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gb virus b infection of the common marmoset (callithrix jacchus) and associated liver pathology.gb virus b (gbv-b) is a flavivirus that is related closely to hepatitis c virus (hcv) and induces an acute hepatitis when inoculated into several species of new world primates. common marmosets (callithrix jacchus) are a widely available, non-endangered primate species that is susceptible to gbv-b infection and develops a characteristic acute hepatitis. here, animals were found to be susceptible to serially passaged serum and gbv-b transcripts. hepatic pathology and peripheral viraemia could be ...200415302946
[tick borne zoonosis: selected clinical and diagnostic aspects].tick-borne zoonotic infections are among the most diffuse vector borne diseases: these large group of infections is caused by different microorganisms: babesia spp., borrelia spp., rickettsia spp., ehrlichia spp., francisella tularensis, coxiella burnetii) and tick-borne encephalitis virus. babesiosis is caused by the protozoa (sporozoa) babesia microti and it is quite rare in humans in europe. the ixodids ticks are the competent vectors. a few symptomatic cases have been reported, mainly in spl ...200415305697
introduction of mutations into the non-structural genes or 3' untranslated region of an attenuated dengue virus type 4 vaccine candidate further decreases replication in rhesus monkeys while retaining protective immunity.a dengue virus vaccine candidate, rden4delta30, has been previously reported to be safe and immunogenic in humans, but a subset of vaccinees developed asymptomatic rash, elevation of liver enzymes and/or mild neutropenia. in the current study, mutations that had previously been shown to reduce replication of den4 virus in suckling mice and/or in scid mice engrafted with human liver cells (scid-huh-7 mice) were introduced into rden4delta30 in an attempt to further attenuate this virus. three of t ...200415308370
hepatitis c virus e2 has three immunogenic domains containing conformational epitopes with distinct properties and biological functions.mechanisms of virion attachment, interaction with its receptor, and cell entry are poorly understood for hepatitis c virus (hcv) because of a lack of an efficient and reliable in vitro system for virus propagation. infectious hcv retroviral pseudotype particles (hcvpp) were recently shown to express native e1e2 glycoproteins, as defined in part by hcv human monoclonal antibodies (hmabs) to conformational epitopes on e2, and some of these antibodies block hcvpp infection (a. op de beeck, c. voiss ...200415308717
blocking of the alpha interferon-induced jak-stat signaling pathway by japanese encephalitis virus infection.the induction of alpha/beta interferon (ifn-alpha/beta) is a powerful host defense mechanism against viral infection, and many viruses have evolved strategies to overcome the antiviral effects of ifn. in this study, we found that ifn-alpha had only some degree of antiviral activity against japanese encephalitis virus (jev) infection, in contrast to another flavivirus, dengue virus serotype 2, which was highly sensitive to ifn-alpha in the cultured cell system. jev infection appeared to render ce ...200415308723
effect of interferon-alpha2b therapy on st. louis viral meningoencephalitis: clinical and laboratory results of a pilot study.the safety and potential efficacy of interferon (ifn)-alpha2b were determined for 15 patients during an outbreak of meningoencephalitis due to st. louis encephalitis (sle) virus. clinical and laboratory results were compared with those of 17 untreated patients who were admitted to the same hospital during this nonrandomized preliminary trial. quadriplegia, quadriparesis, or respiratory insufficiency persisted after the first week of hospitalization, for 11 of 17 untreated patients and for only 2 ...200415319857
rodent models for the study of therapy against flavivirus infections.flaviviruses cause a variety of diseases including (meningo)encephalitis and hemorrhagic fevers. there is no specific antiviral therapy available for the treatment of infections with flaviviruses and such therapy should be urgently developed. small animal models that are reminiscent of the disease in man will be instrumental to identify therapeutic strategies against flavivirus infections. here we review models in mice and hamsters that may be used to assess the efficacy of novel antiviral strat ...200415321702
enzymatic characterization and homology model of a catalytically active recombinant west nile virus ns3 protease.west nile virus (wnv) is a mosquito-borne flavivirus with a rapidly expanding global distribution. infection causes severe neurological disease and fatalities in both human and animal hosts. the west nile viral protease (ns2b-ns3) is essential for post-translational processing in host-infected cells of a viral polypeptide precursor into structural and functional viral proteins, and its inhibition could represent a potential treatment for viral infections. this article describes the design, expre ...200415322074
a plasmid encoding japanese encephalitis virus prm and e proteins elicits protective immunity in suckling mice.a plasmid encoding japanese encephalitis virus (jev) prm and e proteins was constructed, and its efficacy as a candidate vaccine against jev was evaluated in suckling mice. groups of 10 balb/c mice (5-7 days old) were immunized twice via muscular injection with this dna vaccine, an empty vector or pbs at an interval of 3 weeks, and were challenged with a lethal dose of jev 3 weeks after the second inoculation. both cellular and humoral immune responses were examined before the challenge. two ani ...200415322338
phylogenetic analysis of west nile virus, nuevo leon state, mexico.west nile virus rna was detected in brain tissue from a horse that died in june 2003 in nuevo leon state, mexico. nucleotide sequencing and phylogenetic analysis of the premembrane and envelope genes showed that the virus was most closely related to west nile virus isolates collected in texas in 2002.200415324558
yellow fever 17d virus: pseudo-revertant suppression of defective virus penetration and spread by mutations in domains ii and iii of the e protein.a yellow fever (yfv) 17d virus variant, which causes persistent infection of mouse neuroblastoma cells associated with defective cell penetration and small plaque size, yielded plaque-revertant viruses from cells transfected with viral transcripts encoding the adaptive mutation (gly360 in the e protein). reconstruction of a plaque-purified revertant which contained gly360 and additional substitutions (asn for lys303 and val for ala261) yielded a virus whose infectious center size, growth efficie ...200415327896
involvement of a bovine viral diarrhea virus ns5b locus in virion assembly.a novel mutant of bovine viral diarrhea virus (bvdv) was found with a virion assembly phenotype attributable to an insertion into the ns5b polymerase locus. this mutant, termed 5b-741, was engineered by reverse genetics to express ns5b with a c-terminal peptide tag of 22 amino acids. electroporation of bovine cells with genomic rna from this mutant showed levels rna synthesis which were regarded as sufficient for infectivity, yet infectious virions were not produced. pseudorevertants of mutant 5 ...200415331694
genetic relationships and evolution of genotypes of yellow fever virus and other members of the yellow fever virus group within the flavivirus genus based on the 3' noncoding region.genetic relationships among flaviviruses within the yellow fever (yf) virus genetic group were investigated by comparing nucleotide sequences of the 3' noncoding region (3'ncr). size heterogeneity was observed between members and even among strains of the same viral species. size variation between yf strains was due to duplications and/or deletions of repeated nucleotide sequence elements (ryf). west african genotypes had three copies of the ryf (ryf1, ryf2, and ryf3); the angola and the east an ...200415331698
[investigation of arboviruses in lancang river down-stream area in yunnan province].to investigate the epidemic state of arboviruses in the downstream area of lancang river in yunnan province.200315340542
conformational changes of the flavivirus e glycoprotein.dengue virus, a member of the flaviviridae family, has a surface composed of 180 copies each of the envelope (e) glycoprotein and the membrane (m) protein. the crystal structure of an n-terminal fragment of e has been determined and compared with a previously described structure. the primary difference between these structures is a 10 degrees rotation about a hinge relating the fusion domain dii to domains di and diii. these two rigid body components were used for independent fitting of e into t ...200415341726
susceptibility of mosquito and tick cell lines to infection with various flaviviruses.the genus flavivirus consists of more than 70 virus species and subtypes, the majority of which are transmitted by mosquitoes or ticks, although some have no known vector (nkv). the ability of these viruses to infect cultured cells derived from mosquito or tick species offers a useful insight into the suitability of such vectors to harbour and replicate particular viruses. we undertook a comparative study of the susceptibility of mammalian vero cells, a clonal mosquito cell line (c6/36) and rece ...200415347394
flavivirus isolations from mosquitoes collected from saibai island in the torres strait, australia, during an incursion of japanese encephalitis virus.adult mosquitoes (diptera: culicidae) were collected in january and february 2000 from saibai island in the torres strait of northern australia, and processed for arbovirus isolation during a period of japanese encephalitis (je) virus activity on nearby badu island. a total of 84 210 mosquitoes were processed for virus isolation, yielding six flavivirus isolates. viruses obtained were single isolates of je and kokobera (kok) and four of kunjin (kun). all virus isolates were from members of the c ...200415347396
[molecular analysis of hepatitis c virus in pathogenesis of chronic hepatitis c]. 200415359835
can we really learn from model pathogens?cytolytic t (tc) lymphocytes are the first order response of the adaptive immune system in the recovery from primary viral infections. these effector cells execute their function either by direct cytotoxicity through the fas or perforin pathway and/or by the release of cytokines that either directly or indirectly exert antiviral activity. mice respond to infection by closely related viruses with a vigorous tc response, which is characterized by extensive crossreactivity on target cells infected ...200415364054
use of recombinant e protein domain iii-based enzyme-linked immunosorbent assays for differentiation of tick-borne encephalitis serocomplex flaviviruses from mosquito-borne flaviviruses.the serological diagnosis of infection by flaviviruses is complicated by the presence of flavivirus cross-reactive antibodies that produce false-positive results for flavivirus infections, especially in regions where more than one virus is endemic. current diagnostic reagents for tick-borne flavivirus infection have been found to cross-react with yellow fever- or dengue virus-positive sera. this study utilized recombinant flavivirus e protein domain 3 (re-d3) as a diagnostic reagent to different ...200415364996
n- t-boc-amino acid esters of isomannide. potential inhibitors of serine proteases.hepatitis c, dengue and west nile virus are some of the most important flaviviruses, that share one important serine protease enzyme. serine proteases are the most studied class of proteolytic enzyme and, in these cases, a primary target for drug discovery. in this paper, we describe the synthesis and preliminary molecular modeling studies of a novel class of n- t-boc amino acid esters derived of isomannide as potential serine proteases inhibitors.200415365909
infectious entry of west nile virus occurs through a clathrin-mediated endocytic pathway.the pathway of west nile flavivirus early internalization events was mapped in detail in this study. overexpression of dominant-negative mutants of eps15 strongly inhibits west nile virus (wnv) internalization, and pharmacological drugs that blocks clathrin also caused a marked reduction in virus entry but not caveola-dependent endocytosis inhibitory agent, filipin. using immunocryoelectron microscopy, wnv particles were seen within clathrin-coated pits after 2 min postinfection. double-labeling ...200415367621
different chemokine expression in lethal and non-lethal murine west nile virus infection.west nile (wn) virus is a mosquito-borne flavivirus that can cause lethal encephalitis in humans and horses. the wn virus endemic in new york city (ny) in 1999 caused large-scale mortality of wild birds that was not evident in endemic areas in other parts of the world, and the pathogenesis of the wn virus strain isolated in ny (ny strain) appears to differ from that of previously isolated strains. however, the pathogenesis of ny strain infection remains unclear. this study examined cc (rantes/cc ...200415368509
cytopathological changes induced by selected brazilian flaviviruses in mouse macrophages.scanning and transmission electron microscopy were used to analyse the ultrastructure of peritoneal mouse macrophage cells infected with brazilian flavivirus (yellow fever, rocio, bussuquara and saint louis encephalitis viruses). macrophage cells collected 3 days after viral infection had a flattened shape, with an increased number of large spikes of cytoplasm prolongations, giving an appearance of hairy cells. cytopathological changes to the macrophage cells were similar regardless of the infec ...200415369478
in vivo monitoring of acute flavivirus (modoc) encephalitis with regional and whole-brain quantitative diffusion magnetic resonance imaging.in vivo imaging of structural changes in the brain of patients with encephalitis has become an important aid in diagnostic and therapeutic procedures. diffusion-weighted magnetic resonance imaging (dwi) was employed to quantitate regional and whole-brain diffusion-weighted mri changes in a hamster model for acute flavivirus encephalitis. the regional apparent diffusion coefficient (adc) was determined in hyperintense regions seen on t2-weighted images (i.e., the thalamic area and the temporal lo ...200415371156
experimental usutu virus infection of suckling mice causes neuronal and glial cell apoptosis and demyelination.usutu virus (usuv), a mosquito-borne flavivirus of the japanese encephalitis virus group has been responsible for avian mortality in austria since 2001. in the present study, the neuropathogenicity and neuroinvasiveness of usuv for 1-week-old suckling mice was investigated. after intraperitoneal inoculation, clinical signs like depression, disorientation, paraplegia, paralysis and coma were observed between 6 and 11 days post infection. histologically, there was widespread neuronal apoptosis esp ...200415372281
specific interaction between the classical swine fever virus ns5b protein and the viral genome.the ns5b protein of the classical swine fever virus (csfv) is the rna-dependent rna polymerase of the virus and is able to catalyze the viral genome replication. the 3' untranslated region is most likely involved in regulation of the pestivirus genome replication. however, little is known about the interaction between the csfv ns5b protein and the viral genome. we used different rna templates derived from the plus-strand viral genome, or the minus-strand viral genome and the csfv ns5b protein ob ...200415373834
transmission cycles, host range, evolution and emergence of arboviral disease.many pandemics have been attributed to the ability of some rna viruses to change their host range to include humans. here, we review the mechanisms of disease emergence that are related to the host-range specificity of selected mosquito-borne alphaviruses and flaviviruses. we discuss viruses of medical importance, including venezuelan equine and japanese encephalitis viruses, dengue viruses and west nile viruses.200415378043
dengue-specific cd8+ t cells have both protective and pathogenic roles in dengue virus infection.to analyze roles of memory t cells in the pathogenesis of dengue (den) virus infection, a den virus-specific cd8+ cell clone (2d42 cell) was employed to investigate its in vivo function after den virus infection using an animal model. hepg2 grafted severe combined immunodeficient (hepg2-grafted scid) mice were divided into three groups--group a: hepg2-grafted scid mice were inoculated intraperitoneally (ip) with 2d42 cells and then ip-infected with den virus type 2 (den-2); group b: hepg2-grafte ...200415388257
single point mutation in tick-borne encephalitis virus prm protein induces a reduction of virus particle secretion.flaviviruses are assembled to bud into the lumen of the endoplasmic reticulum (er) and are secreted through the vesicle transport pathway. virus envelope proteins play important roles in this process. in this study, the effect of mutations in the envelope proteins of tick-borne encephalitis (tbe) virus on secretion of virus-like particles (vlps), using a recombinant plasmid expression system was analysed. it was found that a single point mutation at position 63 in prm induces a reduction in secr ...200415448368
epidemic west nile virus encephalitis in tunisia.west nile fever (wnf) is a mosquito-borne flavivirus infection. it is epidemic in africa and asia. in autumn 1997, a wnf epidemic occurred in the sfax area (southeastern tunisia). fifty-seven patients were hospitalized with aseptic meningitis and/or encephalitis. search for specific anti-west nile virus (wnv) antibodies in serum and cerebrospinal fluid (csf) was performed using an elisa test. reverse transcriptase-polymerase chain reaction (rt-pcr) was used to detect the wnv genome in csf and br ...200515459502
complete genome analysis and molecular characterization of usutu virus that emerged in austria in 2001: comparison with the south african strain saar-1776 and other flaviviruses.here we describe the complete genome sequences of two strains of usutu virus (usuv), a mosquito-borne member of the genus flavivirus in the japanese encephalitis virus (jev) serogroup. usuv was detected in austria in 2001 causing a high mortality rate in blackbirds; the reference strain (saar-1776) was isolated in 1958 from mosquitoes in south africa and has never been associated with avian mortality. the austrian and south african isolates exhibited 97% nucleotide and 99% amino acid identity. p ...200415464850
performance of immunoglobulin g (igg) and igm enzyme-linked immunosorbent assays using a west nile virus recombinant antigen (prem/e) for detection of west nile virus- and other flavivirus-specific antibodies.focus technologies developed an indirect immunoglobulin g (igg) enzyme-linked immunosorbent assay (elisa) and a mu-capture igm elisa for the detection of west nile virus (wnv)-specific antibodies based on a wnv prem/e protein recombinant antigen. normal and disease state serum panels were used to assess the performance characteristics of the two wnv elisa kits. totals of 807 and 1,423 sera were used to assess the igg elisa and igm elisa kits, respectively. the focus technologies igg elisa had a ...200415472323
noninfectious recombinant antigen for detection of st. louis encephalitis virus-specific antibodies in serum by enzyme-linked immunosorbent assay.proper surveillance of virus activity and a timely response to viral outbreaks depend upon the rapid diagnosis of viral infections. the immunoglobulin m (igm) antibody-capture enzyme-linked immunosorbent assay (mac-elisa) is a fast, sensitive test routinely used for the diagnosis of the medically important west nile and st. louis encephalitis flaviviruses. however, the suckling mouse brain-derived (smb) antigen used in this assay is tedious to prepare and has a risk of exposing personnel to live ...200415472331
interaction of west nile virus with alpha v beta 3 integrin mediates virus entry into cells.the functional receptor for the flavivirus west nile (wnv) infection has been characterized in this study with a combination of biochemical and molecular approaches. a 105-kda protease-sensitive glycoprotein that binds wnv was isolated from the plasma membrane of cells permissive to wnv infection. the protein was subjected to peptide sequencing, and this glycoprotein was identified as a member of the integrin superfamily. infection of wnv was shown to be markedly inhibited in vero cells pretreat ...200415475343
the ns3 protein of hepatitis c virus induces caspase-8-mediated apoptosis independent of its protease or helicase activities.apoptosis has been implicated in the pathogenesis of hepatitis c virus (hcv)-related disease. here, we show that expression of hcv ns3, or the ns2/ns3 precursor protein, in mammalian cells results in induction of apoptosis and activation of caspases. hcv ns3-induced apoptosis was blocked by a caspase-8, but not a caspase-9-specific inhibitor. hcv ns3 coimmunoprecipitated with caspase-8, but not with other caspases or with fadd. coexpression of hcv ns3 and caspase-8 resulted in aggregation of the ...200415476874
enhancement of dengue virus translation: role of the 3' untranslated region and the terminal 3' stem-loop domain.an essential step for a productive infection by the dengue flavivirus (den) is translation of the m(7)g-capped, nonpolyadenylated positive-sense rna genome. we have recently identified sequences within the den 3' untranslated region (utr) that modulate viral translation. here, we show that the den type 2 (den2) 3'utr stimulated translation of m(7)g-capped den2 5'utr-containing reporter mrnas in baby hamster kidney (bhk) cells compared to a 3' vector sequence. analogous to the 3' poly(a) tail, th ...200415476880
proinflammatory cytokines and chemokines in humans with japanese encephalitis.japanese encephalitis virus (jev), the mosquito-borne flavivirus, annually causes an estimated 35,000-50,000 encephalitis cases and 10,000-15,000 deaths in asia, and there is no antiviral treatment. the role played by the immune response in determining the outcome of human infection with jev is poorly understood, although, in animal models of flavivirus encephalitis, unregulated proinflammatory cytokine responses can be detrimental.200415478067
characterization of tick-borne encephalitis virus from estonia.tick-borne encephalitis virus (tbev) is a severe problem in estonia. in the present article the first genetic analysis of estonian tbev strains is described. in total, seven tbev strains were isolated from ticks (ixodes ricinus and i. persulcaus), rodents (apodemus agrarius and cletrionomys glareolus), and serum from a tick-borne encephalitis (tbe) patient. the nucleic acid sequences of the viral genome encoding almost the complete e protein (nt 41-1250) and the 3'-ncr-termini of the estonian tb ...200415484275
site-directed mutagenesis and kinetic studies of the west nile virus ns3 protease identify key enzyme-substrate interactions.the flavivirus west nile virus (wnv) has spread rapidly throughout the world in recent years causing fever, meningitis, encephalitis, and fatalities. because the viral protease ns2b/ns3 is essential for replication, it is attracting attention as a potential therapeutic target, although there are currently no antiviral inhibitors for any flavivirus. this paper focuses on elucidating interactions between a hexapeptide substrate (ac-kpglkr-p-nitroanilide) and residues at s1 and s2 in the active sit ...200515494419
flavivirus encephalitis. 200415496637
analysis of adaptive mutations in kunjin virus replicon rna reveals a novel role for the flavivirus nonstructural protein ns2a in inhibition of beta interferon promoter-driven transcription.the establishment of persistent noncytopathic replication by replicon rnas of a number of positive-strand rna viruses usually leads to generation of adaptive mutations in nonstructural genes. some of these adaptive mutations (e.g., in hepatitis c virus) increase the ability of rna replication to resist the antiviral action of alpha/beta interferon (ifn-alpha/beta); others (e.g., in sindbis virus) may also lead to more efficient ifn production. using puromycin-selectable kunjin virus (kun) replic ...200415507609
chimerivax-west nile virus live-attenuated vaccine: preclinical evaluation of safety, immunogenicity, and efficacy.the availability of chimerivax vaccine technology for delivery of flavivirus protective antigens at the time west nile (wn) virus was first detected in north america in 1999 contributed to the rapid development of the vaccine candidate against wn virus described here. chimerivax-japanese encephalitis (je), the first live- attenuated vaccine developed with this technology has successfully undergone phase i and ii clinical trials. the chimerivax technology utilizes yellow fever virus (yf) 17d vacc ...200415507637
the transmembrane domains of the prm and e proteins of yellow fever virus are endoplasmic reticulum localization signals.the immature flavivirus particle contains two envelope proteins, prm and e, that are associated as a heterodimer. virion morphogenesis of the flaviviruses occurs in association with endoplasmic reticulum (er) membranes, suggesting that there should be accumulation of the virion components in this compartment. this also implies that er localization signals must be present in the flavivirus envelope proteins. in this work, we looked for potential subcellular localization signals in the yellow feve ...200415507646
the role of tumor necrosis factor in modulating responses of murine embryo fibroblasts by flavivirus, west nile.murine embryo fibroblasts (mef) transcribe tumor necrosis factor (tnf) mrna and secrete soluble tnf in response to infection by west nile virus (wnv) and tnf was demonstrated to be protective against wnv infection in vitro. tnf is not required for the wnv-induced upregulation of mhc-i expression on mef, as tnf deficiency did not affect the upregulation of major histocompatibility complex class i (mhc-i) by wnv. furthermore, nf-kappab was activated by wnv in tnf-deficient mef, demonstrating that ...200415518815
development and evaluation of an enzyme-linked immunosorbent assay for quantifying antibodies to japanese encephalitis virus nonstructural 1 protein to detect subclinical infections in vaccinated horses.antibodies to japanese encephalitis virus (jev) nonstructural 1 (ns1) protein constitute a marker of natural jev infection among populations vaccinated with inactivated je vaccine. in japan, with few recent human je cases, the natural infection rate is critical to evaluate the necessity of continuing je vaccination. a sensitive immunochemical staining method for detecting ns1 antibodies in individuals naturally and subclinically infected with jev was previously established. here, an enzyme-linke ...200415528700
structure and dynamics of a predicted ferredoxin-like selenoprotein in japanese encephalitis virus.homologues of the selenoprotein glutathione peroxidase (gpx) have been previously identified in poxviruses and in rna viruses including hiv-1 and hepatitis c virus (hcv). sequence analysis of the ns4 region of japanese encephalitis virus (jev) suggests it may encode a structurally related but functionally distinct selenoprotein gene, more closely related to the iron-binding protein ferredoxin than to gpx, with three highly conserved uga codons that align with essential cys residues of ferredoxin ...200415530818
experimental transmission of karshi and langat (tick-borne encephalitis virus complex) viruses by ornithodoros ticks (acari: argasidae).selected species of mosquitoes and ornithodoros ticks were evaluated for their potential to transmit karshi and langat (tick-borne encephalitis virus complex) viruses in the laboratory. although there was no evidence of replication of karshi virus in either of the two mosquito species tested [ochlerotatus taeniorhynchus (wiedemann) or culex pipiens (l.)], karshi virus replicated in and was transmitted by all three species of ornithodoros ticks tested (ornithodoros parkeri cooley, ornithodoros so ...200415535630
evaluation of a diagnostic algorithm using immunoglobulin m enzyme-linked immunosorbent assay to differentiate human west nile virus and st. louis encephalitis virus infections during the 2002 west nile virus epidemic in the united states.a diagnostic algorithm was developed to differentiate between human infections of west nile virus (wnv) and st. louis encephalitis virus (slev) using positive-to-negative (p/n) ratios derived from the immunoglobulin m capture enzyme-linked immunosorbent assay (mac-elisa). to validate this algorithm, we tested 1,418 serum and cerebrospinal fluid (csf) samples from confirmed wnv and slev infections collected during the wnv epidemic of 2002 in the united states. wnv p/n-to-slev p/n ratios (w/s rati ...200415539517
chimpanzee fab fragments and a derived humanized immunoglobulin g1 antibody that efficiently cross-neutralize dengue type 1 and type 2 viruses.passive immunization with monoclonal antibodies from humans or nonhuman primates represents an attractive alternative to vaccines for prevention of illness caused by dengue viruses (denv) and other flaviviruses, including the west nile virus. in a previous study, repertoire cloning to recover fab fragments from bone marrow mrna of chimpanzees infected with all four denv serotypes (dengue virus serotype 1 [denv-1] to denv-4) was described. in that study, a humanized immunoglobulin g1 (igg1) antib ...200415542643
epitope determinants of a chimpanzee fab antibody that efficiently cross-neutralizes dengue type 1 and type 2 viruses map to inside and in close proximity to fusion loop of the dengue type 2 virus envelope glycoprotein.the epitope determinants of chimpanzee fab antibody 1a5, which have been shown to be broadly reactive to flaviviruses and efficient for cross-neutralization of dengue virus type 1 and type 2 (denv-1 and denv-2), were studied by analysis of denv-2 antigenic variants. sequence analysis showed that one antigenic variant contained a gly-to-val substitution at position 106 within the flavivirus-conserved fusion peptide loop of the envelope protein (e), and another variant contained a his-to-gln subst ...200415542644
histidine 39 in the dengue virus type 2 m protein has an important role in virus assembly.the mature flavivirus particle comprises a nucleocapsid core surrounded by a lipid bilayer containing the membrane (m) (derived from the precursor prm) and envelope (e) proteins. the formation of intracellular prm/e heterodimers occurs rapidly after translation and is believed to be important for the assembly and secretion of immature virus particles. in this study, the role of the his residue at position 39 in the m protein (m39) of dengue virus type 2 (denv-2) in the virus life cycle was inves ...200415557235
viral envelope protein glycosylation is a molecular determinant of the neuroinvasiveness of the new york strain of west nile virus.two new york (ny) strains of the west nile (wn) virus were plaque-purified and four variants that had different amino acid sequences at the n-linked glycosylation site in the envelope (e) protein sequence were isolated. the e protein was glycosylated in only two of these strain variants. to determine the relationship between e protein glycosylation and pathogenicity of the wn virus, 6-week-old mice were infected subcutaneously with these variants. mice infected with viruses that carried the glyc ...200415557236
toll-like receptor 3 mediates west nile virus entry into the brain causing lethal encephalitis.west nile virus (wnv), a mosquito-borne single-stranded (ss)rna flavivirus, causes human disease of variable severity. we investigated the involvement of toll-like receptor (tlr) 3, which recognizes viral double-stranded (ds)rna, on wnv infection. tlr3-deficient (tlr3(-/-)) mice were more resistant to lethal wnv infection and had impaired cytokine production and enhanced viral load in the periphery, whereas in the brain, viral load, inflammatory responses and neuropathology were reduced compared ...200415558055
rapid detection of west nile virus in birds using the vectest wnv antigen assay.to determine if the vectest west nile virus antigen assay (for testing mosquitoes) could be adapted to detect west nile virus (wnv) rapidly and accurately in birds for screening purposes.200415559727
a conserved histidine in the ij loop of the semliki forest virus e1 protein plays an important role in membrane fusion.the enveloped alphavirus semliki forest virus (sfv) infects cells via a low ph-triggered membrane fusion reaction mediated by the e1 protein. e1 is a class ii fusion protein that contains the hydrophobic fusion peptide loop and converts to a stable homotrimer during the fusion reaction. intriguingly, the fusion loop is closely associated with a loop connecting the i and j beta-strands. this ij loop plays a role in the cholesterol dependence of membrane fusion and is specifically susceptible to p ...200415564465
identification of residues in the dengue virus type 2 ns2b cofactor that are critical for ns3 protease activation.proteolytic processing of the dengue virus polyprotein is mediated by host cell proteases and the virus-encoded ns2b-ns3 two-component protease. the ns3 protease represents an attractive target for the development of antiviral inhibitors. the three-dimensional structure of the ns3 protease domain has been determined, but the structural determinants necessary for activation of the enzyme by the ns2b cofactor have been characterized only to a limited extent. to test a possible functional role of t ...200415564480
localization and characterization of flavivirus envelope glycoprotein cross-reactive epitopes.the flavivirus e glycoprotein, the primary antigen that induces protective immunity, is essential for membrane fusion and mediates binding to cellular receptors. human flavivirus infections stimulate virus species-specific as well as flavivirus cross-reactive immune responses. flavivirus cross-reactive antibodies in human sera create a serious problem for serodiagnosis, especially for secondary flavivirus infections, due to the difficulty of differentiating primary from secondary cross-reactive ...200415564505
identification of tick-borne encephalitis virus ribonucleic acid in tick suspensions and in clinical specimens by a reverse transcription-nested polymerase chain reaction assay.tick-borne encephalitis virus (tbev) is a major human pathogenic flavivirus. sensitive assays for the detection of viral rna may be valuable both for the identification of virus in ticks as well as for diagnostic purposes.199515566853
identification and enzymatic characterization of ns2b-ns3 protease of alkhurma virus, a class-4 flavivirus.alkhurma virus (alkv) is a recently discovered class-4 flavivirus that was responsible for several cases of severe haemorrhagic fever in humans in saudi arabia. it has been shown for other flaviviruses that processing of the viral polyprotein is partly due to the virus-encoded ns2b/ns3 trypsin-like serine protease. as the viral proteinase plays a critical role in the virus replication cycle, it represents one of the main targets for antiviral therapy against members of the flavivirus genus. we r ...200515567034
emerging flaviviruses: the spread and resurgence of japanese encephalitis, west nile and dengue viruses.mosquito-borne flaviviruses provide some of the most important examples of emerging and resurging diseases of global significance. here, we describe three of them: the resurgence of dengue in tropical and subtropical areas of the world, and the spread and establishment of japanese encephalitis and west nile viruses in new habitats and environments. these three examples also illustrate the complexity of the various factors that contribute to their emergence, resurgence and spread. whereas some of ...200415577938
identification and characterization of nonsubstrate based inhibitors of the essential dengue and west nile virus proteases.the 72 known members of the flavivirus genus include lethal human pathogens such as yellow fever, west nile, and dengue viruses. there is at present no known chemotherapy for any flavivirus and no effective vaccines for most. a common genomic organization and molecular mechanisms of replication in hosts are shared by flaviviruses with a viral serine protease playing a pivotal role in processing the viral polyprotein into component polypeptides, an obligatory step in viral replication. using the ...200515582469
an animal model for the tickborne flavivirus--omsk hemorrhagic fever virus.the tickborne encephalitis (tbe) serocomplex of flaviviruses consists primarily of viruses that cause neurologic disease; these viruses include omsk hemorrhagic fever virus (ohfv), a virus that is genetically related to other tbe serocomplex viruses but that circulates in an ecologically distinct niche and causes markedly different human disease. the objective of this study was to examine a potential small-animal model for ohfv and to compare the pathology of infection with that of the neurotrop ...200415593010
[comparative analysis of virulence of the siberian and far-east subtypes of the tick-born encephalitis virus].the siberian subtype of the tick-borne encephalitis virus (tev) is different from the far-east subtype by a moderate virulence observed in siberian hamsters and by a low infection development rate (100 strains were compared). no differences were found in neuro-invasiveness. clinical findings and experiments with monkeys denote the ability of the siberian subtype to provoke severe forms of tick-borne encephalitis (tbe). the inflammation-and-degenerative changes were localized in the brain cortex, ...200415597957
[immunity to flavivirus in amerindian population of the sierra de perijá, zulia state, venezuela].little information is available about flavivirus infection in amerindian populations in western venezuela. on this account the activity and seroprevalence of these viruses were determined and the hypothesis concerning the existence of a sylvatic cycle, conditioning the infection transmission of these viruses in indigenous populations, was studied. for this, blood samples from yukpas (n=144) and barí (n=110) communities were collected, 35 (yukpas=25 and barí=10) of which were processed for viral ...200415602900
identification of new flaviviruses in the kokobera virus complex.novel flavivirus isolates from mosquitoes collected in northern australia were analysed by partial genomic sequencing, monoclonal antibody-binding assays and polyclonal cross-neutralization tests. two isolates were found to be antigenically distinct from, but related to, viruses of the kokobera virus complex, which currently contains kokobera (kokv) and stratford (strv) viruses. nucleotide sequence comparison of two separate regions of the genome revealed that an isolate from saibai island in th ...200515604438
tick-borne virus diseases of human interest in europe.several human diseases in europe are caused by viruses transmitted by tick bite. these viruses belong to the genus flavivirus, and include tick-borne encephalitis virus, omsk haemorrhagic fever virus, louping ill virus, powassan virus, nairovirus (crimean-congo haemorrhagic fever virus) and coltivirus (eyach virus). all of these viruses cause more or less severe neurological diseases, and some are also responsible for haemorrhagic fever. the epidemiology, clinical picture and methods for diagnos ...200415606630
bovine viral diarrhoea virus is internalized by clathrin-dependent receptor-mediated endocytosis.bovine viral diarrhoea virus (bvdv) is a pestivirus within the family flaviviridae. in contrast to the members of the genus flavivirus, nothing is known about the viral entry route for pestiviruses. in this study, the process of bvdv infection following attachment to the cell surface was examined. bvdv clearly co-localizes with clathrin, with early endosome antigen-1 (eea-1), an early endosome marker, and also with lysosomal-associated membrane protein-2 (lamp-2), a lysosomal marker. bvdv intern ...200415606865
a structural perspective of the flavivirus life cycle.dengue, japanese encephalitis, west nile and yellow fever belong to the flavivirus genus, which is a member of the flaviviridae family. they are human pathogens that cause large epidemics and tens of thousands of deaths annually in many parts of the world. the structural organization of these viruses and their associated structural proteins has provided insight into the molecular transitions that occur during the viral life cycle, such as assembly, budding, maturation and fusion. this review foc ...200515608696
live measles vaccine expressing the secreted form of the west nile virus envelope glycoprotein protects against west nile virus encephalitis.the schwarz strain of measles virus (mv), a live attenuated rna virus, is one of the safest and most effective human vaccines available. immunization with mv vaccine expressing heterologous antigen is an attractive strategy to prevent emerging viral diseases. west nile virus (wnv), which recently emerged in north america, is an important mosquito-borne flavivirus that causes numerous cases of human encephalitis, thus urging the development of a vaccine. to evaluate the efficacy of recombinant mv ...200415609230
viral rna replication in association with cellular membranes.all plus-strand rna viruses replicate in association with cytoplasmic membranes of infected cells. the rna replication complex of many virus families is associated with the endoplasmic reticulum membranes, for example, picorna-, flavi-, arteri-, and bromoviruses. however, endosomes and lysosomes (togaviruses), peroxisomes and chloroplasts (tombusviruses), and mitochondria (nodaviruses) are also used as sites for rna replication. studies of individual nonstructural proteins, the virus-specific co ...200515609503
[west nile virus, an emerging arbovirus].the west nile virus (family flaviviridae, genus flavivirus), first isolated in 1937 in africa, is an arthropod-borne virus transmitted through culex mosquitoes bite. its natural cycle includes a vector (culex mosquitoes), a reservoir (birds of various species) and humans and large mammals are epidemiological dead-ends. progressive dissemination: this virus recently drew attention after several epidemics and epizooties were identified in france, russia, romania, and israel. however, the most stri ...200415614177
[detection of flaviviruses by reverse-transcription polymerase chain reaction with universal primer set].for the purpose of early and rapid diagnosis of flavivirus infection, the universal primer set was selected on the ns1 gene. another five different internal primers were selected on the ns1 genes of den1, 2, 3, 4 and jev. with the universal primer set designed, the ns1 fragment about the size of 413 bp and with the five internal primers, the ns1 fragments about the sizes of 262 bp (den1), 189 bp (den2), 392 bp (den3), 97 bp (den4) and 323 bp (jev) were amplified respectively. the reverse transcr ...199715617345
[the cloning and sequence analysis of cdna of the partial e genomic region of dengue type 4 virus from a chinese patient].the partial envelope (e) protein gene of dengue virus type 4 (dv4), derived from the serum of a patient with dengue fever in an epidemic during october 1993 in guangdong province of china, was cloned and sequenced. dv rna was converted to cdna by reverse transcription with random primers before the polymerase chain reaction using dv4 specific primers was performed. the amplified product of 421bp was subsequently filled in 3' recessed ends, isolated, purified and inserted into puc18 and puc19 pla ...199715619909
[tick borne flavivirus encephalitis]. 200415624474
infection of human dendritic cells by dengue virus activates and primes t cells towards th0-like phenotype producing both th1 and th2 cytokines.dengue viruses (dv) infection is an important public health issue all over the world. although the pathogenesis remains unclear, the overwhelmingly triggered immune responses have been consistently observed. recently, we and other researchers demonstrated that the natural hosts for dv are dendritic cells (dc), the primary sentinels of immune system. in light of the significance of t cells in dengue virus pathogenesis, here, we examine the possible consequences of dc-t cell interaction that is su ...200415624700
the majority of the nucleotides in the top loop of the genomic 3' terminal stem loop structure are cis-acting in a west nile virus infectious clone.the flavivirus genome rna terminates with a conserved 3' stem loop (sl) structure that was shown to be essential for virus replication. a stretch of conserved nts is located in the top loop (tl) of this structure. mutation of the tl nts (5' acagugc 3') in a wnv infectious clone indicated that 3 of the 7 tl nts (5' acagugc 3') are critical for virus replication. mutation of 3 of the other nts reduced the efficiency of virus replication. the four 5' tl nts are conserved in both mosquito- and tick- ...200515629768
construction and applications of yellow fever virus replicons.subgenomic replicons of yellow fever virus (yfv) were constructed to allow expression of heterologous reporter genes in a replication-dependent manner. expression of the antibiotic resistance gene neomycin phosphotransferase ii (neo) from one of these yfv replicons allowed selection of a stable population of cells (bhk-rep cells) in which the yfv replicon persistently replicated. bhk-rep cells were successfully used to trans-complement replication-defective yfv replicons harboring large internal ...200515629769
the flavivirus-conserved penta-nucleotide in the 3' stem-loop of the west nile virus genome requires a specific sequence and structure for rna synthesis, but not for viral translation.a reporting replicon of west nile virus (wn) was used to distinguish between the function of the 3' untranslated region (utr) in viral translation and rna replication. deletions of various regions of the 3' utr of the replicon did not significantly affect viral translation, but abolished rna replication. a systematic mutagenesis showed that the flavivirus-conserved penta-nucleotide (5'-cacag-3' located at the top of the 3' stem-loop of the genome) requires a specific sequence and structure for w ...200515629780
adaptation of west nile virus replicons to cells in culture and use of replicon-bearing cells to probe antiviral action.flaviviruses are emerging threats to public health worldwide. recently, one flavivirus, west nile virus (wnv), has caused the largest epidemic of viral encephalitis in us history. like other flaviviruses, wnv is thought to cause a persistent infection in insect cells, but an acute cytopathic infection of mammalian cells. to study adaptation of wnv to persistently replicate in cell culture and generate a system capable of detecting antiviral compounds in the absence of live virus, we generated su ...200515629788
differential induction of antiviral effects against west nile virus in primary mouse macrophages derived from flavivirus-susceptible and congenic resistant mice by alpha/beta interferon and poly(i-c).a cell model of primary macrophages isolated from the peritoneal cavity of flavivirus-susceptible and congenic resistant mice has been used to study the extent and kinetics of antiviral effects against west nile virus upon priming with alpha/beta interferon (ifn-alpha/beta) or poly(i-c) (pic). the pattern of flavivirus resistance expressed after priming of cells in this model was in good agreement with the pattern of flavivirus resistance described in the brains of the corresponding mouse strain ...200515650200
broadening the horizons for yellow fever: new uses for an old vaccine.the vaccine against yellow fever is one of the safest and most effective ever developed. with an outstanding record in humans, has this live attenuated vaccine been overlooked as a promising vector for the development of vaccines against pathogens outside its own genus? recent studies, including a report by tao et al. on page 201 of this issue, have sparked renewed interest.200515657285
inhibition of west nile virus entry by using a recombinant domain iii from the envelope glycoprotein.the envelope glycoprotein located at the outermost surface of the flavivirus particle mediates entry of virus into host cells. in this study, the involvement of domain iii of west nile virus (wnv-diii) envelope protein in binding to host cell surface was investigated. wnv-diii was first expressed as a recombinant protein and purified after a solubilization and refolding procedure. the refolded wnv-diii protein displays a content of beta-sheets consistent with known homologous structures of other ...200515659760
neuroblastoma cell-adapted yellow fever virus: mutagenesis of the e protein locus involved in persistent infection and its effects on virus penetration and spread.persistent infection of mouse neuroblastoma nb41a3 cells with yellow fever 17d virus generates viral variants which exhibit defective cell penetration, poor cell-to-cell spread, small plaque size and reduced growth efficiency, caused by substitution of glycine for aspartic acid or glutamic acid at positions 360 and 362 in the envelope protein. these positions occur within a charge cluster, asp360-asp361-glu362, located in domain iii, near its interface with domain i. to characterize further the ...200515659761
genetic characterization of yokose virus, a flavivirus isolated from the bat in japan.yokose virus (strain oita-36) was isolated from the bat in japan in 1971. in the present study, we determined complete nucleotide sequences of yokose virus using rt-pcr and race techniques. yokose virus genome consists of 10,857 nucleotides in length (accession no. ab114858), containing a single open reading frame (3425 amino acids) encoding 11 viral proteins. we deduced the boundaries of each protein in the polyprotein sequence according to the protein cleavage sites of other flaviviruses. the ...200515661139
molecular models of ns3 protease variants of the hepatitis c virus.hepatitis c virus (hcv) currently infects approximately three percent of the world population. in view of the lack of vaccines against hcv, there is an urgent need for an efficient treatment of the disease by an effective antiviral drug. rational drug design has not been the primary way for discovering major therapeutics. nevertheless, there are reports of success in the development of inhibitor using a structure-based approach. one of the possible targets for drug development against hcv is the ...200515663787
flavivirus immunization with capsid-deletion mutants: basics, benefits, and barriers.the flaviviruses comprise a number of arthropod-transmitted human disease agents that cause significant and increasing health threats in major parts of the world. the development of new vaccines is of vital importance, but the stringent need for safety, efficacy and cost-effectiveness together with the problems associated with the specific immune pathogenesis of some flavivirus infections impose significant challenges to innovative vaccine research. using tick-borne encephalitis virus (tbev) as ...200415671744
trends in dengue diagnosis.the conventional diagnosis of dengue virus infections includes the detection of the virus in serum or tissue samples, both by isolation in culture or through detection of specific viral molecules (genome rna or dengue antigens) and detection of specific anti-dengue antibodies (serology). isolation of dengue virus provides the most direct and conclusive approach to diagnosis, despite the demand for high-level equipment, technical skills and manpower. however, it is useless in early diagnosis beca ...200515672450
a novel mouse chr5 locus diht controls dopamine-induced hypothermia.mice of the strain c3h.pri-flv(r), carrying genetically determined resistance to flaviviruses, have been shown to be more sensitive to the hypothermic effect of dopamine than congenic flavivirus-susceptible c3h/hejarc mice. in the current study, the greater sensitivity to dopamine-induced hypothermia observed in flavivirus-resistant mice was shown to be dose-dependent, with strain differences being the most prominent at a moderate dose of apomorphine (1 mg/kg). in addition, hypothermic responses ...200415672594
the topology of bulges in the long stem of the flavivirus 3' stem-loop is a major determinant of rna replication competence.all flavivirus genomes contain a 3'terminal stem-loop secondary structure (3'sl) formed by the most downstream approximately 100 nucleotides (nt) of the viral rna. the 3'sl is required for virus replication and has been shown to bind both virus-coded and cellular proteins. results of the present study using an infectious dna for wn virus strain 956 initially demonstrated that the dengue virus serotype 2 (den2) 3'sl nucleotide sequence could not substitute for that of the wn 3'sl to support wn ge ...200515681432
sampling phylogenetic tree space with the generalized gibbs sampler.the generalized gibbs sampler (ggs) is a recently developed markov chain monte carlo (mcmc) technique that enables gibbs-like sampling of state spaces that lack a convenient representation in terms of a fixed coordinate system. this paper describes a new sampler, called the tree sampler, which uses the ggs to sample from a state space consisting of phylogenetic trees. the tree sampler is useful for a wide range of phylogenetic applications, including bayesian, maximum likelihood, and maximum par ...200515683921
duplex reverse transcription-pcr followed by nested pcr assays for detection and identification of brazilian alphaviruses and flaviviruses.a new approach was developed for the rapid detection and identification of brazilian alphaviruses and flaviviruses. the methodology involves the genus-specific detection of alphavirus and flavivirus by a duplex reverse transcription-pcr (d-rt-pcr), followed by multiplex nested pcr (m-n-pcr) or nested pcr (n-pcr) assays for species-specific identification. by this protocol, 25 arboviruses were specifically detected and identified. detection levels between 10(1.3) and 10(3.5) 50% tissue culture in ...200515695666
[the prevalence of hepatitis g virus in patients with hepatitis b and c virus infections].gb virus c/hepatitis g virus (gbv-c/hgv) is a recently identified flavivirus, which has been frequently detected in patients with chronic hepatitis b virus (hbv) and hepatitis c virus (hcv) infections. in this study, the prevalence of hgv-rna and antibodies to e2 envelope antigen (anti-e2) which is a marker of past infection, have been investigated in the samples of patients with hcv and hbv infections, and the prevalence rates were compared with the control group. the study group consisted of 5 ...200415700668
japanese encephalitis in a u.s. traveler returning from thailand, 2004.japanese encephalitis (je) virus is a mosquito-borne flavivirus that is closely related to the west nile and st. louis encephalitis viruses endemic to north america. je virus is a leading cause of viral encephalitis in asia but is rarely reported among travelers to countries where je is endemic. this report describes a case of an unvaccinated washington resident who had je after traveling to northern thailand. the advisory committee on immunization practices (acip) recommends je vaccine for trav ...200515703694
secretion of noninfectious dengue virus-like particles and identification of amino acids in the stem region involved in intracellular retention of envelope protein.dna plasmids that express flavivirus premembrane/membrane (prm/m) and envelope (e) proteins in the form of virus-like particles (vlps) have an excellent potential as dna vaccine candidates against virus infection. the plasmid-expressed vlps are also useful as safe, noninfectious antigens in serodiagnostic assays. we have constructed plasmids containing the prm/m and e gene regions for denv-1, -3, and -4 that express and secrete vlps when electroporated into chinese hamster ovary cells. construct ...200515721358
isolation of bovine viral diarrhea virus 1, a pestivirus from autopsied lamb specimen from tamil nadu, india.an epizootic of febrile illness among the madras red breed of sheep had occurred in 1994 in verrapuram, chennai, india. the epizootic was suspected as rift valley fever (rvf)-like sickness based on clinical features. however, its etiological agent could neither be isolated nor implicated conclusively. during the post-epizootic period a male lamb died of similar clinical features and the spleen was immediately collected. inoculation of spleen suspension in infant mouse brain yielded a virus that ...200415745045
[residual neurovirulence of the chimera of langat and denge-4 flaviviruses in intracerebral infection of monkeys].the residual neurovirulence of the previously obtained chimeric virus tp21/den4, containing the rna region encoding the pre m and e structural enzymes, strain tp21, virus langat, and the remaining part of the genome from the denge 4 virus, was studied in experiments with monkeys cercopithecus aethiops involving the intracerebral administration of the virus. the tick-borne encephalitis virus, strain absettarov, was used as positive control. a comparative analysis of the experimental and published ...200515747868
an infectious west nile virus that expresses a gfp reporter gene.west nile virus is a mosquito-borne, neurotropic flavivirus that causes encephalitis in humans and animals. since being introduced into the western hemisphere in 1999, wnv has spread rapidly across north america, identifying this virus as an important emerging pathogen. in this study, we developed a dna-launched infectious molecular clone of wnv that encodes a gfp reporter gene. transfection of cells with the plasmid encoding this recombinant virus (pwnii-gfp) resulted in the production of infec ...200515749120
novel flavivirus or new lineage of west nile virus, central europe.a flavivirus (strain 97-103) was isolated from culex pipens mosquitoes in 1997 following floods in south moravia, czech republic. the strain exhibited close antigenic relationship to west nile virus (wnv) prototype strain eg-101 in a cross-neutralization test. in this study, mouse pathogenicity characteristics and the complete nucleotide and putative amino acid sequences of isolate 97-103, named rabensburg virus (rabv) after a nearby austrian city, were determined. rabv shares only 75%-77% nucle ...200515752439
in vitro host-cell susceptibility to usutu virus.we investigated the susceptibility to usutu virus (flavivirus) of 13 permanent cell lines, 3 primary cell cultures, and chicken embryos. vero, pk-15, and goose embryo fibroblast cells developed cytopathic effects; however, viral multiplication was detected in all mammalian cell types by immunohistochemical tests. chicken embryo fibroblast cells and chicken embryos were resistant.200515752450
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