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 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
expression of the japanese encephalitis virus ns3 and ns2b proteins as glutathione s-transferase fusions.flaviviruses generate their structural and nonstructural proteins by proteolytic processing of a single large polyprotein precursor. these proteolytic events are brought about both by host cell signalase and a virally encoded protease. the virally encoded proteolytic activity has been shown to reside within the nonstructural protein 3 (ns3) and requires the product of the nonstructural 2b (ns2b) gene. in order to obtain sufficient quantities of pure ns2b and ns3 proteins for kinetic analysis, we ...19958714204
evidence of axonal reinnervation in two arthropod-borne viral encephalomyelitis patients. 19968719656
antigenic similarity of central european encephalitis and louping-ill viruses.twenty isolates of central european encephalitis (cee) virus were compared with 20 isolates of louping-ill (li) virus in indirect immunofluorescence test (iift), using a panel of 17 monoclonal antibodies (moabs) prepared against the prototype li virus. three asian members of the tick-borne encephalitis (tbe) complex were also included in the comparison: turkish sheep encephalitis (tse), russian spring-summer encephalitis (rsse) and langat (lgt) viruses. antigenic relationships of the viruses wer ...19958722293
hepatitis c virus as a lymphotropic agent: evidence and pathogenetic implications.hepatitis c virus has been proven to be the major cause of nanb hepatitis, cirrhosis and hepatocellular carcinoma worldwide. based on the genome similarities between hcv and flavivirus or pestivirus, this agent has been included within the family flaviviridae as a separate genus. among the analogies between hcv and the other members of the same family there is the possibility of infecting blood cells. in particular, significant evidence obtained through studies performed in vivo and in vitro sup ...19958730474
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
molecular epidemiology and evolution of mosquito-borne flaviviruses and alphaviruses enzootic in australia.three distinct patterns in the molecular epidemiology and evolution are evident among the alphaviruses and flaviviruses enzootic in australia. one pattern, exemplified by mve and kun viruses, is of a single genetic type evolving slowly and uniformly in geographically widely separated regions of australia with no evidence of independent divergence. the second pattern, exemplified by rr virus, is of separate genotypes evolving in different geographic regions with significant nucleotide divergence ...19958828149
dominant recognition by human cd8+ cytotoxic t lymphocytes of dengue virus nonstructural proteins ns3 and ns1.2a.a severe complication of dengue virus infection, dengue hemorrhagic fever (dhf), is hypothesized to be immunologically mediated and virus-specific cytotoxic t lymphocytes (ctls) may trigger dhf. it is also likely that dengue virus-specific ctls are important for recovery from dengue virus infections. there is little available information on the human cd8+ t cell responses to dengue viruses. memory cd8+ctl responses were analyzed to determine the diversity of the t cell response to dengue virus a ...19968833919
characterization of langat virus antigenic determinants defined by monoclonal antibodies to e, ns1 and prem and identification of a protective, non-neutralizing prem-specific monoclonal antibody.hybridomas secreting monoclonal antibodies (mab) to the tick-borne encephalitis (tbe) group virus, langat virus (lgtv), were prepared. of more than 200 mab screened, 19 antibodies, which cross-reacted with the etiologic agent of central european encephalitis, were selected for further characterization. of these mab, 15 were specific for lgtv e glycoprotein, two for the ns1 protein, and three for prem protein. the two ns1-specific mab and two of the e-specific mab reacted with all six of the othe ...19968864202
hepatitis g virus: identification and prevalence.a new flavivirus, provisionally designated as hepatitis g virus, has recently been identified. its genomic organization is similar to that of the hepatitis c virus (hcv) with which it has only 25% nucleotide homology. the virus is transmissible by blood transfusion, by exposure to blood products or by intravenous drug use. concurrent infection with hepatitis b virus and hcv is common and persistent viraemia has been documented, in many cases in the absence of transaminase elevations.19968879706
identification of peptides mimicking the antigenicity and immunogenicity of conformational epitopes on japanese encephalitis virus protein using synthetic peptide libraries.monoclonal antibodies (mabs) n.03 and n.08 that recognize conformational epitopes on the prm protein of japanese encephalitis virus (jev) were analyzed to identify their peptide ligands by using a novel approach that combined two different synthetic peptide libraries. immunoscreening of a library containing 20(5) sequences of pentapeptides revealed that the ligands for n.03 and n.08 had motif sequences, (y/w/f)gg(i/l/m) and (n/q)wy(d/e), respectively. to select higher-affinity ligands, we synthe ...19968882934
expression and purification of the seven nonstructural proteins of the flavivirus kunjin in the e. coli and the baculovirus expression systems.all seven nonstructural (ns) proteins of the flavivirus kunjin (kun) ranging from ns1 to ns5 were expressed either alone or as fusion proteins with glutathione-s-transferase (gst). high level expression of recombinant proteins was achieved in spodoptera frugiperda (sf9) cells using the baculovirus expression system in contrast to the low level of expression in e. coli. the order of the level of expression of the recombinant fusion proteins per 4 x 10(7) sf9 cells was: gst-ns5 (yields approximate ...19968882936
structural requirements for low-ph-induced rearrangements in the envelope glycoprotein of tick-borne encephalitis virus.the exposure of the flavivirus tick-borne encephalitis (tbe) virus to an acidic ph is necessary for virus-induced membrane fusion and leads to a quantitative and irreversible conversion of the envelope protein e dimers to trimers. to study the structural requirements for this oligomeric rearrangement, the effect of low-ph treatment on the oligomeric state of different isolated forms of protein e was investigated. full-length e dimers obtained by solubilization of virus with the detergent triton ...19968892942
infection with hepatitis g virus among recipients of plasma products.hepatitis g virus (hgv or gbv-c) is a newly discovered human flavivirus distantly related to hepatitis c virus (hcv). little information is available on its natural history or routes of transmission, although it can be transmitted parenterally. we investigated the prevalence of persistent infection of hgv and hcv in patients exposed to non-virus-inactivated pooled blood products associated with transmission of hcv.19968918279
enhancement of hepatitis c virus ns3 proteinase activity by association with ns4a-specific synthetic peptides: identification of sequence and critical residues of ns4a for the cofactor activity.the ns3 proteinase of hepatitis c virus utilizes ns4a as a cofactor for cleavages at four sites (3/4a, 4a/4b, 4b/5a, and 5a/5b) in the nonstructural region of the viral polyprotein. to characterize ns4a for its role in modulating the ns3 proteinase activity at various cleavage sites, synthetic peptides spanning various parts of ns4a were synthesized and tested in a cell-free trans-cleavage reaction using purified ns3 proteinase domain and polyprotein substrates. the ns3 proteinase domain was exp ...19968918919
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
genetic analysis of the yellow fever virus ns1 protein: identification of a temperature-sensitive mutation which blocks rna accumulation.the flavivirus ns1 protein is a highly conserved nonstructural glycoprotein that is capable of eliciting protective immunity. ns1 homodimers are secreted from virus-infected mammalian cells, but the protein is also present at the plasma membrane and in the lumen of intracellular vesicles. based on these properties, it has been speculated that ns1 may function in virus maturation or release. to gain further insight into ns1 function, we used clustered charged-amino-acid-to-alanine mutagenesis to ...19978985349
[recent data on the epidemiology of japanese encephalitis].japanese encephalitis is an arbovirosis the incidence and geographic distribution of which are increasing in rural areas of tropical and temperate asia. a total of about 45,000 to 50,000 clinical cases occur annually. the flavivirus responsible for the disease shows birds as usual hosts, and culex mosquitoes as vectors. after a first amplification cycle in birds, the virus can be transmitted to domestic pigs, then to man. this scheme, however, shows large variations in the different regions, acc ...19968991613
subgenomic replicons of the flavivirus kunjin: construction and applications.several kunjin virus (kun) subgenomic replicons containing large deletions in the structural region (c-prm-e) and in the 3' untranslated region (3'utr) of the genome have been constructed. replicon rna deltame with 1,987 nucleotides deleted (from nucleotide 417 [in codon 108] in the c gene to nucleotide 2403 near the carboxy terminus of the e gene, inclusive) and replicon rna c20rep with 2,247 nucleotides deleted (from nucleotide 157 [in codon 20] in c to nucleotide 2403) replicated efficiently ...19978995675
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
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
internal proteolysis of the ns3 protein specified by dengue virus 2.the ns3 protein of flaviviruses is a multifunctional polypeptide required for virus replication. enzymic activities that have been demonstrated or predicted from the presence of sequence motifs include protease, ntpase, helicase and rna triphosphatase. both full-length and truncated forms of ns3 have been identified in infected cells. to examine internal cleavage of the ns3 protein of dengue virus 2 (den-2), infected cells or cos cells transfected with cdna encoding ns2b/3 were radiolabelled and ...19979018055
poxvirus-based japanese encephalitis vaccine candidates induce je virus-specific cd8+ cytotoxic t lymphocytes in mice.recombinant japanese encephalitis (je) vaccine candidates based on a highly attenuated vaccinia virus (nyvac-jev) and a canarypox virus (alvac-jev) were evaluated for their ability to induce specific antibodies and cytotoxic t lymphocytes (ctls) in mice. six- to eight-week-old male balb/c mice that received one or two intraperitoneal inoculations with these je vaccine candidates at a dose of 1 x 10(7) pfu per mouse produced neutralizing antibody and antibodies to the envelope (e) and nonstructur ...19979018134
detection of antibodies to a putative hepatitis g virus envelope protein.a flavivirus designated hepatitis g virus (hgv) has been isolated from the serum of patients with non-a-e hepatitis. hitherto, the presence of hgv rna in serum has been detected with the reverse transcription-polymerase chain reaction (rt-pcr) amplification method. we have now developed an immunoassay for antibodies against an hgv protein.19979024375
[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
the clinical significance of the detection of hepatitis gbv-c rna in the serum of patients with fulminant, presumed viral, 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
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 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
[flavivirus rna replication and involvement of host factors]. 19969123892
five new or recently discovered (gbv-a) virus species are indigenous to new world monkeys and may constitute a separate genus of the previous studies, human hepatitis viruses have been experimentally transmitted to new world monkeys of the genus saguinus (tamarins). recently, two flaviviridae-like agents (gbv-a and gbv-b) were identified in tamarins that developed hepatitis following inoculation with serum of the 11th tamarin passage of a potentially new human hepatitis agent. however, it was not shown that these viruses originated from the initial inoculum. we here report the discovery of indigenous species-specific virus ...19979126255
infection with gb virus c/hepatitis g virus in brazilian hemodialysis and hepatitis patients and asymptomatic individuals.recently, sequences from a novel human flavivirus, termed gb virus c (gbv-c) or hepatitis g virus (hgv), have been identified in serum from patients with cryptogenic hepatitis and others. sera from 116 patients with different clinical backgrounds were tested for the presence of gbv-c/hgv rna by a reverse transcription-polymerase chain reaction with primers from the nonstructural (ns) 5 region. ten (15%) patients on maintenance hemodialysis and 5 (19%) non a-c hepatitis patients were gbv-c/hgv rn ...19979131459
genotype determination of three dengue type 2 virus strains from myanmar by sequencing e/nsi gene junction.genotype of three dengue-2 virus strains from myanmar was determined as genotype ii by sequencing 240 nucleotide long fragment across the e/ns1 gene junction by the primer extension dideoxy chain termination method, applying direct sequencing of the pcr product. these strains were isolated from a dengue shock syndrome (dss) patient and two patients with dengue hemorrhagic fever (dhf) grade 1, in yangon (rangoon), myanmar (burma), in 1987. sequence homology of all three strains were highest (96%) ...19959139372
gb virus c, hepatitis g virus, or human orphan flavivirus? 19979141455
construction of infectious cdna clones for dengue 2 virus: strain 16681 and its attenuated vaccine derivative, strain pdk-53.we identified nine nucleotide differences between the genomes of dengue-2 (den-2) 16681 virus and its vaccine derivative, strain pdk-53. these included a c-to-t (16681-to-pdk-53) mutation at nucleotide position 57 of the 5'-untranslated region, three silent mutations, and substitutions prm-29 asp to val, ns1-53 gly to asp, ns2a-181 leu to phe, ns3-250 glu to val, and ns4a-75 gly to ala. unpassaged pdk-53 vaccine contained two genetic variants as a result of partial mutation at ns3-250. we constr ...19979143286
upregulation of signalase processing and induction of prm-e secretion by the flavivirus ns2b-ns3 protease: roles of protease components.recently, we have shown that the ability of the flavivirus ns2b-ns3 protease complex to promote efficient signalase processing of the c-prm precursor, as well as secretion of prm and e, does not appear to depend strictly on cleavage of the precursor at its lys-arg-gly dibasic site by the protease. we suggested that the association of the protease with the precursor via ns2b may be sufficient by itself for the above effects. to study the proposed association in more detail, we have developed an a ...19979151825
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
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 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
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 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, 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 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 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 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 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
Displaying items 901 - 1000 of 3318