Publications

TitleAbstractYear(sorted ascending)
Filter
PMID
Filter
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 virus.seven 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
identification of new flaviviruses in the kokobera virus complex.novel flavivirus isolates from mosquitoes collected in northern australia were analysed by partial genomic sequencing, monoclonal antibody-binding assays and polyclonal cross-neutralization tests. two isolates were found to be antigenically distinct from, but related to, viruses of the kokobera virus complex, which currently contains kokobera (kokv) and stratford (strv) viruses. nucleotide sequence comparison of two separate regions of the genome revealed that an isolate from saibai island in th ...200515604438
identification and characterization of nonsubstrate based inhibitors of the essential dengue and west nile virus proteases.the 72 known members of the flavivirus genus include lethal human pathogens such as yellow fever, west nile, and dengue viruses. there is at present no known chemotherapy for any flavivirus and no effective vaccines for most. a common genomic organization and molecular mechanisms of replication in hosts are shared by flaviviruses with a viral serine protease playing a pivotal role in processing the viral polyprotein into component polypeptides, an obligatory step in viral replication. using the ...200515582469
identification and enzymatic characterization of ns2b-ns3 protease of alkhurma virus, a class-4 flavivirus.alkhurma virus (alkv) is a recently discovered class-4 flavivirus that was responsible for several cases of severe haemorrhagic fever in humans in saudi arabia. it has been shown for other flaviviruses that processing of the viral polyprotein is partly due to the virus-encoded ns2b/ns3 trypsin-like serine protease. as the viral proteinase plays a critical role in the virus replication cycle, it represents one of the main targets for antiviral therapy against members of the flavivirus genus. we r ...200515567034
the majority of the nucleotides in the top loop of the genomic 3' terminal stem loop structure are cis-acting in a west nile virus infectious clone.the flavivirus genome rna terminates with a conserved 3' stem loop (sl) structure that was shown to be essential for virus replication. a stretch of conserved nts is located in the top loop (tl) of this structure. mutation of the tl nts (5' acagugc 3') in a wnv infectious clone indicated that 3 of the 7 tl nts (5' acagugc 3') are critical for virus replication. mutation of 3 of the other nts reduced the efficiency of virus replication. the four 5' tl nts are conserved in both mosquito- and tick- ...200515629768
construction and applications of yellow fever virus replicons.subgenomic replicons of yellow fever virus (yfv) were constructed to allow expression of heterologous reporter genes in a replication-dependent manner. expression of the antibiotic resistance gene neomycin phosphotransferase ii (neo) from one of these yfv replicons allowed selection of a stable population of cells (bhk-rep cells) in which the yfv replicon persistently replicated. bhk-rep cells were successfully used to trans-complement replication-defective yfv replicons harboring large internal ...200515629769
the flavivirus-conserved penta-nucleotide in the 3' stem-loop of the west nile virus genome requires a specific sequence and structure for rna synthesis, but not for viral translation.a reporting replicon of west nile virus (wn) was used to distinguish between the function of the 3' untranslated region (utr) in viral translation and rna replication. deletions of various regions of the 3' utr of the replicon did not significantly affect viral translation, but abolished rna replication. a systematic mutagenesis showed that the flavivirus-conserved penta-nucleotide (5'-cacag-3' located at the top of the 3' stem-loop of the genome) requires a specific sequence and structure for w ...200515629780
adaptation of west nile virus replicons to cells in culture and use of replicon-bearing cells to probe antiviral action.flaviviruses are emerging threats to public health worldwide. recently, one flavivirus, west nile virus (wnv), has caused the largest epidemic of viral encephalitis in us history. like other flaviviruses, wnv is thought to cause a persistent infection in insect cells, but an acute cytopathic infection of mammalian cells. to study adaptation of wnv to persistently replicate in cell culture and generate a system capable of detecting antiviral compounds in the absence of live virus, we generated su ...200515629788
differential induction of antiviral effects against west nile virus in primary mouse macrophages derived from flavivirus-susceptible and congenic resistant mice by alpha/beta interferon and poly(i-c).a cell model of primary macrophages isolated from the peritoneal cavity of flavivirus-susceptible and congenic resistant mice has been used to study the extent and kinetics of antiviral effects against west nile virus upon priming with alpha/beta interferon (ifn-alpha/beta) or poly(i-c) (pic). the pattern of flavivirus resistance expressed after priming of cells in this model was in good agreement with the pattern of flavivirus resistance described in the brains of the corresponding mouse strain ...200515650200
broadening the horizons for yellow fever: new uses for an old vaccine.the vaccine against yellow fever is one of the safest and most effective ever developed. with an outstanding record in humans, has this live attenuated vaccine been overlooked as a promising vector for the development of vaccines against pathogens outside its own genus? recent studies, including a report by tao et al. on page 201 of this issue, have sparked renewed interest.200515657285
inhibition of west nile virus entry by using a recombinant domain iii from the envelope glycoprotein.the envelope glycoprotein located at the outermost surface of the flavivirus particle mediates entry of virus into host cells. in this study, the involvement of domain iii of west nile virus (wnv-diii) envelope protein in binding to host cell surface was investigated. wnv-diii was first expressed as a recombinant protein and purified after a solubilization and refolding procedure. the refolded wnv-diii protein displays a content of beta-sheets consistent with known homologous structures of other ...200515659760
neuroblastoma cell-adapted yellow fever virus: mutagenesis of the e protein locus involved in persistent infection and its effects on virus penetration and spread.persistent infection of mouse neuroblastoma nb41a3 cells with yellow fever 17d virus generates viral variants which exhibit defective cell penetration, poor cell-to-cell spread, small plaque size and reduced growth efficiency, caused by substitution of glycine for aspartic acid or glutamic acid at positions 360 and 362 in the envelope protein. these positions occur within a charge cluster, asp360-asp361-glu362, located in domain iii, near its interface with domain i. to characterize further the ...200515659761
genetic characterization of yokose virus, a flavivirus isolated from the bat in japan.yokose virus (strain oita-36) was isolated from the bat in japan in 1971. in the present study, we determined complete nucleotide sequences of yokose virus using rt-pcr and race techniques. yokose virus genome consists of 10,857 nucleotides in length (accession no. ab114858), containing a single open reading frame (3425 amino acids) encoding 11 viral proteins. we deduced the boundaries of each protein in the polyprotein sequence according to the protein cleavage sites of other flaviviruses. the ...200515661139
molecular models of ns3 protease variants of the hepatitis c virus.hepatitis c virus (hcv) currently infects approximately three percent of the world population. in view of the lack of vaccines against hcv, there is an urgent need for an efficient treatment of the disease by an effective antiviral drug. rational drug design has not been the primary way for discovering major therapeutics. nevertheless, there are reports of success in the development of inhibitor using a structure-based approach. one of the possible targets for drug development against hcv is the ...200515663787
[residual neurovirulence of the chimera of langat and denge-4 flaviviruses in intracerebral infection of monkeys].the residual neurovirulence of the previously obtained chimeric virus tp21/den4, containing the rna region encoding the pre m and e structural enzymes, strain tp21, virus langat, and the remaining part of the genome from the denge 4 virus, was studied in experiments with monkeys cercopithecus aethiops involving the intracerebral administration of the virus. the tick-borne encephalitis virus, strain absettarov, was used as positive control. a comparative analysis of the experimental and published ...200515747868
an infectious west nile virus that expresses a gfp reporter gene.west nile virus is a mosquito-borne, neurotropic flavivirus that causes encephalitis in humans and animals. since being introduced into the western hemisphere in 1999, wnv has spread rapidly across north america, identifying this virus as an important emerging pathogen. in this study, we developed a dna-launched infectious molecular clone of wnv that encodes a gfp reporter gene. transfection of cells with the plasmid encoding this recombinant virus (pwnii-gfp) resulted in the production of infec ...200515749120
novel flavivirus or new lineage of west nile virus, central europe.a flavivirus (strain 97-103) was isolated from culex pipens mosquitoes in 1997 following floods in south moravia, czech republic. the strain exhibited close antigenic relationship to west nile virus (wnv) prototype strain eg-101 in a cross-neutralization test. in this study, mouse pathogenicity characteristics and the complete nucleotide and putative amino acid sequences of isolate 97-103, named rabensburg virus (rabv) after a nearby austrian city, were determined. rabv shares only 75%-77% nucle ...200515752439
in vitro host-cell susceptibility to usutu virus.we investigated the susceptibility to usutu virus (flavivirus) of 13 permanent cell lines, 3 primary cell cultures, and chicken embryos. vero, pk-15, and goose embryo fibroblast cells developed cytopathic effects; however, viral multiplication was detected in all mammalian cell types by immunohistochemical tests. chicken embryo fibroblast cells and chicken embryos were resistant.200515752450
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
the topology of bulges in the long stem of the flavivirus 3' stem-loop is a major determinant of rna replication competence.all flavivirus genomes contain a 3'terminal stem-loop secondary structure (3'sl) formed by the most downstream approximately 100 nucleotides (nt) of the viral rna. the 3'sl is required for virus replication and has been shown to bind both virus-coded and cellular proteins. results of the present study using an infectious dna for wn virus strain 956 initially demonstrated that the dengue virus serotype 2 (den2) 3'sl nucleotide sequence could not substitute for that of the wn 3'sl to support wn ge ...200515681432
sampling phylogenetic tree space with the generalized gibbs sampler.the generalized gibbs sampler (ggs) is a recently developed markov chain monte carlo (mcmc) technique that enables gibbs-like sampling of state spaces that lack a convenient representation in terms of a fixed coordinate system. this paper describes a new sampler, called the tree sampler, which uses the ggs to sample from a state space consisting of phylogenetic trees. the tree sampler is useful for a wide range of phylogenetic applications, including bayesian, maximum likelihood, and maximum par ...200515683921
duplex reverse transcription-pcr followed by nested pcr assays for detection and identification of brazilian alphaviruses and flaviviruses.a new approach was developed for the rapid detection and identification of brazilian alphaviruses and flaviviruses. the methodology involves the genus-specific detection of alphavirus and flavivirus by a duplex reverse transcription-pcr (d-rt-pcr), followed by multiplex nested pcr (m-n-pcr) or nested pcr (n-pcr) assays for species-specific identification. by this protocol, 25 arboviruses were specifically detected and identified. detection levels between 10(1.3) and 10(3.5) 50% tissue culture in ...200515695666
viral rna replication in association with cellular membranes.all plus-strand rna viruses replicate in association with cytoplasmic membranes of infected cells. the rna replication complex of many virus families is associated with the endoplasmic reticulum membranes, for example, picorna-, flavi-, arteri-, and bromoviruses. however, endosomes and lysosomes (togaviruses), peroxisomes and chloroplasts (tombusviruses), and mitochondria (nodaviruses) are also used as sites for rna replication. studies of individual nonstructural proteins, the virus-specific co ...200515609503
a structural perspective of the flavivirus life cycle.dengue, japanese encephalitis, west nile and yellow fever belong to the flavivirus genus, which is a member of the flaviviridae family. they are human pathogens that cause large epidemics and tens of thousands of deaths annually in many parts of the world. the structural organization of these viruses and their associated structural proteins has provided insight into the molecular transitions that occur during the viral life cycle, such as assembly, budding, maturation and fusion. this review foc ...200515608696
trends in dengue diagnosis.the conventional diagnosis of dengue virus infections includes the detection of the virus in serum or tissue samples, both by isolation in culture or through detection of specific viral molecules (genome rna or dengue antigens) and detection of specific anti-dengue antibodies (serology). isolation of dengue virus provides the most direct and conclusive approach to diagnosis, despite the demand for high-level equipment, technical skills and manpower. however, it is useless in early diagnosis beca ...200515672450
site-directed mutagenesis and kinetic studies of the west nile virus ns3 protease identify key enzyme-substrate interactions.the flavivirus west nile virus (wnv) has spread rapidly throughout the world in recent years causing fever, meningitis, encephalitis, and fatalities. because the viral protease ns2b/ns3 is essential for replication, it is attracting attention as a potential therapeutic target, although there are currently no antiviral inhibitors for any flavivirus. this paper focuses on elucidating interactions between a hexapeptide substrate (ac-kpglkr-p-nitroanilide) and residues at s1 and s2 in the active sit ...200515494419
epidemic west nile virus encephalitis in tunisia.west nile fever (wnf) is a mosquito-borne flavivirus infection. it is epidemic in africa and asia. in autumn 1997, a wnf epidemic occurred in the sfax area (southeastern tunisia). fifty-seven patients were hospitalized with aseptic meningitis and/or encephalitis. search for specific anti-west nile virus (wnv) antibodies in serum and cerebrospinal fluid (csf) was performed using an elisa test. reverse transcriptase-polymerase chain reaction (rt-pcr) was used to detect the wnv genome in csf and br ...200515459502
japanese encephalitis in a u.s. traveler returning from thailand, 2004.japanese encephalitis (je) virus is a mosquito-borne flavivirus that is closely related to the west nile and st. louis encephalitis viruses endemic to north america. je virus is a leading cause of viral encephalitis in asia but is rarely reported among travelers to countries where je is endemic. this report describes a case of an unvaccinated washington resident who had je after traveling to northern thailand. the advisory committee on immunization practices (acip) recommends je vaccine for trav ...200515703694
secretion of noninfectious dengue virus-like particles and identification of amino acids in the stem region involved in intracellular retention of envelope protein.dna plasmids that express flavivirus premembrane/membrane (prm/m) and envelope (e) proteins in the form of virus-like particles (vlps) have an excellent potential as dna vaccine candidates against virus infection. the plasmid-expressed vlps are also useful as safe, noninfectious antigens in serodiagnostic assays. we have constructed plasmids containing the prm/m and e gene regions for denv-1, -3, and -4 that express and secrete vlps when electroporated into chinese hamster ovary cells. construct ...200515721358
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
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
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
differential responses of human brain cells to west nile virus infection.in 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
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
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
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
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
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 hiv.gb 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
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
Displaying items 1901 - 2000 of 3318