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characterization of rna synthesis during a one-step growth curve and of the replication mechanism of bovine viral diarrhoea virus.the noncytopathic australian bovine viral diarrhoea virus (bvdv) trangie isolate was used to establish a one-step growth curve and to investigate previously uncharacterized aspects of pestivirus replication. the eclipse phase was found to be approximately 8 to 10 h and the first appearance of viral antigen assayed by immunofluorescence occurred around 6 h post-infection (p.i.). both positive- and negative-sense virus rnas were first detected at 4 h p.i. by northern blot hybridization using stran ...19968922466
diagnosis of tick-borne encephalitis: evaluation of sera with borderline titers with the tbe-elisa.tick-borne encephalitis (tbe) is a member of the flaviviridae family. strong cross-reactions can occur between members of this family, so that it may be difficult to diagnose specific flavivirus infections, especially when tests with frequent cross-reactions e.g. elisa tests are used. we tested 238 sera with borderline titers for tbe using the indirect immunofluorescence or neutralization test for other flaviviruses (yellow fever, dengue, west nile) to detect cross-reactions due to other flavivi ...19968923059
[the risk of urban yellow fever outbreaks in brazil by dengue vectors. aedes aegypti and aedes albopictus].urban yellow fever (yf) epidemics have disappeared from brazil since about 50 years, but a selvatic cycle still exist. in many states, cases are more or less numerous each year. ae. aegypti was eradicated in 1954, re-appeared temporarily in 1967, and then definitively in 1976-1977. ae. aegypti is a vector of yellow few (yf), but also of dengue, whose first cases were reported in 1982. today, dengue is endemic in many regions. a second flavivirus vector, aedes albopictus is present since about te ...19968924767
[effectiveness of the interferon inducers ridostin and camedon in prevention and treatment of experimental alpha- and flavivirus infections].antiviral activity of rybamidil (virasol) and interferon inducers ridostine and camedone developed in russia and introduced in practical medicine has been studied in mice with experimentally induced arboviral infections, flavivirus (tick-borne encephalitis-tbe, and yellow fever-yf) and alphavirus ones (western and eastern equine encephalomyelitis-wee and eee). rybamidil injected subcutaneously proved to be ineffective both for prevention and treatment of these infections. early interferon induce ...19968928508
flavivirus-induced up-regulation of mhc class i antigens; implications for the induction of cd8+ t-cell-mediated autoimmunity.infection of a wide variety of cells of human, mouse and other species' origin by flaviviruses such as wnv, yf, den, mve, kun and je, increases the cell-surface expression of mhc class i. this mhc class i up-regulation is not due to increased mhc class i synthesis per se, but the result of increased peptide availability in the er for mhc class i assembly. this is most likely due to the interaction of the viral polyprotein with the er membrane during viral replication. flavivirus infection can ov ...19968930665
the immunology of eta-1/osteopontin.the cytokine eta-1/osteopontin is secreted by activated macrophages and may constitute the most abundant molecule secreted by activated t-lymphocytes. it causes macrophages to migrate and suppress production of reactive oxygen species. it enhances generation of immunoglobulins or proliferation of b-lymphocytes. its biochemical characteristics suggest that eta-1/osteopontin may be the t-lymphocyte suppressor factor. the apparently conflicting effects on individual immune functions may reflect hom ...19968971479
evaluation of monoclonal antibodies for generic detection of flaviviruses by elisa.three monoclonal antibodies (mabs) specific for the envelope (e) protein of flaviviruses were evaluated for use in an antigen capture elisa. three combinations of mabs and a combination of polyclonal antibodies (pabs) were evaluated in antigen capture elisas for their ability to detect 18 flaviviruses. the mab elisas detected 50% of flavivirus antigens with a sensitivity between 1 and 9 x 10(4)/ng viral protein/ml, however, none of the elisas evaluated proved to be useful for generic detection o ...19969002072
gbv-c/hgv is not the major cause of autoimmune hepatitis.recently, gbv-c and hgv-two isolates of the same new flavivirus-were identified in serum samples of patients with indeterminate hepatitis and posttransfusion hepatitis, respectively. the pathogenic relevance of these viruses is still uncertain. as viral infections are presumed to trigger autoimmune processes, we investigated gbv-c in autoimmune hepatitis as well as in cryptogenic hepatitis, and compared the prevalences to patients with chronic viral hepatitis and those of blood donors. we found ...19969007730
[an analysis of the stability of the antigenic structure in productive strain 205 of the tick-borne encephalitis virus during prolonged passage].the stability of the antigenic structure of tick-borne encephalitis (tbe) virus strain 205 in the process of passage through the brain of balb/c mice has been studied. its relationships with other viruses of the tbe complex have been analyzed with the use of monoclonal antibodies to virus proteins e and ns3. the stability of the protein structure of the virus has been determined by the immunofluorescence test and the enzyme immunoassay.19969027159
hepatitis g virus/gb virus c in brazil. preliminary report.hepatitis g virus/gb virus c is a novel flavivirus recently detected in hepatitis non a-e cases. in this study, the presence of this virus in chronic non-b, non-c hepatitis patients was evaluated using gbv-c specific pcr and this virus was detected in one out of thirteen patients. this patient has presented a severe liver failure, has lived for a long time in the western amazon basin and no other cause for this clinical picture was reported. the impact of the discovery of this new agent is still ...19969163994
absence of double-stranded replicative forms of hcv rna in liver tissue from chronically infected patients.the mechanism of hepatitis c virus (hcv) replication is unknown, although the classification of hcv in the flaviviridae has led to the postulation that hcv may adopt a replication strategy similar to that of the flaviviruses. to determine if hcv double-stranded replicative forms, consistent with this strategy, were present in total liver rna extracted from hcv-infected individuals, hcv-specific rna was detected by reverse transcription followed by polymerase chain reaction (rt-pcr). initially, a ...19968736238
testing of a dengue 2 live-attenuated vaccine (strain 16681 pdk 53) in ten american volunteers.a live-attenuated dengue 2 vaccine (strain 16681 pdk 53) developed at mahidol university, thailand was evaluated for safety and immunogenicity by administering 10(4) p.f.u. subcutaneously to ten flavivirus non-immune american volunteers. the vaccine was safe; there were no serious adverse reactions. eight recipients experienced no or mild side effects. one recipient reported headaches on 7 separate days. one volunteer, who had a fracture of the humerus 1 day after vaccination requiring surgical ...19968744561
epidemic dengue 2 in the city of djibouti 1991-1992.from october 1991 to february 1992, an outbreak of acute fever (in which thick blood films were negative for malaria) spread rapidly in the city of djibouti, djibouti republic, affecting all age groups and both nationals and foreigners. the estimated number of cases was 12,000. the clinical features were consistent with a non-haemorrhagic dengue-like illness. serum samples from 91 patients were analysed serologically for flavivirus infection (dengue 1-4, west nile, yellow fever, zika, banzi, and ...19968758061
the new lymphotropic herpesviruses (hhv-6, hhv-7, hhv-8) and hepatitis c virus (hcv) in human lymphoproliferative diseases: an overview.considerable evidence has been accumulating in favor of a possible involvement of viral agents in the pathogenesis of human lymphomas. the most recent proposal for a lymphoma classification, the revised european-american classification, emphasized for the first time the pathogenetic importance of two viruses, namely epstein-barr virus (ebv) and human t lymphotropic virus i (htlv-i) in the development of certain lymphoid neoplasias. however, in the last ten years new viral agents possibly related ...19968767534
use of the yellow fever virus vaccine strain 17d for the study of strategies for the treatment of yellow fever virus infections.we have employed the attenuated vaccine strain 17d of yellow fever virus (yfv) to evaluate the inhibitory effect of a selected series of compounds on yfv in vero cells. use of the vaccine strain does not require high-level microbiological containment facilities and should allow extensive screening. in addition, yfv may serve as a model for other flaviviruses including hepatitis c virus (hcv), and thus strategies for the treatment of yfv infections may apply to flavivirus infections in general. i ...19968783804
activity of purified hepatitis c virus protease ns3 on peptide substrates.the protease domain of the hepatitis c virus (hcv) protein ns3 was expressed in escherichia coli, purified to homogeneity, and shown to be active on peptides derived from the sequence of the ns4a-ns4b junction. experiments were carried out to optimize protease activity. buffer requirements included the presence of detergent, glycerol, and dithiothreitol, ph between 7.5 and 8.5, and low ionic strength. c- and n-terminal deletion experiments defined a peptide spanning from the p6 to the p4' residu ...19968794305
hepatitis g virus in immunosuppressed paediatric allograft recipients. 19968806304
hepatitis g viral rna in italian haemophiliacs with and without hepatitis c infection. 19968806323
mutagenesis of the n-linked glycosylation sites of the yellow fever virus ns1 protein: effects on virus replication and mouse neurovirulence.the flavivirus nonstructural glycoprotein ns1 is highly conserved and contains two n-linked glycosylation sites which are both utilized for addition of oligosaccharides during replication in cell culture. ns1 has been shown to contain epitopes for protective antibodies; however, its roles in virus replication and pathogenesis remain unknown. to study the function of ns1 during yellow fever virus replication, six mutant viruses which lack either one or both glycosylation sites and another one con ...19968806496
generation and characterization of organ-tropism mutants of japanese encephalitis virus in vivo and in vitro.using gamma-ray irradiation, a pair of virulent (rp-9) and attenuated (rp-2ms) variants of japanese encephalitis virus (jev) were generated from a taiwanese isolate, nt109. the two variants differed in plaque morphology, virus adsorption, and growth properties in bhk-21 cells: (i) rp-2ms produced smaller plaques than rp-9; (ii) rp-2ms adsorbed less efficiently to host cells but yielded a higher virus titer (burst size); and (iii) rp-2ms virions were mostly accumulated intracellularly, whereas rp ...19968806542
characterization of the ntpase activity of japanese encephalitis virus ns3 protein.japanese encephalitis (je) virus ns3 protein and two n-terminally truncated (delta 1-148 and delta 1-323) forms of ns3 were engineered and expressed in e. coli as fusion proteins with a histidine tag at the n terminus. the purified recombinant proteins his-ns3 and his-ns3(delta 1-148) were found to possess ntpase activity which was stimulated by single-stranded rna, whereas ns3(delta 1-323) did not. the requirements for mgcl2 and mncl2 and the salt and ph ranges necessary for optimal activity of ...19968811006
correlation between elisa, hemagglutination inhibition, and neutralization tests after vaccination against tick-borne encephalitis.the significance of igg antibody levels determined by a binding assay (elisa) was investigated as a surrogate marker for the presence of neutralizing and hemagglutination inhibiting antibodies in sera from individuals vaccinated against tick-borne encephalitis (tbe). to assess the extent of interference by flavivirus cross-reactive antibodies, sera from persons with a proven or suspected history of other flavivirus infections and/or vaccinations were also examined. an excellent and highly signif ...19968825718
recombinant dengue type 1 virus ns5 protein expressed in escherichia coli exhibits rna-dependent rna polymerase activity.the complete nonstructural ns5 gene of dengue type 1 virus, singapore strain s275/90 (d1-s275/90) was expressed in escherichia coli as a glutathione s-transferase (gst) fusion protein (126 kda). the gst-ns5 fusion protein was purified and the recombinant ns5 protein released from the fusion protein by thrombin cleavage. the recombinant ns5 had a predicted molecular weight of 100 kda and reacted with antiserum against d1-s275/90 virus in western blot analysis. the purified recombinant ns5 protein ...19968607261
characterization and complete genome sequences of high- and low- virulence variants of tick-borne encephalitis virus.the entire genomic sequences of two strains (hypr and 263) of the flavivirus tick-borne encephalitis (tbe) virus differing in virulence from the prototypic strain neudoerfl were determined. strain hypr is a human isolate of tbe virus with a high laboratory passage history which exhibits a significantly higher neuro-invasiveness in mice compared to the prototype strain. strain 263 is a low-passage tick-isolate with a temperature-sensitive and attenuated phenotype. except for the heterogeneous 3' ...19968609469
molecular characterization of the japanese encephalitis serocomplex of the flavivirus genus.the japanese encephalitis (je) serocomplex of flaviviruses comprises 10 members, 9 of which: alfuy (alf); koutango (kou); kokobera (kok); kunjin (kun); murray valley encephalitis (mve); je; stratford (str); usutu (usu); and west nile (wn) have been isolated from africa, southern europe, middle east, asia, and australia. the tenth member, st. louis encephalitis (sle) virus, is confined to north, central, and south america. for alf, kok, kou, str, and usu, no sequence data have as yet been reporte ...19968610471
does gbv-c cause fulminant hepatitis in japan? 19968622432
molecular evidence for transmission of hepatitis g virus by blood transfusion. 19968622433
nitric oxide and viral infection: no antiviral activity against a flavivirus in vitro, and evidence for contribution to pathogenesis in experimental infection in vivo.upon stimulation murine macrophages produce high levels of nitric oxide (no), a potent microbicidal and tumoricidal agent recently also implicated as a mediator of antiviral defense. as dysregulated production of no may lead to extensive tissue damage, the production of this powerful mediator is tightly regulated. viral infection, however, may alter the regulation of certain macrophage functions, and recent work from our group demonstrated that viral infection--via induction of interferon-alpha ...19968623546
identification of amino acids involved in recognition by dengue virus ns3-specific, hla-dr15-restricted cytotoxic cd4+ t-cell clones.the majority of t-cell clones derived from a donor who experienced dengue illness following receipt of a live experimental dengue virus type 3 (den3) vaccine cross-reacted with all four serotypes of dengue virus, but some were serotype specific or only partially cross-reactive. the nonstructural protein, ns3, was immuno-dominant in the cd4+ t-cell response of this donor. the epitopes of four ns3-specific t-cell clones were analyzed. jk15 and jk13 recognized only den3 ns3, while jk44 recognized d ...19968627790
[new hepatitis viruses "e, gb, etc."].some cases of hepatitis were non a, non b, non c, non d. hepatitis e virus (calicivirus) transmission is fecal-oral similar to that of the hepatitis a virus. viral hepatitis e is endemic and frequently epidemic in many developing countries, but exceptionally observed in france. a high mortality rate was observed in pregnant women. recently, elisa assays for igm anti-hcv are available. many hepatitis cases (acute and chronic) are not caused by known viruses (non a-non e). four flavivirus like hav ...19968640310
pathogen-derived resistance to dengue type 2 virus in mosquito cells by expression of the premembrane coding region of the viral genome.the full-length premembrane (prm) coding region of the dengue virus type 2 (den-2; jamaica) genome was expressed in c6/36 (aedes albopictus) cells in either the sense or the antisense orientation from a double subgenomic sindbis (dssin) virus. northern (rna) blot analysis confirmed the expression of sense or antisense den-2 prm rna in infected c6/36 cells. prm protein was demonstrated in cells infected with dssin virus expressing den-2 sense rnas by an immunofluorescence assay. c6/36 cells were ...19968642634
cytokine regulation by virus infection: bovine viral diarrhea virus, a flavivirus, downregulates production of tumor necrosis factor alpha in macrophages in vitro.bovine bone marrow-derived macrophages were infected in vitro with noncytopathic or cytopathic strains of bovine viral diarrhea virus. infection with both biotypes resulted in a decreased production of tumor necrosis factor alpha upon stimulation with heat-inactivated salmonella dublin or lipopolysaccharide. other macrophage functions were not downregulated, indicating that the observed effect was not due to a loss in macrophage viability. the downregulated production of tumor necrosis factor al ...19968642701
rna binding properties of core protein of the flavivirus kunjin.kunjin virus (kun) c is a typical flavivirus core protein which is truncated in vivo to a mature form of 105 residues enriched in lysine and arginine. in order to study the possible association of kun c with rna in vitro, we prepared several recombinant c proteins with specific deletions, each fused at the amino-terminus to glutathione-s-transferase (gst) and expressed in e. coli. they were reacted with kun rna probes transcribed in vitro from cdna representing the 5' untranslated region (5' utr ...19968645104
immunisation with dna polynucleotides protects mice against lethal challenge with st. louis encephalitis virus.in vivo transfection by intramuscular injection with plasmids expressing the immunogenic proteins of microbial pathogens has considerable potential as a vaccination strategy against many pathogens of both man and animals. here we report that weanling mice given a single intramuscular injection of 50 micrograms of a plasmid, psle1 expressing the st. louis encephalitis virus (sle) prm/e protein under the control of the cytomegalovirus immediate early protein promoter produced sle-specific antibody ...19968645110
immunolocalization of the dengue virus nonstructural glycoprotein ns1 suggests a role in viral rna replication.although many workers have investigated the maturation and processing of the flavivirus nonstructural glycoprotein ns1 in infected cells, these studies have provided little insight into a possible function for ns1. in this study we investigated the subcellular localization of ns1 both by immunofluorescence and cryo-immuno electron microscopy of infected vero and c6/36 cells. ns1 was found to be tightly associated with intracellular membranes, in particular with vesicle packets and large cytoplas ...19968659120
hepatitis g virus in long-term survivors of haematological malignancy. 19968667905
evidence for the existence of a pseudoknot structure at the 3' terminus of the flavivirus genomic rna.the 3'-terminal nucleotides of the flavivirus genomic rna form conserved secondary structures that may function as cis-acting signals for rna replication. here we provide evidence for the existence of a conserved pseudoknot structure at the 3' terminus of the flavivirus genomic rna. a truncated version of the west nile virus (wnv) 3'-terminal rna sequence was used as the model for these studies. circular dichroism spectra indicated the presence of a highly structured rna conformation with a sign ...19968672458
recombinant subviral particles from tick-borne encephalitis virus are fusogenic and provide a model system for studying flavivirus envelope glycoprotein functions.recombinant subviral particles (rsps) obtained by coexpression of the envelope (e) and premembrane (prm) proteins of tick-borne encephalitis virus in cos cells (s. l. allison, k. stadler, c. w. mandl, c. kunz, and f. x. heinz, j. virol. 69:5816-5820, 1995) were extensively characterized and shown to be ordered structures containing envelope glycoproteins with structural and functional properties very similar to those in the virion envelope. the particles were spherical, with a diameter of about ...19968676481
guanidine-hcl extraction of proteins expressed in escherichia coli using polycistronic operons based on the pur expression vectors. 19968679184
protective immune responses to the e and ns1 proteins of murray valley encephalitis virus in hybrids of flavivirus-resistant mice.the lack of an effective animal model has been a major obstacle in attempts to define the role of humoral and cellular immune responses in protection against flavivirus infection. we have used f1 hybrid mice (balb/c x c3h/rv) that are heterozygous for the flavivirus resistance allele f1vr and show reduced virus replication in the brain after intracerebral inoculation. f1 hybrid mice challenged by intracerebral inoculation with murray valley encephalitis (mve) virus developed encephalitis 2-3 day ...19968683218
[hepatitis viruses: from the old ones to the new ones. will the alphabet be enough to list them all?].viral infection is by far the most frequent cause of hepatitis. search for the causal virus is however difficult since they cannot be cultured on most cell lines in vitro and because regulatory factors required for viral expression are found only in the human hepatocytes which cannot be maintained in vitro sufficiently long for experiments. to date, viruses a, b, c and e have been well documented. virus d, a defective virus which only develops in association with virus b has also been identified ...19968685178
[preparation and study of properties of anti-idiotypic antibodies, carrying hemagglutinating paratopes of tick-borne encephalitis virus on their surface].rabbit polyclonal and rat monoclonal anti-idiotypical antibodies (aia) against two hemagglutinating murine monoclonal antibodies to glycoprotein e of tick-borne encephalitis virus (tbe) have been obtained, purified, and studied. all aia reacted with murine monoclonal antibodies to tbe protein e and did not react with normal murine immunoglobulins in enzyme immunoassay (eia). polyclonal aia to monoclonal e6b and 10h10 antibodies specifically reacted with rh, spev, and goose red cells. in addition ...19968686271
improved membrane preservation of flavivirus-infected cells with cryosectioning.ultra-cryomicrotomy and electron microscopy were used to investigate membranous structures in dengue virus-infected mammalian and insect cells. the cryo-sectioned samples displayed ultrastructure comparable to their resin-embedded counterparts with all previously identified virus-induced structures being observed. structures not previously identified were also found. in particular, membrane-bound packets of vesicles, 100-200 nm in diameter were seen distributed throughout areas of virus-induced ...19968690769
mother-to-baby transmission of hepatitis g virus.a mother tested positive for hepatitis g virus (hgv) by reverse transcription-polymerase chain reaction (rt-pcr) before and at delivery. her baby tested hgv negative by rt-pcr at birth but serum samples at four and six weeks of age were hgv positive, suggesting transmission of hgv from mother to baby.19968692068
translation initiation in gb viruses a and c: evidence for internal ribosome entry and implications for genome organization.gb viruses a and c (gbv-a and gbv-c) are two recently described rna viruses which appear to be members of the flaviviridae. although both viruses appear to contain long 5' nontranslated regions, the sites of polyprotein initiation and the presence of core-like proteins remain to be determined. translation studies were undertaken to determine the mechanism and sites of polyprotein initiation in gbv-a and gbv-c. rabbit reticulocyte lysates programmed with monocistronic rnas containing 5' ends of g ...19968709237
cell proteins bind specifically to west nile virus minus-strand 3' stem-loop rna.the first 96 nucleotides of the 5'noncoding region (ncr) of west nile virus (wnv) genomic rna were previously reported to form thermodynamically predicted stem-loop (sl) structures that are conserved among flaviviruses. the complementary minus-strand 3' ncr rna, which is thought to function as a promoter for the synthesis of plus-strand rna, forms a corresponding predicted sl structure. rnase probing of the wnv 3' minus-strand stem-loop rna [wnv (-)3' sl rna] confirmed the existence of a termina ...19968709255
evolutionary relationship of hepatitis c, pesti-, flavi-, plantviruses, and newly discovered gb hepatitis agents.two flavivirus-like viruses, gb virus-a (gbv-a) and gb virus-b (gbv-b), were recently identified in the gb hepatitis agent, and are distinct from the hepatitis a to e viruses. the putative helicase domain of gbv-a and gbv-b was found to have amino acid sequence homology with hepatitis c virus (hcv), and distantly, is also related to pestiviruses, flaviviruses, and plant viruses. a phylogenetic tree construction showed that gbvs and hcv are closely related, and they are clustered with pestiviruse ...19968557107
evolving virus plagues. 19968570592
population dynamics of flaviviruses revealed by molecular phylogenies.the phylogeny of 123 complete envelope gene sequences was reconstructed in order to understand the evolution of tick- and mosquito-borne flaviviruses. an analysis of phylogenetic tree structure reveals a continual and asymmetric branching process in the tick-borne flaviviruses, compared with an explosive radiation in the last 200 years in viruses transmitted by mosquitoes. the distinction between these two viral groups probably reflects differences in modes of dispersal, propagation, and changes ...19968570593
identification of two epitopes on the dengue 4 virus capsid protein recognized by a serotype-specific and a panel of serotype-cross-reactive human cd4+ cytotoxic t-lymphocyte clones.we analyzed the cd4+ t-lymphocyte response of a donor who had received an experimental live-attenuated dengue 4 virus (d4v) vaccine. bulk culture proliferative responses of peripheral blood mononuclear cells (pbmc) to noninfectious dengue virus (dv) antigens showed the highest proliferation to d4v antigen, with lesser, cross-reactive proliferation to d2v antigen. we established cd4+ cytotoxic t-lymphocyte clones (ctl) by stimulation with d4 antigen. using recombinant baculovirus antigens, we ide ...19968523518
medical microbiologyat least 27 alphaviruses and 68 flaviviruses have been recognized, approximately one-third of which are medically important human pathogens. they vary widely in their basic ecology; each virus occupies a distinct ecologic niche, often with restricted geographic and biologic distribution. as shown in tables 54-1 and 54-2, alphaviruses and flaviviruses can cause various syndromes, ranging from benign febrile illnesses to severe system ...199621413253
phosphorylation of tick-borne encephalitis virus ns5 protein.the largest tick-borne encephalitis virus (tbev) non-structural protein ns5 (100 kda) is believed to be involved in rna replication. the protein is phosphorylated in infected cell extracts in the presence of [gamma-32p]atp, as shown by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (sds-page) and western blot analysis using monoclonal antibodies raised against tbev ns5 protein. radioactive labeling of ns5 in cellular extracts at an early stage post-infection is higher than at 24 h po ...19979178492
towards defining a minimal functional domain for ntpase and rna helicase activities of the hepatitis c virus ns3 protein.hepatitis c virus (hcv) possesses two separate enzymatic functions in the ns3 protein: a protease and an ntpase/rna helicase. in order to determine the minimal domain for ntpase and rna helicase activities of the hcv ns3 protein, serial deletion mutants were constructed. the ns3h protein a fusion protein of 25 amino acids (aa) from an expression vector and the c-terminal 466 aa of the hcv ns3 protein, contains an ntpase/rna helicase activity. we made deletion mutants of 10, 30, 50, 97, and 135 a ...19979178493
complete sequence of two tick-borne flaviviruses isolated from siberia and the uk: analysis and significance of the 5' and 3'-utrs.the complete nucleotide sequence of two tick-transmitted flaviviruses, vasilchenko (vs) from siberia and louping ill (li) from the uk, have been determined. the genomes were respectively, 10928 and 10871 nucleotides (nt) in length. the coding strategy and functional protein sequence motifs of tick-borne flaviviruses are presented in both vs and li viruses. the phylogenies based on maximum likelihood, maximum parsimony and distance analysis of the polyproteins, identified vs virus as a member of ...19979178494
[a comparative analysis of proteins from persistent and antigen-defective strains of tick-borne encephalitis virus].structural (e) and three nonstructural (ns1, ns3, and ns5) proteins of persistent and antigen-defective strains of tick-borne encephalitis virus are compared by immunoblotting with monoclonal antibodies to the corresponding proteins of strain sofyin. appreciable phenotypical differences were revealed between antigen-defective strains, but no immunological modifications as concerns the studied antigenic structures. the size of the reference ns3 protein differed from that of the persistent virus s ...19979182398
application of an immunoperoxidase monolayer assay for the detection of arboviral antibodies.an immunoperoxidase monolayer assay (ipma) was adapted for the detection of antibodies to six arboviruses: three viruses within the flavivirus group (dengue 2, west nile (wn) and yellow fever) and three in the phlebovirus group (rift valley fever (rvf), sandfly fever naples and sandfly fever sicilian). antibody titers of homologous hyper-immune mouse ascitic fluid (hmaf) measured by ipma were two to eight-fold less than those determined by elisa. in tests with heterologous hmaf, cross-reactions ...19979186937
communicable diseases surveillance. 19979188219
inhibition of japanese encephalitis virus infection by nitric oxide: antiviral effect of nitric oxide on rna virus replication.the antiviral effects of nitric oxide (no) on japanese encephalitis virus (jev), a member of the family flaviviridae, were investigated in this study. in vitro, inhibition of replication of jev in gamma interferon-activated raw 264.7 murine macrophages was correlated to cellular no production. when cocultured with infected murine neuroblastoma n18 cells, gamma interferon-activated raw 264.7 cells also efficiently hindered jev replication in contiguous bystanders, and this anti-jev effect could b ...19979188590
changes in the dengue virus major envelope protein on passaging and their localization on the three-dimensional structure of the protein.to help define the molecular events involved in dengue virus adaptation during serial passage in vivo and in cultured cells, we have sequenced the structural protein genes of three dengue type 3 isolates after intracerebral passage in mice and after passage in cultured monkey kidney (vero) and aedes albopictus (mosquito) cells. passaging in each host selected for amino acid changes in the envelope protein e and occasionally in prm but not in the capsid protein. most changes were first apparent w ...19979191841
yellow fever virus envelope protein has two discrete type-specific neutralizing epitopes.two monoclonal antibody neutralization resistant (mabr) variants of the yellow fever (yf) 17d-204 vaccine virus strain were selected using yf type-specific mab b39. these b39r variants were compared with the variant virus selected by lobigs et al. (virology 161, 474-478, 1987) using a second yf-type specific mab (2e10) which mapped to amino acid position 71/72 in the envelope (e) protein. neutralization assays with a panel of mabs suggested that these two yf-type-specific epitopes are located in ...19979191929
isolation of a flavivirus related to the tick-borne encephalitis complex from human cases in saudi arabia.a flavivirus related to the tick-borne encephalitis complex was isolated from the blood of 6 male butchers, aged 24-39 years, in jeddah, saudi arabia in november and december 1995. two of the patients died and the other 4 recovered completely. four more patients, 3 males and 1 female, were diagnosed serologically by immunoglobulin m capture enzyme-linked immunosorbent assay and seroconversion in acute and convalescent blood samples examined by indirect immunofluorescent test using vero cells inf ...19979196762
a conserved internal hydrophobic domain mediates the stable membrane integration of the dengue virus capsid protein.the mature flavivirus capsid protein (virion c) is commonly thought to be free in the cytoplasm of infected cells and to form a nucleocapsid-like complex with genomic rna in mature virus particles. there is little sequence conservation among flavivirus virion c proteins, but they are similar in size (e.g., 99 amino acids [aa] for the dengue-4 [den4] c) and in bearing a net positive charge. in addition, we noted that c contained a conserved internal hydrophobic segment (spanning aa 45-65 in the d ...19979201220
high prevalence of gb virus c/hepatitis g virus in healthy persons in ho chi minh city, vietnam.gb virus c or hepatitis g virus (gbv-c/hgv), a novel flavivirus, is detected in 1.5% of us blood donors. the prevalence is higher in multiply transfused patients and in persons with liver disease. because of the increased incidence of hepatitis in asia, sera from healthy vietnamese were tested for the presence of gbv-c/hgv rna by the reverse transcription polymerase chain reaction. viral rna was detected in 5.7% of those tested; 6 of 81 volunteer blood donors had positive samples as did 5 of 97 ...19979203671
secondary structure of the 3'-noncoding region of flavivirus genomes: comparative analysis of base pairing probabilities.the prediction of the complete matrix of base pairing probabilities was applied to the 3' noncoding region (ncr) of flavivirus genomes. this approach identifies not only well-defined secondary structure elements, but also regions of high structural flexibility. flaviviruses, many of which are important human pathogens, have a common genomic organization, but exhibit a significant degree of rna sequence diversity in the functionally important 3'-ncr. we demonstrate the presence of secondary struc ...19979214660
automated type specific elisa probe detection of amplified ns3 gene products of dengue viruses.to apply an automated system of nucleic acid hybridisation coupled with the enzyme linked immunosorbent assay (elisa) for the type specific detection of amplification products of dengue viruses.19979215155
affinity selection of a camelized v(h) domain antibody inhibitor of hepatitis c virus ns3 protease.the hcv genome encodes, within the ns3 gene, a serine protease whose activity specifically cleaves the viral polyprotein precursor. proteolytic processing of hcv polyprotein precursor by the viral ns3 proteinase is essential for virion maturation and designing specific inhibitors of this protease as possible anti-viral agents is a desirable and practical objective. with a view to studying both the function of hcv ns3 protease and to designing inhibitors of this enzyme, we directed our interest t ...19979215580
biology of tick-borne encephalitis virus.tick-borne encephalitis (tbe) virus is an important human pathogen belonging to the genus flavivirus within the family flaviviridae. the genome of the tbe virus is a single-stranded rna (ssrna) molecule of positive polarity encoding all the viral proteins within a single open reading frame (orf). tbe virus shares common physical and genetic characteristic of the flavivirus genus. two subtypes of the tbe virus have been described: (1) european, endemic in many parts of europe and transmitted by i ...19979219644
effect of enforced expression of human bcl-2 on japanese encephalitis virus-induced apoptosis in cultured cells.infection by japanese encephalitis virus (jev), a mosquito-borne flavivirus, causes acute encephalitis in humans and induces severe cytopathic effects in different types of cultured cells. this study attempted to determine whether apoptosis contributes to virus-induced cell death in a culture system by characterizing jev lytic infection in baby hamster kidney bhk-21 cells, murine neuroblastoma n18 cells, and human neuronal progenitor nt2 cells. according to our results, the replication of jev, a ...19979223486
venezuelan equine encephalitis and oropouche virus infections among peruvian army troops in the amazon region of peru.an outbreak of a febrile illness characterized by headache, ocular pain, myalgia, and arthralgia occurred during june 1994 among peruvian army troops in northern peru. on june 14-16, 1994, clinical data and blood samples were obtained from eight soldiers with a febrile illness, and from 26 others who had a history of febrile illness during the past three months. a follow-up blood sample was obtained 107 days later from four of the febrile and seven of the afebrile soldiers. serum samples were te ...19979230800
proteins c and ns4b of the flavivirus kunjin translocate independently into the nucleus.the subcellular locations in infected vero cells of kunjin (kun) virus core protein c and ns4b were analyzed by immunofluorescence (if) and by immunoelectron microscopy using monospecific antibodies. selection of appropriate fixation methods for if showed that both proteins were associated at all times with perinuclear membranes spreading outward in a reticular pattern and they entered the nucleus late during the latent period. subsequently ns4b was also dispersed through the nucleoplasm, while ...19979234944
the yellow fever 17d vaccine virus: molecular basis of viral attenuation and its use as an expression vector.the yellow fever (yf) virus is the prototype flavivirus. the use of molecular techniques has unraveled the basic mechanisms of viral genome structure and expression. recent trends in flavivirus research include the use of infectious clone technology with which it is possible to recover virus from cloned cdna. using this technique, mutations can be introduced at any point of the viral genome and their resulting effect on virus phenotype can be assessed. this approach has opened new possibilities ...19979239300
gb virus c rna in serum, liver, and peripheral blood mononuclear cells from patients with chronic hepatitis b, c, and d.no conclusive data about gb virus c (gbv-c) tropism are available. we have studied the presence of genomic and antigenomic gbv-c rna in serum, liver, and peripheral blood cells of 56 patients with chronic hepatitis b, c, or d virus infection.19979247478
virus isolation from wild-caught mosquitoes during a japanese encephalitis outbreak in kerala in 1996.out of 5357 wild-caught mosquitoes in 163 pools tested for virus using antigen capture elisa and an insect-bioassay (inoculation into toxorhynchites splendens larvae and identification by ifa using je virus-specific monoclonal antibody), 16 flavivirus isolations were made of which 12 (75%) were identified as je virus. of the 12 je virus isolations, 7 were from culex tritaeniorhynchus, 3 from mansonia uniformis and 1 each from ma. indiana and anopheles subpictus. four isolations from mansonia spe ...19979248207
transmission of gbv-c/hgv from drug-addicted mothers to their babies.in 1995, a new flavivirus, gbv-c/hgv was identified. little information is available on the clinical manifestations and epidemiology of gbv-c/hgv infection. we investigated the risk of mother-to-infant transmission in a group of gbv-c/hgv rna positive women and followed up the gbv-c/hgv infected babies.19979252078
dengue virus infectivity depends on envelope protein binding to target cell heparan sulfate.dengue virus is a human pathogen that has reemerged as an increasingly important public health threat. we found that the cellular receptor utilized by dengue envelope protein to bind to target cells is a highly sulfated type of heparan sulfate. heparin, highly sulfated heparan sulfate, and the polysulfonate pharmaceutical suramin effectively prevented dengue virus infection of target cells, indicating that the envelope protein-target cell receptor interaction is a critical determinant of infecti ...19979256277
a 45,000-m(r) glycoprotein in the sendai virus envelope triggers virus-cell fusion.sendai virus envelopes devoid of hemagglutinin-neuraminidase but containing the fusion protein (f-virosomes) were prepared. f-virosomes exhibited discernible serine protease activity at neutral ph. electrophoretic analysis of the protein profile of the f-virosomes under nonreducing conditions, by both sodium dodecyl sulfate-polyacrylamide gel electrophoresis and isoelectric focusing, led to the identification of a previously unknown glycoprotein with a relative molecular weight of 45,000 (45k pr ...19979261357
translation elongation factor-1 alpha interacts with the 3' stem-loop region of west nile virus genomic rna.the conserved 3'-terminal stem-loop (3' sl) of the west nile virus (wnv) genomic rna was previously used to probe for cellular proteins that may be involved in flavivirus replication and three cellular proteins were detected that specifically interact with the wnv 3' sl rna (j. l. blackwell and m. a. brinton, j. virol. 69:5650-5658, 1995). in this study, one of these cellular proteins was purified to apparent homogeneity by ammonium sulfate precipitation and liquid chromatography. amino acid seq ...19979261361
ultrastructure of kunjin virus-infected cells: colocalization of ns1 and ns3 with double-stranded rna, and of ns2b with ns3, in virus-induced membrane structures.the subcellular location of the nonstructural proteins ns1, ns2b, and ns3 in vero cells infected with the flavivirus kunjin was investigated using indirect immunofluorescence and cryoimmunoelectron microscopy with monospecific antibodies. comparisons were also made by dual immunolabelling using antibodies to double-stranded rna (dsrna), the putative template in the flavivirus replication complex. at 8 h postinfection, the immunofluorescent patterns showed ns1, ns2b, ns3, and dsrna located in a p ...19979261387
superinfection exclusion of alphaviruses in three mosquito cell lines persistently infected with sindbis virus.three aedes albopictus (mosquito) cell lines persistently infected with sindbis virus excluded the replication of both homologous (various strains of sindbis) and heterologous (aura, semliki forest, and ross river) alphaviruses. in contrast, an unrelated flavivirus, yellow fever virus, replicated equally well in uninfected and persistently infected cells of each line. sindbis virus and semliki forest virus are among the most distantly related alphaviruses, and our results thus indicate that mosq ...19979261447
schizophrenia, rheumatoid arthritis and natural resistance genes.the strong negative correlation between schizophrenia and rheumatoid arthritis might provide clues as to the aetiology of these two diseases. an immunological explanation has been sought in the hla sector of the major histocompatibility complex, which has been shown to have a role in the development of rheumatoid arthritis. the search for an association between schizophrenia and hla haplotypes, however, has yielded only controversial results. nevertheless, an autoimmune aetiology is still suspec ...19979264173
expression of the dengue virus structural proteins in pichia pastoris leads to the generation of virus-like particles.we have expressed cdna encoding the dengue virus structural proteins in pichia pastoris by chromosomal integration of an expression cassette containing the dengue virus structural genes (cprme). the yeast recombinant e protein migrated during sds-page as a 65 kda protein when analysed by western blotting and radioimmunoprecipitation, which is the expected molecular mass for correctly processed and glycosylated e protein. treatment with endoglycosidases showed that the recombinant e protein was m ...19979266980
expression of immunoglobulin superfamily cell adhesion molecules on murine embryonic stem cells.the expression of cell adhesion molecules of the ig superfamily (ig-cam) were examined on embryonic stem (es) cells during culture in vitro. es cells maintained an undifferentiated phenotype when cultured in the presence of leukemia inhibitory factor (lif) or with fibroblast feeder cells; > 90% of cells reacted positively to an antibody (ecma-7) that marks undifferentiated es cells. using flow cytometry, high concentrations of icam-1, vcam-1, and ncam antigens were detected on undifferentiated e ...19979282991
the clinical significance of the detection of hepatitis gbv-c rna in the serum of patients with fulminant, presumed viral, hepatitis.in a significant number of cases of fulminant (presumed viral) hepatitis worldwide, no aetiological agent has been identified. recently, it has been suggested that a newly described flavivirus, gbv-c, is responsible for some of these cases. this study aimed to assess the clinical significance of gbv-c rna, demonstrated by reverse transcriptase-polymerase chain reaction (rt-pcr), in the serum of patients with fulminant non-a to e hepatitis. twenty-three consecutive cases of non-a to e fulminant h ...19979031064
expression of highly active recombinant ns3 protease domain of hepatitis c virus in e. coli.the serine protease domain of hcv comprising amino acids 1027-1218 (deltans3) was expressed in e. coli with a his tag at its n-terminal end. the protease was purified to apparent homogeneity by a single step affinity chromatography resulting in high yields (approximately 3 mg/l of cultured cells). the deltans3 efficiently cleaves a 17-mer peptide corresponding to the ns5a-ns5b junction with kcat/km = 160 x 10(-3) min(-1) microm(-1) in the presence of ns4a peptide. our deltans3 represents the min ...19979037197
pre- and postexposure protection by passive immunoglobulin but no enhancement of infection with a flavivirus in a mouse model.antibody-dependent enhancement of flavivirus infection, which except for dengue virus is without clear proof in vivo, is still under debate. recently, postexposure immunoglobulin prophylaxis against tick-borne encephalitis virus, a flavivirus, was claimed to possibly have worsened the outcome of infection due to antibody-dependent enhancement. in the present study, antibody-dependent enhancement and pre- or postexposure protection by passive administration of tick-borne encephalitis virus immuno ...19979060650
g(ee): a new hepatitis virus.hepatitis g virus (hgv) is a newly discovered virus of the flavivirus family. it has recently been identified by two independent laboratories. we review the discovery of this virus and summarize the molecular biology techniques that were employed to isolate and sequence hgv although hgv can cause both acute and chronic hepatitis and is found in approximately 1% of u.s. blood donors, it is unclear whether hgv is a major cause of hepatic pathology. at present, it is difficult to screen blood donor ...19979077717
evaluation of four pcr systems amplifying different genomic regions for molecular diagnosis of gb virus c infections.diagnosis of gb virus c (gbv-c) infection is based on rt-pcr methodology that detects genomic viral rna. four sets of primers located in different genomic regions were compared. these primers were used to amplify a reference panel of sera used by the french blood banks, including five positive sera, five negative sera and 10-fold serial dilutions of one positive serum. three sets of primers located in the 5'utr, ns3 and ns5a genomic regions gave comparable results with undiluted sera. when dilut ...19979079759
[molecular evolutionary analysis of gb viruses and hepatitis g virus].recently, new blood-transfusion transmissible viruses, called hepatitis g virus(hgv) and gb virus-c(gbv-c), have been reported. it was found that two viruses were independent isolates of the same virus, the genomic structure resembled that of flavivirus family, and gbv-c/hgv was closely related to hcv. to elucidate the evolutionary relationship between hepatitis c virus(hcv) and gbv-c/hgv, we constructed the phylogenetic trees for the putative rna helicase and the rna-dependent rna polymerase re ...19979086754
secondary structure of the 3' untranslated region of flaviviruses: similarities and differences.genetic algorithm-based rna secondary structure prediction was used in combination with comparative sequence analysis to construct models of folding for the distal part of the 3'-untranslated region of flaviviruses belonging to four serological groups. elements of rna secondary structure that are preserved among all the flaviviruses studied were revealed, despite the high degree of sequence divergence between them. at the same time, structural elements were observed that distinguish members of d ...19979092629
rna-protein interactions: involvement of ns3, ns5, and 3' noncoding regions of japanese encephalitis virus genomic rna.the mechanism of replication of the flavivirus japanese encephalitis virus (jev) is not well known. the structures at the 3' end of the viral genome are highly conserved among divergent flaviviruses, suggesting that they may function as cis-acting signals for rna replication and, as such, might specifically bind to cellular or viral proteins. uv cross-linking experiments were performed to identify the proteins that bind with the jev plus-strand 3' noncoding region (ncr). two proteins, p71 and p1 ...19979094618
a new hepatitis c virus-like flavivirus in patients with cryptogenic liver disease associated with elevated ggt and alkaline phosphatase serum levels.the intriguing co-infection of two flaviviruses (gbv-a and gbv-b) in tamarins and the recent discovery of another flavivirus (gbv-c/hgv) in humans raises the question of the relations between hepatitis c virus (hcv) and gbv-c/hgv. to address this issue the sera of 285 patients with liver disease (102 patients with cryptogenic and 183 with known forms of chronic liver disease) and 19 patients without liver disease were tested for hgv-rna. gbv-c/hgv-rna was detected by rt-pcr using primers encompa ...19979097279
gb virus-c/hepatitis g virus infection in an area endemic for viral hepatitis, chronic liver disease, and liver cancer.gb virus-c/hepatitis g virus (gbv-c/hgv) is a newly identified flavivirus, and little is known about its clinical significance. gbv-c/hgv was investigated in different populations, and its coinfection was investigated in patients with liver disease in taiwan where hepatitis b and c are endemic.19979098011
japanese encephalitis vaccine in travellers. is wider use prudent?vaccination against japanese encephalitis has been carried out extensively in many asian countries for the past 20 years and is also increasingly recommended for travellers to endemic areas. although the currently available vaccine, manufactured from mouse brain, is generally considered to be highly effective and of low reactogenicity, approximately 50% of vaccinees report experiencing usually mild adverse effects following vaccination. concern has been raised regarding potential neurological ad ...19979098653
[hepatitis c--clinical aspects, diagnosis and therapy].hepatitis c is caused by a flavivirus measuring 30 to 60 nm in diameter which in germany has an incidence of 0.4 to 0.7% among the general population. transmission is largely hematogenous and high-risk groups include needle-using drug addicts, hemophiliacs, and patients on dialysis. the diagnosis is based on the detection of hepatitis c antibodies, hcv-rns pcr and histological findings. the symptoms are mild and the chronification rate may by as high as 80%. the treatment of choice is alpha inte ...19979102384
ultrastructural observations of viral particles within hepatitis c virus-infected human b lymphoblastoid cell line.hepatitis c virus (hcv)-infected tofe cells, a human bone marrow-derived b-cell line, were studied by transmission electron microscopy (tem). we reported the presence of virus-like particles, (vlps) having a diameter of 45 nm on average, within the cytoplasm of hcv-infected cells and their absence in uninfected cells. the vlps were mostly seen in dilated cisternae of endoplasmic reticulum (er) and consisted of an electron-dense core and a membrane envelope with surface projections. in the hcv-in ...19979108618
molecular characterization of virus-specific rna produced in the brains of flavivirus-susceptible and -resistant mice after challenge with murray valley encephalitis virus.natural resistance to flaviviruses in mice is controlled by a single genetic locus, fiv, on chromosome 5. although the mechanism of this resistance is not fully understood, it is believed to operate at the level of virus replication rather than the immune response. it has been hypothesized that enhanced production of viral defective interfering (di) particles is responsible for a substantial reduction in the titres of infectious virus in resistant mice. however, this has never been established a ...19979010281
characterization of monoclonal antibody-escape mutants of tick-borne encephalitis virus with reduced neuroinvasiveness in mice.escape mutants of tick-borne encephalitis (tbe) virus were selected using neutralizing monoclonal antibodies (mabs) that react with three different and previously unrecognized epitopes in the envelope protein e of tbe virus. two of these variants (v-ic3 and v-ie3) exhibited a significantly reduced reactivity with their selecting mabs, as determined by elisa, whereas with one variant (v-io3), reactivity was completely unchanged. comparative sequence analyses demonstrated that each of the variants ...19979010282
purification and characterization of the ns3 serine protease domain of hepatitis c virus expressed in saccharomyces cerevisiae.cdna encoding the putative core of the hepatitis c virus ns3 serine protease domain (residues 1-181 of ns3; ns3 (181)) was expressed as an n-terminally (his)6-tagged fusion protein in saccharomyces cerevisiae. ns3 (181) protease activity was found in soluble cell lysates, and the n-terminal metal-chelating domain facilitated the efficient purification of active enzyme, using immobilized metal affinity chromatography. the purified ns3(181), protease activity was characterized by assaying the tran ...19979010283
genetic diversity between hepatitis g virus isolates: analysis of nucleotide variation in the ns-3 and putative 'core' peptide genes.significant variation was found, between 46 isolates of hepatitis g virus (hgv), following direct sequencing of subgenomic pcr fragments from either or both the ns-3 and putative 'core' peptide. nucleotide sequences of most hgv ns-3 fragments varied by 10-30% and of most putative 'core' peptide fragments by 2-20%. hgv was therefore shown to be much less variable than hepatitis c virus (hcv) and pairwise comparisons of hgv sequences demonstrated a single distinct distribution of evolutionary dist ...19979010285
sequence analyses of ns3 genes of recent pakistan and singapore strains of dengue virus types 1 and 2. 19979017828
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