development of immunoglobulin m capture enzyme-linked immunosorbent assay to differentiate human flavivirus infections occurring in australia.we report the development of a flavivirus immunoglobulin m (igm) capture enzyme-linked immunosorbent assay (mac-elisa) which improves the determination of an infecting flavivirus serotype over that by current serological methods. a panel of 165 igm-positive sera from flavivirus patients with specific diagnostic results was tested by the flavivirus mac-elisa using a panel of 10 antigens. for 134 of these sera (81.2%), the highest reactivity was demonstrated against the infecting virus, which was ...200515753249
class i and class ii viral fusion protein structures reveal similar principles in membrane fusion.recent crystal structures of flavivirus and alphavirus fusion proteins (class ii) confirm two major principles of protein machineries that mediate the merger of two opposing lipid bilayers. first, the fusion protein can bridge both membranes tethered by two membrane anchors. second, refolding or domain rearrangement steps lead to the positioning of both anchors into close proximity at the same end of an elongated structure. although these two steps are in principle sufficient to pull two opposin ...200415764366
flaviviruses in motor neuron disease.sporadic motor neuron disease (mnd) causes a progressive loss of motor neurons. west nile virus can attack motor neurons, so we examined whether flavivirus infection could be detected in mnd cases. spinal cord sections from 22 mnd cases were stained immunohistochemically with a flavivirus-specific antibody. no staining for flavivirus was seen in any case. sporadic mnd does not appear to arise from a recent infection with a flavivirus.200515779013
quantitative trait loci that control dengue-2 virus dissemination in the mosquito aedes aegypti.the mosquito aedes aegypti is the most important vector of yellow fever and dengue fever flaviviruses. ae. aegypti eradication campaigns have not been sustainable and there are no effective vaccines for dengue viruses. alternative control strategies may depend upon identification of mosquito genes that condition flavivirus susceptibility and may ultimately provide clues for interrupting transmission. quantitative trait loci affecting the ability of ae. aegypti to develop a dengue-2 infection in ...200515781707
heterologous gene expression by infectious and replicon vectors derived from tick-borne encephalitis virus and direct comparison of this flavivirus system with an alphavirus replicon.the flavivirus tick-borne encephaltis virus (tbev) was established as a vector system for heterologous gene expression. the variable region of the genomic 3' non-coding region was replaced by an expression cassette consisting of the reporter gene enhanced green fluorescent protein (egfp) under the translational control of an internal ribosomal entry site element, both in the context of an infectious virus genome and of a replicon lacking the genes of the surface proteins prm/m and e. the express ...200515784898
inhibition of flavivirus infections by antisense oligomers specifically suppressing viral translation and rna replication.rna elements within flavivirus genomes are potential targets for antiviral therapy. a panel of phosphorodiamidate morpholino oligomers (pmos), whose sequences are complementary to rna elements located in the 5'- and 3'-termini of the west nile (wn) virus genome, were designed to anneal to important cis-acting elements and potentially to inhibit wn infection. a novel arg-rich peptide was conjugated to each pmo for efficient cellular delivery. these pmos exhibited various degrees of antiviral acti ...200515795246
hepatitis g virus rna positivity among the voluntary blood donors: a summary.hepatitis virus infection is an increasing problem. millions of humans all over the world are infected. viral hepatitis is accepted as a significant public health problem with several life altering complications. recently, new viruses have been identified for their association with hepatitis. hepatitis g virus (hgv) is a single stranded rna virus which represents a newly discovered virus belonging to the flavivirus family. epidemiological data indicate that the virus is transmitted via blood/blo ...200515798660
characterization of west nile viral replication and maturation in peripheral neurons in culture.the north american west nile virus (wnv), new york 1999 strain, appears to be highly neurotropic, and its neuroinvasiveness is an important aspect of human disease. the authors have developed an in vitro model to study wnv replication and protein processing in neurons. they compared wnv infection of the dorsal root ganglion (drg) neurons (sensory neurons) and pc-12 cells (sympathetic neurons) to wnv infection of the mosquito cell line, c6/36, and vero cells. wnv infection of both neuronal cell t ...200515804955
recombination and flavivirus vaccines: a commentary. 200515811640
role of the n-linked glycans of the prm and e envelope proteins in tick-borne encephalitis virus particle secretion.the tick-borne encephalitis (tbe) virus has two membrane glycoproteins (prm and e), which each has one n-linked glycan. constructs that express prm and e proteins of tbe virus have been shown to produce virus-like particles (vlps), which have surface properties that are similar to those of infectious viruses. to reveal the function of glycosylation of the tbe virus prm and e proteins in the secretion of vlps, we expressed glycosylation-mutated prm and e proteins and compared the secretion levels ...200515811651
[west nile virus (wnv): generalities and implications for blood transfusion].west nile virus (wnv) is an arbovirus (genus flavivirus, family flaviviridae, transmitted to humans by mosquito bite. in most cases (80%), human infection remains asymptomatic. severe central nervous system complications (encephalitis and meningoencephalitis) are rare. in the old world, the virus circulation has been demonstrated in asia, australia, africa, middle east and europe. several outbreaks in humans have been described. following its introduction into north america in 1999, wn virus has ...200515814286
alkhumra haemorrhagic fever: case report and infection control details. 200515816213
competitive inhibition of the dengue virus ns3 serine protease by synthetic peptides representing polyprotein cleavage sites.the ns3 serine protease of dengue virus is required for the maturation of the viral polyprotein and consequently represents a promising target for the development of antiviral inhibitors. however, the substrate specificity of this enzyme has been characterized only to a limited extent. in this study, we have investigated product inhibition of the ns3 protease by synthetic peptides derived from the p6-p1 and the p1'-p5' regions of the natural polyprotein substrate. n-terminal cleavage site peptid ...200515823576
yellow fever virus ns2b-ns3 protease: characterization of charged-to-alanine mutant and revertant viruses and analysis of polyprotein-cleavage activities.a series of 46 charged-to-alanine mutations in the yellow fever virus ns2b-ns3 protease, previously characterized in cell-free and transient cellular expression systems, was tested for their effects on virus recovery. four distinct plaque phenotypes were observed in cell culture: parental plaque-size (13 mutants), reduced plaque-size (17 mutants), small plaque-size (8 mutants) and no plaque-formation (8 mutants). no mutants displayed any temperature sensitivity based on recovery of virus after r ...200515831952
review on flavivirus vaccine development. proceedings of a meeting jointly organised by the world health organization and the thai ministry of public health, 26-27 april 2004, bangkok, light of the continuous spread of human pathogenic flaviviruses, in particular the mosquito-transmitted species, vaccine development remains a high priority on the public health agenda. on 26-27 april 2004, a conference was held in bangkok, thailand, to review current status of flavivirus vaccine development and related issues, focussing on dengue (den) and japanese encephalitis (je). this event, co-sponsored by the world health organization (who) and the thai ministry of public health, revie ...200515841565
stereophysicochemical variability plots highlight conserved antigenic areas in flaviviruses.flaviviruses, which include dengue (dv) and west nile (wn), mutate in response to immune system pressure. identifying escape mutants, variant progeny that replicate in the presence of neutralizing antibodies, is a common way to identify functionally important residues of viral proteins. however, the mutations typically occur at variable positions on the viral surface that are not essential for viral replication. methods are needed to determine the true targets of the neutralizing antibodies.200515845145
generic rt-nested-pcr for detection of flaviviruses using degenerated primers and internal control followed by sequencing for specific identification.flaviviruses are a widespread and numerous group of arboviruses that can cause serious illness in humans. the continuous and slow spread of certain flaviviruses, such as dengue viruses, and the recent entry and spread of west nile virus to the american continent, point to the need to control these infections. this control requires the use of suitable techniques for diagnostic and surveillance programmes. a generic rt-nested-pcr that is, theoretically, able to detect each member of the group has ...200515847925
dendritic cell-specific intercellular adhesion molecule 3-grabbing non-integrin (dc-sign)-mediated enhancement of dengue virus infection is independent of dc-sign internalization signals.dengue virus (dv) is a mosquito-borne flavivirus that causes hemorrhagic fever in humans. in the natural infection, dv is introduced into human skin by an infected mosquito vector where it is believed to target immature dendritic cells (dcs) and langerhans cells (lcs). we found that dv productively infects dcs but not lcs. we show here that the interactions between dv e protein, the sole mannosylated glycoprotein present on dv particles, and the c-type lectin dendritic cell-specific intercellula ...200515855154
differences in the postfusion conformations of full-length and truncated class ii fusion protein e of tick-borne encephalitis virus.the trimeric postfusion structure of the c-terminally truncated fusion protein e of the flavivirus tick-borne encephalitis virus, a class ii viral fusion protein, was previously determined (s. bressanelli, k. stiasny, s. l. allison, e. a. stura, s. duquerroy, j. lescar, f. x. heinz, and f. a. rey, embo j. 23:728-738, 2004). in this study we compared the properties of this truncated form with the full-length trimer and found that the so-called stem-anchor region not only confers additional stabil ...200515858034
gb virus type c ns5a sequence polymorphisms: association with interferon susceptibility and inhibition of pkr-mediated eif2alpha virus type c (gbv-c) causes persistent infection in humans, although the mechanism by which the virus avoids clearance by the host is unknown. to determine if amino acid polymorphisms in the gb virus type c (gbv-c) ns5a and e2 proteins alter response to interferon (ifn) therapy, we studied the sequence of gbvc ns5a and e2 obtained from people receiving ifn therapy. in addition, we expressed recombinant gbvc ns5a protein to determine if it interferes with rna-activated protein kinase (pkr) fun ...200515871663
steps of the tick-borne encephalitis virus replication cycle that affect neuropathogenesis.tick-borne encephalitis virus (tbev) is an important human pathogen that causes severe neurological illness in large areas of europe and asia. the neuropathogenesis of this disease agent is determined by its capacity to enter the central nervous system (cns) after peripheral inoculation ("neuroinvasiveness") and its ability to replicate and cause damage within the cns ("neurovirulence"). tbev is a small, enveloped flavivirus with an unsegmented, positive-stranded rna genome. mutations affecting ...200515871909
probable chronic viral encephalitis with microglial nodules in the entire brain: a case report with necropsy.chronic encephalitis has rarely been seen, probably due to its viral origins, which may produce the disease in healthy or immunocompromised hosts. the etiology and pathophysiology of these types of encephalitis have not yet been clarified.200515874892
duplex microsphere-based immunoassay for detection of anti-west nile virus and anti-st. louis encephalitis virus immunoglobulin m antibodies.west nile (wn) virus was introduced into the united states in 1999, when the first human cases of wn fever and encephalitis appeared in new york city. from there, the virus has spread throughout north america, in some areas cocirculating with the related flavivirus st. louis encephalitis (sle) virus. public health laboratories currently use an immunoglobulin m (igm) antibody capture enzyme-linked immunosorbent assay (mac-elisa) as a primary test for human serodiagnosis, followed by a confirmator ...200515879016
[the occurrence rate of hgv/gbv-c rna and risk factors in patients of narcological dispensary in novosibirsk].the occurrence rate of hgv/gbv-c rna, genotypic variety of isolates and various risk factors of infection with hgv/gbv-c were evaluated in 500 patients of the narcological dispensary of novosibirsk. the occurrence rate of hgv/gbv-c rna among all examined blood sera was 33.6%. at the same time in blood sera with hcv markers the occurrence rate of hgv/ gbv-c was 42.9% and in sera with negative results for markers hcv--25%. for gene typing of obtained isolates the direct sequencing of the amplifica ...200515881934
low diversity of alkhurma hemorrhagic fever virus, saudi arabia, 1994-1999.alkhurma hemorrhagic fever virus (genus flavivirus, ahfv) was recently identified as the agent of a viral hemorrhagic fever in saudi arabia and characterized serologically and genetically as a variant genotype of kyasanur forest disease virus (kfdv). since viral diagnosis and vaccine development may be hindered by genetic diversity, this study was intended to address ahfv genetic heterogeneity. eleven strains isolated from hospitalized patients from 1994 to 1999 in saudi arabia were sequenced in ...200515890119
serologic evidence of exposure of wild mammals to flaviviruses in the central and eastern united states.serosurveys were conducted to obtain flavivirus and west nile virus (wnv) seroprevalence data from mammals. sera from 513 small- and medium-sized mammals collected during late summer and fall 2003 from colorado, louisiana, new york, ohio, and pennsylvania were screened for flavivirus-specific antibodies. sera samples containing antibody to flaviviruses were screened for wnv-specific antibodies by epitope-blocking enzyme-linked immunosorbent assays and confirmed with plaque reduction neutralizati ...200515891139
effect of mosquito midgut trypsin activity on dengue-2 virus infection and dissemination in aedes aegypti.the effect of mosquito midgut trypsins in dengue serotype 2 flavivirus (denv-2) infectivity to aedes aegypti was studied. addition of soybean trypsin inhibitor (sti) in a denv-2 infectious blood meal resulted in a 91-97% decrease in midgut denv-2 rna copies (qrt-pcr analysis). sti treatment also resulted in slower denv-2 replication in the midgut, less denv-2 e protein expression, and decreased dissemination to the thorax and the head. a second uninfected blood meal, 7 days after the sti-treated ...200515891140
recombinant canarypox vectored west nile virus (wnv) vaccine protects dogs and cats against a mosquito wnv challenge.the safety and efficacy of a canarypox vector expressing prm and e genes of west nile virus (wnv) (alvac-wnv) was evaluated in dogs and cats. one group of 17 dogs (vaccinated with 10(5.6) tcid(50)) and two groups of cats (groups 1 [n=14] vaccinated with 10(7.5) tcid(50) and 2 [n=8] 10(5.6) tcid(50)) were vaccinated twice at 28-day intervals. fifteen dogs and eleven cats served as negative controls. the cats and dogs were challenged 120 and 135 days after the second immunization, respectively via ...200515893618
association mapping of segregating sites in the early trypsin gene and susceptibility to dengue-2 virus in the mosquito aedes aegypti.evidence suggests that midgut trypsins in aedes aegypti condition the mosquito's ability to become infected with the dengue-2 flavivirus (den2). the activity of early trypsin protein peaks approximately 3 h after blood feeding and then drops within a few hours. we use association mapping to test the hypothesis that segregating sites in early trypsin condition midgut susceptibility to den2 virus. a total of 1642 females from throughout mexico and the southern us were fed an artificial blood meal ...200515894193
characterization of an infectious clone of the wild-type yellow fever virus asibi strain that is able to infect and disseminate in mosquitoes.infectious clone technology provides an opportunity to study the molecular basis of arthropod-virus interactions in detail. this study describes the development of an infectious clone of the prototype yellow fever virus asibi strain (yfv-as) with the purpose of identifying sequences or domains that influence infection dynamics in the mosquito vector. the full-length cdna of yfv-as virus was produced from rt-pcr products of parental viral rna. these were cloned into a low-copy-number plasmid prev ...200515914853
a recombinant envelope protein vaccine against west nile virus.west nile (wn) virus is a flavivirus that first appeared in north america in 1999. since then, more than 600 human deaths and 22,000 equine infections have been attributed to the virus in the united states. we expressed a truncated form of wn virus envelope (e) protein in drosophila s2 cells. this soluble recombinant e protein was recognized by antibodies from naturally infected horses, indicating that it contains native epitopes. mice and horses produced high-titer antibodies when immunized wit ...200515917113
modulation of the nucleoside triphosphatase/rna helicase and 5'-rna triphosphatase activities of dengue virus type 2 nonstructural protein 3 (ns3) by interaction with ns5, the rna-dependent rna polymerase.dengue virus type 2 (den2), a member of the flaviviridae family, is a re-emerging human pathogen of global significance. den2 nonstructural protein 3 (ns3) has a serine protease domain (ns3-pro) and requires the hydrophilic domain of ns2b (ns2bh) for activation. ns3 is also an rna-stimulated nucleoside triphosphatase (ntpase)/rna helicase and a 5'-rna triphosphatase (rtpase). in this study the first biochemical and kinetic properties of full-length ns3 (ns3fl)-associated ntpase, rtpase, and rna ...200515917225
chimeric dengue 2 pdk-53/west nile ny99 viruses retain the phenotypic attenuation markers of the candidate pdk-53 vaccine virus and protect mice against lethal challenge with west nile virus.chimeric dengue serotype 2/west nile (d2/wn) viruses expressing prm-e of wn ny99 virus in the genetic background of wild-type d2 16681 virus and two candidate d2 pdk-53 vaccine variants (pdk53-e and pdk53-v) were engineered. the viability of the d2/wn viruses required incorporation of the wn virus-specific signal sequence for prm. introduction of two mutations at m-58 and e-191 in the chimeric cdna clones further improved the viability of the chimeras constructed in all three d2 carriers. two d2 ...200515919884
peptide inhibitors of dengue virus and west nile virus infectivity.viral fusion proteins mediate cell entry by undergoing a series of conformational changes that result in virion-target cell membrane fusion. class i viral fusion proteins, such as those encoded by influenza virus and human immunodeficiency virus (hiv), contain two prominent alpha helices. peptides that mimic portions of these alpha helices inhibit structural rearrangements of the fusion proteins and prevent viral infection. the envelope glycoprotein (e) of flaviviruses, such as west nile virus ( ...200515927084
rapid subgroup identification of the flaviviruses using degenerate primer e-gene rt-pcr and site specific restriction enzyme analysis.a simplified and rapid method for the diagnosis of all flaviviruses could provide an important tool for understanding their epidemiology. a protocol based on the use of degenerate nested oligonucleotide primers and rt-pcr was developed for the identification of flaviviruses. the primers were selected to flank the three e-gene markers that identify the viruses, giving dna products of 971-986 (outer primers) and 859-884 bp (inner primers). eighty five percent of e genes from flaviviruses represent ...200515927275
the suitability of yellow fever and japanese encephalitis vaccines for immunization against west nile volunteers involved in flavivirus studies have been immunized with commercial japanese encephalitis and yellow fever vaccines je-vax and yf-vax. strong homologous and cross-reactive with west nile virus (wnv) antibody responses with titers 1:1600 to 1:51200 were found in all donors. all donors developed high levels of yellow fever virus (yfv) and japanese encephalitis virus (jev) neutralizing antibodies with titers 1:50 to 1:1600 and 1:20 to 1:640, respectively, and wnv neutralizing antibo ...200515939510
prevalence and incidence of antibodies to borrelia burgdorferi and to tick-borne encephalitis virus in agricultural and forestry workers from tuscany, italy.the ticks ixodes persulcatus and ixodes ricinus are the main vectors of both borrelia burgdorferi sensu lato and tick-borne encephalitis (tbe) virus in eurasia. borrelia burgdorferi is the cause of lyme borreliosis, and tbe is a biphasic meningoencephalitis induced by an arbovirus belonging to the flavivirus family. the principal aims of the current investigation were (i) to determine the frequency of serological evidence of borrelia burgdorferi sensu lato and tbe infections in healthy agricultu ...200515948001
west nile virus infection after cardiac transplantation.west nile virus is a mosquito-borne rna flavivirus infection transmitted to humans and other vertebrates, mainly by the culex species of mosquito. since the mid-1990s, the frequency and apparent clinical severity of west nile virus outbreaks have increased. we report the case of a patient who developed west nile virus encephalitis shortly after undergoing cardiac transplantation. clinicians should be aware of the possibility of west nile virus infection in transplant recipients and in patients r ...200515949740
optimized diagnosis of acute dengue fever in swedish travelers by a combination of reverse transcription-pcr and immunoglobulin m detection.the dengue viruses (genus flavivirus, family flaviviridae) are mosquito borne and cause 100 million cases of dengue fever each year in most tropical and subtropical areas of the world. increased global travel has been accompanied by an increased import not only of dengue but also of severe fevers of unknown origin to sweden. fifty-seven swedish travelers to dengue epidemic areas, with clinical and serologically diagnosed dengue fever, were included in this study. to find fast and reliable method ...200515956408
rapid detection and differentiation of dengue virus serotypes by a real-time reverse transcription-loop-mediated isothermal amplification assay.the development and validation of a one-step, real-time, and quantitative dengue virus serotype-specific reverse transcription-loop-mediated isothermal amplification (rt-lamp) assay targeting the 3' noncoding region for the rapid detection and differentiation of dengue virus serotypes are reported. the rt-lamp assay is very simple and rapid, wherein the amplification can be obtained in 30 min under isothermal conditions at 63 degrees c by employing a set of four serotype-specific primer mixtures ...200515956414
inhibition of alpha/beta interferon signaling by the ns4b protein of flaviviruses.flaviviruses are insect-borne, positive-strand rna viruses that have been disseminated worldwide. their genome is translated into a polyprotein, which is subsequently cleaved by a combination of viral and host proteases to produce three structural proteins and seven nonstructural proteins. the nonstructural protein ns4b of dengue 2 virus partially blocks activation of stat1 and interferon-stimulated response element (isre) promoters in cells stimulated with interferon (ifn). we have found that t ...200515956546
flavivirus activates phosphatidylinositol 3-kinase signaling to block caspase-dependent apoptotic cell death at the early stage of virus infection.flaviviruses such as dengue virus (den) and japanese encephalitis virus (jev) are medically important in humans. the lipid kinase, phosphatidylinositol 3-kinase (pi3k) and its downstream target akt have been implicated in the regulation of diverse cellular functions such as proliferation, and apoptosis. since jev and den appear to trigger apoptosis in cultured cells at a rather late stage of infection, we evaluated the possible roles of the pi3k/akt signaling pathway in flavivirus-infected cells ...200515956583
histidine at residue 99 and the transmembrane region of the precursor membrane prm protein are important for the prm-e heterodimeric complex formation of japanese encephalitis virus.the formation of the flavivirus prm-e complex is an important step for the biogenesis of immature virions, which is followed by a subsequent cleavage of prm to m protein through cellular protease to result in the production and release of mature virions. in this study, the intracellular formation of the prm-e complex of japanese encephalitis virus was investigated by baculovirus coexpression of prm and e in trans in sf9 insect cells as analyzed by anti-e antibody immunoprecipitation and sucrose ...200515956595
attenuation of recombinant yellow fever 17d viruses expressing foreign protein epitopes at the surface.the yellow fever (yf) 17d vaccine is a live attenuated virus. three-dimensional (3d) homology modeling of the e protein structure from yf 17d virus and its comparison with that from tick-borne encephalitis virus revealed that it is possible to accommodate inserts of different sizes and amino acid compositions in the flavivirus e protein fg loop. this is consistent with the 3d structures of both the dimeric and trimeric forms in which the fg loop lies exposed to solvents. we demonstrate here that ...200515956601
mosquito-borne flaviviruses and human disease. 200515960190
persistent west nile virus infection in the golden hamster: studies on its mechanism and possible implications for other flavivirus infections.golden hamsters (mesocricetus auratus) experimentally infected with west nile virus (wnv) developed chronic renal infection and persistent shedding of virus in urine for up to 8 months, despite initial rapid clearance of virus from blood and the timely appearance of high levels of specific neutralizing antibodies. infectious wnv could be recovered by direct culture of their urine and by cocultivation of kidney tissue for up to 247 days after initial infection. only moderate histopathologic chang ...200515962223
sentinel chicken surveillance program in australia, july 2003 to june 2004.detection of flavivirus seroconversions in sentinel chicken flocks located in four australian states are used to provide an early warning of increased levels of murray valley encephalitis virus (mvev) and kunjin virus (kunv) activity in the region. during the 2003-2004 season low levels of flavivirus activity were detected in northern australia with both mvev and kunv virus activity detected in the kimberley and pilbara regions of western australia and in the northern territory. a single case of ...200515966677
japanese encephalitis in india. 200515970050
safety testing for neurovirulence of novel live, attenuated flavivirus vaccines: infant mice provide an accurate surrogate for the test in monkeys.current requirements for control of live viral vaccines, including yellow fever 17d, produced from potentially neurotropic wild-type viruses include tests for neurovirulence in nonhuman primates. we have used yellow fever 17d virus as a live vector for novel flavivirus vaccines (designated chimerivax) against dengue, japanese encephalitis (je), and west nile (wn) viruses. for control of these vaccines, it would be preferable to substitute a test in mice for the test in a higher species (monkeys) ...200515975826
visualization of central european tick-borne encephalitis infection in fatal human cases.central european tick-borne encephalitis (tbe) is caused by a flavivirus vectored by the ixodes ricinus tick. in severe infections, tbe presents as (myelo)meningoencephalitis with considerable mortality. characteristic neuropathologic changes feature a multinodular to patchy polioencephalomyelitis accentuated in spinal cord, brainstem, and cerebellum. visualization of viral infection by immunohistochemistry has not yet been achieved. we analyzed immunohistochemically the distribution of viral an ...200515977642
comparative analysis of immunoglobulin m (igm) capture enzyme-linked immunosorbent assay using virus-like particles or virus-infected mouse brain antigens to detect igm antibody in sera from patients with evident flaviviral infections.the use of immunoglobulin m (igm) antibody-capture enzyme-linked immunosorbent assay (mac-elisa) serves as a valuable tool for the diagnosis of acute flaviviral infections, since igm antibody titers are detectable early, peak at about 2 weeks postinfection, and subsequently decline to lower levels over the next few months. traditionally, virus-infected tissue culture or suckling mouse brain (smb) has been the source of viral antigens used in the assay. in an effort to provide a reliable source o ...200516000440
semliki forest virus and kunjin virus rna replicons elicit comparable cellular immunity but distinct humoral immunity.rna replicons offer a number of qualities which make them attractive as vaccination vectors. both alphavirus and flavivirus replicon vaccines have been investigated in preclinical models yet there has been little direct comparison of the two vector systems. to determine whether differences in the biology of the two vectors influence immunogenicity, we compared two prototypic replicon vectors based on semliki forest virus (sfv) (alphavirus) and kunjin virus (kun) (flavivirus). both vectors when d ...200516005737
west nile virus survey of birds and mosquitoes in the dominican republic.we report west nile virus (wnv) activity from a new area on hispaniola, in the vicinity of monte cristi national park in northwest dominican republic. specific anti-wnv antibodies were detected in 12 of 58 (21%) resident birds sampled in march 2003, representing six species in the orders cuculiformes (cuckoos), strigiformes (owls), and passeriformes (song birds). this seroprevalence is the highest reported from any site in the caribbean basin. virus was not detected in any mosquitoes or tissues ...200516011427
the identification of immunodominant linear epitopes of dengue type 2 virus capsid and ns4a proteins using pin-bound peptides.we have used multi-pin peptide synthesis strategy to identify b-cell epitopes on two small dengue virus proteins, capsid and ns4a. we have identified several linear, immunodominant epitopes on both these proteins. almost all these epitopes mapped to regions predicted to be hydrophilic based on kyte and doolittle profiles. of the capsid epitopes identified in this study, the most immunogenic ones mapped to the c-terminal alpha4 helix, which lies on the solvent-exposed surface of the capsid dimer. ...200516022901
a synthetic peptide based on the ns1 non-structural protein of tick-borne encephalitis virus induces a protective immune response against fatal encephalitis in an experimental animal model.linear immunogenic peptides corresponding to amino acid sequences from the ns1 non-structural protein from tick-borne encephalitis virus (strain sophyin) were predicted using established algorithms and synthesized. of the 12 peptides predicted, 11 were able to induce peptide-specific antibodies in balb/c mice but only 1 of these 11 was able to induce antibodies, which reacted with the native protein in a radio-immune precipitation assay. this peptide corresponds to amino acids 37--55, and forms ...200516022903
when is a mosquito not? 200516028475
the article on mosquito-borne diseases was timely and well written. 200516028476
first record of aedes (aedimorphus) vexans vexans (meigen) in australia.aedes (aedimorphus) vexans vexans has become widely distributed in the australasian and oceanic islands zoogeographic regions, and in this paper, we describe the 1st confirmed report of ae. vexans vexans in australia. a total of 45 adult individuals were collected around the town of kununurra in the northeast kimberley region of western australia during the late wet seasons between 1996 and 2003. the majority (84%) was collected at trap sites in or near the ord stage i irrigation area. aedes vex ...200516033126
analysis of two imported cases of yellow fever infection from ivory coast and the gambia to germany and belgium.yellow fever remains one of the great burdens for public health in the endemic regions in africa and south america. the under reporting of yellow fever cases in the respective regions and lack of international interest leads to an underestimation of the constant danger in these areas. non-vaccinated travelers take a high risk without the effective protection of yfv 17d vaccination.200516036176
alkhumra virus infection, a new viral hemorrhagic fever in saudi arabia.four patients with typical acute viral hemorrhagic fever were identified in the holy city of makkah, saudi arabia, between 8 and 23 february 2001, the hajj (pilgrimage) period of that year. tests for rift valley fever (rvf), crimean-congo hemorrhagic fever (cchf), and dengue were negative. blood specimens were sent to the centres for disease control and prevention (cdc), atlanta for viral culture and testing for other hemorrhagic fever viruses. a new flavivirus closely related to the tick-borne ...200516038757
structure of the flavivirus helicase: implications for catalytic activity, protein interactions, and proteolytic processing.yellow fever virus (yfv), a member of the flavivirus genus, has a plus-sense rna genome encoding a single polyprotein. viral protein ns3 includes a protease and a helicase that are essential to virus replication and to rna capping. the 1.8-a crystal structure of the helicase region of the yfv ns3 protein includes residues 187 to 623. two familiar helicase domains bind nucleotide in a triphosphate pocket without base recognition, providing a site for nonspecific hydrolysis of nucleoside triphosph ...200516051820
structure of the dengue virus helicase/nucleoside triphosphatase catalytic domain at a resolution of 2.4 a.dengue fever is an important emerging public health concern, with several million viral infections occurring annually, for which no effective therapy currently exists. the ns3 protein from dengue virus is a multifunctional protein of 69 kda, endowed with protease, helicase, and nucleoside 5'-triphosphatase (ntpase) activities. thus, ns3 plays an important role in viral replication and represents a very interesting target for the development of specific antiviral inhibitors. we present the struct ...200516051821
combined prime-boost vaccination against tick-borne encephalitis (tbe) using a recombinant vaccinia virus and a bacterial plasmid both expressing tbe virus non-structural ns1 protein.heterologous prime-boost immunization protocols using different gene expression systems have proven to be successful tools in protecting against various diseases in experimental animal models. the main reason for using this approach is to exploit the ability of expression cassettes to prime or boost the immune system in different ways during vaccination procedures. the purpose of the project was to study the ability of recombinant vaccinia virus (vv) and bacterial plasmid, both carrying the ns1 ...200516076390
dna probe array for the simultaneous identification of herpesviruses, enteroviruses, and flaviviruses.viral infections of the central nervous system (cns) are caused by a variety of viruses, namely, herpesviruses, enteroviruses, and flaviviruses. the similar clinical signs provoked by these viruses make the diagnosis difficult. we report on the simultaneous detection of these major cns pathogens using amplification by pcr and detection of amplified products using dna microarray technology. consensus primers were used for the amplification of all members of each genus. sequences specific for the ...200516081910
determining genetic stabilities of chimeric dengue vaccine candidates based on dengue 2 pdk-53 virus by sequencing and quantitative taqmama.the genetic stabilities of the three attenuation loci of the candidate dengue 2 (d2) pdk-53 vaccine virus were evaluated for the pdk-53 virus and pdk-53-vectored chimeric d2/1, d2/3, and d2/4 viruses following 10 sequential passages in vero cells. sequencing revealed that the dominant ns1-53-asp and the ns3-250-val attenuation loci were extremely stable, whereas reversion occurred at the 5'ncr-57-u locus in 10 of the 18 viral lineages tested. a more sensitive and quantitative assay, the taqman m ...200616087248
dengue virus nonstructural protein ns5 induces interleukin-8 transcription and secretion.elevated circulating levels of chemokines have been reported in patients with dengue fever and are proposed to contribute to the pathogenesis of dengue disease. to establish in vitro models for chemokine induction by dengue 2 virus (den2v), we studied a variety of human cell lines and primary cells. den2v infection of hepg2 and primary dendritic cells induced the production of interleukin-8 (il-8), rantes, mip-1alpha, and mip-1beta, whereas only il-8 and rantes were induced following dengue viru ...200516103156
the secreted form of dengue virus nonstructural protein ns1 is endocytosed by hepatocytes and accumulates in late endosomes: implications for viral infectivity.the flavivirus nonstructural protein ns1 is expressed as three discrete species in infected mammalian cells: an intracellular, membrane-associated form essential for viral replication, a cell surface-associated form that may be involved in signal transduction, and a secreted form (sns1), the biological properties of which remain elusive. to determine the distribution of the dengue virus (den) sns1 protein in vivo, we have analyzed by immunohistological means the tissue tropism of purified den sn ...200516103191
serologic evidence for west nile virus transmission in puerto rico and cuba.during the spring of 2004, approximately 1,950 blood specimens were collected from resident and nearctic-neotropical migratory birds on the caribbean islands of puerto rico and cuba prior to northerly spring migrations. eleven birds and seven birds, collected in puerto rico and cuba, respectively, showed evidence of antibody in a flavivirus enzyme-linked immunosorbent assay. confirmatory plaque-reduction neutralization test results indicated neutralizing antibodies to west nile virus in non-migr ...200516103626
[diagnostic tests: japanese encephalitis virus and the other flavivirus]. 200516111267
yellow fever vaccine.yellow fever, a mosquito-borne viral hemorrhagic fever, is one of the most lethal diseases of humankind. the etiologic agent is the prototype member of the genus flavivirus, family flaviviridae, a group of small, enveloped, positive-sense, single-strand rna viruses. approximately one in seven people who become infected develop a rapidly progressive illness, with hepatitis, renal failure, hemorrhage and cardiovascular shock, with a case fatality rate of 20-50%. yellow fever occurs in sub-saharan ...200516117712
strategically examining the full-genome of dengue virus type 3 in clinical isolates reveals its mutation spectra.previous studies presented the quasispecies spectrum of the envelope region of dengue virus type 3 (denv-3) from either clinical specimens or field-caught mosquitoes. however, the extent of sequence variation among full genomic sequences of denv within infected individuals remains largely unknown.200516120221
perturbations induced by synthetic peptides from hepatitis g virus structural proteins in lipid model membranes: a fluorescent approach.the name hgv/gbv-c remains as an acronym for hepatitis g virus (hgv) and gb virus-c (gbv-c), strain variants of this enveloped rna virus independently but simultaneously discovered in 1995. nowadays there is no evidence that it causes hepatitis in humans either during initial infection or after long-term carriage, but it has been recently related with hiv regarding the inhibition of progression to aids. the overall genomic organization of hgv/gbv-c is similar to that of hepatitis c virus (hcv) a ...200516134194
resuscitating mutations in a furin cleavage-deficient mutant of the flavivirus tick-borne encephalitis virus.cleavage of the viral surface protein prm by the proprotein convertase furin is a key step in the maturation process of flavivirus particles. a mutant of tick-borne encephalitis virus (tbev) carrying a deletion mutation within the furin recognition motif of protein prm (changing r-t-r-r to r-t-r) was previously shown to be noninfectious in bhk-21 cells. we now demonstrate how natural selection can overcome this lethal defect in two different growth systems by distinct resuscitating mutations. in ...200516140758
development and persistence of west nile virus-specific immunoglobulin m (igm), iga, and igg in viremic blood donors.west nile virus (wnv) antibody development and persistence were investigated in blood donors who made wnv rna-positive (viremic) donations in 2003. plasma samples from the index donations and follow-up serum or plasma samples were tested for wnv immunoglobulin m (igm), iga, and igg by using enzyme-linked immunosorbent assays. antibody development was investigated with 154 samples collected from 84 donors 1 to 21 days after their rna-positive, antibody-negative, index donation. wnv igm and iga we ...200516145071
clinical utility of commercial enzyme immunoassays during the inaugural season of west nile virus activity, alberta, canada.west nile virus (wnv) has spread rapidly across north america, creating a need for rapid and accurate laboratory diagnosis on a large scale. immunoglobulin m (igm) capture enzyme immunoassays (eia) became commercially available in the summer of 2003, but limited data are available on their clinical performance. consolidated human wnv diagnostic testing for the province of alberta, canada, at the public health laboratory permitted a large-scale evaluation of the assays, covering a wide clinical s ...200516145128
critical roles for both stat1-dependent and stat1-independent pathways in the control of primary dengue virus infection in mice.dengue virus (den), a flavivirus, causes dengue fever and dengue hemorrhagic fever/dengue shock syndrome, the most common mosquito-borne viral illnesses in humans worldwide. in this study, using stat1(-/-) mice bearing two different mutant stat1 alleles in the 129/sv/ev background, we demonstrate that ifnr-dependent control of primary den infection involves both stat1-dependent and stat1-independent mechanisms. the stat1 pathway is necessary for clearing the initial viral load, whereas the stat1 ...200516148142
new developments in flavivirus vaccines with special attention to yellow we review recent epidemiological trends in flavivirus diseases, findings related to existing vaccines, and new directions in flavivirus vaccine research. we emphasize the need for stepped-up efforts to stop further spread and intensification of these infections worldwide.200516148524
immune responses to non-structural protein 3 (ns3) of bovine viral diarrhoea virus (bvdv) in ns3 dna vaccinated and naturally infected cattle.immune responses to non-structural protein 3 (ns3) of bovine viral diarrhoea virus (bvdv) were investigated. cdna encoding ns3 from type 1a bvdv was used to vaccinate five calves, another five calves remained unvaccinated. three weeks after final vaccination animals were challenged intranasally with heterologous type 1a bvdv. anti-ns3 antibodies were detected in only one animal post-vaccination. partial protection from virus challenge was observed in the vaccinates. virus was not isolated from n ...200516169103
a multigene analysis of the phylogenetic relationships among the flaviviruses (family: flaviviridae) and the evolution of vector transmission.the genus flavivirus (family flaviviridae) presently comprises around 70 single-strand positive-sense rna viruses. these replicate in a range of vertebrate and invertebrate cells and may be mosquito-borne, tick-borne or have no-known-vector. since transmission mode correlates strongly with phylogeny, the flaviviruses constitute a valuable model for the evolution of vector-borne disease. attempts to resolve the higher-level taxonomic relationships of the flaviviruses through molecular phylogeneti ...200616172840
immunogenicity of combination dna vaccines for rift valley fever virus, tick-borne encephalitis virus, hantaan virus, and crimean congo hemorrhagic fever virus.dna vaccines for rift valley fever virus (rvfv), crimean congo hemorrhagic fever virus (cchfv), tick-borne encephalitis virus (tbev), and hantaan virus (htnv), were tested in mice alone or in various combinations. the bunyavirus vaccines (rvfv, cchfv, and htnv) expressed gn and gc genes, and the flavivirus vaccine (tbev) expressed the prem and e genes. all vaccines were delivered by gene gun. the tbev dna vaccine and the rvfv dna vaccine elicited similar levels of antibodies and protected mice f ...200616174542
antigenicity of chimeric and cyclic synthetic peptides based on nonstructural proteins of gbv-c/ this work, new putative epitopes located in nonstructural proteins of gbv-c/hgv were synthesized using solid-phase chemistry for their use in immunoassays. the antigens were obtained in linear, chimeric and cyclic forms with the main aim of improving the sensitivity of the enzyme immunoassays. our results showed, on one hand, that the combination of different antigens seems to be necessary to ensure good sensitivity and more specificity and, on the other hand, that cyclic compounds show highe ...200616180243
flavivirus induces interferon-beta gene expression through a pathway involving rig-i-dependent irf-3 and pi3k-dependent nf-kappab this study, we found that infection with flaviviruses, such as japanese encephalitis virus (jev) and dengue virus serotype 2 (den-2), leads to interferon-beta (ifn-beta) gene expression in a virus-replication- and de novo protein-synthesis-dependent manner. nf-kappab activation is essential for ifn-beta induction in jev- and den-2-infected cells. however, these two viruses seem to preferentially target different members of the interferon regulatory factor (irf) family. the activation of const ...200616182584
experimental transmission of west nile virus (flaviviridae: flavivirus) by carios capensis ticks from north america.seabird soft ticks, carios capensis (ixodida: argasidae), originally collected from coastal georgia, usa, were allowed to ingest a blood meal from pekin ducklings (anas domesticus) infected with wnv. after 35 days of extrinsic incubation, the ticks transmitted virus to naive ducklings. wnv was detected via plaque assay and rtpcr in ticks and in tissues and serum of ducklings 7 days post infestation.200516187900
inhibition of interferon-stimulated jak-stat signaling by a tick-borne flavivirus and identification of ns5 as an interferon antagonist.the tick-borne encephalitis (tbe) complex of viruses, genus flavivirus, can cause severe encephalitis, meningitis, and/or hemorrhagic fevers. effective interferon (ifn) responses are critical to recovery from infection with flaviviruses, and the mosquito-borne flaviviruses can inhibit this response. however, little is known about interactions between ifn signaling and tbe viruses. langat virus (lgtv), a member of the tbe complex of viruses, was found to be highly sensitive to the antiviral effec ...200516188985
[flavivirus encephalitis: focus on west nile encephalitis].the genus flavivirus, family flaviviridae includes a serocomplex of vector-borne neurotropic viruses as in the tick-borne encephalitis virus serocomplex and the japanese encephalitis virus serocomplex. the tick-borne encephalitis virus serocomplex includes central european encephalitis virus and russian spring summer encephalitis virus. west nile virus (wnv), which in the western hemisphere was first detected in new york, in the united states in 1999, is one of several mosquito-borne members of ...200516190358
gb virus-c--a virus without a disease: we cannot give it chronic fatigue syndrome.chronic fatigue syndrome (cfs) is an illness in search of an infectious etiology. gb virus-c (gbv-c) virus is a flavivirus with cell tropism and host defense induction qualities compatible with a role in producing the syndrome. the gbv-c genome is detectable in 4% of the population and 12% of the population is seropositive. the present study evaluated the association between infection with gbv and cfs.200516191201
proteomic profiling and neurodegeneration in west-nile-virus-infected neurons.west nile virus, a mosquito-borne flavivirus, is a human, equine, and avian pathogen. high-resolution two-dimensional differential-gel electrophoresis (2d-dige) was used to characterize protein expression in primary rat neurons and to examine the proteomic profiling to understand the pathogenesis of west-nile-associated meningoencephalitis. three ph ranges, 3-10, 4-7, and 5-6, were used to analyze the protein spots. the proteins are labeled with fluorescent dyes cy3 and cy5 before being separate ...200516192685
structural basis of west nile virus neutralization by a therapeutic antibody.west nile virus is a mosquito-borne flavivirus closely related to the human epidemic-causing dengue, yellow fever and japanese encephalitis viruses. in establishing infection these icosahedral viruses undergo endosomal membrane fusion catalysed by envelope glycoprotein rearrangement of the putative receptor-binding domain iii (diii) and exposure of the hydrophobic fusion loop. humoral immunity has an essential protective function early in the course of west nile virus infection. here, we investi ...200516193056
[molecular characteristics of three new isolates of japanese encephalitis virus in fujian province].to analyze the genotype of newly isolated japanese encephalitis viruses in fujian province and the characteristics of amino acid sequence in the e gene.200516201460
serotype-specific detection of dengue viruses in a fourplex real-time reverse transcriptase pcr assay.the dengue (den) viruses are positive-strand rna viruses in the genus flavivirus. dengue fever and dengue hemorrhagic fever/dengue shock syndrome are important human arboviral diseases caused by infection with one of four closely related but serologically distinct den viruses, designated den-1, den-2, den-3, and den-4 viruses. all four den serotypes are currently co-circulating throughout the subtropics and tropics, and genotypic variation occurs among isolates within a serotype. a real-time qua ...200516207951
alkhurma hemorrhagic fever virus is an emerging tick-borne flavivirus. 200616216331
domain iii from class ii fusion proteins functions as a dominant-negative inhibitor of virus membrane fusion.alphaviruses and flaviviruses infect cells through low ph-dependent membrane fusion reactions mediated by their structurally similar viral fusion proteins. during fusion, these class ii viral fusion proteins trimerize and refold to form hairpin-like structures, with the domain iii and stem regions folded back toward the target membrane-inserted fusion peptides. we demonstrate that exogenous domain iii can function as a dominant-negative inhibitor of alphavirus and flavivirus membrane fusion and ...200516216925
molecular epidemiology of dengue 2 viruses in the philippines: genotype shift and local evolution.the pre-membrane (prm) and envelope (e) genes of 41 viruses isolated from dengue fever (df), dengue hemorrhagic fever (dhf), and dengue shock syndrome (dss) patients from 1995 to 2002 were sequenced to determine the genetic variability of dengue 2 (denv 2) viruses in the philippines. the envelope sequence data were compared with a global sample of denv 2 obtained from genbank. phylogenetic analysis revealed that two distinct genotypes, asian 2 and cosmopolitan, are currently circulating locally, ...200516222028
nucleotide and amino acid changes in west nile virus strains exhibiting renal tropism in hamsters.recent studies have shown that west nile virus (wnv) can induce an asymptomatic persistent infection in the kidneys of experimentally infected hamsters. the chronically infected rodents shed virus in their urine for up to 8 months, despite the disappearance of viremia and the development of high levels of neutralizing antibodies. wnv, like most members of the japanese encephalitis virus complex (flavivirus; flaviviridae), is assumed to be mainly neurotropic; little is known about the genetic bas ...200516222029
shifting epidemiology of flaviviridae.the dengue, west nile, japanese encephalitis and yellow fever viruses are important mosquito-borne viruses whose epidemiology is shifting in response to changing societal factors, such as increasing commerce, urbanization of rural areas, and population growth. all four viruses are expanding geographically, as exemplified by the emergence of west nile virus in the americas and japanese encephalitis virus in australasia. the large, recent global outbreaks of severe neurological disease caused by w ...200516225801
hantavirus gc glycoprotein: evidence for a class ii fusion protein.hantavirus cell entry is promoted by its envelope glycoproteins, gn and gc, through cell attachment and by fusion between viral and endosomal membranes at low ph. however, the role of gn and gc in receptor binding and cell fusion has not yet been defined. in this work, a sequence presenting characteristics similar to those of class ii fusion peptides (fps) of alphavirus e1 and flavivirus e proteins is identified within the hantavirus gc glycoprotein. a three-dimensional comparative molecular mod ...200516227214
n-linked glycosylation of west nile virus envelope proteins influences particle assembly and infectivity.west nile virus (wnv) encodes two envelope proteins, premembrane (prm) and envelope (e). while the prm protein of all wnv strains contains a single n-linked glycosylation site, not all strains contain an n-linked site in the e protein. the presence of n-linked glycosylation on flavivirus e proteins has been linked to virus production, ph sensitivity, and neuroinvasiveness. therefore, we examined the impact of prm and e glycosylation on wnv assembly and infectivity. similar to other flaviviruses, ...200516227249
alpha/beta interferon protects against lethal west nile virus infection by restricting cellular tropism and enhancing neuronal survival.west nile virus (wnv) is a mosquito-borne flavivirus that is neurotropic in humans, birds, and other animals. while adaptive immunity plays an important role in preventing wnv spread to the central nervous system (cns), little is known about how alpha/beta interferon (ifn-alpha/beta) protects against peripheral and cns infection. in this study, we examine the virulence and tropism of wnv in ifn-alpha/beta receptor-deficient (ifn- alpha/betar-/-) mice and primary neuronal cultures. ifn-alpha/beta ...200516227257
hippocampal involvement in dengue fever.flaviviruses are among the most important emerging viruses known to man. dengue is the most common flavivirus infection in singapore, and is transmitted between humans by the aedes mosquito. we report a 25-year-old man with dengue fever complicated by selective hippocampal involvement manifesting as amnesia. this has not been described in the literature previously. dengue polymerase chain reaction and serology were positive. magnetic resonance imaging of the brain showed bilateral hippocampal in ...200516228099
cleavage targets and the d-arginine-based inhibitors of the west nile virus ns3 processing proteinase.mosquito-borne wnv (west nile virus) is an emerging global threat. the ns3 proteinase, which is essential for the proteolytic processing of the viral polyprotein precursor, is a promising drug target. we have isolated and biochemically characterized the recombinant, highly active ns3 proteinase. we have determined that the ns3 proteinase functions in a manner that is distantly similar to furin in cleaving the peptide and protein substrates. we determined that aprotinin and d-arginine-based 9-12- ...200616229682
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