Publications

TitleAbstractYear(sorted descending)
Filter
PMID
Filter
dengue virus infection perturbs lipid homeostasis in infected mosquito cells.dengue virus causes ∼50-100 million infections per year and thus is considered one of the most aggressive arthropod-borne human pathogen worldwide. during its replication, dengue virus induces dramatic alterations in the intracellular membranes of infected cells. this phenomenon is observed both in human and vector-derived cells. using high-resolution mass spectrometry of mosquito cells, we show that this membrane remodeling is directly linked to a unique lipid repertoire induced by dengue virus ...201222457619
serratia odorifera a midgut inhabitant of aedes aegypti mosquito enhances its susceptibility to dengue-2 virus.mosquito midgut plays a crucial role in its vector susceptibility and pathogen interaction. identification of the sustainable microflora of the midgut environment can therefore help in evaluating its contribution in mosquito-pathogen interaction and in turn vector competence. to understand the bacterial diversity in the midgut of aedes aegypti mosquitoes, we conducted a screening study of the gut microbes of these mosquitoes which were either collected from fields or reared in the laboratory "cu ...201222848375
[biological properties of virus dengue-3 strains isolated during the epidemic ocurred in havana, 2001-2002].during dengue epidemics in cuba, an increase in clinical severity with the epidemics progression in time, particularly in secondary infections, have been frequently observed. it is considered that this increase could be related with genetic changes in the circulating virus.201223444637
effects of ribavirin and hydroxyurea on oral infection of aedes aegypti (l.) with dengue virus.this study was conducted to determine the inhibitory effects of ribavirin and hydroxyurea on dengue virus replication in aedes aegypti mosquitoes. female ae. aegypti mosquitoes were infected with dengue-2 virus and fed ribavirin at a dose of 0.3 mg/ml and/or hydroxyurea at a dose of 6 mg/ml via artificial membrane feeding technique. the virus in infected mosquitoes was isolated using c6/36 cell culture. peroxidase-antiperoxidase (pap) staining was used to detect dengue-infected c6/36 cells and t ...201223413698
immunogenicity and protective efficacy of a vaxfectin-adjuvanted tetravalent dengue dna vaccine.a prototype dengue-1 dna vaccine was shown to be safe and immunogenic in a previous phase 1 clinical trial. anti-dengue-1 neutralizing antibody responses were detectable only in the group of volunteers receiving the high dose of nonadjuvanted vaccine and the antibody titers were low. vaxfectin(®), a lipid-based adjuvant, enhances the immunogenicity of dna vaccines. we conducted a nonhuman primate study to evaluate the effect of vaxfectin(®) on the immunogenicity of a tetravalent dengue dna vacci ...201222085548
Chemical modifications of algal mannans and xylomannans: Effects on antiviral activity.The structures of two sulfated xylomannans extracted from the red alga Nemalion helminthoides were determined. These two fractions plus a sulfated mannan, isolated from the same alga and whose structure was previously reported, were subjected to chemical modification. The mannan was oversulfated with SO(3)-pyridine in dimethyl sulfoxide at 60°C during two and three hours and the xylomannans were subjected to Smith degradation in order to eliminate xylose side-chains. Structural analysis of all d ...201222071136
rna sensors enable human mast cell anti-viral chemokine production and ifn-mediated protection in response to antibody-enhanced dengue virus infection.dengue hemorrhagic fever and/or dengue shock syndrome represent the most serious pathophysiological manifestations of human dengue virus infection. despite intensive research, the mechanisms and important cellular players that contribute to dengue disease are unclear. mast cells are tissue-resident innate immune cells that play a sentinel cell role in host protection against infectious agents via pathogen-recognition receptors by producing potent mediators that modulate inflammation, cell recrui ...201222479521
viral hemorrhagic fevers: advancing the level of treatment.the management of viral hemorrhagic fevers (vhfs) has mainly focused on strict infection control measures, while standard clinical interventions that are provided to patients with other life-threatening conditions are rarely offered to patients with vhfs. despite its complexity, a proper clinical case management of vhfs is neither futile nor is it lacking in scientific rationale. given that patient outcomes improve when treatment is started as soon as possible, development and implementation of ...201222458265
association of mast cell-derived vegf and proteases in dengue shock syndrome.recent in-vitro studies have suggested that mast cells are involved in dengue virus infection. to clarify the role of mast cells in the development of clinical dengue fever, we compared the plasma levels of several mast cell-derived mediators (vascular endothelial cell growth factor [vegf], soluble vegf receptors [svegfrs], tryptase, and chymase) and -related cytokines (il-4, -9, and -17) between patients with differing severity of dengue fever and healthy controls.201222363824
inhibition of cellular autophagy deranges dengue virion maturation.autophagy is an important component of the innate immune response, directly destroying many intracellular pathogens. however, some pathogens, including several rna viruses, subvert the autophagy pathway, or components of the pathway, to facilitate their replication. in the present study, the effect of inhibiting autophagy on the growth of dengue virus was tested using a novel inhibitor, spautin-1 (specific and potent autophagy inhibitor 1). inhibition of autophagy by spautin-1 generated heat-sen ...201223175363
dengue virus type 2 modulates endothelial barrier function through cd73.dengue hemorrhagic fever is characterized by a unique vascular leakage syndrome. the mechanisms of endothelial barrier dysfunction in dengue hemorrhagic fever are not well understood. we examined the modulation of endothelial barrier function in dengue virus type 2 (denv2) infections using primary human umbilical vein endothelial cells. we demonstrated that the increase in endothelial barrier function within 72 hours after denv2 infection is mediated by type i interferon-dependent cd73 up-regula ...201223149581
weather-driven variation in dengue activity in australia examined using a process-based modeling approach.the impact of weather variation on dengue transmission in cairns, australia, was determined by applying a process-based dengue simulation model (densim) that incorporated local meteorologic, entomologic, and demographic data. analysis showed that inter-annual weather variation is one of the significant determinants of dengue outbreak receptivity. cross-correlation analyses showed that densim simulated epidemics of similar relative magnitude and timing to those historically recorded in reported d ...201223166197
light-addressable measurements of cellular oxygen consumption rates in microwell arrays based on phase-based phosphorescence lifetime detection.a digital light modulation system that utilizes a modified commercial digital micromirror device (dmd) projector, which is equipped with a uv light-emitting diode as a light modulation source, has been developed to spatially direct excited light toward a microwell array device to detect the oxygen consumption rate (ocr) of single cells via phase-based phosphorescence lifetime detection. the microwell array device is composed of a combination of two components: an array of glass microwells contai ...201224348889
epimedium koreanum nakai water extract exhibits antiviral activity against porcine epidermic diarrhea virus in vitro and in vivo.porcine epidemic diarrhea virus (pedv) causes diarrhea of pigs age-independently and death of young piglets, resulting in economic loss of porcine industry. we have screened 333 natural oriental herbal medicines to search for new antiviral candidates against pedv. we found that two herbal extracts, kiom 198 and kiom 124, contain significant anti-ped viral effect. kiom 198 and kiom 124 were identified as epimedium koreanum nakai and lonicera japonica thunberg, respectively. the further plaque and ...201223259003
novel antiviral activity of baicalein against dengue virus.dengue is a serious arboviral disease currently with no effective antiviral therapy or approved vaccine available. therefore, finding the effective compound against dengue virus (denv) replication is very important. among the natural compounds, bioflavonoids derived mainly from plants are of interest because of their biological and medicinal benefits.201223140177
a noncoding rna produced by arthropod-borne flaviviruses inhibits the cellular exoribonuclease xrn1 and alters host mrna stability.all arthropod-borne flaviviruses generate a short noncoding rna (sfrna) from the viral 3' untranslated region during infection due to stalling of the cellular 5'-to-3' exonuclease xrn1. we show here that formation of sfrna also inhibits xrn1 activity. cells infected with dengue or kunjin viruses accumulate uncapped mrnas, decay intermediates normally targeted by xrn1. xrn1 repression also resulted in the increased overall stability of cellular mrnas in flavivirus-infected cells. importantly, a m ...201223006624
the rig-i-like receptor lgp2 controls cd8(+) t cell survival and fitness.the rig-i-like receptors (rlrs) signal innate immune defenses upon rna virus infection, but their roles in adaptive immunity have not been clearly defined. here, we showed that the rlr lgp2 was not essential for induction of innate immune defenses, but rather was required for controlling antigen-specific cd8(+) t cell survival and fitness during peripheral t cell-number expansion in response to virus infection. adoptive transfer and biochemical studies demonstrated that t cell-receptor signaling ...201222841161
chimeric hepatitis b core antigen virus-like particles displaying the envelope domain iii of dengue virus type 2.dengue is a global public health problem for which no drug or vaccine is available. currently, there is increasing interest in developing non-replicating dengue vaccines based on a discrete antigenic domain of the major structural protein of dengue viruses (denvs), known as envelope domain iii (ediii). the use of bio-nanoparticles consisting of recombinant viral structural polypeptides, better known as virus-like particles (vlps), has emerged as a potential platform technology for vaccine develo ...201222794664
probing of exosites leads to novel inhibitor scaffolds of hcv ns3/4a proteinase.hepatitis c is a treatment-resistant disease affecting millions of people worldwide. the hepatitis c virus (hcv) genome is a single-stranded rna molecule. after infection of the host cell, viral rna is translated into a polyprotein that is cleaved by host and viral proteinases into functional, structural and non-structural, viral proteins. cleavage of the polyprotein involves the viral ns3/4a proteinase, a proven drug target. hcv mutates as it replicates and, as a result, multiple emerging quasi ...201222768327
evolutionary responses to a constructed niche: ancient mesoamericans as a model of gene-culture coevolution.culture and genetics rely on two distinct but not isolated transmission systems. cultural processes may change the human selective environment and thereby affect which individuals survive and reproduce. here, we evaluated whether the modes of subsistence in native american populations and the frequencies of the abca1*arg230cys polymorphism were correlated. further, we examined whether the evolutionary consequences of the agriculturally constructed niche in mesoamerica could be considered as a ge ...201222768049
one misdated sequence of rabbit hemorrhagic disease virus prevents accurate estimation of its nucleotide substitution rate.the literature is ripe with phylogenetic estimates of nucleotide substitution rates, especially of measurably evolving species such as rna viruses. however, it is not known how robust these rate estimates are to inaccuracies in the data, particularly in sampling dates that are used for molecular clock calibration. here we report on the rate of evolution of the emerging pathogen rabbit hemorrhagic disease virus (rhdv), which has significantly different rates of evolution for the same outer capsid ...201222646287
west nile virus infection causes endocytosis of a specific subset of tight junction membrane proteins.west nile virus (wnv) is a blood-borne pathogen that causes systemic infections and serious neurological disease in human and animals. the most common route of infection is mosquito bites and therefore, the virus must cross a number of polarized cell layers to gain access to organ tissue and the central nervous system. resistance to trans-cellular movement of macromolecules between epithelial and endothelial cells is mediated by tight junction complexes. while a number of recent studies have doc ...201222655077
filovirus research in gabon and equatorial africa: the experience of a research center in the heart of africa.health research programs targeting the population of gabon and equatorial africa at the international center for medical research in franceville (cirmf), gabon, have evolved during the years since its inception in 1979 in accordance with emerging diseases. since the reemergence of ebola virus in central africa, the cirmf "emerging viral disease unit" developed diagnostic tools and epidemiologic strategies and transfers of such technology to support the response of the national public health syst ...201223170174
detection and typing of viruses using broadly sensitive cocktail-pcr and mass spectrometric cataloging: demonstration with dengue virus.virus detection and taxonomic identification of serotypes, strains, or genotypes provide important information relevant for diagnosis, and for the epidemiological characterization and tracking of new strains in an endemic region. in the specific case of dengue virus, rapid serotype identification can also be useful in the treatment of secondary infections that may cause the more severe dengue hemorrhagic fever and dengue shock syndrome. in this work, dengue virus was used as a model to test a ne ...201222579629
virus identification in unknown tropical febrile illness cases using deep sequencing.dengue virus is an emerging infectious agent that infects an estimated 50-100 million people annually worldwide, yet current diagnostic practices cannot detect an etiologic pathogen in ∼40% of dengue-like illnesses. metagenomic approaches to pathogen detection, such as viral microarrays and deep sequencing, are promising tools to address emerging and non-diagnosable disease challenges. in this study, we used the virochip microarray and deep sequencing to characterize the spectrum of viruses pres ...201222347512
Analyses of mutations selected by passaging a chimeric flavivirus identify mutations that alter infectivity and reveal an interaction between the structural proteins and the nonstructural glycoprotein NS1.We previously described a single-cycle dengue vaccine (RepliVAX D2) engineered from a capsid (C) gene-deleted West Nile virus (WNV) expressing dengue virus serotype 2 (DENV2) prM/E genes in place of the corresponding WNV genes. That work demonstrated that adaptation of RepliVAX D2 to grow in WNV C-expressing cells resulted in acquisition of non-synonymous mutations in the DENV2 prM/E and WNV NS2A/NS3 genes. Here we demonstrate that the prM/E mutations increase the specific infectivity of chimeri ...201121999990
use of parallel validation high-throughput screens to reduce false positives and identify novel dengue ns2b-ns3 protease inhibitors.dengue virus (denv), a mosquito-borne member of the family flaviviridae, is a significant global pathogen affecting primarily tropical and subtropical regions of the world and placing tremendous burden on the limited medical infrastructure that exists in many of the developing countries located within these regions. recent outbreaks in developed countries, including australia (hanna et al., 2009), france (la ruche et al., 2010), taiwan (kuan et al., 2010), and the usa (cdc, 2010), lead many rese ...201122193283
ifn-γ production depends on il-12 and il-18 combined action and mediates host resistance to dengue virus infection in a nitric oxide-dependent manner.dengue is a mosquito-borne disease caused by one of four serotypes of dengue virus (denv-1-4). severe dengue infection in humans is characterized by thrombocytopenia, increased vascular permeability, hemorrhage and shock. however, there is little information about host response to denv infection. here, mechanisms accounting for ifn-γ production and effector function during dengue disease were investigated in a murine model of denv-2 infection. ifn-γ expression was greatly increased after infecti ...201122206036
displacement of the predominant dengue virus from type 2 to type 1 with a subsequent genotype shift from iv to i in surabaya, indonesia 2008-2010.indonesia has annually experienced approximately 100,000 reported cases of dengue fever (df) and dengue hemorrhagic fever (dhf) in recent years. however, epidemiological surveys of dengue viruses (denvs) have been limited in this country. in surabaya, the second largest city, a single report indicated that dengue virus type 2 (denv2) was the predominant circulating virus in 2003-2005. we conducted three surveys in surabaya during: (i) april 2007, (ii) june 2008 to april 2009, and (iii) september ...201122087290
expression and immunoaffinity purification of recombinant dengue virus 2 ns1 protein as a cleavable sumostar fusion.dengue virus (denv) encoded nonstructural one (ns1) is a 352 amino acid protein that exists in multiple oligomeric states and is conserved within the flavivirus family. although ns1 has been heavily researched for its diagnostic utility, there is a gap in the understanding of its role in a range of viral processes, including replication and development of clinical pathologies such as vascular leakage. many of these functions involve unknown interactions with viral and host proteins. this study d ...201122100526
antiviral activity of distictella elongata (vahl) urb. (bignoniaceae), a potentially useful source of anti-dengue drugs from the state of minas gerais, brazil.to investigate the in vitro antiviral activity of distictella elongata (vahl) urb. ethanol extracts from leaves (lee), fruits (fee), stems and their main components.201121895729
systems-biology approaches to discover anti-viral effectors of the human innate immune response.virus infections elicit an immediate innate response involving antiviral factors. the activities of some of these factors are, in turn, blocked by viral countermeasures. the ensuing battle between the host and the viruses is crucial for determining whether the virus establishes a foothold and/or induces adaptive immune responses. a comprehensive systems-level understanding of the repertoire of anti-viral effectors in the context of these immediate virus-host responses would provide significant a ...201121994773
antiviral activity of four types of bioflavonoid against dengue virus type-2.abstract: background: dengue is a major mosquito-borne disease currently with no effective antiviral or vaccine available. effort to find antivirals for it has focused on bioflavonoids, a plant-derived polyphenolic compounds with many potential health benefits. in the present study, antiviral activity of four types of bioflavonoid against dengue virus type -2 (denv-2) in vero cell was evaluated. anti-dengue activity of these compounds was determined at different stages of denv-2 infection and ...201122201648
[secreted expression of dengue virus type 2 envelope glycoprotein in eukaryotic cells].to secreted express envelope glycoprotein (e) of dengue virus type 2 extracellularly.201121863624
clinicohematological profile and platelet trends in children with dengue during 2010 epidemic in north india.objective: to study the clinicohematological profile and the platelet trends in children presenting with dengue infection during the 2010 dengue epidemic in north india and to compare the it with previous epidemics. methods: this retrospective study was carried out in a tertiary care hospital of north india. of the 219 children admitted from august 2010 through november 2010 with suspected dengue infection, 135 w ...201122037856
development of dengue type-2 virus replicons expressing gfp reporter gene in study of viral rna replication.insertion of green fluorescent protein (gfp) encoding-gene into virus genes has provided a valuable tool for flavivirus research. this study aimed to develop dengue virus (denv) replicons expressing gfp reporter that would provide a fast in vitro system to analyze functional roles of specific denv sequences in viral replication. two classes of recombinant replicon constructs were generated; one was a rna-launched replicon with a gfp gene directly inserted into a full-length denv genome (fl-denv/ ...201122197424
internally quenched fluorescent peptide libraries with randomized sequences designed to detect endopeptidases.identification of synthetic peptide substrates for novel peptidases is an essential step for their study. with this purpose we synthesized fluorescence resonance energy transfer (fret) peptide libraries abz (or mca)-gxxxxxq-eddnp and abz (or mca)-gxxzxxq-eddnp, where x consists of an equimolar mixture of all amino acids, the z position is fixed with one of the proteinogenic amino acids (cysteine was excluded), abz (ortho-aminobenzoic acid) or mca ([7-amino-4-methyl]coumarin) is the fluorescence ...201122067978
b-cell responses during primary and secondary dengue virus infections in humans.low-avidity serotype-cross-reactive antibodies are hypothesized to play a key role in triggering severe disease in patients with secondary dengue virus (denv) infection. however, there is little systematic information about the frequency, avidity, and cross-reactivity of denv-specific b cells in individuals experiencing primary instead of secondary infection. we compared denv-specific b-cell responses in a cohort of thai children with primary or secondary denv infection. b cells specific for den ...201121930609
circulation of different lineages of dengue virus type 2 in central america, their evolutionary time-scale and selection pressure analysis.dengue is caused by any of the four serotypes of dengue virus (denv-1 to 4). each serotype is genetically distant from the others, and each has been subdivided into different genotypes based on phylogenetic analysis. the study of dengue evolution in endemic regions is important since the diagnosis is often made by nucleic acid amplification tests, which depends upon recognition of the viral genome target, and natural occurring mutations can affect the performance of these assays. here we report ...201122076162
analysis of the complete genome of tembusu virus, a flavivirus isolated from ducks in china.during investigations into the outbreak of duck viral infection in 2010 in china, with a severe drop in egg production, a flavivirus was isolated from the affected ducks. it was characterized as a tembusu virus (tmuv). in this study, we obtained a complete genome sequence of tembusu virus using rt-pcr and race techniques. tmuv genome is a singled-stranded rna, with 10 990 nucleotides in length, and contains a single open reading frame (3410 amino acids) encoding 11 viral proteins with 5'and 3'no ...201122103739
label-free electrochemical detection of the specific oligonucleotide sequence of dengue virus type 1 on pencil graphite electrodes.a biosensor that relies on the adsorption immobilization of the 18-mer single-stranded nucleic acid related to dengue virus gene 1 on activated pencil graphite was developed. hybridization between the probe and its complementary oligonucleotides (the target) was investigated by monitoring guanine oxidation by differential pulse voltammetry (dpv). the pencil graphite electrode was made of ordinary pencil lead (type 4b). the polished surface of the working electrode was activated by applying a pot ...201122163916
Strategies to facilitate the development of uncloned or cloned infectious full-length viral cDNAs: Apple chlorotic leaf spot virus as a case study.Approaches to simplify and streamline the construction of full-length infectious cDNA clones (FL-cDNAs) are needed. Among desirable improvements are the ability to use total nucleic acids (TNA) extracts from infected hosts (to bypass viral purification limitations) for the direct one-step amplification of large FL-cDNAs, the possibility to inoculate plants with uncloned FL-cDNAs and the simplified cloning of these large molecules.201122040379
a thiopurine drug inhibits west nile virus production in cell culture, but not in mice.many viruses within the flavivirus genus cause significant disease in humans; however, effective antivirals against these viruses are not currently available. we have previously shown that a thiopurine drug, 6-methylmercaptopurine riboside (6mmpr), inhibits replication of distantly related viruses within the flaviviridae family in cell culture, including bovine viral diarrhea virus and hepatitis c virus replicon. here we further examined the potential antiviral effect of 6mmpr on several diverse ...201122039536
Insights into the internalization and retrograde trafficking of dengue 2 virus in BHK-21 cells.Dengue virus (DENV) enters cells via endocytosis, traffics to perinuclear (PN) region, the site of morphogenesis and exits by exocytosis. This study aims to understand the role of dynamin II, endosomes, microtubules (MT) and dynein in the early events of DENV replication.201121991304
Distinct Humoral and Cellular Immunity Induced by Alternating Prime-boost Vaccination Using Plasmid DNA and Live Viral Vector Vaccines Expressing the E Protein of Dengue Virus Type 2.Dengue virus, which belongs to the Flavivirus genus of the Flaviviridae family, causes fatal dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS) with infection risk of 2.5 billion people worldwide. However, approved vaccines are still not available. Here, we explored the immune responses induced by alternating prime-boost vaccination using DNA vaccine, adenovirus, and vaccinia virus expressing E protein of dengue virus type 2 (DenV2).201122194710
Establishment of a Stable Cell Line Coexpressing Dengue Virus-2 and Green Fluorescent Protein for Screening of Antiviral Compounds.This study aimed to generate a stable cell line harboring subgenomic dengue virus replicon and a green fluorescent gene (DENV/GFP) for a cell-based model to screen anti-DENV compounds. The gene-encoding envelope protein of DENV-2 was deleted and then replaced with fragments of the GFP gene and a foot-and-mouth-disease virus 2A-derived cleavage site. The human cytomegalovirus immediate early and antisense hepatitis delta virus ribozyme sequences were added at the 5'- and 3'-ends. An internal ribo ...201122068705
espirito santo virus: a new birnavirus that replicates in insect cells.espirito santo virus (esv) is a newly discovered virus recovered as a contamination in a sample of a virulent strain of dengue-2 virus (strain 44/2), which was recovered from a patient in the state of espirito santo, brazil and amplified in insect cells. esv was found to be dependent upon co-infection with a virulent strain of dengue-2 and to replicate in c6/36 insect cells but not in mammalian vero cells. a sequence of the genome has been produced by de novo assembly and was not found to match ...201122171264
expression, purification, and initial structural characterization of nonstructural protein 2b, an integral membrane protein of dengue-2 virus, in detergent micelles.dengue virus causes serious diseases affecting people in tropical and sub-tropical regions. the nonstructural (ns) protein 2b is an integral membrane protein and important for the regulation of viral protease ns3, which is significant for virus replication. the ns2b-ns3 complex is an important drug target for treating dengue fever. however, little is known about the structure of ns2b in its entirety. herein, we describe the expression and purification of this integral membrane protein from cell ...201121875670
successful propagation of flavivirus infectious cdnas by a novel method to reduce the cryptic bacterial promoter activity of virus genomes.reverse genetics is a powerful tool to study single-stranded rna viruses. despite tremendous efforts having been made to improve the methodology for constructing flavivirus cdnas, the cause of toxicity of flavivirus cdnas in bacteria remains unknown. here we performed mutational analysis studies to identify escherichia coli promoter (ecp) sequences within nucleotides (nt) 1 to 3000 of the dengue virus type 2 (denv2) and japanese encephalitis virus (jev) genomes. eight and four active ecps were d ...201121228244
letter to the editor: molecular genotyping of dengue virus types 2 and 4 from the guatemalan and honduran epidemics of 2007 using the envelope glycoprotein gene.eight serum specimens collected from dengue patients in guatemala and honduras during the central american epidemic of 2007 were analyzed. virus identification and serotyping performed by a nested rt-pcr assay revealed two denv-1 isolates from guatemala, four denv-2 isolates, two each from guatemala and honduras, and two denv-4 isolates from honduras. viral genotyping determined by phylogenetic analysis of the complete envelope gene sequences demonstrated that the denv-2 isolates from guatemala ...201121234665
virus role during intraepidemic increase in dengue disease severity.dengue epidemics in cuba have repeatedly demonstrated a month-to-month increase in clinical severity during secondary infections. the dengue 2 outbreak that occurred in santiago de cuba in 1997 was accompanied by the most severe intraepidemic increase in disease severity reported to date. it was initially proposed that the appearance of neutralization escape mutants during the course of the epidemic might explain this phenomenon. recent studies have revealed that during the course of this epidem ...201121254883
endurance, refuge, and reemergence of dengue virus type 2, puerto rico, 1986-2007.to study the evolution of dengue virus (denv) serotype 2 in puerto rico, we examined the genetic composition and diversity of 160 denv-2 genomes obtained through 22 consecutive years of sampling. a clade replacement took place in 1994-1997 during a period of high incidence of autochthonous denv-2 and frequent, short-lived reintroductions of foreign denv-2. this unique clade replacement was complete just before denv-3 emerged. by temporally and geographically defining denv-2 lineages, we describe ...201121192856
dengue virus type 2 recognizes the carbohydrate moiety of neutral glycosphingolipids in mammalian and mosquito cells.dengue viruses infect cells by attaching to a surface receptor which remains unknown. the putative receptor molecules of dengue virus type 2 on the surface of mosquito (ap-61) and mammalian (llc-mk2) cell lines were investigated. the immunochemical detection and structural analysis of carbohydrates demonstrated that the neutral glycosphingolipids, l-3 (glcnacß1-3manß1-4glcß1-1'cer) in ap-61 cells, and nlc(4) cer (galß1-4glcnacß1-3galß1-4glcß1-1'cer) in llc-mk2 cells were recognized by the virus. ...201121265875
replication of the primary dog kidney-53 dengue 2 virus vaccine candidate in aedes aegypti is modulated by a mutation in the 5' untranslated region and amino acid substitutions in nonstructural proteins 1 and 3.previous studies have demonstrated reduced replication of the cell culture-adapted dengue-2 virus (denv-2) vaccine candidate, primary dog kidney (pdk)-53, compared with the parental denv-2 strain, 16681, in c6/36 cells. various denv-2 mutants incorporating pdk-53 substitutions singly and in combination into the 16681 genetic backbone were used to identify the genetic basis for impaired replication of the vaccine candidate in vitro in aedes aegypti cell culture (aag2 cells) as well as the reduced ...201121284523
differential inhibition of dengue virus infection in mammalian and mosquito cells by iota-carrageenan.the antiviral activity against dengue virus-2 (denv-2) of carrageenans reported here has shown a differential susceptibility of c6/36 ht and vero cells, taken as models of mosquito and mammalian cells, depending on the structural class of polysaccharides: all polysaccharides blocked denv-2 infection in monkey vero cells, but only iota-carrageenans were virus inhibitors in mosquito cells. however, iota-carrageenans were less effective in mosquito cells in comparison with mammalian cells with effe ...201121325483
dengue virus infection of sk hep1 cells: inhibition of in vitro angiogenesis and altered cytomorphology by expressed viral envelope glycoprotein.dengue virus (denv) infection of human endothelial cells has been implicated in the pathobiology of dengue hemorrhagic fever and dengue shock syndrome. however, the mechanisms by which denv infections alter the functional physiology of endothelial cells remain incompletely understood. in the present study, we examined the susceptibility of a human liver sinusoidal endothelial cell line sk hep1 to all four serotypes of denv and studied the effect of the virus on in vitro angiogenesis. all four se ...201121332827
kinetics of plasma viremia and soluble nonstructural protein 1 concentrations in dengue: differential effects according to serotype and immune status.we describe the magnitude and kinetics of plasma viremia and nonstructural protein 1 (sns1) levels in sequential samples from 167 children with acute dengue, enrolled early in a community study in vietnam. all children recovered fully, and only 5 required hospitalization. among those with dengue virus type 1 (denv-1), plasma viremia was significantly greater in primary (49) than secondary (44) infections and took longer to resolve. in primary denv-2 and 3 infections, viremia was significantly lo ...201121335562
evaluation of widely used diagnostic tests to detect west nile virus infections in horses previously infected with st. louis encephalitis virus or dengue virus type 2.primary west nile virus (wnv) infections can be diagnosed using a number of tests that detect infectious particles, nucleic acid, and specific igm and/or igg antibodies. however, serological identification of the infecting agent in secondary or subsequent flavivirus infections is problematic due to the extensive cross-reactivity of flavivirus antibodies. this is particularly difficult in the tropical americas where multiple flaviviruses cocirculate. a study of sequential flavivirus infection in ...201121346058
amino acid changes within the e protein hinge region that affect dengue virus type 2 infectivity and fusion.fifteen mutant dengue viruses were engineered and used to identify aas in the molecular hinge of the envelope protein that are critical to viral infection. substitutions at q52, a54, or e133 reduced infectivity in mammalian cells and altered the ph threshold of fusion. mutations at f193, g266, i270, or g281 affected viral replication in mammalian and mosquito cells, but only i270w had reduced fusion activity. t280y affected the ph threshold for fusion and reduced replication in c6/36 cells. thre ...201121353281
nf90 binds the dengue virus rna 3' terminus and is a positive regulator of dengue virus replication.viral rna translation and replication are regulated by sequence and structural elements in the 5' and 3' untranslated regions (utr) and by host cell and/or viral proteins that bind them. dengue virus has a single-stranded rna genome with positive polarity, a 5' m7gpppg cap, and a conserved 3'-terminal stem loop (sl) that is linked to proposed functions in viral rna transcription and translation. mechanisms explaining the contributions of host proteins to viral rna translation and replication are ...201121386893
dengue infection increases the locomotor activity of aedes aegypti females.aedes aegypti is the main vector of the virus causing dengue fever, a disease that has increased dramatically in importance in recent decades, affecting many tropical and sub-tropical areas of the globe. it is known that viruses and other parasites can potentially alter vector behavior. we investigated whether infection with dengue virus modifies the behavior of aedes aegypti females with respect to their activity level.201121408119
synthetic peptides containing b- and t-cell epitope of dengue virus-2 e domain iii provoked b- and t-cell responses.our previous work applied a combination of bioinformatics approaches and in vitro assays to identify the dengue-2 virus (denv-2)-specific b- and t-cell epitopes. in this report, we first evaluated the antigenicity of both b- and t-cell epitopes reacting with different sera against denv-2 by elisa as well as the ability of t-cell epitope to activate cd4(+) t-cell producing ifn-? using elispot, which showed a specific reactivity between either b- or t-cell epitope and denv-2 antisera, and a signif ...201121419774
evaluation of two molecular methods for the detection of yellow fever virus genome.yellow fever virus (yfv), a member of the family flaviviridae, genus flavivirus is endemic to tropical areas of africa and south america and is among the arboviruses that pose a threat to public health. recent outbreaks in brazil, bolivia, and paraguay and the observation that vectors capable of transmitting yfv are presenting in urban areas underscore the urgency of improving surveillance and diagnostic methods. two novel methods (rt-hemi-nested-pcr and sybr(®) green qrt-pcr) for efficient dete ...201121419803
n-linked glycosylation of dengue virus ns1 protein modulates secretion, cell-surface expression, hexamer stability, and interactions with human complement.dengue virus (denv) ns1 is a versatile non-structural glycoprotein that is secreted as a hexamer, binds to the cell surface of infected and uninfected cells, and has immune evasive functions. denv ns1 displays two conserved n-linked glycans at n130 and n207. in this study, we examined the role of these two n-linked glycans on ns1 secretion, stability, and function. because some groups have reported reduced yields of infectious denv when n130 and n207 are changed, we analyzed glycosylation-defici ...201121429549
inhibition of bovine viral diarrhea virus rna synthesis by thiosemicarbazone derived from 5,6-dimethoxy-1-indanone.in the present work, we described the activity of the thiosemicarbazone derived from 5,6-dimethoxy-1-indanone (tsc), which we previously characterized as a new compound that inhibits bovine viral diarrhea virus (bvdv) infection. we showed that tsc acts at a point of time that coincides with the onset of viral rna synthesis and that it inhibits the activity of bvdv replication complexes (rcs). moreover, we have selected five bvdv mutants that turned out to be highly resistant to tsc but still sus ...201121430053
the two component adjuvant ic31® potentiates the protective immunity induced by a dengue 2 recombinant fusion protein in mice.here we evaluated the suitability of the synthetic adjuvant ic31® to potentiate the protective capacity of pd5 protein (domain iii of the envelope protein of dengue 2 virus fused to the carrier protein p64k). unlike alum, pd5 mixed with ic31® induced complete protection against virus challenge in mice and increased ifn-? secretion after in vitro re-stimulation. the induced antibody response was highly specific to the homologous serotype and showed both igg1 and igg2a subtypes. ic31® is a promisi ...201121447316
evolution of attenuating mutations in dengue-2 strain s16803 pdk50 vaccine and comparison of growth kinetics with parent virus.a live-attenuated dengue-2 virus strain s16803 vaccine candidate that is immunogenic and safe in humans was derived by 50 passages in primary dog kidney (pdk) cells. to identify mutations associated with attenuation of the dengue-2 pdk50 vaccine strain, we determined the nucleotide changes that arose during pdk passage of the dengue-2 virus. thirteen mutations distinguished the pdk50 virus from low-passage parent resulting in amino acid substitutions in the premembrane (e89g), envelope (e202k, n ...201121461924
identification of cis-acting elements in the 3'-untranslated region of the dengue virus type 2 rna that modulate translation and replication.using the massively parallel genetic algorithm for rna folding, we show that the core region of the 3'-untranslated region of the dengue virus (denv) rna can form two dumbbell structures (5' and 3'dbs) of unequal frequencies of occurrence. these structures have the propensity to form two potential pseudoknots between identical five-nucleotide terminal loops 1 and 2 (tl1 and tl2) and their complementary motifs, pk2 and pk1. mutagenesis using a denv2 replicon rna encoding the renilla luciferase re ...201121515677
secreted dengue virus nonstructural protein ns1 is an atypical barrel-shaped high-density lipoprotein.dengue virus (denv) causes the major arboviral disease of the tropics, characterized in its severe forms by signs of hemorrhage and plasma leakage. denv encodes a nonstructural glycoprotein, ns1, that associates with intracellular membranes and the cell surface. ns1 is eventually secreted as a soluble hexamer from denv-infected cells and circulates in the bloodstream of infected patients. extracellular ns1 has been shown to modulate the complement system and to enhance denv infection, yet its st ...201121518917
highly conserved region 141‒168 of the ns1 protein is a new common epitope region of dengue virus.dengue virus (denv) nonstructural protein 1 (ns1) is a major target of humoral immunity in patients and is believed to be involved in denv pathogenesis. in addition, ns1 is a diagnostic target as it is secreted, and circulates, in patients' plasma at an early stage of viral infection. in this study, we aimed to identify common epitope regions for all serotypes by preparation of mouse monoclonal antibodies (mabs) against ns1. a total of 10 out of the 20 hybridoma clones which were specific to den ...201121519123
[circulation of a different lineage of dengue virus serotype 2 american / asian genotype in the peruvian amazon, 2010.]our objective was to determine the genotype of the dengue virus type 2 (denv-2) that circulated in the amazon region of peru between november 2010 and january 2011. we analyzed eight samples collected during dengue surveillance activities in the cities of iquitos, yurimaguas, trujillo, tarapoto and lima between november 2010 and january 2011 that were sent to insitituto nacional de salud. the viruses were isolated in c6/36 ht cell line. viral rna was extracted and the serotype (rt - pcr multiple ...201121537772
phylogenetic characterization of dengue virus type 2 in espírito santo, brazil.over the last decade, the espírito santo state, brazil has become an endemic dengue fever location with annual outbreaks of varying magnitude. it is still unclear which geographical route allowed the virus entry in the state and how it has genetically changed since then. therefore we have set out to study the local molecular constitution of the virus and determine phylogenetic similarities and differences with other brazilian locations, as well as locations worldwide. viral envelope genes were p ...201121562769
maturation of flaviviruses starts from one or more icosahedrally independent nucleation centres.flaviviruses assemble as fusion-incompetent immature particles and subsequently undergo conformational change leading to release of infectious virions. flavivirus infections also produce combined 'mosaic' particles. here, using cryo-electron tomography, we report that mosaic particles of dengue virus type 2 had glycoproteins organized into two regions of mature and immature structure. furthermore, particles of a maturation-deficient mutant had their glycoproteins organized into two regions of im ...201121566648
polyclonal antibodies against properly folded dengue virus ns1 protein expressed in e. coli enable sensitive and early dengue diagnosis.the non-structural 1 (ns1) protein plays an important role in dengue diagnosis because it has been detected as a soluble serum antigen in both primary and secondary infections. the ns1 protein was expressed in escherichia coli cells, and the efficiency of four different refolding protocols was tested. all of the protocols generated dimeric ns1 in a conformation similar to that of the protein expressed by eukaryotic cells. a polyclonal antibody produced from the properly folded e. coli recombinan ...201121569796
subcellular localizations and time-course expression of dengue envelope and non-structural 1 proteins in human endothelial cells.we performed subcellular fractionation of human endothelial cells (ea.hy926) after a challenge with dengue virus serotype-2 (den-2) at multiplicity of infection (moi) of 10 for 2 h. the cells were fractionated into four fractions including cytosol, membrane/organelle, nucleus and cytoskeleton, and their purity was nicely confirmed by immunofluorescence staining of markers for individual subcellular compartments. western blot analysis of dengue envelope (e) and non-structural 1 (ns1) proteins sho ...201121575706
binding of flavivirus nonstructural protein ns1 to c4b binding protein modulates complement activation.the complement system plays a pivotal protective role in the innate immune response to many pathogens including flaviviruses. flavivirus nonstructural protein 1 (ns1) is a secreted nonstructural glycoprotein that accumulates in plasma to high levels and is displayed on the surface of infected cells but absent from viral particles. previous work has defined an immune evasion role of flavivirus ns1 in limiting complement activation by forming a complex with c1s and c4 to promote cleavage of c4 to ...201121642539
structural mutants of dengue virus 2 transmembrane domains exhibit host-range phenotype.there are over 700 known arboviruses and at least 80 immunologically distinct types that cause disease in humans. arboviruses are transmitted among vertebrates by biting insects, chiefly mosquitoes and ticks. these viruses are widely distributed throughout the world, depending on the presence of appropriate hosts (birds, horses, domestic animals, humans) and vectors. mosquito-borne arboviruses present some of the most important examples of emerging and resurgent diseases of global significance.201121658241
unique heparan sulfate from shrimp heads exhibits a strong inhibitory effect on infections by dengue virus and japanese encephalitis virus.the structure and biological activities of a highly sulfated heparan sulfate (hs) extracted from shrimp (penaeus brasiliensis) heads were characterized. structurally the shrimp hs was more heterogenous than heparin, although it is still highly sulfated. the molecular mass of the shrimp hs preparation was determined to be 32.3kda by gel filtration hplc. analysis by surface plasmon resonance demonstrated that various growth/differentiation factors specifically bound to the shrimp hs with comparabl ...201121806963
dna vaccines against dengue virus type 2 based on truncate envelope protein or its domain iii.two dna vaccines were constructed encoding the ectodomain (domains i, ii and iii) of the denv2 envelope protein (pe1d2) or only its domain iii (pe2d2), fused to the human tissue plasminogen activator signal peptide (t-pa). the expression and secretion of recombinant proteins was confirmed in vitro in bhk cells transfected with the two plasmids, detected by immunofluorescence or immunoprecipitation of metabolically labeled gene products, using polyclonal and monoclonal antibodies against denv2. b ...201121779317
tripeptide inhibitors of dengue and west nile virus ns2b-ns3 protease.a series of tripeptide aldehyde inhibitors were synthesized and their inhibitory effect against dengue virus type 2 (denv2) and west nile virus (wnv) ns3 protease was evaluated side by side with the aim to discover potent flaviviral protease inhibitors and to examine differences in specificity of the two proteases. the synthesized inhibitors feature a varied n-terminal cap group and side chain modifications of a p(2)-lysine residue. in general a much stronger inhibitory effect of the tripeptide ...201121763725
genotype v japanese encephalitis virus is emerging.japanese encephalitis (je) is a global public health issue that has spread widely to more than 20 countries in asia and has extended its geographic range to the south pacific region including australia. je has become the most important cause of viral encephalitis in the world. japanese encephalitis viruses (jev) are divided into five genotypes, based on the nucleotide sequence of the envelope (e) gene. the muar strain, isolated from patient in malaya in 1952, is the sole example of genotype v je ...201121750744
recombination in the nonstructural gene region in type 2 dengue viruses.in view of the rising prevalence of dengue virus and mixing of host and vector populations, complete full-length sequence determination of dengue strains isolated from different epidemic areas is important for the study of virus evolution, pathogenicity, vaccine efficiency and diagnosis. based on the genomic analysis of 51 complete dengue virus sequences, all of which cocirculated in thailand between 1974 and 2001, we report here the occurrence of homologous recombination in the ns5 nonstructura ...201121821995
the ns1 glycoprotein can generate dramatic antibody-enhanced dengue viral replication in normal out-bred mice resulting in lethal multi-organ disease.antibody-enhanced replication (aer) of dengue type-2 virus (denv-2) strains and production of antibody-enhanced disease (aed) was tested in out-bred mice. polyclonal antibodies (pabs) generated against the nonstructural-1 (ns1) glycoprotein candidate vaccine of the new guinea-c (ng-c) or nsx strains reacted strongly and weakly with these antigens, respectively. these pabs contained the igg2a subclass, which cross-reacted with the virion-associated envelope (e) glycoprotein of the denv-2 nsx stra ...201121731643
first report of sylvatic denv-2-associated dengue hemorrhagic fever in west africa.dengue virus (denv) circulates in human and sylvatic cycles. sylvatic strains are both ecologically and evolutionarily distinct from endemic viruses. although sylvatic dengue cycles occur in west african countries and malaysia, only a few cases of mild human disease caused by sylvatic strains and one single case of dengue hemorrhagic fever in malaysia have been reported. here we report a case of dengue hemorrhagic fever (dhf) with thrombocytopenia (13000/-ál), a raised hematocrit (32% above base ...201121829739
vector competence of new zealand mosquitoes for selected arboviruses.new zealand (nz) historically has been free of arboviral activity with the exception of whataroa virus (togaviridae: alphavirus), which is established in bird populations and is transmitted by local mosquitoes. this naive situation is threatened by global warming, invasive mosquitoes, and tourism. to determine the threat of selected medically important arboviruses to nz, vector competence assays were conducted using field collected endemic and introduced mosquito species. four alphaviruses (toga ...201121734146
designing cyclic peptide inhibitor of dengue virus ns3-ns2b protease by using molecular docking approach.peptides are preferred for designing inhibitors because of their high activity and specificity. seven cyclopentapeptide inhibitors were designed in this study against dengue virus type 2 (den-2) ns3-ns2b protease: ckrrc, cgrrc, crgrc, crtrc, ctrrc, ckrkc and crrkc. docking analysis was performed to study the enzyme-inhibitor binding interactions. the free energy binding and estimated ki values for all the inhibitors were found to be small (within micromolar range), indicating that the inhibitors ...201021364826
quantifying the spatial dimension of dengue virus epidemic spread within a tropical urban environment.dengue infection spread in naive populations occurs in an explosive and widespread fashion primarily due to the absence of population herd immunity, the population dynamics and dispersal of ae. aegypti, and the movement of individuals within the urban space. knowledge on the relative contribution of such factors to the spatial dimension of dengue virus spread has been limited. in the present study we analyzed the spatio-temporal pattern of a large dengue virus-2 (denv-2) outbreak that affected t ...201021200419
west nile virus rna not detected in urine of 40 people tested 6 years after acute west nile virus disease.west nile virus (wnv) causes an acute infection that is usually cleared by an effective immune response after several days of viremia. however, a recent study detected wnv rna in the urine of 5 of 25 persons (20%) tested several years after their initial acute wnv disease. we evaluated an established cohort of 40 persons >6 years after initial infection with wnv. urine collected from all participants tested negative for wnv rna by reverse-transcription polymerase chain reaction and transcription ...201021208926
the toll immune signaling pathway control conserved anti-dengue defenses across diverse ae. aegypti strains and against multiple dengue virus serotypes.dengue virus has become one of the most important arboviral pathogens affecting the world today. the virus is transmitted among humans by the mosquitoes aedes aegypti and ae. albopictus. like other vector-borne pathogens, this virus encounters innate immune defenses within the mosquito vector that limit infection. we have previously demonstrated the involvement of the toll pathway in the anti-dengue defense at 7 days after infection. in the present study, we have investigated the activity of thi ...201020079370
differential regulation of toll-like receptor-2, toll-like receptor-4, cd16 and human leucocyte antigen-dr on peripheral blood monocytes during mild and severe dengue fever.dengue fever (df), a public health problem in tropical countries, may present severe clinical manifestations as result of increased vascular permeability and coagulation disorders. dengue virus (denv), detected in peripheral monocytes during acute disease and in in vitro infection, leads to cytokine production, indicating that virus-target cell interactions are relevant to pathogenesis. here we investigated the in vitro and in vivo activation of human peripheral monocytes after denv infection. t ...201020113369
the dengue virus type 2 envelope protein fusion peptide is essential for membrane fusion.the flaviviral envelope (e) protein directs virus-mediated membrane fusion. to investigate membrane fusion as a requirement for virus growth, we introduced 27 unique mutations into the fusion peptide of an infectious cdna clone of dengue 2 virus and recovered seven stable mutant viruses. the fusion efficiency of the mutants was impaired, demonstrating for the first time the requirement for specific fp aas in optimal fusion. mutant viruses exhibited different growth kinetics and/or genetic stabil ...201019913272
analysis of rickettsia typhi-infected and uninfected cat flea (ctenocephalides felis) midgut cdna libraries: deciphering molecular pathways involved in host response to r. typhi infection.murine typhus is a flea-borne febrile illness that is caused by the obligate intracellular bacterium, rickettsia typhi. the cat flea, ctenocephalides felis, acquires r. typhi by imbibing a bloodmeal from a rickettsemic vertebrate host. to explore which transcripts are expressed in the midgut in response to challenge with r. typhi, cdna libraries of r. typhi-infected and uninfected midguts of c. felis were constructed. in this study, we examined midgut transcript levels for select c. felis serine ...201020017753
in vitro antiviral activity of neem (azardirachta indica l.) bark extract against herpes simplex virus type-1 infection.herpes simplex virus type 1 (hsv-1) causes significant health problems from periodical skin and corneal lesions to encephalitis. we report here that an aqueous extract preparation from the barks of neem plant azardirachta indica acts as a potent entry inhibitor against hsv-1 infection into natural target cells. the neem bark extract (nbe) significantly blocked hsv-1 entry into cells at concentrations ranging from 50 to 100 microg/ml. the blocking activity of nbe was observed when the extract was ...201020041417
exploring different strategies to express dengue virus envelope protein in a plant system.dengue virus envelope glycoprotein (e-protein) is the main protein associated with immunity induction. to produce a candidate for subunit vaccines and to provide an antigen for diagnostic kits, it was expressed in a novel plant system using deconstructed viral modules. a truncated version of the e-protein was designed to be expressed alone and co-expressed with dengue virus structural proteins. as well, the critical domain iii of e-protein was fused to hepatitis b core antigen (hbcore). the reco ...201020213522
replication of not-known-vector flaviviruses in mosquito cells is restricted by intracellular host factors rather than by the viral envelope proteins.chimeric yellow fever virus 17d (yfv-17d) and dengue virus type 2 (denv2) carrying the surface proteins of modoc virus (modv), a not-known-vector (nkv) flavivirus, replicated efficiently in mammalian (vero-b) and mosquito (c6/36) cells, whereas modv failed to replicate in mosquito cells. transfection of c6/36 cells with modv rna did not result in virus replication; however, transfection of these mosquito cells with yfv-17d or denv2 rna did. the inability of nkv viruses (such as modv) to infect a ...201020219898
both e protein glycans adversely affect dengue virus infectivity but are beneficial for virion release.the e protein of most flaviviruses is modified by asn-linked glycosylation at residue 153/154 and in the case of the four dengue virus (denv) serotypes by a second glycan at residue 67. however, the absence of e protein glycosylation among numerous natural isolates of different flaviviruses suggests that the glycan, per se, is not critically important in the virus life cycle. consistent with this notion, we show that ablation of both glycans from the denv-2 e protein reduces but does not prevent ...201020219924
nss encoded by groundnut bud necrosis virus is a bifunctional enzyme.groundnut bud necrosis virus (gbnv), a member of genus tospovirus in the family bunyaviridae, infects a large number of leguminosae and solanaceae plants in india. with a view to elucidate the function of nonstructural protein, nss encoded by the small rna genome (s rna), the nss protein of gbnv- tomato (karnataka) was over-expressed in e. coli and purified by ni-nta chromatography. the purified rnss protein exhibited an rna stimulated ntpase activity. further, this activity was metal ion depend ...201020305786
dengue virus replicons: production of an interserotypic chimera and cell lines from different species, and establishment of a cell-based fluorescent assay to screen inhibitors, validated by the evaluation of ribavirin's activity.the prevention and treatment of flavivirus infections are public health priorities. dengue fever is the most prevalent mosquito-borne viral disease of humans, affecting more than 50 million people annually. despite the urgent need to control dengue infections, neither specific antiviral therapies nor licensed vaccines exist and the molecular basis of dengue pathogenesis is not well understood. in this study we produced a novel dengue virus type 2 (dv2) subgenomic replicon that expresses a fusion ...201020307577
antagonism of the complement component c4 by flavivirus nonstructural protein ns1.the complement system plays an essential protective role in the initial defense against many microorganisms. flavivirus ns1 is a secreted nonstructural glycoprotein that accumulates in blood, is displayed on the surface of infected cells, and has been hypothesized to have immune evasion functions. herein, we demonstrate that dengue virus (denv), west nile virus (wnv), and yellow fever virus (yfv) ns1 attenuate classical and lectin pathway activation by directly interacting with c4. binding of ns ...201020308361
characterization of recombinant dengue-2 virus derived from a single nucleotide substitution in the 5' noncoding region.variants of wild-type dengue serotype 2 (den-2) virus containing nucleotide substitutions at positions 14, 15, or 57 in the 5' ncr were constructed by pcr-mediated site-directed mutagenesis. all three viruses containing a single point substitution demonstrated attenuation phenotype as evidenced by decreases replication and plaque size in cell culture assay. all three variants were less neurovirulent in newborn mice compared to the wild type. the mutants were immunogenic in adult mice immunogenic ...201020339476
Refresh
firstprev
12345678910...
nextlast
Displaying items 301 - 400 of 1218