the last two decades can be attributed to an extent by the change in national practices to keeping records and reporting dengue to the Ministries of Health, and WHO. Dengue diagnosis is routinely carried out by detection of dengue virus (DENV) antigen NS1 (Non-structural Antigen 1) and/or anti-DENV IgM/IgG antibodies using enzyme-linked immunosorbent assays (ELISAs) and rapid diagnostic tests (RDTs). This study compared the performance of three RDTs and one ELISA used for dengue diagnosis in southeastern, Nigeria. Design: This study adopted a cross-sectional design that included prospective hospital-based surveillance of cases among febrile participants attending two major health facilities within the southeastern region of Nigeria. In this study, 338 HIV-infected participants from two teaching hospitals in Nigeria’s southeast were systematically tested for Dengue with four methods: NS1 RDT, IgG RDT, IgM RDT, and NS1 ELISA. Their specificities and sensitivities were compared, as well as their level of concordance. Their respective performances were also evaluated using the Receivers Operational curve (ROC). Results: Out of the 338 patients, the dengue prevalence from the four dengue diagnostic methods Dengue virus NS1 ELISA, NS1 RDT, IgM and IgG seropositivity were 8.9%, 0.6%, 5.6%, and 8.0%, respectively. The Dengue IgM RDT test indicated 36.8% sensitivity, 92.8% specificity, the IgG anti-dengue specific test indicated 29.6% sensitivity, 92.9% specificity and the dengue NS1 RDT test indicated 3.3% sensitivity, 99.4% specificity when compared with the Dengue NSI Elisa test method as a reference method. Conclusion: The use of NSI ELISA for DENV diagnosis showed good performance and the RDTs showed, to an extent, reliable results compared with ELISA. However, diagnostic laboratories should be aware of performance variations across tests and the possibilities of cross-reactivity that may affect results.
基金supported by grants from the National Natural Science Foundation of China (30872198 30972566)
文摘Obejective The domainⅢof dengue virus type 2 envelope was cloned and expressed in Escherichia coli and the inhibited effects of recombinant protein on virus was detected. Methods In this study, the domainⅢ(DⅢ) protein of the dengue virus type-2 (DENV-2) envelope (E) antigen was expressed in Escherichia coli by fusion with a carrier protein. The protein was puriifed using enzymatic cleavage and afifnity puriifcation. Rabbit immunization and antibody detection was carried out. Inhibition of DENV-2 infection was observed by DENV-2 EDⅢprotein and its immunity rabbits serum. Results The recombinant expression DENV-2 EDⅢ protein plasmid was constructed successfully. After isopropyl thiogalactoside induction, a speciifc soluble 29 kD protein was obtained, and the expression product accounted for 68.87%of the total protein of the cell lysate. Western blot demonstrated the reactivity of the recombinant protein with his-tag and DENV (Ⅰ-Ⅳ) monoclonal antibodies. The protein was puriifed using enzymatic cleavage and affinity purification. The purified recombinant EDⅢ protein inhibited the entry of DENV-2 into BHK-21 cells. DENV-2 plaque neutralization assays were carried out using serially diluted antibodies against EDⅢprotein. At a 1︰16 dilution, the antibodies produced at least 90%neutralization of the DENV-2 virus. Furthermore, the antibodies continued to exhibit high neutralization effects (approximately 80%) until the anti-EDⅢantibody titer reached 1︰1 024. Conclusions DENV-2 EDⅢwas cloned and expressed successfully. DENV-2 EDⅢprotein could be useful in the development of inexpensive dengue vaccine. The data also suggested that DENV-2 employed an attachment molecule or receptor for its entry into C6/36 mosquito cells.
基金supported by a research grant from the National University of Singapore
文摘Objective:To evaluate the in vitro activities of the ethyl acetate(EA) fraction of Houttuynia cordata(H.cordata) Thunb.(Saururaceae) and three of its constituent flavonoids(quercetin.quercitrin and rutin) against murine coronavirus and dengue virus(DENV).Methods:The antiviral activities of various concentrations of the EA fraction of H.cordata and flavonoids were assessed using virus neutralization tests against mouse hepatitis virus(MHV) and DENV type 2(DENV-2).Cinanserin hydrochloride was also tested against MHV.The EA fraction of H.cordata was tested for acute oral toxicity in C57BL/6 mice.Results:The EA fraction of H.cordata inhibited viral infectivity up to 6 d.Cinanserin hydrochloride was able to inhibit MHV for only 2 d.The 50%inhibitory concentrations(IC_(50)) of the EA fraction of H.cordata added before the viral adsorption stage were 0.98 μg/mL for MHV and 7.50 μg/mL for DENV-2with absence of cytotoxicity.The mice fed with the EA fraction up to 2 000 mg/kg did not induce any signs of acute toxicity,with normal histological features of major organs.Certain flavonoids exhibited comparatively weaker antiviral activity,notably quercetin which could inhibit both MHV and DENV-2.This was followed by quercitrin which could inhibit DENV-2but not MHV,whereas rutin did not exert any inhibitory effect on either virus.When quercetin was combined with quercitrin,enhancement of anti-DENV-2 activity and reduced cytotoxicity were observed.However,the synergistic efficacy of the flavonoid combination was still less than that of the EA fraction.Conclusions:The compounds in H.cordata contribute to the superior antiviral efficacy of the EA fraction which lacked cytotoxicity in vitro and acute toxicity in vim.H.cordata has much potential for the development of antiviral agents against coronavirus and dengue infections.
基金Supported by Higher Education Commission (HEC) with Grant#PM-IPFP/HRD/HEC/2012/2770
文摘Dengue virus infection has become a global threat affecting around 100 countries in the world.Currently,there is no licensed antiviral agent available against dengue.Thus,there is a strong need to develop therapeutic strategies that can tackle this life threatening disease.RNA interference is an important and effective gene silencing process which degrades targeted RNA by a sequence specific process.Several studies have been conducted during the last decade to evaluate the efficiency of siRNA in inhibiting dengue virus replication.This review summarizes siRNAs as a therapeutic approach against dengue virus serotypes and concludes that siRNAs against virus and host genes can be next generation treatment of dengue virus infection.
基金supported by the Center of Excellence in Clinical Virology.Chulalongkorn University,CU Centenary Academic Development ProjectKing Chulalongkorn Memorial Hospital,the National Research University Project of CHEthe Ratchadaphiseksonphot Endowment Fund(HR1155A)
文摘Objective:To develop diagnostic test for detection chikungunya virus(CHIKV and Dengue virus (DENV) infection.Methods:We have performed a rapid,accurate laboratory confirmative method to simultaneously detect,quantify and differentiate CHIKV and DENV infection by single-step multiplex real-time RT-PCR.Results:The assay’s sensitivity was 97.65%,specificity was 92.59% and accuracy was 95.82%when compared to conventional RT-PCR.Additionally,there was no cross-reaction between CHIKV,DENV,Japanese encephalitis virus,hepatitis C,hepatitis A or hepatitis E virus.Conclusions:This rapid and reliable assay provides a means for simultaneous early diagnosis of CHIKV and DENV in a single-step reaction.
文摘Objective: To describe the clinical manifestation of patient with severe dengue, to identify the serotypes and genotypes of dengue viruses(DENV) which concurrently infecting the patient, and to explore the possible relationship of severe dengue with the concurrent infection of DENV. Methods: Dengue diagnosis was performed using NS1 antigen detection and Ig G/Ig M ELISA. Standard clinical and laboratory examinations were performed to obtain the clinical and hematological data. DENV concurrent infections were detected and confirmed using RT-PCR and DENV Envelope gene sequencing. Phylogenetic analyses were performed to determine the genotypes of the viruses. Results: The patient was classified as having severe dengue characterized by severe plasma leakage, hemorrhage, and organ damage involving lung, liver, and kidney. Concurrent infection of DENV serotype 2 and 3 was observed. The infecting DENV-2 virus was grouped into Cosmopolitan genotype while DENV-3 virus was classified into Genotype Ⅰ. Both viruses were closely related to isolates that were endemic in Jakarta. Viremia measurement was conducted and revealed a significantly higher virus titer of DENV-3 compared to DENV-2. Conclusions: The occurrence of multi-serotype DENV infections was presented in a patient with severe clinical manifestation in Indonesia. The hyperendemicity of dengue in Indonesia may contribute to the DENV concurrent infections cases and may underlie the severity of the disease.
基金the Universiti Tunku Abdul Rahman,Malaysia,in providing funding to this project through UTARSRF strategic research funding scheme IPRS/RMC/UTARSRF/PROGRAMME 2014-C1/007。
文摘Dengue virus(DENV) has emerged as a major virus that is spread by mosquitoes. Recently, it has spread to more than a hundred nations but continues to lack specific treatable medication. Many traditional Chinese medicinal(TCM) plants are in practice for dengue fever in dengue endemic regions. These traditional medicines persevere with treatments, which modern medicines lack. The study aims to substantiate the anti-dengue potential of some traditional herbs and make them available for further studies to facilitate TCM users. Twelve TCM plants aqueous extracts were evaluated, which are described as cool herbs used for the diseases with high fever. Lead plants were established through detailed in vitro foci forming unit reduction analysis(FFURA) against all four serotypes and validated through quantitative real-time RT-PCR(q RT-PCR). Four plants potentially inhibited the virus in primary phenotypic in vitro evaluation. Two lead plants Dryopteris crassirhizoma(DC) and Morus alba(MA) were identified with half minimal inhibitory concentration(IC50) 130 and 221 μg m L^-1, respectively, while the selectivity indices(SI) were 4.21 and 4.62, respectively. Lead plants equally inhibited all four serotypes of DENV. Time-of-addition analysis suggested that, DC was active at later stages of viral replication, whereas MA was active during the early stages and even showed some prophylactic activity. Liquid chromatography-mass spectrometry(HPLC/MS) analysis revealed presence of flavonoids. DC and MA are identified as potential anti-dengue plants, active against varied stages of dengue virus replication cycle. These results may serve as the base knowledge for further investigation on their combined treatments or integrative treatment with western medicines, which may improve the overall anti-dengue activity in future.
文摘The risk of dengue virus transmission via blood transfusion is confirmed.As a similar virus,the risk for the case of Zika virus should be mentioned.Here,the authors calculated for the risk of Zika virus transmission via blood transmission referring to the previous data on the risk in case of dengue virus.
基金supported by Important National Science & Technology Specific Projects (2012ZX10004219, 2012ZX10004403)the National Natural Scientific Fund of China (81072675)the Wuhan Key Laboratory on Emerging Infectious Diseases and Biosafety
文摘Dengue virus(DENV) nonstructural protein 1(NS1) is a highly conserved 46-kDa protein that contains 2 glycosylation sites(Asn-130 and Asn-207) and 12 conserved cysteine(Cys) residues. Here, we performed site-directed mutagenesis to generate systematic mutants of viral strain TSV01. The results of the subsequent analysis showed that an alanine substitution at the second N-linked glycan Asn-207 in NS1 delayed viral RNA synthesis, reduced virus plaque size, and weakened the cytopathic effect. Three mutants at Cys sites(Cys-4, Cys-55, Cys-291) and a C-terminal deletion(ΔC) mutant significantly impaired RNA synthesis, and consequently abolished viral growth, whereas alanine mutations at Asn-130 and Glu-173 resulted in phenotypes that were similar to the wild-type(WT) virus. Further analysis showed that the Asn-207 mutation slightly delayed viral replication. These results suggest that the three conserved disulfide bonds and the second N-linked glycan in NS1 are required for DENV-2 replication.
文摘The major envelope glycoprotein E of dengue (DEN) virus plays a central role in the biology of flaviviruses. It is capable of inducing a protective immune response in vivo and responsible for the viral binding to the cellular receptor. The crystal structures of glycoprotein E ectodomains have already been determined. However, it is still un-clear where the well-defined B-cell epitopes for glycoprotein E which induce the neutralizing an-tibodies locates. Thus, in order to characterize the role of glycoprotein E in the pathogenesis of dengue virus infection, we first used network servers (http://bio.dfci. harvard.edu/Tools/ &http://www. imtech. res. in) to predict and analyze the well defined B-cell and T-cell epitopes of the glycoprotein of the DEN-1 HAWAII strain. Then based on the highly conserved envelop glyco-protein amino acids, the hydrophilicity, antigenic-ity, accessibility and flexibility of envelop glyco-protein E were further predicted by using Biotic softwares (DNASTAR) and network servers (http://bio. dfci.harvard.edu/Tools/), the secondary structure was putatively obtained. In our study, the sequence at 281-295 amino acid (aa) for den-gue virus type 1 HAWAII strain and the sequence at 345-359, 383-397 for dengue virus type 2 NGC strain were predicted as the more prevalent epi-topes by using multiple parameters and different analysis softwares, respectively. Two epitopes of DEN-2 and one of DEN-1 locate on the domain Ш and domainⅡ of the protein E, respectively. Sub-sequently, further studies will be carried out to examine the antigenicity and protection of the synthetic peptides with higher scores in the av-erage antigen index (AI) and better hydrophilic properties determined by our data.
文摘Global incidence of dengue, a vector-borne tropical disease, has seen a dramatic increase with several major outbreaks in the past few decades. We formulate and analyze a stochastic epidemic model for the transmission dynamics of a single strain of dengue virus. The stochastic model is constructed using a continuous time Markov chain (CTMC) and is based on an existing deterministic model that suggests the existence of a backward bifurcation for some values of the model parameters. The dynamics of the stochastic model are explored through numerical simulations in this region of bistability. The mean of each random variable is numerically estimated and these are compared to the dynamics of the deterministic model. It is observed that the stochastic model also predicts the co-existence of a locally asymptotically stable disease-free equilibrium along with a locally stable endemic equilibrium. This co-existence of equilibria is important from a public health perspective because it implies that dengue can persist in populations even if the value of the basic reproduction number is less than unity.
