single nucleotide polymorphisms in genes for 2'-5'-oligoadenylate synthetase and rnase l inpatients hospitalized with west nile virus infection.infection with the flavivirus west nile virus (wnv) is a growing problem across the united states, where there is a case-fatality rate of 15%-29% in individuals >70 years old and no consistently effective treatment. susceptibility to wnv disease in inbred strains of mice was mapped to a nonsense mutation in the gene encoding the 1b isoform of 2'-5'-oligoadenylate synthetase (oas), a member of the oas/rnase l system of innate viral resistance. genetic susceptibility to severe wnv disease in human ...200516235172
limited pathogenicity of usutu virus for the domestic chicken (gallus domesticus).in summer 2001, usutu virus (usuv), a mosquito-borne flavivirus, was isolated for the first time in europe during a mortality incident among eurasian blackbirds (turdus merula) in austria. chickens are frequently used as sentinel animals for arbovirus surveillance systems. in the present study, the pathogenicity of usuv for specific pathogen free chickens was investigated. ten 2-week-old chickens were inoculated intravenously with 0.1 ml inoculum containing 10(3) median (50%) tissue culture infe ...200516236570
peptide inhibitors of dengue virus ns3 protease. part 1: warhead.substrate-based tetrapeptide inhibitors with various warheads were designed, synthesized, and evaluated against the dengue virus ns3 protease. effective inhibition was achieved by peptide inhibitors with electrophilic warheads such as aldehyde, trifluoromethyl ketone, and boronic acid. a boronic acid has the highest affinity, exhibiting a k(i) of 43 nm.200616246553
peptide inhibitors of dengue virus ns3 protease. part 2: sar study of tetrapeptide aldehyde inhibitors.with the aim of discovering potent and selective dengue ns3 protease inhibitors, we systematically synthesized and evaluated a series of tetrapeptide aldehydes based on lead aldehyde 1 (bz-nle-lys-arg-arg-h, k(i)=5.8 microm). in general, we observe that interactions of p(2) side chain are more important than p(1) followed by p(3) and p(4). tripeptide and dipeptide aldehyde inhibitors also show low micromolar activity. additionally, an effective non-basic, uncharged replacement of p(1) arg is ide ...200616246563
synthesis of 5-aza-7-deazaguanine nucleoside derivatives as potential anti-flavivirus agents.coupling suitable sugars (d- or l-ribofuranose, 2' or 3-deoxysugar, branched sugars) with 2-aminoimidazo[1,2-a]-s-triazin-4-one was carried out using the different reaction conditions: 1) condensation in the presence of sodium hydride; or 2) condensation using vorbrüggen's methods. the 5-aza- 7-deazaguanine nucleoside analogues obtained were evaluated in cell culture experiments for the inhibition of the replication of a number of rna viruses, including bvdv, yfv, and wnv.200516248011
[flavivirus infections: yellow fever, dengue fever and japanese encephalitis].flavivirus infections, such as dengue fever, yellow fever and japanese encephalitis, are untreatable. as a result of the high prevalence of dengue fever in endemic areas, it poses a substantial risk for travellers to those areas. when it comes to japanese encephalitis and yellow fever, the risk for travellers is limited but the diseases are extremely serious, creating a dilemma for the physician when it comes to deciding whether to vaccinate against them. the vaccines against both potentially ha ...200516251091
randomized, placebo-controlled trial of nonpegylated and pegylated forms of recombinant human alpha interferon 2a for suppression of dengue virus viremia in rhesus monkeys.dengue fever and dengue hemorrhagic fever are caused by infection with any one of the four dengue viruses (dvs) and are significant public health burdens throughout the tropics. higher viremia levels are associated with greater dengue disease severity. a therapeutic intervention to suppress viremia early in dv infection could potentially ameliorate severe disease. recombinant alpha interferon 2a (rifn-alpha-2a, roferon-a) suppressed dv replication in human peripheral blood mononuclear cells in v ...200516251289
a case of post-japanese encephalitis with partial hypothalamic dysfunction showing repetitive hyperthermia in summertime.japanese encephalitis (je) virus is a mosquito-borne virus belonging to the flavivirus family, including the west nile and st louis encephalitis viruses endemic to north america. je virus is prevalent in east asian countries and can cause acute lethal encephalitis. although vaccination programs have decreased the incidence of je in japan, the cases that do occur are often fatal or associated with considerable clinical sequelae. we report, for the first time to our knowledge, a patient who had re ...200616253337
noncytopathogenic pestivirus strains generated by nonhomologous rna recombination: alterations in the ns4a/ns4b coding region.several studies have demonstrated that cytopathogenic (cp) pestivirus strains evolve from noncytopathogenic (noncp) viruses by nonhomologous rna recombination. in addition, two recent reports showed the rapid emergence of noncp bovine viral diarrhea virus (bvdv) after a few cell culture passages of cp bvdv strains by homologous recombination between identical duplicated viral sequences. to allow the identification of recombination sites from noncp bvdv strains that evolve from cp viruses, we con ...200516254361
dna microarray technique for detection and identification of seven flaviviruses pathogenic for man.a flavivirus microarray was developed for detection and identification of yellow fever (yf), west nile, japanese encephalitis (je), and the dengue 1-4 viruses, which are causing severe human disease all over the world. the microarray was based on 500-nucleotide probe fragments from five different parts of the seven viral genomes. a low-stringent amplification method targeting the corresponding regions of the viral genomic rna was developed and combined with hybridization to the microarray for de ...200516254977
live attenuated yellow fever 17d infects human dcs and allows for presentation of endogenous and recombinant t cell epitopes.the yellow fever (yf) 17d vaccine is one of the most successful live attenuated vaccines available. a single immunization induces both long-lasting neutralizing antibody and yf-specific t cell responses. surprisingly, the mechanism for this robust immunity has not been addressed. in light of several recent reports suggesting flavivirus interaction with dendritic cells (dcs), we investigated the mechanism of yf17d interaction with dcs and the importance of this interaction in generating t cell im ...200516260489
[screening and cloning of hepatitis c virus non-structural protein 4b interacting protein gene in hepatocytes].to investigate biological functions of non-structural protein 4b (ns4b) of hepatitis c virus (hcv), yeast-two hybrid technique was performed to seek proteins in hepatocytes interacting with hcv ns4b.200516261208
revisiting the liver in human yellow fever: virus-induced apoptosis in hepatocytes associated with tgf-beta, tnf-alpha and nk cells activity.flavivirus infection as dengue and yellow fever persists as a terrible menace to pandemics, due to aedes prevalence in the americas. yellow fever is characterized by hepatocyte damage, with steatosis, apoptosis and necrosis, mainly in the midzonal region of the liver, but the injury mechanism has not been studied at the light of recent knowledge, such as the advances in cell death mechanisms, inflammatory response and cytokine cell expression tools. we studied 53 human liver paraffin embedded bl ...200616278000
protective and therapeutic capacity of human single-chain fv-fc fusion proteins against west nile virus.west nile virus has spread rapidly across the united states, and there is currently no approved human vaccine or therapy to prevent or treat disease. passive immunization with antibodies against the envelope protein represents a promising means to provide short-term prophylaxis and treatment for west nile virus infection. in this study, we identified a panel of 11 unique human single-chain variable region antibody fragments (scfvs) that bind the envelope protein of west nile virus. selected scfv ...200516282460
emerging zoonotic encephalitis viruses: lessons from southeast asia and oceania.the last decade of the 20th century saw the introduction of an unprecedented number of encephalitic viruses emerge or spread in the southeast asian and western pacific regions (mackenzie et al, 2001; solomon, 2003a). most of these viruses are zoonotic, either being arthropod-borne viruses or bat-borne viruses. thus japanese encephalitis virus (jev), a mosquito-borne flavivirus, has spread through the indonesian archipelago to papua new guinea (png) and to the islands of the torres strait of nort ...200516287684
south african gb virus c isolates: interactions between genotypes 1 and 5 isolates and virus c (gbv-c) is a common, apparently nonpathogenic human flavivirus that has been associated in some studies with prolonged survival in human immunodeficiency virus (hiv)-positive persons. there are 5 distinct gbv-c genotypes localized to specific geographic regions, and genotype 2 has been previously shown to inhibit hiv replication in vitro in lymphocyte cultures. we identified gbv-c virus isolates representing genotypes 1, 2, and 5 in samples from south african blood donors. gbv-c genot ...200516288381
japanese encephalitis virus ns2b-ns3 protease binding to phage-displayed human brain proteins with the domain of trypsin inhibitor and basic region leucine zipper.flavivirus ns2b-ns3 proteases are associated with neurovirulence, becoming an important target for insight into the virus-induced pathogenesis. in this study, a phage-displayed human brain cdna library was used to detect possible interaction between brain proteins and the japanese encephalitis virus (jev) ns2b-ns3 protease. after six rounds of biopanning, eight high-affinity ns2b-ns3 protease-interacting phages were identified. identified ns2b-ns3 protease-interacting brain proteins contained se ...200616289409
st. louis encephalitis virus: first isolation from a human in são paulo state, brazil.this paper reports the isolation of st. louis encephalitis virus (slev) from a febrile human case suspected to be dengue, in são pedro, são paulo state. a mac-elisa done on the patient's acute and convalescent sera was inconclusive and hemagglutination inhibition test detected igg antibody for flaviviruses. an indirect immunofluorescent assay done on the c6/36 cell culture inoculated with the acute serum was positive for flaviviruses but negative when tested with dengue monoclonal antibodies. rn ...200516302112
molecular characterization of attenuated japanese encephalitis live vaccine strain ml-17.the japanese encephalitis (je) zoonotic vaccine strain ml-17 was sequenced and compared to related je virus strains to identify genomic attenuation markers. relative to its parental strain, jaoh0566, 25 nucleotide alterations and 10 amino acid changes to, prm/m(2), ns2a(1), ns4b(3) and ns5(4) proteins were recorded. both structural-gene changes were in the prm/m region (127met-->ile and 274asn-->thr). to study the effects of these prm/m changes, mutants bearing the changes were prepared using an ...200616303214
high-throughput assays using a luciferase-expressing replicon, virus-like particles, and full-length virus for west nile virus drug discovery.many flaviviruses cause significant human disease worldwide. the development of flavivirus chemotherapy requires reliable high-throughput screening (hts) assays. although genetic systems have been developed for many flaviviruses, their usage in antiviral hts assays has not been well explored. here we compare three cell-based hts assays for west nile virus (wnv) drug discovery: (i) an assay that uses a cell line harboring a persistently replicating subgenomic replicon (containing a deletion of vi ...200516304161
humoral and cellular immune response to rna immunization with flavivirus replicons derived from tick-borne encephalitis virus.a new vaccination principle against flaviviruses, based on a tick-borne encephalitis virus (tbev) self-replicating noninfectious rna vaccine that produces subviral particles, has recently been introduced (r. m. kofler, j. h. aberle, s. w. aberle, s. l. allison, f. x. heinz, and c. w. mandl, proc. natl. acad. sci. usa 7:1951-1956, 2004). in this study, we evaluated the potential of the self-replicating rna vaccine in mice in comparison to those of live, attenuated vaccines and a formalin-inactiva ...200516306582
end-to-end communication in the modulation of translation by mammalian rna viruses.a 5'-3' end interaction leading to stimulation of translation has been described for many cellular and viral mrnas. enhancement of viral translational efficiency mediated by 5' and 3' untranslated regions (utrs) has been shown to occur via rna-rna interactions or novel rna-protein interactions. mammalian rna viruses make use of end-to-end communication in conjunction with both viral and cellular factors to regulate multiple processes including translation initiation and the switch between transl ...200616307817
a single immunization with a minute dose of a lentiviral vector-based vaccine is highly effective at eliciting protective humoral immunity against west nile virus.lentiviral vectors, due to their capacity to transduce non-dividing cells, have become precious and worldwide used gene transfer systems. their ability to efficiently and stably transduce dendritic cells (dcs) has led to their successful use as vaccination vectors for eliciting strong, specific and protective cellular immune responses mostly in anti-tumoral but also in anti-viral applications. however, the ability of lentiviral vectors to elicit an antibody-based protective immunity has, to date ...200616308885
antiviral effect of the heparan sulfate mimetic, pi-88, against dengue and encephalitic flaviviruses.many viruses, including flaviviruses, display affinity for cell surface heparan sulfate (hs) proteoglycans with biological relevance in virus attachment/entry. this raises the possibility of the application of hs mimetics in antiviral therapy. we have evaluated the antiviral effect of the sulfated polysaccharides, suramin, pentosan polysulfate (pps) and pi-88, which are currently approved or in trial for clinical use, against dengue virus (den) and the encephalitic flaviviruses, japanese encepha ...200616309754
a general method for nested rt-pcr amplification and sequencing the complete hcv genotype 1 open reading frame.hepatitis c virus (hcv) is a pathogenic hepatic flavivirus with a single stranded rna genome. it has a high genetic variability and is classified into six major genotypes. genotype 1a and 1b cause the majority of infections in the usa. viral genomic sequence information is needed to correlate viral variation with pathology or response to therapy. however, reverse transcription-polymerase chain reaction (rt-pcr) of the hcv genome must overcome low template concentration and high target sequence d ...200516321149
a rapid and quantitative assay for measuring antibody-mediated neutralization of west nile virus infection.west nile virus (wnv) is a neurotropic flavivirus within the japanese encephalitis antigenic complex that is responsible for causing west nile encephalitis in humans. the surface of wnv virions is covered by a highly ordered icosahedral array of envelope proteins that is responsible for mediating attachment and fusion with target cells. these envelope proteins are also primary targets for the generation of neutralizing antibodies in vivo. in this study, we describe a novel approach for measuring ...200616325883
immunological properties of recombinant classical swine fever virus ns3 protein in vitro and in vivo.classical swine fever (csf) is a highly contagious and often fatal disease of pigs characterised by fever, severe leukopenia and haemorrhages. with vaccines having an importance in disease control, studies are seeking improved protein-based subunit vaccine against the virus (csfv). in this respect, recombinant viral ns3 protein was analysed for its immunopotentiating capacity, particularly in terms of cytotoxic immune responses. ns3 was effective at inducing in vitro responses, quantified by lym ...200616336932
differential responses of human brain cells to west nile virus recent years, west nile virus (wnv) has emerged as a major cause of encephalitis in the united states. however, the neuropathogenesis of this flavivirus is poorly understood. in the present study, the authors used primary human brain cell cultures to investigate two neuropathogenic features: viral replication and induction of cytokines. although neurons and astrocytes were found to support productive wnv infection, viral growth was poorly permissive in microglial cells. compared to neuronal c ...200516338745
west nile virus serosurveillance in iowa white-tailed deer (1999-2003).sera from white-tailed deer (odocoileus virginianus) were collected in iowa during the winter months (1999-2003), 2 years before and after west nile virus (wnv) was first reported in iowa (2001), and were analyzed for antibodies to wnv. samples from 1999 to 2001 were antibody negative by blocking enzyme-linked immunosorbent assay (belisa) and plaque reduction neutralization test (prnt(90)). prevalence derived from belisa (2002, 12.7%; 2003, 11.2%) and wnv prnt(90) (2002, 7.9%; 2003, 8.5%) assays ...200516354809
class ii virus membrane fusion proteins.enveloped animal viruses fuse their membrane with a host cell membrane, thus delivering the virus genetic material into the cytoplasm and initiating infection. this critical membrane fusion reaction is mediated by a virus transmembrane protein known as the fusion protein, which inserts its hydrophobic fusion peptide into the cell membrane and refolds to drive the fusion reaction. this review describes recent advances in our understanding of the structure and function of the class ii fusion prote ...200616364734
inhibitory effect of rnai on japanese encephalitis virus replication in vitro and in vivo.flaviviruses include many insect-mediated small viruses and still cause serious problems in the world. in humans, jev can cause acute meningioencephalomyelitis, resulting in fatality rates of 5 to 40%. rna-interference (rnai) as an antiviral mechanism was originally discovered in plants and then found in the specific suppression of gene expression of other organisms such as caenorhabditis elegans, drosophila and vertebrates. as jev is an rna virus, rnai could be a reasonable approach for therape ...200516365529
isolation of viruses from mosquitoes (diptera: culicidae) collected in the amazon basin region of part of a comprehensive study on the ecology of arthropod-borne viruses in the amazon basin region of peru, we assayed 539,694 mosquitoes captured in loreto department, peru, for arboviruses. mosquitoes were captured either by dry ice-baited miniature light traps or with aspirators while mosquitoes were landing on human collectors, identified to species, and later tested on vero cells for virus. in total, 164 virus isolations were made and included members of the alphavirus (eastern equine en ...200516366001
unexpected similarity between the cytosolic west nile virus ns3 and the secretory furin-like serine proteinases.many viral proteins undergo proteolytic processing events that are required for virus infection and virion assembly. in this issue of biochemical journal, strongin and co-workers report that the ns3 protease from west nile virus unexpectedly cleaves certain substrates at pairs of basic residues, a specificity that resembles that of the furin-like pcs (proprotein convertases). this led to the demonstration that furin/pc inhibitors containing poly(d-arginine) are also potent inhibitors of ns3, and ...200616371006
interferon: ten stories in one. a short review of some of the highlights in the history of an almost quinquagenarian.this short review article on some pertinent observations in the unfolding story of interferon is dedicated to professor ilona béládi on the occasion of her 80th birthday. this by no means covers the whole story on interferon. it just highlights some of the more striking findings made with interferon (or its inducers) over a time span of almost 50 years since its original discovery (in 1957) by isaacs and lindenmann. these observations concern (i) the induction of interferon by synthetic polyanio ...200516400870
west nile flavivirus polioencephalomyelitis in a harbor seal (phoca vitulina).a 12-year-old male harbor seal presented with progressive signs of neurologic dysfunction including head tremors, muzzle twitching, clonic spasms, and weakness. lesions included polioencephalomyelitis with glial nodules, spheroids, neuronophagia, ring hemorrhages, and a few neutrophils. neurons, fibers, and glial nodules were multifocally colonized with intracytoplasmic west nile flavivirus antigens that were demonstrated using indirect immunohistochemical analysis. flavivirus on cultured cells ...200616407488
energetics of rna binding by the west nile virus rna triphosphatase.the west nile virus (wnv) rna genome harbors the characteristic methylated cap structure present at the 5' end of eukaryotic mrnas. in the present study, we report a detailed study of the binding energetics and thermodynamic parameters involved in the interaction between rna and the wnv rna triphosphatase, an enzyme involved in the synthesis of the rna cap structure. fluorescence spectroscopy assays revealed that the initial interaction between rna and the enzyme is characterized by a high entha ...200616413541
west nile virus discriminates between dc-sign and dc-signr for cellular attachment and infection.the c-type lectins dc-sign and dc-signr bind mannose-rich glycans with high affinity. in vitro, cells expressing these attachment factors efficiently capture, and are infected by, a diverse array of appropriately glycosylated pathogens, including dengue virus. in this study, we investigated whether these lectins could enhance cellular infection by west nile virus (wnv), a mosquito-borne flavivirus related to dengue virus. we discovered that dc-signr promoted wnv infection much more efficiently t ...200616415006
antibodies against west nile virus nonstructural protein ns1 prevent lethal infection through fc gamma receptor-dependent and -independent mechanisms.the flavivirus nonstructural protein ns1 is a highly conserved secreted glycoprotein that does not package with the virion. immunization with ns1 elicits a protective immune response against yellow fever, dengue, and tick-borne encephalitis flaviviruses through poorly defined mechanisms. in this study, we purified a recombinant, secreted form of west nile virus (wnv) ns1 glycoprotein from baculovirus-infected insect cells and generated 22 new ns1-specific monoclonal antibodies (mabs). by perform ...200616415011
[isolation and identification of arboviruses from mosquito pools in yunnan province].to survey arboviruses in yunnan province.200516415987
[molecular biological survey of tick-born arboviruses in southern part of xinjiang].to disclose the species and distribution of tick-borne arboviruses in the southern part of xinjiang.200516415988
[expression of tick-borne encephalitis virus prm-e protein in insect cells and studies on its antigenicity].to express the prm-e protein in sf9 cells, and lay a basis for further study on the function of the viral proteins and development of specific diagnostic reagents.200516415990
[comparison and discrimination of the biological characteristics between west nile virus and japanese encephalitis virus].to compare the biological characteristics of west nile virus (wnv) and japanese encephalitis virus (jev), including cells sensitivity, pathogenicity, viral morphology, as well as the results of immunological and molecular biological detection.200516415991
west nile virus in southern portugal, 2004.west nile virus (wnv) genomic rna was detected by reverse transcription-polymerase chain reaction (rt-pcr) in six out of 57 mosquito pools collected in southern portugal, during the summer of 2004, yielding an infection rate (ir) of 2.8/1,000 mosquitoes. phylogenetic analysis of a 217-nucleotide fragment of the ns5 coding region, amplified from culex pipiens s.l. and culex univittatus unfed females, demonstrated a close relationship with wnv strains circulating in the mediterranean basin (italy, ...200516417437
assessing the genetic component of the susceptibility of mice to viral infections.laboratory mice often exhibit wide differences in susceptibility when infected experimentally with viruses. based on such observations, experiments have been designed to investigate the determinism of these differences at the molecular level, and a few genes that play a major role in the innate mechanisms of defence of the species toward viral aggressions have been characterised. for example, the extraordinary resistance of sjl mice to experimental infections with hepatitis virus strain a59 is t ...200516420748
the anti-yellow fever virus activity of ribavirin is independent of error-prone replication.the precise mechanism by which the broad-spectrum anti-rna virus agent ribavirin elicits its in vitro antiviral effect has remained a matter of debate. we have demonstrated that inhibition of cellular inosine monophosphate dehydrogenase (impdh) activity, and thus depletion of intracellular gtp pools, is the predominant mechanism by which ribavirin inhibits the replication of four flavi- and two paramyxoviruses (j virol 79:1943-1947, 2005). as a consequence, induction of error catastrophe, which ...200616421290
immunoglobulin g avidity in differentiation between early and late antibody responses to west nile 1999 west nile virus (wnv) surfaced in the united states in the city of new york and spread over successive summers to most of the continental united states, canada, and mexico. because wnv immunoglobulin m (igm) antibodies have been shown to persist for up to 1 year, residents in areas of endemicity can have persistent wnv igm antibodies that are unrelated to a current illness with which they present. we present data on the use of igg avidity testing for the resolution of conflicting data ar ...200616425997
biological, antigenic and phylogenetic characterization of the flavivirus alfuy.alfuy virus (alfv) is classified as a subtype of the flavivirus murray valley encephalitis virus (mvev); however, despite preliminary reports of antigenic and ecological similarities with mvev, alfv has not been associated with human disease. here, it was shown that alfv is at least 10(4)-fold less neuroinvasive than mvev after peripheral inoculation of 3-week-old swiss outbred mice, but alfv demonstrates similar neurovirulence. in addition, it was shown that alfv is partially attenuated in mice ...200616432019
kunjin virus replicons: an rna-based, non-cytopathic viral vector system for protein production, vaccine and gene therapy applications.the application of viral vectors for gene expression and delivery is rapidly evolving, with several entering clinical trials. however, a number of issues, including safety, gene expression levels, cell selectivity and antivector immunity, are driving the search for new vector systems. a number of replicon-based vectors derived from positive-strand rna viruses have recently been developed, and this paper reviews the current knowledge on the first flavivirus replicon system, which is based on the ...200616436039
[west nile fever and west nile encephalitis].west nile virus is a mosquito-borne flavivirus, and maintained in mosquito-bird cycle in nature. humans are a dead-end host in west nile virus infection. symptoms are developed in approximately 20% of west nile virus-infected humans. encephalitis and meningitis are developed in about 1 out of 150 infected humans, especially in elderly populations. it has recently been reported that west nile virus causes polio-like, acute flaccid paralysis and polyneuritis. these symptoms occur in patients witho ...200516447753
serologic survey of select infectious diseases in coyotes and raccoons in obtain data about select zoonotic and other infectious diseases in free-ranging predators in five ecoregions in nebraska, sera were collected from 67 coyotes (canis latrans) and 63 raccoons (procyon lotor) from november 2002 through january 2003. for coyotes, antibodies were detected against canine distemper virus (cdv, 61%), francisella tularensis (32%), rickettsia rickettsi (13%), and flaviviruses (48%). none of the coyote sera had antibodies to borrelia burgdorferi, brucella canis, or six ...200516456169
humoral immunity and correlation between elisa, hemagglutination inhibition, and neutralization tests after vaccination against tick-borne encephalitis virus in children.vaccination against tick-borne encephalitis (tbe) virus is the measure of choice for disease control in endemic areas, as no treatment is available. in italy, the province of belluno is one of the most active tbe virus infection foci. in this study sera were examined from vaccinated children living in areas around belluno in order to monitor the immune response after anti-tbe vaccination. for the assessment of neutralizing antibodies, a plaque reduction neutralization test (prnt) was optimized a ...200616458368
natural infection with japanese encephalitis virus among inhabitants of japan: a nationwide survey of antibodies against nonstructural 1 japan, only a few cases of japanese encephalitis presently occur annually, raising arguments about the necessity of vaccination. here, using a novel immunoassay, we obtained natural infection rates for 2001 of 0.2-3.4% in eight selected prefectures across japan. our results provide direct evidence of the risk of reemergence.200616460843
sentinel pigeon surveillance for west nile virus by using lard-can traps at differing elevations and canopy cover classes.sentinel pigeons, columba livia, were installed in lard-can traps at heights of 1.5 m and 7.6-9.1 m within differing canopy cover classes in new york city. adult mosquitoes were collected weekly from july to october 2002, as were serum samples from each pigeon. culex pipiens l. and culex restuans theobald comprised 97% of mosquitoes collected and were most numerous in canopy-level, forested traps. the west nile virus (family flaviviridae, genus flavivirus, wnv) seroconversion rate was significan ...200516465746
monitoring of japanese encephalitis virus infection in mosquitoes (diptera: culicidae) at guandu nature park, taipei, 2002-2004.japanese encephalitis virus (jev) infection in mosquitoes was monitored at guandu nature park in taipei city from september 2002 to december 2004. in total, 30,386 female mosquitoes consisting of six genera and 14 species were processed for virus in 1,229 pools by using flavivirus ns5 gene sequences detected by reverse transcription-polymerase chain reaction (pcr) and nested pcr assay. overall, 101 pools were positive, including 95, 1, 4, and 1 for culex tritaeniorhynchus giles, culex sitiens wi ...200516465752
rna secondary structure in the coding region of dengue virus type 2 directs translation start codon selection and is required for viral replication.dengue virus is a positive-strand rna virus and a member of the genus flavivirus, which includes west nile, yellow fever, and tick-borne encephalitis viruses. flavivirus genomes are translated as a single polyprotein that is subsequently cleaved into 10 proteins, the first of which is the viral capsid (c) protein. dengue virus type 2 (denv2) and other mosquito-borne flaviviruses initiate translation of c from a start codon in a suboptimal context and have multiple in-frame augs downstream. here, ...200616474125
a single amino acid substitution in the west nile virus nonstructural protein ns2a disables its ability to inhibit alpha/beta interferon induction and attenuates virus virulence in mice.alpha/beta interferons (ifn-alpha/beta) are key mediators of the innate immune response against viral infection. the ability of viruses to circumvent ifn-alpha/beta responses plays a crucial role in determining the outcome of infection. in a previous study using subgenomic replicons of the kunjin subtype of west nile virus (wnv(kun)), we demonstrated that the nonstructural protein ns2a is a major inhibitor of ifn-beta promoter-driven transcription and that a single amino acid substitution in ns2 ...200616474146
a clinico epidemiological study on acute viral infection of brain among children admitted in north bengal medical college, west bengal.a clinico epidemiological prospective study was carried out on acute viral infection of brain among children admitted in a rural based medical college from september '99 to oct '01. out of 80 cases, 8 cases (10%) of aseptic meningitis, 35 cases (43.75%) of encephalitis and 37 cases (6.25%) of meningo-encephalitis were found. overall case fatality was 47.5% and found higher (77%) among normally nourished children in comparison to malnourished children (47.5%). virological investigation did not is ...200516479917
concentration of procalcitonin and c-reactive protein in patients with human granulocytic anaplasmosis and the initial phase of tick-borne encephalitis.the aim of this prospective study was to assess the value of procalcitonin (pct) level and serum concentration of c-reactive protein (crp) in differentiating viral from bacterial infection in selected groups of patients, including those with acute human granulocytic anaplasmosis (hga), which is caused by an intracellular bacteria anaplasma phagocytophilum, and patients with the initial phase of tick-borne encephalitis (tbe), which is a viral disease caused by an rna virus belonging to the flaviv ...200516481557
probing the substrate specificity of the dengue virus type 2 ns3 serine protease by using internally quenched fluorescent peptides.the ns3 (dengue virus non-structural protein 3) serine protease of dengue virus is an essential component for virus maturation, thus representing an attractive target for the development of antiviral drugs directed at the inhibition of polyprotein processing. in the present study, we have investigated determinants of substrate specificity of the dengue virus ns3 protease by using internally quenched fluorogenic peptides containing abz (o-aminobenzoic acid; synonymous to anthranilic acid) and 3-n ...200616489931
analysis of the endocytic pathway mediating the infectious entry of mosquito-borne flavivirus west nile into aedes albopictus mosquito (c6/36) cells.the initial interaction between mosquito-borne flavivirus west nile and mosquito cells is poorly characterized. this study analyzed the endocytic and the associated signaling pathway that mediate the infectious entry of west nile virus (wnv) into mosquito cell line (c6/36). pretreatment of c6/36 cells with pharmacological drugs that blocks clathrin-mediated endocytosis significantly inhibited virus entry. furthermore, the transfection of functional blocking antibody against clathrin molecules an ...200616490225
rapid identification of dengue virus by reverse transcription-polymerase chain reaction using field-deployable instrumentation.dengue virus universal and dengue serotype 1 to 4, fluorogenic probe hydrolysis (taqman), reverse transcription-polymerase chain reaction assays were developed for screening and serotype identification of infected mosquito vectors and human sera using a field-deployable, fluorometric thermocycler. dengue universal and dengue 1 to 4 serotype assay in vitro sensitivity and specificity results were 100% concordant when tested with total nucleic acid extracts of multiple strains of dengue serotype 1 ...200516491947
prevalence and clinical significance of hgv/gbv-c infection in patients with chronic hepatitis b or c.hepatitis g virus/gb virus-c (hgv/gbv-c) is a newly identified flavivirus. its clinical significance in chronic hepatitis b and c remains controversial. infection with hgv/gbv-c was surveyed in 500 blood donors, 130 patients with chronic hepatitis b and 173 with hepatitis c, with chronic liver disease, cirrhosis, and/or hepatocellular carcinoma (hcc). hgv/gbv-c rna was detected by reverse transcription-polymerase chain reaction. an antibody to hgv/gbv-c's second envelope protein (anti-e2 ab) was ...200616495630
rnase l plays a role in the antiviral response to west nile virus.alleles at the flv locus determine disease outcome after a flavivirus infection in mice. although comparable numbers of congenic resistant and susceptible mouse embryo fibroblasts (mefs) are infected by the flavivirus west nile virus (wnv), resistant mefs produce approximately 100- to 150-fold lower titers than susceptible ones and flavivirus titers in the brains of resistant and susceptible animals can differ by >10,000-fold. the flv locus was previously identified as the 2'-5' oligoadenylate s ...200616501108
functional characterization of the ns2b/ns3 protease complex from seven viruses belonging to different groups inside the genus flavivirus.the genus flavivirus, family flaviviridae, comprises more than 70 viruses. many of them cause severe, potentially fatal, human diseases. human vaccines are available for only three viruses and no effective antiviral drug is available. in order to limit the consequences of infections with flaviviruses, a promising approach consists in developing specific compounds that target the virus-encoded ns2b/ns3 protease complex, which is crucial for the viral polyprotein processing. in order to develop su ...200616504332
bird-baited traps for surveillance of west nile mosquito vectors: effect of bird species, trap height, and mosquito escape mosquitoes were sampled in bird-baited traps at four sites in new york state in 2003-2004. trap placement and efficacy of chickens, gallus gallus domesticus l., as bait compared with house sparrows, passer domesticus l., an important reservoir of west nile virus (family flaviviridae, genus flavivirus, wnv), was evaluated. each site had a chicken-baited trap near ground level (approximately 1.5 m) and in the tree canopy (approximately 9 m), and a house sparrow-baited trap at ground l ...200616506452
quantitation of flaviviruses by fluorescent focus indirect immunofluorescence assay for quantitation of flaviviruses was developed as an alternative to the standard plaque assay. the assay was validated with west nile virus (wnv), st. louis encephalitis virus (slev), and dengue virus (denv) types 1-4. vero cells were plated in 8-well chamber slides, and infected with 10-fold serial dilutions of virus. about 1-3 days after infection, cells were fixed, incubated with specific monoclonal antibody, and stained with a secondary antibody labeled w ...200616510196
isolation of a new strain of the flavivirus cell fusing agent virus in a natural mosquito population from puerto rico.the genus flavivirus contains approximately 70 single-stranded, positive-sense rna viruses that are mosquito-borne, tick-borne or have no known vector. two discoveries support previous suggestions of the existence of a large number of unsampled flaviviruses: (i) a new flavivirus, kamiti river virus, was recently isolated from kenyan mosquitoes, and (ii) sequences with high similarity to those of flaviviruses have been found integrated into the genome of aedes mosquitoes, suggesting a past infect ...200616528021
molecular evolution of dengue 2 virus in puerto rico: positive selection in the viral envelope accompanies clade reintroduction.dengue virus is a circumtropical, mosquito-borne flavivirus that infects 50-100 million people each year and is expanding in both range and prevalence. of the four co-circulating viral serotypes (denv-1 to denv-4) that cause mild to severe febrile disease, denv-2 has been implicated in the onset of dengue haemorrhagic fever (dhf) in the americas in the early 1980s. to identify patterns of genetic change since denv-2's reintroduction into the region, molecular evolution in denv-2 from puerto rico ...200616528038
genome analysis and phylogenetic relationships between east, central and west african isolates of yellow fever virus.yellow fever virus (yfv), a reemerging disease agent in africa and south america, is the prototype member of the genus flavivirus. based on examination of the prm/m, e and 3' non-coding regions of the yfv genome, previous studies have identified seven genotypes of yfv, including the angolan, east/central african and east african genotypes, which are highly divergent from the prototype strain asibi. in this study, full genome analysis was used to expand upon these genetic relationships as well as ...200616528039
structural basis for the activation of flaviviral ns3 proteases from dengue and west nile virus.the replication of flaviviruses requires the correct processing of their polyprotein by the viral ns3 protease (ns3pro). essential for the activation of ns3pro is a 47-residue region of ns2b. here we report the crystal structures of a dengue ns2b-ns3pro complex and a west nile virus ns2b-ns3pro complex with a substrate-based inhibitor. these structures identify key residues for ns3pro substrate recognition and clarify the mechanism of ns3pro activation.200616532006
development of an enzyme-linked immunosorbent assay for serological diagnosis of tick-borne encephalitis using subviral particles.the similarity of symptoms produced by tick-borne encephalitis (tbe) and japanese encephalitis (je) and the high degree of cross-reactivity between tbe and je viruses by serological tests make the development of a differential diagnostic test a priority. in this study, recombinant prm/e proteins of tbe virus strain oshima 5-10 expressed in mammalian cells resulted in the release of subviral particles (sps) into the culture medium. using the sps as antigens, enzyme-linked immunosorbent assay (eli ...200616540179
[japanese encephalitis].japanese encephalitis is an arboviral disease due to a flavivirus transmitted by a mosquito of the genus culex. it is a major public health problem in southeast asia where it is endemo-epidemic. the socio-economic impact of japanese encephalitis is great since most cases occur in children and young adults and lead to death in 25 to 30 % and neurological sequelae in survivors. the tendency of japanese encephalitis to spread geographically and the existence of imported cases are particularly impor ...200516548493
west nile virus activity in latin america and the caribbean.west nile virus (flavivirus: flaviviridae; wnv) has spread rapidly throughout the caribbean basin since its initial detection there in 2001. this report summarizes our current knowledge of wnv transmission in tropical america.200616551385
differential dengue cross-reactive and neutralizing antibody responses in balb/c and swiss albino mice induced by immunization with flaviviral vaccines and by infection with homotypic dengue-2 virus strains.we investigated whether cross-reactive and/or cross-protective antibodies against dengue virus could be generated in 6-week-old balb/c mice by immunization with currently approved flaviviral vaccines, i.e., japanese encephalitis (je) biken and yellow fever (yf) 17d. cross-reactivity with dengue antigens was apparent in at least one-third each of je-vaccinated mouse sera and of je/yf-vaccinated mouse sera by dengue enzyme immunoassay, but was not detected in sera of mice immunized with yf vaccine ...200616553548
[viral fusion mechanisms].the majority of viral fusion proteins can be divided into two classes. the influenza hemagglutinin (ha) belongs to the class i fusion proteins and undergoes a series of conformational changes at acidic ph, leading to membrane fusion. the crystal structures of the prefusion and the postfusion forms of ha have been revealed in 1981 and 1994, respectively. on the basis of these structures, a model for the mechanism of membrane fusion mediated by the conformational changes of ha has been proposed. t ...200516557006
evolutionary influences in arboviral disease.arthropod-borne viruses (arboviruses) generally require horizontal transmission by arthropod vectors among vertebrate hosts for their natural maintenance. this requirement for alternate replication in disparate hosts places unusual evolutionary constraints on these viruses, which have probably limited the evolution of arboviruses to only a few families of rna viruses (togaviridae, flaviviridae, bunyaviridae, rhabdoviridae, reoviridae, and orthomyxoviridae) and a single dna virus. phylogenetic st ...200616568903
triaryl pyrazoline compound inhibits flavivirus rna replication.triaryl pyrazoline {[5-(4-chloro-phenyl)-3-thiophen-2-yl-4,5-dihydro-pyrazol-1-yl]-phenyl-methanone} inhibits flavivirus infection in cell culture. the inhibitor was identified through high-throughput screening of a compound library using a luciferase-expressing west nile (wn) virus infection assay. the compound inhibited an epidemic strain of wn virus without detectable cytotoxicity (a 50% effective concentration of 28 microm and a compound concentration of >or=300 microm required to reduce 50% ...200616569847
functional analysis of the tick-borne encephalitis virus cyclization elements indicates major differences between mosquito-borne and tick-borne flaviviruses.the linear, positive-stranded rna genome of flaviviruses is thought to adopt a circularized conformation via interactions of short complementary sequence elements located within its terminal regions. this process of rna cyclization is a crucial precondition for rna replication. in the case of mosquito-borne flaviviruses, highly conserved cyclization sequences (cs) have been identified, and their functionality has been experimentally confirmed. here, we provide an experimental identification of c ...200616571826
japanese encephalitis: development of new candidate vaccines.japanese encephalitis (je) is the most common form of viral encephalitis that appears in the form of frequent epidemics of brain fever throughout southeast asia, china and india. the disease is caused by a flavivirus named japanese encephalitis virus that is spread to humans by mosquitoes. an internationally approved mouse brain-derived inactivated vaccine has been available that is relatively expensive, gives immunity of uncertain duration and is not completely safe. cell culture-derived inacti ...200616597211
understanding helicases as a means of virus control.helicases are promising antiviral drug targets because their enzymatic activities are essential for viral genome replication, transcription, and translation. numerous potent inhibitors of helicases encoded by herpes simplex virus, severe acute respiratory syndrome coronavirus, hepatitis c virus, japanese encephalitis virus, west nile virus, and human papillomavirus have been recently reported in the scientific literature. some inhibitors have also been shown to decrease viral replication in cell ...200616611118
regulated cleavages at the west nile virus ns4a-2k-ns4b junctions play a major role in rearranging cytoplasmic membranes and golgi trafficking of the ns4a protein.a common feature associated with the replication of most rna viruses is the formation of a unique membrane environment encapsulating the viral replication complex. for their part, flaviviruses are no exception, whereupon infection causes a dramatic rearrangement and induction of unique membrane structures within the cytoplasm of infected cells. these virus-induced membranes, termed paracrystalline arrays, convoluted membranes, and vesicle packets, all appear to have specific functions during rep ...200616611922
[west nile virus fever].west nile virus (wnv) is a member of the flaviviridae family, genus flavivirus. its reservoir hosts are wild birds. infection is transmitted to humans by infected mosquitoes of the genus culex. in most cases, it is either asymptomatic or manifests itself as mild fever. typically, wnv illnesshas a sudden onset with fever above 39 degrees c and accompanying symptoms such as chills, headache, arthralgia, myalgia, back ache, cough and sore throat. gastrointestinal symptoms are frequently reported. g ...200616617842
impact of trap elevation on estimates of abundance, parity rates, and body size of culex pipiens and culex restuans (diptera: culicidae).trapping success, abundance, parity rate, and body size indices of culex pipiens (l.) and culex restuans theobald, important vectors of west nile virus (family flaviviridae, genus flavivirus, wnv), were determined for specimens captured from both ground level (approximately 1-m) and elevated (approximately 6- to 7-m) co2-baited cdc miniature light traps. mosquitoes were collected from six study sites in albany county, new york, from mid-may to mid-october 2004. there was no significant differenc ...200616619596
laboratory transmission of japanese encephalitis and west nile viruses by molestus form of culex pipiens (diptera: culicidae) collected in uzbekistan in 2004.we evaluated the molestus form of culex pipiens pipiens (l.) (hereafter referred to as "molestus") captured near tashkent, uzbekistan, for their ability to transmit japanese encephalitis (family flaviviridae, genus flavivirus, jev) and west nile (family flaviviridae, genus flavivirus, wnv) viruses under laboratory conditions. these molestus were highly competent laboratory vectors of wnv, with infection and dissemination rates of 96 and 81%, respectively. approximately 75% of female molestus tha ...200616619614
effects of temperature on the transmission of west nile virus by culex tarsalis (diptera: culicidae).culex tarsalis coquillett females were infected with the ny99 strain of west nile virus (family flaviviridae, genus flavivirus, wnv) and then incubated under constant temperatures of 10-30 degrees c. at selected time intervals, transmission was attempted using an in vitro capillary tube assay. the median time from imbibing an infectious bloodmeal until infected females transmitted wnv (median extrinsic incubation period, eip50) was estimated by probit analysis. by regressing the eip rate (invers ...200616619616
overwintering of west nile virus in southern california.west nile virus (family flaviviridae, genus flavivirus, wnv) invaded southern california during 2003, successfully overwintered, amplified to epidemic levels, and then dispersed to every county in the state. although surveillance programs successfully tracked and measured these events, mechanisms that allowed the efficient overwintering and subsequent amplification of wnv have not been elucidated. our current research provided evidence for three mechanisms whereby wnv may have persisted in south ...200616619621
a single amino acid substitution in the central portion of the west nile virus ns4b protein confers a highly attenuated phenotype in mice.west nile virus (wnv) ns4b is a small hydrophobic nonstructural protein that is hypothesized to participate both in viral replication and evasion of host innate immune defenses. the protein has four cysteine residues (residues 102, 120, 227, and 237). since cysteines are often critical for the function of proteins, each of the four cysteine residues found in wnv ns4b was mutated to serine by site-directed mutagenesis. while three of these substitutions had little effect on replication or mouse v ...200616624366
limited pathogenicity of usutu virus for the domestic goose (anser anser f. domestica) following experimental inoculation.usutu virus (usuv) is a mosquito-borne flavivirus of the japanese encephalitis virus group, which has been associated with avian mortality in austria since 2001. the affected birds are predominantly eurasian blackbirds (turdus merula). in the present study, the pathogenicity of usuv for domestic geese (anser anser f. domestica) was investigated. eleven 2-week-old geese were inoculated intramuscularly with 5 x 10(4) 50% tissue culture infectious dose of usuv strain vienna-2001 blackbird. no clini ...200616629984
comparative mechanistic studies of de novo rna synthesis by flavivirus rna-dependent rna polymerases.flavivirus protein ns5 harbors the rna-dependent rna polymerase (rdrp) activity. in contrast to the rdrps of hepaci- and pestiviruses, which belong to the same family of flaviviridae, ns5 carries two activities, a methyltransferase (mtase) and a rdrp. rdrp domains of dengue virus (dv) and west nile virus (wnv) ns5 were purified in high yield relative to full-length ns5 and showed full rdrp activity. steady-state enzymatic parameters were determined on homopolymeric template poly(rc). the presenc ...200616631221
innate and adaptive cellular immunity in flavivirus-naïve human recipients of a live-attenuated dengue serotype 3 vaccine produced in vero cells (vdv3).vdv3, a clonal derivative of the mahidol live-attenuated dengue 3 vaccine was prepared in vero cells. despite satisfactory preclinical evaluation, vdv3 was reactogenic in humans. we explored whether immunological mechanisms contributed to this outcome by monitoring innate and adaptive cellular immune responses for 28 days after vaccination. while no variations were seen in serum il12 or tnfalpha levels, a high ifngamma secretion was detected from day 8, concomitant to ifnalpha, followed by il10. ...200616632108
molecular characterization and clinical evaluation of dengue outbreak in 2002 in bangladesh.during the febrile illness epidemic in bangladesh in 2002, 58 people died out of the 6,132 affected. two hundred hospitalized patients were analyzed clinically, serologically and virologically to determine the features of this dengue infection. among the 10- to 70-year-old age group of the 200 clinically suspected dengue patients, 100 (50%) were confirmed as dengue cases by virus isolation and dengue igm-capture elisa. of the 100 dengue-confirmed cases, the mean age was 29.0 (+/-12.4). the possi ...200616632907
[epitope mapping of antigenic determinants of hepatitis c virus proteins by phage display].study of individual hepatitis c (hcv) proteins could help to find a molecular structure and conformation, localization of antigenic and immunogenic determinants, to reveal of protective epitopes. it is necessary for practical medicine - development of diagnostic test-systems, vaccines and therapeutics. linear and conformation dependent epitopes of hcv proteins was localized in this work and immunogenic properties of phage displayed peptides screened on monoclonal antibodies to hcv proteins have ...200616637277
[isolation and identification of japanese encephalitis virus in liaoning province].to study arboviruses carried by mosquitoes in liaoning province in 2002.200616642222
comparative attractiveness of two chicken breeds to mosquitoes in southern california.each transmission season (april-october), mosquito control districts deploy more than 2,000 white leghorn hens as sentinels in california's arbovirus surveillance program. in 2002, rhode island red hybrids were used instead, because of insufficient availability of leghorns. although arboviral seroconversions occurred in both breeds, their attractiveness to host-seeking mosquitoes was not compared. during august and september 2004, florida medical entomology laboratory traps, each containing 1 he ...200616646319
tick-borne disease systems: mapping geographic and phylogenetic space.evidence is presented that the evolution of the tick-borne flaviviruses is driven by biotic factors, principally the exploitation of new hosts as transmission routes. because vector-borne diseases are limited by climatic conditions, however, abiotic factors have the potential to direct and constrain the evolutionary pathways. this idea is explored by testing the hypothesis that closely related viruses occupy more similar eco-climatic spaces than do more distantly related viruses. a statistical c ...200616647973
a single tube rt-pcr assay for the detection of mosquito-borne flaviviruses.mosquito-borne flaviviruses include several important agents of human disease and have provided striking examples of emerging infections. in this study we present the design and validation of a single tube rt-pcr assay using a pair of consensus primers for the detection of mosquito-borne flaviviruses. sequencing of the amplicons permits the species identification. the assay was validated using rna from the yellow fever virus vaccine strain and from representative strains of dengue viruses 1, 2, ...200616650488
fatal hemorrhagic fever caused by west nile virus in the united states.most west nile virus (wnv) infections in humans are asymptomatic; severe disease occurs in relatively few patients and typically manifests as encephalitis, meningitis, or acute flaccid paralysis. a few cases of life-threatening disease with diffuse hemorrhagic manifestations have been reported in africa; however, this clinical presentation has not been documented for any of the >16,700 cases of wnv disease reported in the united states during 1999-2004. we describe a case of fulminant wnv infect ...200616652309
west nile virus antibodies in colombian horses. 200516673523
expression of foreign protein epitopes at the surface of recombinant yellow fever 17d viruses based on three-dimensional modeling of its envelope protein.the yellow fever (yf) 17d vaccine is a live attenuated virus, and its genetic manipulation constitutes a new platform for vaccine development. in this article, we review one of the possible approaches to enable this development, which is the insertion of foreign protein epitopes into different locations of the genome. we describe the three-dimensional (3d) modeling of the yf 17d virus e protein structure based on tick-borne encephalitis (tbe) and the identification of a potential insertion site ...200616679518
serological evidence for japanese encephalitis and west nile viruses in domestic animals of nepal.a regional survey was conducted in nepal for antibody to japanese encephalitis virus (jev) in domestic animals. sera from pigs, and limited numbers of ducks and horses were collected from 16 districts in 2002-2003 and subjected to three serological tests. of 270 porcine sera tested by c-elisa, 55% were found positive for the presence of antibodies against japanese encephalitis virus. additional testing for igm antibody to jev revealed less than 2% of c-elisa positive sera had evidence of recent ...200616697904
Displaying items 2001 - 2100 of 3318