yellow fever virus ns2b-ns3 protease: charged-to-alanine mutagenesis and deletion analysis define regions important for protease complex formation and function.charged-to-alanine substitutions and deletions within the yellow fever virus ns2b-ns3(181) protease were analyzed for effects on protease function. during cell-free translation of ns2b-3(181) polyproteins, mutations at three charge clusters markedly impaired cis cleavage activity: a single n-terminal cluster in the conserved domain of ns2b (residues elkk(52-55)) and two in ns3 (ed(21-22), and residue h(47)). these mutations inhibited other protease-dependent cleavages of a transiently expressed ...200010998334
attenuation of tick-borne encephalitis virus by structure-based site-specific mutagenesis of a putative flavivirus receptor binding site.the impact of a specific region of the envelope protein e of tick-borne encephalitis (tbe) virus on the biology of this virus was investigated by a site-directed mutagenesis approach. the four amino acid residues that were analyzed in detail (e308 to e311) are located on the upper-lateral surface of domain iii according to the x-ray structure of the tbe virus protein e and are part of an area that is considered to be a potential receptor binding determinant of flaviviruses. mutants containing si ...200011000232
[transmission and conservation of the amaril virus in nature].the yellow fever virus is a monkey flavivirus transmitted by mosquitoes. the transmission cycles and vectors vary from western to eastern africa and in south america. there are two types of endemic areas where the virus is maintained: humid forests and emerging zones and areas where intermediary and urban epidemics occur. on both continents, the virus circulates in forest areas by moving epizooties from one region to another among non immune monkeys. the virus can also be maintained in an enzoot ...199911000958
prospective follow-up of patients with gbv-c/hgv infection: specific mutational patterns, clinical outcome, and genetic association between a specific mutational pattern within the nonstructural (ns)3 region of gb virus-c/hepatitis g virus (gbv-c/hgv) genome and fulminant hepatic failure has been suggested recently. the mutational pattern consists of 3-6 nucleotide mutations of which one is leading to an amino acid exchange. in the present study, patients with gbv-c/hgv mono-infection (n = 24) or gbv-c/hgv and hcv co-infection (n = 20) were investigated prospectively. in 6/44 patients (14%) the mutational patt ...200011002248
single amino acid differences are sufficient for cd4(+) t-cell recognition of a heterologous virus by cattle persistently infected with bovine viral diarrhea virus.cattle that are persistently infected (pi) with one strain of bovine viral diarrhea virus (bvdv) can resolve infection with a second, antigenically heterologous strain but not the homologous strain. since cd4(+) t cells are thought to be critical for the resolution of acute bvdv infection (howard et al., 1992, vet. immunol. immunopathol. 32, 303-314), we have examined the recognition of a heterologous virus (nadl) by cd4(+) t cells from pe515-pi animals. the immune response of non-pi control cat ...200011021996
[circulation of virus and interspecies contamination in wild animals].paradoxically, just when we have succeeded in eradicating and/or bringing under control the major viral infections (smallpox, poliomyelitis, measles) numerous viral infections are emerging in man and in animals. changes in our social environment, technological and ecological equilibrium have facilitated this phenomenon. furthermore, certain of these viruses have demonstrated an almost unlimited capacity to adapt genetically to environmental change. hiv has already infected 40 million individuals ...200011030047
[detection of hgv ns5 antigen in liver tissue of patients with chronic liver disease].to investigate the existence of hepatitis g virus (hgv) in liver tissue.199811038810
hepatitis c virus internal ribosome entry site (ires) stem loop iiid contains a phylogenetically conserved ggg triplet essential for translation and ires folding.the hepatitis c virus (hcv) internal ribosome entry site (ires) is a highly structured rna element that directs cap-independent translation of the viral polyprotein. morpholino antisense oligonucleotides directed towards stem loop iiid drastically reduced hcv ires activity. mutagenesis studies of this region showed that the ggg triplet (nucleotides 266 through 268) of the hexanucleotide apical loop of stem loop iiid is essential for ires activity both in vitro and in vivo. sequence comparison sh ...200011044087
heparan sulfate proteoglycans initiate dengue virus infection of hepatocytes.dengue viruses (den) cause a broad spectrum of clinical manifestations including potentially life-threatening conditions such as hemorrhagic shock syndrome and less frequently acute hepatitis with liver failure and encephalopathy. in addition, dengue viruses provide a potential model to understand the initiation of hepatocyte infection by the structurally closely related hepatitis c virus (hcv), because this virus at present cannot be grown in cell culture. although the initial steps of viral in ...200011050058
[prevalence of flavivirus antibodies in alouatta caraya primate autochthonous of argentina].flavivirus constitute a human health problem in our country. primates are known to participate in the maintenance of dengue and yellow fever viruses. however, these animals play a role which still remains to be determined in the maintenance of other viruses with potential pathogenicity for human beings and/or animals. detección of antibodies was performed for different flavivirus in 105 sera samples of alouatta caraya primates by the hemagglutination inhibition (hi) test. the neutralization (nt) ...200011050814
structures and mechanisms in flavivirus fusion. 200011050944
tick-borne encephalitis virus strains of western siberia.tick-borne encephalitis virus (tbev) strains were isolated from ticks in western siberia for 12 years. molecular hybridization of the 46 viral rna with the tbev cdna and oligonucleotide probes revealed differences between the siberian and far eastern strains. a comparison of the viral e gene fragment nucleotide sequence showed 89-98% homology between siberian tbev strains, whereas their similarity with strains from other populations was less than 83%. however, the viral e and ns1 glycoprotein an ...200011074120
[tick-borne meningoencephalitis in thurgau canton: a clinical and epidiomological analysis].tick-borne meningo-encephalitis (tbe) is caused by a flavivirus species that is transmitted from rodents to humans by ixodes ticks. the clinical picture of central nervous system involvement varies from febrile headache to lethal encephalitis. to date no specific treatment exists, although protective active immunisation is available.200011075408
trends in flavivirus infections in japan.although japanese encephalitis has declined as an important cause of illness and death in japan, infection with other flaviviruses has become a public health concern. recently, reports of imported dengue cases, as well as isolations of tick-borne encephalitis virus, have increased.200011076713
recombinant plasmid expressing a truncated dengue-2 virus e protein without co-expression of prm protein induces partial protection in mice.a nucleic acid vaccine candidate against dengue-2 virus was constructed to express a truncated dengue-2 e glycoprotein without concomitant expression of prm. the truncated e protein was properly expressed even in the absence of prm. mice inoculated intramuscularly with the recombinant plasmid containing 94% of the e gene did not respond with anti-dengue antibodies, cellular proliferation, or synthesis of cytokines by their lymphoid cells when stimulated with purified dengue-2 virus. however, pro ...200011090717
genetic heterogeneity and molecular epidemiology of gb virus c/hepatitis g virus in china.the inter- and intrapatient genetic variation of gb virus c (gbv-c)/hepatitis g virus (hgv) was investigated to characterize the molecular epidemiologic profile of gbv-c/ hgv infection in china, an area endemic for viral hepatitis. the intrapatient variation of hepatitis c virus (hcv) from the same patients was compared to that of gbv-c/hgv.200011100910
the brazilian flaviviruses.ten flaviviruses occur in brazil: bussuquara, cacipacoré, dengue 1, 2 and 4, iguape, ilhéus, rocio, saint louis encephalitis and yellow fever. aspects of sylvatic maintenance cycles and human diseases caused by these viruses are analyzed. large dengue outbreaks are occurring in brazil and there is a risk of yellow fever urbanization.200011113383
the rna aptamer-binding site of hepatitis c virus ns3 protease.nonstructural protein 3 (ns3) of hepatitis c virus (hcv) is a trypsin-like protease and is essential for processing of viral polyprotein. accordingly, it is a potential target for anti-hcv drugs. recently we could isolate rna aptamers (g9-i, ii, and iii) which bind and inhibit ns3 protease using in vitro selection strategy. in addition, g9-i aptamer showed noncompetitive inhibition. in order to elucidate the binding site of g9-i aptamer in ns3 protease domain (deltans3), we carried out alanine s ...200011118325
recent advances in prevention and treatment of hepatitis c virus infections.hepatitis c virus (hcv) is the leading cause of chronic hepatitis in humans. as members of the flavivirus family, hcvs are a group of small single-stranded, positive-sense rna viruses. upon translation of the genome, a polyprotein precursor is synthesized and further processed by both cellular and viral proteases to generate functional viral proteins. treatment options are currently limited to the administration of alpha-interferon alone or in combination with ribavirin. unfortunately, these app ...200011127961
the yellow fever 17d vaccine virus as a vector for the expression of foreign proteins: development of new live flavivirus vaccines.the flaviviridae is a family of about 70 mostly arthropod-borne viruses many of which are major public health problems with members being present in most continents. among the most important are yellow fever (yf), dengue with its four serotypes and japanese encephalitis virus. a live attenuated virus is used as a cost effective, safe and efficacious vaccine against yf but no other live flavivirus vaccines have been licensed. the rise of recombinant dna technology and its application to study fla ...200011142718
a novel model for the study of the therapy of flavivirus infections using the modoc virus.the murine flavivirus modoc replicates well in vero cells and appears to be as equally sensitive as both yellow fever and dengue fever virus to a selection of antiviral agents. infection of scid mice, by either the intracerebral, intraperitoneal, or intranasal route, results in 100% mortality. immunocompetent mice and hamsters proved to be susceptible to the virus only when inoculated via the intranasal or intracerebral route. animals ultimately die of (histologically proven) encephalitis with f ...200111145886
stable expression of noncytopathic kunjin replicons simulates both ultrastructural and biochemical characteristics observed during replication of kunjin virus.this report focuses mainly on the characterization of a vero cell line stably expressing the flavivirus kunjin (kun) replicon c20sdrep (c20sdrepvero). we showed by immunofluorescence and cryoimmunoelectron microscopy that unique flavivirus-induced membrane structures, termed convoluted membranes/paracrystalline structures, were induced in the c20sdrepvero cells. these induced cytoplasmic foci were immunolabeled with kun virus anti-ns3 antibodies and with antibodies to the cellular markers ergic5 ...200111145899
[west nile virus (wnv) encephalitis].a disease on the come back: west nile encephalitis has been known since the thirties. it generally occurs in africa and western asia, rarely in europe. the disease has disappeared from france since 1960, but has reappeared in the united states and in israel. a severe viral infection: west nile encephalitis is caused by a flavivirus. after 2 to 15 days incubation, the patient experiences fever, headache, diffuse pain, and sometimes skin rash. disorientation, stiff neck, convulsions and paralysis ...200011155732
solution structure and dynamics of the single-chain hepatitis c virus ns3 protease ns4a cofactor complex.the backbone assignments, secondary structure, topology, and dynamics of the single-chain hepatitis c virus ns3 protease ns4a cofactor complex have been determined by nmr spectroscopy. residues i34 to s181 of ns3 and the central three residues of the ns4a cofactor were assigned and the secondary structure was verified for these residues. in several x-ray structures of ns4a-bound ns3 protease, residues 1 to 28 are stabilized by crystal packing, which allows for the formation of the a0 strand and ...200111162117
diagnostic immunoassays for tick-borne encephalitis virus based on recombinant baculovirus protein expression.the baculovirus expression system that utilizes autographa californica nuclear polyhedrosis virus was used to express the highly antigenic envelope protein e of a tick-borne encephalitis (tbe) complex virus, as well as a c-terminally truncated form of protein e (etr). the recombinant proteins were produced with a histidine-tag at their carboxy-terminus. protein purification by nickel agarose chromatography resulted in high concentrations of pure etr protein, but only poor yields of e protein. th ...200111164488
expression and purification of enzymatically active recombinant rna-dependent rna polymerase (ns5) of the flavivirus kunjin.the ns5 protein of the flavivirus kunjin (kun) contains conserved sequence motifs characteristic of rna-dependent rna polymerase (rdrp) activity. to investigate this activity in vitro, recombinant ns5 proteins with c-terminal (ns5chis) and n-terminal (ns5nhis) hexahistidine tags were produced in baculovirus-infected insect cells and purified to near homogeneity by nickel affinity chromatography. purified ns5chis exhibited rdrp activity with both specific (9 kb kun replicon) and non-specific (8.3 ...200111164916
development of dengue igm-capture enzyme-linked immunosorbent assay with higher sensitivity using monoclonal detection igm-capture enzyme-linked immunosorbent assay (igm-elisa) is used widely for serodiagnosis of dengue. a dengue igm-elisa with higher sensitivity has been developed. in the new elisa, anti-dengue igm antibody, which had been captured on the solid phase, was reacted with tetravalent dengue viral antigens, and detected by a flavivirus group specific monoclonal antibody, d1-4g2-4-15 (4g2). reaction of 4g2 to viral antigens was similar to that of dengue patients' igg. non-specific reaction of 4g2 ...200111164919
comparison of six different commercial igg-elisa kits for the detection of tbev-antibodies.tick-borne encephalitis virus (tbev) is a pathogenic human flavivirus endemic in some parts of europe and asia. commercial enzyme immunoassays (eia) for the detection of igg antibodies are often used in tbev-seroprevalence studies, as well as for the confirmation of a successful vaccination against tbev. however, the detection of tbev-specific antibodies can be biased by the cross-reactivity between different flavivirus genera.200111166668
antibody to the nonstructural protein ns1 of japanese encephalitis virus: potential application of mab-based indirect elisa to differentiate infection from indirect enzyme-linked immunosorbent assay (elisa) was developed to detect and differentiate the antibody responses to japanese encephalitis (je) virus nonstructural protein ns1 between infected and vaccinated individuals. the results showed that all convalescent sera from je patients contained ns1-specific igg antibodies, while 65 and 40% of these sera showed detectable ns1-specific igm and iga antibodies, respectively. specificity analysis showed that ns1-specific igm and iga antibodies fro ...200111166901
innate resistance to flavivirus infection in mice controlled by flv is nitric oxide-independent.innate resistance to flaviviruses in mice is active in the brain where it restricts virus replication. this resistance is controlled by a single genetic locus, flv, located on mouse chromosome 5 near the locus encoding the neuronal form of nitric oxide synthase (nos1). since nitric oxide (no) has been implicated in antiviral activity, its involvement in natural resistance to flaviviruses has been hypothesized. here we present data on no production before and during flavivirus infection in both b ...200111172102
west nile viral encephalitis.west nile virus (wnv) has emerged in recent years in temperate regions of europe and north america, presenting a threat to both public and animal health. the most serious manifestation of infection is fatal encephalitis in humans and horses, as well as mortality in certain domestic and wild birds. a recent development in the epizootiology of this mosquito-borne flavivirus was the occurrence of a severe outbreak in new york city and surrounding areas. during this outbreak, mortality was observed ...200011189714
west nile virus investigations in south moravia, virus isolates were obtained from 11,334 mosquitoes after the 1997 morava river flooding in south moravia (czech republic): 6 strains of tahyna bunyavirus, california antigenic group (5 from aedes vexans, 1 from ae. cinereus), and 1 strain of west nile flavivirus (wnv) from culex pipiens. in 1999, one isolate of tahyna virus from ae. vexans and one isolate of wnv from cx. pipiens were recovered from a total of 14,354 mosquitoes examined in the same area, whereas no virus was detected there ...200011192289
west nile encephalitis.wnv encephalitis in horses, previously reported in africa, asia, and europe, occurred for the first time in the western hemisphere in 1999. the causative agent, wnv, is a flavivirus maintained in nature by a bird-mosquito cycle. the disease in horses is manifested primarily by ataxia of variable severity. outbreaks of encephalitis may have a case fatality rate in excess of 40%, although this virus infection is inapparent in some horses. early evidence indicates that wnv has overwintered in the n ...200011219341
japanese encephalitis.japanese encephalitis (je) virus is a mosquito-borne flavivirus that can cause encephalitis and death in horses and humans. it is an emerging disease of international concern because it has been spreading into previously nonendemic areas. major epidemics may occur where the virus moves into new areas, but many infections are subclinical. this article presents information on the virus, its epidemiology, and what little information has been published on the disease in horses. the methods available ...200011219350
genetic variation of japanese encephalitis virus in taiwan.a 280-nucleotide sequence from the capsid-premembrane (c/prem) gene region of 44 japanese encephalitis (je) virus strains isolated in taiwan from mosquitoes from 1983 to 1994, and 3 strains, (ling [1965], chang [1965], and hv1 [1958]) isolated from human brain were analyzed by direct sequencing of reverse transcription-polymerase chain reaction (rt-pcr) amplified products and compared with the corresponding sequences of reference strains. the overall sequence homology of the 47 isolates was > or ...200011220759
identification of b-cell epitope of dengue virus type 1 and its application in diagnosis of patients.using a serotype-specific monoclonal antibody (mab) of dengue virus type 1 (den-1), 15f3-1, we identified the b-cell epitope of den-1 from a random peptide library displayed on phage. fourteen immunopositive phage clones that bound specifically to mab 15f3-1 were selected. these phage-borne peptides had a consensus motif of hxyawb (a = s/t, b = k/h/r) that mimicked the sequence hkyswk, which corresponded to amino acid residues 111 to 116 of the nonstructural protein 1 (ns1) of den-1. among the f ...200111230414
[analysis of genetic variability of strains of tick-borne encephalitis virus by primary structure of a fragment of the membrane protein e gene].primary structures of gene fragments of e protein (160 n.b.) have been determined for 29 tick-borne encephalitis (tbe) strains isolated from different parts of a territory. analysis of homology of nucleotide sequences of these strains and data on 6 tbe strains published by other authors showed that they can be divided into 6 groups (genotypes) by the following gene typing criteria: strain structure within the genotypes differing by no more than 9%, differences between strains of different genoty ...200111233280
[genetic typing of tick-borne encephalitis virus based on an analysis of the levels of homology of a membrane protein gene fragment].all heretofore known genomic structures of tick-borne encephalitis (tbe) virus are analyzed. the authors prove the adequacy of using short fragment of e protein gene for characterization of philogenetic relationships between tbe strains. three main genotypes of the virus are distinguished, one corresponding to far eastern variant, one to west, and the third includes strains belonging to ural siberian and central siberian and transbaikal variants. results of genetic typing by nucleotide sequences ...200111233281
[protective activity of a bacterial plasmid, bearing the gene for the tick-borne encephalitis virus ns1 nonstructural protein].three intramuscular injections (50 micrograms each) with bacterial plasmid pmv45 carrying nonstructural gene of ns1 protein of tick-borne encephalitis (tbe) virus protected 88% balb/c mice from lethal challenge with the virus. antibodies to ns1 nonstructural protein were detected in the sera of vaccinated mice after the challenge. absence of antibodies to e structural protein indicated absence of manifest infectious process in mice vaccinated with plasmid and challenged with a lethal dose of tbe ...200111233282
antiviral cytotoxic t cells cross-reactively recognize disparate peptide determinants from related viruses but ignore more similar self- and foreign determinants.we have investigated the reactivities of cytotoxic t (tc) cells against the two immunodominant, h-2k(k)-restricted determinants from the flavivirus: murray valley encephalitis virus (mve), mve(1785) (rehsgnei) and mve(1971) (degegrvi). the respective tc cell populations cross-reactively lysed target cells pulsed with determinants from the mve(1785)- and mve(1971)-corresponding positions of six other flaviviruses, despite low sequence homology in some cases. notably, anti-mve(1785) tc cells recog ...200111238625
purification and characterization of west nile virus nucleoside triphosphatase (ntpase)/helicase: evidence for dissociation of the ntpase and helicase activities of the enzyme.the nucleoside triphosphatase (ntpase)/helicase associated with nonstructural protein 3 of west nile (wn) virus was purified from cell culture medium harvested from virus-infected vero cells. the purification procedure included sequential chromatography on superdex-200 and reactive red 120 columns, followed by a concentration step on an ultrogel hydroxyapatite column. the nature of the purified protein was confirmed by immunoblot analysis using a wn virus-positive antiserum, determination of its ...200111238848
a personal account of the role of peptide research in drug discovery: the case of hepatitis c.although peptides themselves are not usually the end products of a drug discovery effort, peptide research often plays a key role in many aspects of this process. this will be illustrated by reviewing the experience of peptide research carried out at irbm in the course of our study of hepatitis c virus (hcv). the target of our work is the ns3/4a protease, which is essential for maturation of the viral polyprotein. after a thorough examination of its substrate specificity we fine-tuned several su ...200111245202
replicon-based vectors of positive strand rna viruses.vectors based on self-replicating rnas (replicons) of positive strand rna viruses are becoming powerful tools for gene expression in mammalian cells and for the development of novel antiviral and anticancer vaccines. a relatively small genome size and simple procedure allow rapid generation of recombinants. cytoplasmic rna amplification eliminates nuclear involvement and leads to extremely high levels of gene expression, and continuous synthesis of double stranded rna results in induction of enh ...200011249758
production of active mammalian and viral proteases in bacterial expression systems. 200011255667
a small region of the dengue virus-encoded rna-dependent rna polymerase, ns5, confers interaction with both the nuclear transport receptor importin-beta and the viral helicase, ns3.the dengue virus rna-dependent rna polymerase, ns5, and the protease/helicase, ns3, are multidomain proteins that have been shown to interact both in vivo and in vitro. a hyperphosphorylated form of ns5 that does not interact with ns3 has been detected in the nuclei of virus-infected cells, presumably as the result of the action of a functional nuclear localization sequence within the interdomain region of ns5 (residues 369-405). in this study, it is shown by using the yeast two-hybrid system th ...200111257177
langat virus m protein is structurally homologous to prm.langat (lgt) virus m protein has been generated in a recombinant system. antiserum raised against the lgt virus m protein neutralizes tick-borne encephalitis serocomplex flaviviruses but not mosquito-borne flaviviruses, indicating that the m protein is exposed on the surface of virions. the antiserum recognizes intracellular lgt virus prm/m and binds to prm and m in western blots of whole-cell lysates and purified virus, respectively. these data suggest that the prm and m proteins are structural ...200111264391
biophysical characterization and vector-specific antagonist activity of domain iii of the tick-borne flavivirus envelope protein.the molecular determinants responsible for flavivirus host cell binding and tissue tropism are largely unknown, although domain iii of the envelope protein has been implicated in these functions. we examined the solution properties and antagonist activity of langat virus domain iii. our results suggest that domain iii adopts a stably folded structure that can mediate binding of tick-borne flaviviruses but not mosquito-borne flaviviruses to their target cells. three clusters of phylogenetically c ...200111264392
effect of naturally occurring active site mutations on hepatitis c virus ns3 protease specificity.a comparison of the dna sequences from all available genotypes of hcv indicate that the active site residues of the ns3 protease are strictly conserved with the exception of positions 123 and 168, which border the s(4) subsite. in genotype 3, the canonic arginine and aspartic acid have been replaced with threonine and glutamine, respectively. to determine if these differences contribute to an altered specificity, we characterized single-chain ns3 proteases from strains 1a, 1b, and 3a with peptid ...200111276078
a new strategy in design of +rna virus infectious clones enabling their stable propagation in e. coli.infectious clone methodology is a valuable tool of modern experimental virology. however, its use is often constrained by the instability of infectious clone constructs during propagation in e. coli. to circumvent this problem, we have devised a strategy that could be suitable for design of +rna virus molecular clones in general. an infectious clone is assembled as "infectious dna," and expression of problem regions present in the viral cdna is prevented during propagation in e. coli by insertio ...200111277699
an infectious clone of the west nile flavivirus.west nile (wn) virus is the most widespread among flaviviruses, but until recently it was not known on the american continent. we describe here design of a subgenomic replicon, as well as a full-length infectious clone of the lineage ii wn strain, which appeared surprisingly stable compared to other flavivirus infectious clones. this infectious clone was used to investigate effects of 5'- and 3'-nonrelated sequences on virus replication and infectivity of synthetic rna. while a long nonrelated s ...200111277701
prevalence of tick-borne encephalitis virus in ixodes ricinus ticks in finland.approximately 20 cases of tick-borne encephalitis (tbe) occur annually in finland. the known endemic areas are situated mainly in the archipelago and coastal regions of finland, with highest incidence in aland islands. ixodes ricinus panels collected in 1996-1997 from two endemic areas were screened for the presence of rna. two distinct rt-pcr methods were applied, and were shown to have an approximate detection limit of 10 focus forming doses (ffd)/100 microl. one out of 20 pools (a total of 13 ...200111285564
west nile virus recombinant dna vaccine protects mouse and horse from virus challenge and expresses in vitro a noninfectious recombinant antigen that can be used in enzyme-linked immunosorbent assays.introduction of west nile (wn) virus into the united states in 1999 created major human and animal health concerns. currently, no human or veterinary vaccine is available to prevent wn viral infection, and mosquito control is the only practical strategy to combat the spread of disease. starting with a previously designed eukaryotic expression vector, we constructed a recombinant plasmid (pcbwn) that expressed the wn virus prm and e proteins. a single intramuscular injection of pcbwn dna induced ...200111287553
mutational evidence for an internal fusion peptide in flavivirus envelope protein e.the envelope protein e of the flavivirus tick-borne encephalitis (tbe) virus promotes cell entry by inducing fusion of the viral membrane with an intracellular membrane after uptake by endocytosis. this protein differs from other well-studied viral and cellular fusion proteins because of its distinct molecular architecture and apparent lack of involvement of coiled coils in the low-ph-induced structural transitions that lead to fusion. a highly conserved loop (the cd loop), which resides at the ...200111287576
isolation of japanese encephalitis virus from mosquitoes (diptera: culicidae) collected in the western province of papua new guinea, 1997-1998.after japanese encephalitis (je) virus emerged in the torres strait in australia in 1995, investigations were initiated into the origin of the incursion. new guinea was considered the most likely source, given its proximity to islands of the torres strait. almost 400,000 adult mosquitoes were processed for virus isolation from 26 locations in the western province of papua new guinea (png) between february 1996 and february 1998, yielding three isolates of je virus. two isolates of murray valley ...200011289676
infectious cdna clone of attenuated langat tick-borne flavivirus (strain e5) and a 3' deletion mutant constructed from it exhibit decreased neuroinvasiveness in immunodeficient mice.forty-five years ago a naturally attenuated tick-borne flavivirus, langat (lgt) strain tp21, was recovered from ticks in malaysia. subsequently, it was tested as a live attenuated vaccine for virulent tick-borne encephalitis viruses. in a large clinical trial its attenuation was confirmed but there was evidence of a low level of residual virulence. thirty-five years ago further attenuation of lgt tp21 was achieved by multiple passages in eggs to yield mutant e5. to study the genetic determinants ...200111289811
self-replicative rna vaccines elicit protection against influenza a virus, respiratory syncytial virus, and a tickborne encephalitis genetic vaccination, recipients are immunized with antigen-encoding nucleic acid, usually dna. this study addressed the possibility of using the recombinant alpha virus rna molecule, which replicates in the cytoplasm of transfected cells, as a novel approach for genetic vaccination. mice were immunized with recombinant semliki forest virus rna-encoding envelope proteins from one of 3 viruses: influenza a virus, a tickborne flavivirus (louping ill virus), or respiratory syncytial virus (rsv). ...200111294672
virus evolution: how does an enveloped virus make a regular structure? 200111300997
the fusion glycoprotein shell of semliki forest virus: an icosahedral assembly primed for fusogenic activation at endosomal ph.semliki forest virus (sfv) has been extensively studied as a model for analyzing entry of enveloped viruses into target cells. here we describe the trace of the polypeptide chain of the sfv fusion glycoprotein, e1, derived from an electron density map at 3.5 a resolution and describe its interactions at the surface of the virus. e1 is unexpectedly similar to the flavivirus envelope protein, with three structural domains disposed in the same primary sequence arrangement. these results introduce a ...200111301009
phylogenetic analysis of brazilian flavivirus using nucleotide sequences of parts of ns5 gene and 3' non-coding regions.viruses of the genus flavivirus, which are arboviruses, of the flaviviridae family, are amongst the most important agents of infectious disease in brazil, causing human infections with a high morbility and mortality. in this work, the phylogeny of 14 virus amplicon sequences that were obtained by rt-pcr with universal primers for mosquito-borne flavivirus were studied. the amplicons included a region of the flavivirus genome of 129 nucleotides at the 3' terminus of the ns5 gene and the 145 initi ...200111311426
safety and immunogenicity of attenuated dengue virus vaccines (aventis pasteur) in human volunteers.a randomized, controlled, double-blinded study was conducted to determine safety and immunogenicity of five live attenuated dengue vaccines produced by aventis pasteur (avp). the study was completed with 40 flavivirus non-immune volunteers: five recipients of each monovalent (dengue-1, dengue-2, dengue-3, or dengue-4) vaccine, ten recipients of tetravalent (dengue-1, dengue-2, dengue-3, and dengue-4) vaccine, and ten recipients of vaccine vehicle alone. all vaccines were administered in a single ...200111312014
coupling between replication and packaging of flavivirus rna: evidence derived from the use of dna-based full-length cdna clones of kunjin order to study whether flavivirus rna packaging is dependent on rna replication, we generated two dna-based kunjin virus constructs, pkun1 and pkun1dgdd, allowing continuous production of replicating (wild-type) and nonreplicating (with a deletion of the ns5 gene rna-polymerase motif gdd) full-length kunjin virus rnas, respectively, via nuclear transcription by cellular rna polymerase ii. as expected, transfection of pkun1 plasmid dna into bhk cells resulted in the recovery of secreted infect ...200111312333
dengue virus specific t cell responses to live attenuated monovalent dengue-2 and tetravalent dengue vaccines.the proliferative t cell responses to dengue vaccines were studied using the parental strains of dengue vaccines as antigens in 26 dengue immune individuals who resided in bangkok which is the endemic area of dengue infection. the magnitude of the t cell responses in subjects with flavivirus cross-reactive neutralizing antibody was much higher and the cross-reactivity was broader than in those with dengue serotype-specific neutralizing antibodies, japanese encephalitis (je) specific antibodies o ...200011316044
experimental yellow fever virus infection in the golden hamster (mesocricetus auratus). i. virologic, biochemical, and immunologic studies.this report describes the clinical laboratory findings in golden hamsters experimentally infected with yellow fever (yf) virus. an accompanying paper describes the pathologic findings. following intraperitoneal inoculation of a virulent strain of yf virus, hamsters developed a high-titered viremia (up to 109/ml) lasting 5--6 days and abnormal liver function tests. yf hemagglutination-inhibiting antibodies appeared 4 or 5 days after infection, often while viremia was still present. the mortality ...200111319679
comparison of flavivirus universal primer pairs and development of a rapid, highly sensitive heminested reverse transcription-pcr assay for detection of flaviviruses targeted to a conserved region of the ns5 gene sequences.arthropod-transmitted flaviviruses are responsible for considerable morbidity and mortality, causing severe encephalitic, hemorrhagic, and febrile illnesses in humans. because there are no specific clinical symptoms for infection by a determined virus and because different arboviruses could be present in the same area, a genus diagnosis by pcr would be a useful first-line diagnostic method. the six published flavivirus genus primer pairs localized in the ns1, ns3, ns5, and 3' nc regions were eva ...200111326014
detection and isolation of a flavivirus-like agent from a leopard tortoise (geochelone paradalis) in the united kingdom. 200111338718
evolution of base composition and codon usage bias in the genus flavivirus.the extent to which base composition and codon usage vary among rna viruses, and the possible causes of this bias, is undetermined in most cases. a maximum-likelihood statistical method was used to test whether base composition and codon usage bias covary with arthropod association in the genus flavivirus, a major source of disease in humans and animals. flaviviruses are transmitted by mosquitoes, by ticks, or directly between vertebrate hosts. those viruses associated with ticks were found to h ...200111343134
the influence of downstream protein-coding sequence on internal ribosome entry on hepatitis c virus and other flavivirus rnas.some studies suggest that the hepatitis c virus (hcv) internal ribosome entry site (ires) requires downstream 5' viral polyprotein-coding sequence for efficient initiation of translation, but the role of this rna sequence in internal ribosome entry remains unresolved. we confirmed that the inclusion of viral sequence downstream of the aug initiator codon increased ires-dependent translation of a reporter rna encoding secretory alkaline phosphatase, but found that efficient translation of chloram ...200111345437
characterisation of inter- and intra-molecular interactions of the dengue virus rna dependent rna polymerase as potential drug targets.our research is directed towards enhancing the understanding of the molecular biology of dengue virus replication with the ultimate goal being to develop novel antiviral strategies based on preventing critical inter- or intra-molecular interactions required for the normal virus life cycle. the viral rna-dependent rna polymerase (ns5) and the viral helicase (ns3) interaction offers a possible target for inhibitors to bind and prevent replication. in this study the yeast-two hybrid system was used ...200111347963
adaptation of tick-borne encephalitis virus to bhk-21 cells results in the formation of multiple heparan sulfate binding sites in the envelope protein and attenuation in vivo.propagation of the flavivirus tick-borne encephalitis virus in bhk-21 cells selected for mutations within the large surface glycoprotein e that increased the net positive charge of the protein. in the course of 16 independent experiments, 12 different protein e mutation patterns were identified. these were located in all three of the structural domains and distributed over almost the entire upper and lateral surface of protein e. the mutations resulted in the formation of local patches of predom ...200111356970
modulation of transporter associated with antigen processing (tap)-mediated peptide import into the endoplasmic reticulum by flavivirus contrast to many other viruses that escape the cellular immune response by downregulating major histocompatibility complex (mhc) class i molecules, flavivirus infection can upregulate their cell surface expression. previously we have presented evidence that during flavivirus infection, peptide supply to the endoplasmic reticulum is increased (a. müllbacher and m. lobigs, immunity 3:207-214, 1995). here we show that during the early phase of infection with different flaviviruses, the transport ...200111356974
distribution of dengue and japanese encephalitis among children in rural and suburban thai the rainy season of 1989, igg and igm antibodies against dengue and japanese encephalitis viruses (measured by enzyme-linked immunoassay [elisa]) in serum from all primary-school children in two areas of central thailand were sampled in order to choose a study site for more detailed epidemiological and entomological analysis. students in three schools in the largely non-agricultural, suburban community of bang bua thong, nontaburi province were sampled in late june and july. of 1,477 children ...200011357991
enzootic transmission of deer tick virus in new england and wisconsin determine whether rodents that are intensely exposed to the deer tick-transmitted agents of lyme disease, human granulocytic ehrlichiosis, and human babesiosis are also exposed to deer tick virus (dtv), we assayed serum samples from white-footed mice (peromyscus leucopus) and meadow voles (microtus pennsylvanicus) in sites densely infested by deer ticks. to conduct serosurveys, we developed an enzyme-linked immunosorbent assay (elisa) and western blot assay by cloning, expressing, and purifyi ...200011357992
encephalitis and retarded growth of chicks caused by sitiawan virus, a new isolate belonging to the genus flavivirus.a new virus named sitiawan virus (sv) was isolated from sick broiler chicks in chicken embryos. the virus replicated well with cytopathogenic effect (cpe) in the chicken b-lymphocyte cell line lscc-bk3. the virus was an enveloped rna virus of approximately 41 nm in size with hemagglutinating activity (ha) to goose erythrocytes. it was cross-reactive with japanese encephalitis virus (jev), a member of flaviviruses by ha inhibition tests but not by cross-virus neutralization tests. the cdna fragme ...200011358004
distribution and characterization of tick-borne encephalitis viruses from siberia and far-eastern this study, tick-borne encephalitis (tbe) viruses from siberia and far-eastern asia were characterized in order to determine virus subtype distribution. tbe viruses were isolated from ticks (ixodes persulcatus) collected in the far-eastern (khabarovsk and vladivostok) and siberian (irkutsk) regions of russia in 1999. phylogenetic analysis showed that isolates formed distinct clusters of far-eastern and siberian subtypes. there was also a minor difference in antigenicity between the irkutsk is ...200111369875
[secondary serologic responses to dengue epidemic in 1998 in salta, argentina, where other flavivirus co-circulate].in 1998, a dengue outbreak (serotype 2) occurred in salta province in northern argentina, following the first detection of dengue in the same area in 1997. we classified the serologic response of cases from 1998 as primary or secondary, since the risk of severe disease is greater for secondary cases. we studied 154 cases by plaque reduction neutralization and hemagglutination inhibition tests. thirty-eight cases (25%) were classified as primary serologic responses and 84 cases (54%) as secondary ...200111374133
immunogenicity of two peptide determinants in the cytolytic t-cell response to flavivirus infection: inverse correlation between peptide affinity for mhc class i and t-cell precursor frequency.we used the cd8+ cytotoxic t (tc) cell immune response against the flavivirus, murray valley encephalitis virus (mve), restricted by the h-2kk major histocompatibility complex (mhc) class i molecule, to investigate immunodominance. split-clone limiting dilution analysis revealed almost exclusive recognition of two peptides, mve1785 and mve1971, derived from the viral ns3 protein. the precursor frequency of mve-reactive tc cells was determined by limiting dilution analysis for cytotoxic function ...200111398809
tick-borne encephalitis virus ns1 glycoprotein during acute and persistent infection of cells.tick-borne encephalitis virus (tbev) was propagated in porcine embryo kidney (ps) cells until 48 h whereas human kidney (rh) cells maintained the virus persistence during at least 2 months. one of possible reasons of flavivirus chronic infection might be abnormal ns1 gene expression. immunoblotting with monoclonal antibodies (mabs) revealed the similarity of the intracellular and secreted ns1 nonstructural glycoprotein size and linear antigenic determinants in both the infected cell lines. howev ...200111410315
essential role of cyclization sequences in flavivirus rna replication.a possible role in rna replication for interactions between conserved complementary (cyclization) sequences in the 5'- and 3'-terminal regions of flavivirus rna was previously suggested but never tested in vivo. using the m-fold program for rna secondary-structure predictions, we examined for the first time the base-pairing interactions between the covalently linked 5' genomic region (first ~160 nucleotides) and the 3' untranslated region (last ~115 nucleotides) for a range of mosquito-borne fla ...200111413342
mutagenesis of the dengue virus type 2 ns3 proteinase and the production of growth-restricted virus.the n-terminal one-third of the ns3 protein of dengue virus type 2 (den-2) complexes with co-factor ns2b to form an active serine proteinase which cleaves the viral polyprotein. to identify sites within ns3 that may interact with ns2b, seven regions within the ns3 proteinase outside the conserved flavivirus enzyme motifs were mutated by alanine replacement. five sites contained clusters of charged residues and were hydrophilic. two sites were hydrophobic and highly conserved among flaviviruses. ...200111413376
phylogeny of north american powassan determine whether powassan virus (pow) and deer tick virus (dtv) constitute distinct flaviviral populations transmitted by ixodid ticks in north america, we analysed diverse nucleotide sequences from 16 strains of these viruses. two distinct genetic lineages are evident, which may be defined by geographical and host associations. the nucleotide and amino acid sequences of lineage one (comprising new york and canadian pow isolates) are highly conserved across time and space, but those of linea ...200111413377
the degree of attenuation of tick-borne encephalitis virus depends on the cumulative effects of point infectious clone (pggvs) of the tick-borne encephalitis complex virus vasilchenko (vs) was constructed previously. virus recovered from pggvs produced slightly smaller plaques than the vs parental virus. sequence analysis demonstrated five nucleotide differences between the original vs virus and pggvs; four of these mutations resulted in amino acid substitutions, while the fifth mutation was located in the 3' untranslated region (3'utr). two mutations were located in conserved regions and thr ...200111413378
multiple genotypes of st. louis encephalitis virus (flaviviridae: flavivirus) circulate in harris county, louis encephalitis (sle) is endemic in harris county, texas. the disease is a public health concern in houston, the largest city in harris county, and in the state. consequently, intensive surveillance for sle virus in local mosquito populations is carried out by the harris county mosquito control division each year. in this study, we examined genetic variation among sle isolates obtained during routine virus surveillance over a 13-year time period (1986-1999). st. louis encephalitis virus i ...200111425155
[primary infection with west-nile virus].the recent outbreak of an epidemic of west-nile fever in new-york revealed this virus' responsibility in some cases of fatal encephalitis. however the clinical manifestations of the infection may be mild as in the case reported herein.200111427804
[tick-born encephalitis].introduction: tick-borne encephalitis (tbe), a disease contracted through tick bites, is caused by a flavivirus. its geographical distribution comes from the geographical distribution of the reservoir of infection--i.e., mainly the tiny mammals living in the forests and bushes. the endemic area spreads from the rhine to the urals, from scandinavia to italy and greece. current knowledge and key points: symptoms usually evolve in three phases: at first a nonspecific phase with fever and myalgia, t ...200111433563
phylogenetic and evolutionary relationships among yellow fever virus isolates in africa.previous studies with a limited number of strains have indicated that there are two genotypes of yellow fever (yf) virus in africa, one in west africa and the other in east and central africa. we have examined the prm/m and a portion of the e protein for a panel of 38 wild strains of yf virus from africa representing different countries and times of isolation. examination of the strains revealed a more complex genetic relationship than previously reported. overall, nucleotide substitutions varie ...200111435580
flaviviruses isolated from mosquitoes collected during the first recorded outbreak of japanese encephalitis virus on cape york peninsula, response to an outbreak of japanese encephalitis (je) virus on cape york peninsula, australia, in 1998, mosquitoes were collected using co2 and octenol-baited centers for disease control and prevention light traps. a total of 35,235 adult mosquitoes, comprising 31 species, were processed for virus isolation. no isolates of je virus were recovered from these mosquitoes. however, 18 isolates of kokobera virus, another flavivirus were obtained from culex annulirostris. twelve isolates were from ...200111442206
[synthesis, immunogenicity and antigenic characteristics of the glycoprotein e fragments from the tick-borne encephalitis virus].six peptide fragments of the envelope protein e of the tick-borne encephalitis virus involving the predicted t-helper epitopes were synthesized. their ability to induce antibodies without conjugation with any high-molecular-mass carrier was studied in mice of three lines. five of six synthesized peptides exhibited immunogenic properties, which differed in dependence on the haplotype of immunized mice. the peptide binding to the antiviral antibodies was studied, and two peptides were revealed tha ...200111443938
amino acid substitution(s) in the stem-anchor region of langat virus envelope protein attenuates mouse neurovirulence.the identification of variants that are unable to bind membrane receptor preparations (mrps) has previously been shown to select attenuated yellow fever and japanese encephalitis viruses. in this study, this methodology has been extended to the tick-borne serocomplex of flaviviruses. langat (lgt) virus strain tp21 was bound to mouse or human brain mrps and viruses that escaped binding were isolated and characterized. in addition, variant viruses escaping neutralization by the monoclonal antibody ...200111448158
phylogenetic relationships of flaviviruses correlate with their epidemiology, disease association and biogeography.phylogenetic analysis of the flavivirus genus, using either partial sequences of the non-structural 5 gene or the structural envelope gene, revealed an extensive series of clades defined by their epidemiology and disease associations. these phylogenies identified mosquito-borne, tick-borne and no-known-vector (nkv) virus clades, which could be further subdivided into clades defined by their principal vertebrate host. the mosquito-borne flaviviruses revealed two distinct epidemiological groups: ( ...200111457992
role of metastability and acidic ph in membrane fusion by tick-borne encephalitis virus.the envelope protein e of the flavivirus tick-borne encephalitis (tbe) virus is, like the alphavirus e1 protein, a class ii viral fusion protein that differs structurally and probably mechanistically from class i viral fusion proteins. the surface of the native tbe virion is covered by an icosahedrally symmetrical network of e homodimers, which mediate low-ph-induced fusion in endosomes. at the ph of fusion, the e homodimers are irreversibly converted to a homotrimeric form, which we have found ...200111462011
monoclonal antibodies that bind to domain iii of dengue virus e glycoprotein are the most efficient blockers of virus adsorption to vero cells.the specific mechanisms by which antibodies neutralize flavivirus infectivity are not completely understood. to study these mechanisms in more detail, we analyzed the ability of a well-defined set of anti-dengue (den) virus e-glycoprotein-specific monoclonal antibodies (mabs) to block virus adsorption to vero cells. in contrast to previous studies, the binding sites of these mabs were localized to one of three structural domains (i, ii, and iii) in the e glycoprotein. the results indicate that m ...200111462053
molecular organization of a recombinant subviral particle from tick-borne encephalitis virus.the tick-borne encephalitis (tbe) flavivirus contains two transmembrane proteins, e and m. coexpression of e and the m precursor (prm) leads to secretion of recombinant subviral particles (rsps). in the most common form of these rsps, analyzed at a 19 a resolution by cryo-electron microscopy (cryo-em), 60 copies of e pack as dimers in a t = 1 icosahedral surface lattice (outer diameter, 315 a). fitting the high-resolution structure of a soluble e fragment into the rsp density defines interaction ...200111463384
pathologic and immunohistochemical findings in naturally occuring west nile virus infection in horses.the pathologic and peroxidase immunohistochemical features of west nile flavivirus (wnv) infection were compared in four horses from the northeastern united states and six horses from central italy. in all 10 animals, there were mild to severe polioencephalomyelitis with small t lymphocyte and lesser macrophage perivascular infiltrate, multifocal glial nodules, neutrophils, and occasional neuronophagia. perivascular hemorrhages, also noted macroscopically in two animals, were observed in 50% of ...200111467475
salicylates inhibit flavivirus replication independently of blocking nuclear factor kappa b activation.flaviviruses comprise a positive-sense rna genome that replicates exclusively in the cytoplasm of infected cells. whether flaviviruses require an activated nuclear factor(s) to complete their life cycle and trigger apoptosis in infected cells remains elusive. flavivirus infections quickly activate nuclear factor kappa b (nf-kappab), and salicylates have been shown to inhibit nf-kappab activation. in this study, we investigated whether salicylates suppress flavivirus replication and virus-induced ...200111483726
tick-borne langat/mosquito-borne dengue flavivirus chimera, a candidate live attenuated vaccine for protection against disease caused by members of the tick-borne encephalitis virus complex: evaluation in rhesus monkeys and in mosquitoes.langat virus (lgt), strain tp21, a naturally avirulent tick-borne flavivirus, was used to construct a chimeric candidate virus vaccine which contained lgt genes for premembrane (prem) and envelope (e) glycoprotein and all other sequences derived from dengue type 4 virus (den4). the live virus vaccine was developed to provide resistance to the highly virulent, closely related tick-borne flaviviruses that share protective e epitopes among themselves and with lgt. toward that end the chimera, initi ...200111483771
assessment of substrate specificity of hepatitis g virus ns3 protease by a genetic method.the rna genome of hepatitis g virus (hgv) encodes a large polyprotein that is processed to mature proteins by viral-encoded proteases. the hgv ns3 protease is responsible for the cleavage of the hgv polyprotein at four different locations. no conserved sequence motif has been identified for the cleavage sites of the ns3 protease. to determine the substrate specificity of the ns3 protease, amino acid sequences cleaved by the ns3 protease were obtained from randomized sequence libraries by using a ...200111485324
infection with langat flavivirus or expression of the envelope protein induces apoptotic cell death.langat (lgt) flavivirus, derived from infectious full-length cdna clone 636, was investigated for its apoptotic activities in mouse neuroblastoma (neuro-2a) and simian kidney (vero and llc-mk(2)) cells. the hallmark of apoptosis, cleavage of cellular dna, was observed 48 h after infection of vero, llc-mk(2), and neuro-2a cells by electrophoresis analysis. apoptosis in infected cells was also confirmed by tunel assay. lgt-infected neuro-2a cells showed an increase in caspase-3-like protease (devd ...200111485400
rapid elimination of gb virus c (hepatitis g virus) in the mosquito aedes aegypti.the transmissibility of the gb virus c (hepatitis g virus; hgv), a member of the flaviviridae, by a typical flavivirus vector was investigated. female mosquitoes of the species aedes aegypti were fed with hgv-infected human blood and assayed 1, 24, 48, 72 and 96 h after the blood meal for viral rna, human glyceraldehyde-3-phosphate dehydrogenase mrna, human beta-actin dna and a. aegypti actin mrna by total nucleic acid extraction, reverse transcription and pcr. viral rna had already disappeared ...200111489416
the machinery for flavivirus fusion with host cell membranes.a combination of structural, biochemical and functional studies with the flavivirus tick-borne encephalitis virus has revealed the characteristics of a new class of viral fusion protein, class ii, that is unrelated to the class i viral fusion proteins for which influenza virus hemagglutinin is the prototype. new structural data have shown that the alphaviruses, another group of icosahedral enveloped viruses, also have class ii fusion proteins, suggesting a common origin.200111495810
[pathogenesis of hemorrhagic fever]. 200111496775
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