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@#Objective To express dengue virus(DENV)NS2B-NS3 protease in E.coli,optimize the expression conditions and determine the enzyme activity,so as to lay a foundation of screening and discovering of lead compounds targeting DENV.Methods Codon-optimized NS2B-NS3 gene was inserted into pET-28a vector to construct recombinant prokaryotic expression plasmid pET-28a-NS2B-NS3,which was transformed E.coli Rosetta(DE3)competent cells and induced by IPTG to express NS2B-NS3 protease. The optimal expression conditions of NS2B-NS3 protease in E.coli were determined by optimizing induction length,induction temperature and IPTG concentration. NS2B-NS3 protease was isolated and purified by HisTrap~(TM) affinity chromatography column and measured for the protease activity by fluorescence resonance energy transfer(FRET)assay.Results The recombinant prokaryotic expression plasmid pET-28a-NS2B-NS3 was constructed correctly as identified by restriction analysis(NheⅠ/XhoⅠ)and sequencing. The optimal expression conditions of NS2BNS3 protease in E.coli were as follows:induction temperature of 20 ℃,induction length of 10 h and IPTG concentration of0. 2 mmol/L. The purified NS2B-NS3 protease showed a purity of more than 90% with a exhibited a of 20 mg/L,which bound to mouse monoclonal antibody against His-tag specifically and had good hydrolytic activity with a specific activity of 16. 111 U/mg,a K_m of 16. 46 μmol/L and a k_(cat) of 0. 028/s.Conclusion DENV NS2B-NS3 protease with high purity and activity was successfully prepared,which laid an experimental foundation of the establishment of high-throughput screening model for inhibitors targeting NS2B-NS3 protease.
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@#ObjectiveTo establish models of Dengue virus type Ⅲ（DENV-3,DV-3）infection and antibody dependent enhancement(ADE)infection at the acute monocytic leukemia cells(THP-1),investigate the differential expression of long non-coding RNAs(LncRNAs),map the competitive endogenous RNA(CeRNA)regulatory network and predict the translation function of LncRNAs.MethodsThe culture supernatant was harvested 6 d after C6/36 cells were infected with DENV-3,the virus titer was determined by CCID50,and the type and full-length genome amplification were identified by PCR;The DENV-3 standard plasmid was amplified,identified by PCR,and the standard curve was drawn;THP-1 cells were divided into negative control group(THP-1),direct infection group(DV-3),ADE group and blank control group[1640(-)]. After 48 h of infection,the total RNA was extracted and the copy number of intracellular virus nucleic acid was measured;Through the whole transcriptome sequencing technology,the CeRNA regulatory network was constructed for the top five up-regulated and down-regulated LncRNAs in THP-1 vs DENV3,THP-1 vs ADE,DENV3 vs ADE groups,and the functions of their coding proteins were analyzed.ResultsC6/36 cells infected with DENV-3 for 3 d showed obvious cell fusion,vacuoles and abscission;The virus had a titer of about 1. 0 × 104. 64PFU/mL and was identified as DENV-3 by PCR specific primers,of which the complete gene sequence was obtained;The number of viral nucleic acid copies in ADE group was significantly higher than those in DV-3 group and blank control group;In THP-1 vs DENV-3,the expression of cytohesin interacting protein(CYTIP)was predicted to be up-regulated;In THP-1 vs ADE,the expression of kinesin family5A(KIF5A)was predicted to be down-regulated;In DENV-3 vs ADE,the expression of cluster differentiation antigen 9(CD9)and insulin like growth factor 2(IGF2)was predicted to be up-regulated. All of these differential LncRNAs had open reading frames(ORFs). Except Lnc-SH3BP1 and Lnc-RPL41,all of the other LncRNAs had internal ribosome binding site(IRES).ConclusionIn DENV-3 infection of THP-1 cells and ADE infection mediated by DENV-3,the expression of LncRNAs has changed significantly,and may regulate the process of infection through a variety of biological functions,which is helpful for a deeper understanding of the mechanism of ADE infection.
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BackgroundCurrently, no vaccines or modern drugs are available for dengue and chikungunya and only symptomatic relief is provided to the patients. Siddha medicine, a traditional form of indigenous medical system uses specific polyherbal formulations for the treatment of such infections with considerable success. One such polyherbal formulation for the treatment of chikungunya and dengue is Nilavembu kudineer (NVK). The mechanistic details of this drug as an antiviral for chikungunya virus (CHIKV) and dengue virus (DENV) is poorly understood.ObjectivesThe current study was undertaken to study the efficacy of NVK as an antiviral formulation against CHIKV and DENV.Materials and methodsCytotoxicity assays (MTT) were performed to determine the role of NVK as an antiviral during chikungunya and dengue infections in the following conditions-i). post infection, ii). during active infections and iii) protective, not allowing virus infection.ResultsIt was observed that NVK provides protection against CHIKV and DENV-2 during active infection as well can help to prevent virus infection in the cells and it mainly depends on the cellular availability of drugs for maximum protection against both the infections.ConclusionOur study establishes that extraction protocols are important to ensure maximum efficacy of NVK along with the time of addition of the drug during CHIKV and DENV infections in the cells. This study provides insights to the possible mode of action of NVK in in vitro condition during CHIKV and DENV infection.
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Dengue virus (DENV) is one of the most significant mosquito-borne viral pathogens that spread in the tropical and subtropical areas causing severe diseases in humans such as dengue fever (DF), dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). DENV RNA genome encodes three structural proteins and seven non-structural proteins. The non-structural protein 3 (NS3) contains two main functional domains: serine protease and RNA helicase. As a serine protease, NS3 together with host cell proteases can directly hydrolyze the ploy-protein that is translated from the viral genome into functional proteins. Functioning as a RNA helicase, it is closely related to the replication and transcriptional translation of the viral genome RNA. In this paper, the structure and functions of DENV NS3 and the research progress in related antiviral drugs were reviewed systematically.
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A dengue é uma arbovirose causada pelo vírus Dengue (DENV), cujos principais vetores são os mosquitos Aedes aegypti e Aedes albopictus. A. aegypti é o único vetor de DENV em Cabo Verde, país que teve a sua primeira epidemia da dengue registrada em 2009. Contudo, pouco se sabe acerca da variação no nível de competência vetorial das populações do vetor aos diferentes sorotipos de DENV. O estudo teve como objetivo avaliar a competência vetorial de A. aegypti da ilha de Santiago, Cabo Verde, a quatro sorotipos de DENV. Para isso, os mosquitos foram alimentados artificialmente com sangue contendo diferentes sorotipos de DENV, e em seguida dissecados ao 7º, 14º e 21º dia após infecção (dpi) para verificar a presença do vírus no intestino, cabeça e glândulas salivares usando a técnica de RT-PCR. Adicionalmente, o número de cópias de RNA viral presente nas glândulas salivares foi determinado por qRT-PCR. Foram observadas altas taxas de infecção das glândulas salivares para DENV-2 e DENV-3 (65 e 75 por cento respectivamente), enquanto que para DENV-1, o RNA viral só foi detectado no intestino e cabeça, não chegando a infectar as glândulas salivares. DENV-4 não disseminou para cabeça e glândulas salivares, mantendo a infecção apenas no intestino (9 por cento). O número de cópias de RNA viral nas glândulas salivares não variou significativamente entre DENV-2 e DENV-3 e nem entre os diferentes períodos de incubação do vírus e títulos de DENV testados. Conclui-se, que a população de Aedes aegypti da ilha de Santiago, Cabo Verde, possui alta competência vetorial para as cepas de DENV-2 e DENV-3 e são pouco susceptíveis para as de DENV-1 e DENV-4. As cópias de RNA viral nas glândulas salivares mantêm-se relativamente constante por 21 dias após a infecção, o que pode potencializar a capacidade vetorial de mosquito A. aegypti e sugere alguma forma de modulação da replicação do vírus nesse órgão
Dengue is an arboviral diseasecaused by dengue virus (DENV), for which the main vectors are the mosquitoes Aedes aegypti andAedes albopictus. A. aegypti is the only DENV vector in Cape Verde, a country which suffered its first dengue outbreak in 2009. However, little is known about the variation in the level of vector competence of this mosquito population to the different DENV serotypes...
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Aedes , Dengue Virus , Insect Vectors/virology , Polymerase Chain Reaction , Africa, WesternABSTRACT
Objetivo Determinar la frecuencia y severidad del compromiso hepático en niños con Dengue. Métodos Estudio descriptivo que incluyó a 108 niños menores de 13 años con diagnóstico de infección por virus de Dengue, confirmada por detección plasmática de NS1 e IgM dengue-específica, que consultaron al Hospital Universitario de Neiva, en el período de junio de 2009 a mayo de 2010.El grado de daño hepático fue evaluado por criterios clínicos y bioquímicos que incluyeron transaminasas y albúmina. El diagnóstico de infección con Leptospira o Hepatitis A fue realizado por detección de IgM plasmática específica medida en fase aguda y convaleciente. Resultados De los casos incluidos, 98 y 10 casos fueron clasificados como dengue con signos de alarma y Dengue grave, respectivamente. Dos de cada tres pacientes con Dengue presentaron signos de alarma y todos los pacientes con Dengue grave presentaron algún grado de compromiso hapático evidenciado clínica y bioquímicamente. Independientemente de la clasificación clínica, la hepatomegalia fue el signo clínico cardinal del compromiso hepático y se presentó en el 85 % del total de niños incluidos. De resaltar, 5 de los pacientes presentaron probable coinfección de dengue y leptospira, siendo la primera descripción en Colombia. En ninguno de los casos analizados se presentó enfermedad aguda por Hepatitis A. Conclusión El compromiso hepático es muy frecuente en la infección por virus Dengue. Enfermedades como la leptospirosis deben ser tenidas en cuenta no sólo en el diagnóstico diferencial del paciente pediátrico febril con compromiso hepático, sino como causa de coinfección en el niño con Dengue en el sur de Colombia.
Objective Dengue is the most important arthropod-borne viral disease in the world; it can be life-threatening because of liver involvement. Aim Determining liver involvement frequency and severity in dengue-infected children. Methods This was a descriptive case series study which involved studying 108 dengue-infected children aged less than 13 years old whose infection had been confirmed by the detection of dengue-specific IgM and NS1 in plasma. Clinical and biochemical parameters were used for evaluating liver involvement, including transaminases and albumin. Hepatitis A and leptospira infection were also evaluated by using ELISA to detect pathogen-specific IgM in plasma during acute and convalescence phases. The study was carried out at a teaching hospital in Neiva from June 2009 to May 2010. Results Ninety-eight of the aforementioned cases were clinically classified as dengue with warning signs (DWS) and 10 as severe dengue (SD). Two out of three DWS patients and all SD patients had some degree of liver involvement, shown clinically and biochemically. Regardless of the clinical classification, hepatomegaly was the main clinical sign of liver involvement and was present in 85% of all the children in the study. It is worth noting that 5 patients had probable dengue and leptospirosis co-infection, this being the first instance of this in Colombia. None of the cases analyzed here had acute hepatitis A. Conclusions Liver compromise should be considered in confirmed cases of dengue as shown in this series of children. Leptospirosis must be considered as differential diagnosis and also as causing co-infection in a febrile child.