Publications
| Title | Abstract | Year(sorted descending) Filter | PMID Filter |
|---|
| nuclear localization of flavivirus rna synthesis in infected cells. | flaviviral replication is believed to be exclusively cytoplasmic, occurring within virus-induced membrane-bound replication complexes in the host cytoplasm. here we show that a significant proportion (20%) of the total rna-dependent rna polymerase (rdrp) activity from cells infected with west nile virus, japanese encephalitis virus (jev), and dengue virus is resident within the nucleus. consistent with this, the major replicase proteins ns3 and ns5 of jev also localized within the nucleus. ns5 w ... | 2006 | 16699025 |
| blocking of interferon-induced jak-stat signaling by japanese encephalitis virus ns5 through a protein tyrosine phosphatase-mediated mechanism. | japanese encephalitis virus (jev), a mosquito-borne flavivirus that causes severe human disease, has been shown to block the interferon (ifn)-induced janus kinase signal transducer and activation of transcription (jak-stat) signaling cascade by preventing tyk2 tyrosine phosphorylation and stat activation. in this study, we demonstrate that expression of the jev nonstructural protein ns5 readily blocked ifn-stimulated jak-stat signaling events such as stat1 nuclear translocation and tyrosine phos ... | 2006 | 16731929 |
| west nile virus in complex with the fab fragment of a neutralizing monoclonal antibody. | flaviviruses, such as west nile virus (wnv), are significant human pathogens. the humoral immune response plays an important role in the control of flavivirus infection and disease. the structure of wnv complexed with the fab fragment of the strongly neutralizing mab e16 was determined to 14.5-angstrom resolution with cryo-electron microscopy. e16, an antibody with therapeutic potential, binds to domain iii of the wnv envelope glycoprotein. because of steric hindrance, fab e16 binds to only 120 ... | 2006 | 16895988 |
| west nile virus 5'-cap structure is formed by sequential guanine n-7 and ribose 2'-o methylations by nonstructural protein 5. | many flaviviruses are globally important human pathogens. their plus-strand rna genome contains a 5'-cap structure that is methylated at the guanine n-7 and the ribose 2'-oh positions of the first transcribed nucleotide, adenine (m(7)gpppam). using west nile virus (wnv), we demonstrate, for the first time, that the nonstructural protein 5 (ns5) mediates both guanine n-7 and ribose 2'-o methylations and therefore is essential for flavivirus 5'-cap formation. we show that a recombinant full-length ... | 2006 | 16912287 |
| west nile virus meningoencephalitis. | since its first appearance in the us in 1999, west nile virus (wnv) has emerged as the most common cause of epidemic meningoencephalitis in north america. in the 6 years following the 1999 outbreak, the geographic range and burden of the disease in birds, mosquitoes and humans has greatly expanded to include the 48 contiguous us and 7 canadian provinces, as well as mexico, the caribbean islands and colombia. wnv has shown an increasing propensity for neuroinvasive disease over the past decade, w ... | 2006 | 16932563 |
| preliminary crystallographic characterization of an rna helicase from kunjin virus. | kunjin virus is a member of the flavivirus genus and is an australian variant of west nile virus. the c-terminal domain of the kunjin virus ns3 protein displays helicase activity. the protein is thought to separate daughter and template rna strands, assisting the initiation of replication by unwinding rna secondary structure in the 3' nontranslated region. expression, purification and preliminary crystallographic characterization of the ns3 helicase domain are reported. it is shown that kunjin v ... | 2006 | 16946468 |
| resistance to alpha/beta interferon is a determinant of west nile virus replication fitness and virulence. | the emergence of west nile virus (wnv) in the western hemisphere is marked by the spread of pathogenic lineage i strains, which differ from typically avirulent lineage ii strains. to begin to understand the virus-host interactions that may influence the phenotypic properties of divergent lineage i and ii viruses, we compared the genetic, pathogenic, and alpha/beta interferon (ifn-alpha/beta)-regulatory properties of a lineage ii isolate from madagascar (mad78) with those of a new lineage i isola ... | 2006 | 16973548 |
| translation of the flavivirus kunjin ns3 gene in cis but not its rna sequence or secondary structure is essential for efficient rna packaging. | our previous studies using trans-complementation analysis of kunjin virus (kun) full-length cdna clones harboring in-frame deletions in the ns3 gene demonstrated the inability of these defective complemented rnas to be packaged into virus particles (w. j. liu, p. l. sedlak, n. kondratieva, and a. a. khromykh, j. virol. 76:10766-10775). in this study we aimed to establish whether this requirement for ns3 in rna packaging is determined by the secondary rna structure of the ns3 gene or by the essen ... | 2006 | 16971441 |
| cleavage targets and the d-arginine-based inhibitors of the west nile virus ns3 processing proteinase. | mosquito-borne wnv (west nile virus) is an emerging global threat. the ns3 proteinase, which is essential for the proteolytic processing of the viral polyprotein precursor, is a promising drug target. we have isolated and biochemically characterized the recombinant, highly active ns3 proteinase. we have determined that the ns3 proteinase functions in a manner that is distantly similar to furin in cleaving the peptide and protein substrates. we determined that aprotinin and d-arginine-based 9-12- ... | 2006 | 16229682 |
| rna secondary structure in the coding region of dengue virus type 2 directs translation start codon selection and is required for viral replication. | dengue virus is a positive-strand rna virus and a member of the genus flavivirus, which includes west nile, yellow fever, and tick-borne encephalitis viruses. flavivirus genomes are translated as a single polyprotein that is subsequently cleaved into 10 proteins, the first of which is the viral capsid (c) protein. dengue virus type 2 (denv2) and other mosquito-borne flaviviruses initiate translation of c from a start codon in a suboptimal context and have multiple in-frame augs downstream. here, ... | 2006 | 16474125 |
| ebola virus glycoprotein gp is not cytotoxic when expressed constitutively at a moderate level. | transient expression of ebola virus (ebov) glycoprotein gp causes downregulation of surface proteins, cell rounding and detachment, a phenomenon believed to play a central role in the pathogenicity of the virus. in this study, evidence that moderate expression of gp does not result in such morphological changes was provided. it was shown that gp continuously produced in 293t cells from the kunjin virus replicon was correctly processed and transported to the plasma membrane without affecting the ... | 2006 | 16603527 |
| regulated cleavages at the west nile virus ns4a-2k-ns4b junctions play a major role in rearranging cytoplasmic membranes and golgi trafficking of the ns4a protein. | a common feature associated with the replication of most rna viruses is the formation of a unique membrane environment encapsulating the viral replication complex. for their part, flaviviruses are no exception, whereupon infection causes a dramatic rearrangement and induction of unique membrane structures within the cytoplasm of infected cells. these virus-induced membranes, termed paracrystalline arrays, convoluted membranes, and vesicle packets, all appear to have specific functions during rep ... | 2006 | 16611922 |
| a single tube rt-pcr assay for the detection of mosquito-borne flaviviruses. | mosquito-borne flaviviruses include several important agents of human disease and have provided striking examples of emerging infections. in this study we present the design and validation of a single tube rt-pcr assay using a pair of consensus primers for the detection of mosquito-borne flaviviruses. sequencing of the amplicons permits the species identification. the assay was validated using rna from the yellow fever virus vaccine strain and from representative strains of dengue viruses 1, 2, ... | 2006 | 16650488 |
| west nile and st. louis encephalitis virus antibody seroconversion, prevalence, and persistence in naturally infected pig-tailed macaques (macaca nemestrina). | pig-tailed macaques (macaca nemestrina) naturally infected with west nile virus were monitored from 1999 to 2005 to determine virus-specific antibody seroconversion, prevalence, and persistence. antibodies persisted for up to 36 months, as detected by epitope-blocking enzyme-linked immunosorbent and hemagglutination inhibition assays. exposure to cocirculating st. louis encephalitis virus was evaluated by western blotting and immunofluorescence assays. | 2006 | 16760333 |
| development and evaluation of indirect elisa for the detection of antibodies against japanese encephalitis virus in swine. | the japanese encephalitis virus (jev) is one of causative agents of reproductive failure in pregnant sows. an indirect enzyme-linked immunosorbent assay (i-elisa) was examined for its potential use in the rapid monitoring of the jev, and the results were compared with those from the hemagglutination inhibition (hi) and serum neutralization (sn) tests. the comparative analysis showed that the results of i-elisa showed a significant correlation with the conventional hi (r = 0.867) and sn tests (r ... | 2006 | 16871022 |
| a 5' rna element promotes dengue virus rna synthesis on a circular genome. | the mechanisms of rna replication of plus-strand rna viruses are still unclear. here, we identified the first promoter element for rna synthesis described in a flavivirus. using dengue virus as a model, we found that the viral rdrp discriminates the viral rna by specific recognition of a 5' element named sla. we demonstrated that rna-rna interactions between 5' and 3' end sequences of the viral genome enhance dengue virus rna synthesis only in the presence of an intact sla. we propose a novel me ... | 2006 | 16882970 |
| lineage 1 and 2 strains of encephalitic west nile virus, central europe. | two different west nile virus (wnv) strains caused lethal encephalitis in a flock of geese and a goshawk in southeastern hungary in 2003 and 2004, respectively. during the outbreak in geese, 14 confirmed human cases of wnv encephalitis and meningitis were reported in the same area. sequencing of complete genomes of both wnv strains and phylogenetic analyses showed that the goose-derived strain exhibits closest genetic relationship to strains isolated in 1998 in israel and to the strain that emer ... | 2006 | 16704810 |
| production and characterization of vaccines based on flaviviruses defective in replication. | to develop new vaccine candidates for flavivirus infections, we have engineered two flaviviruses, yellow fever virus (yfv) and west nile virus (wnv), that are deficient in replication. these defective pseudoinfectious viruses (pivs) lack a functional copy of the capsid (c) gene in their genomes and are incapable of causing spreading infection upon infection of cells both in vivo and in vitro. however, they produce extracellular e protein in form of secreted subviral particles (svps) that are kno ... | 2006 | 16712897 |
| recombination and selection in the evolution of picornaviruses and other mammalian positive-stranded rna viruses. | picornaviridae are a large virus family causing widespread, often pathogenic infections in humans and other mammals. picornaviruses are genetically and antigenically highly diverse, with evidence for complex evolutionary histories in which recombination plays a major part. to investigate the nature of recombination and selection processes underlying the evolution of serotypes within different picornavirus genera, large-scale analysis of recombination frequencies and sites, segregation by serotyp ... | 2006 | 16956935 |
| pathogenesis of west nile virus infection: a balance between virulence, innate and adaptive immunity, and viral evasion. | 2006 | 16973541 | |
| 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 ... | 2005 | 15681432 |
| kissing-loop interaction in the 3' end of the hepatitis c virus genome essential for rna replication. | the hepatitis c virus (hcv) is a positive-strand rna virus belonging to the flaviviridae. its genome carries at either end highly conserved nontranslated regions (ntrs) containing cis-acting rna elements that are crucial for replication. in this study, we identified a novel rna element within the ns5b coding sequence that is indispensable for replication. by using secondary structure prediction and nuclear magnetic resonance spectroscopy, we found that this rna element, designated 5bsl3.2 by ana ... | 2005 | 15596831 |
| efficient rescue of hepatitis c virus rna replication by trans-complementation with nonstructural protein 5a. | studies of hepatitis c virus (hcv) rna replication have become possible with the development of subgenomic replicons. this system allows the functional analysis of the essential components of the viral replication complex, which so far are poorly defined. in the present study we wanted to investigate whether lethal mutations in hcv nonstructural genes can be rescued by trans-complementation. therefore, a series of replicon rnas carrying mutations in ns3, ns4b, ns5a, and ns5b that abolish replica ... | 2005 | 15613318 |
| west nile virus inhibits the signal transduction pathway of alpha interferon. | west nile virus (wnv) is a human pathogen that can cause neurological disorders, including meningoencephalitis. experiments with mice and mammalian cell cultures revealed that wnv exhibited resistance to the innate immune program induced by alpha interferon (ifn-alpha). we have investigated the nature of this inhibition and have found that wnv replication inhibited the activation of many known ifn-inducible genes, because it prevented the phosphorylation and activation of the janus kinases jak1 ... | 2005 | 15650160 |
| inhibition of interferon-stimulated jak-stat signaling by a tick-borne flavivirus and identification of ns5 as an interferon antagonist. | the tick-borne encephalitis (tbe) complex of viruses, genus flavivirus, can cause severe encephalitis, meningitis, and/or hemorrhagic fevers. effective interferon (ifn) responses are critical to recovery from infection with flaviviruses, and the mosquito-borne flaviviruses can inhibit this response. however, little is known about interactions between ifn signaling and tbe viruses. langat virus (lgtv), a member of the tbe complex of viruses, was found to be highly sensitive to the antiviral effec ... | 2005 | 16188985 |
| s-phase-dependent enhancement of dengue virus 2 replication in mosquito cells, but not in human cells. | dengue virus (den) is the most prevalent cause of arthropod-borne viral illness in humans. we determined the influence of cellular growth state on den type 2 (den2) replication in mosquito and human cells, based on the hypothesis that manipulation of cellular growth state will facilitate identification of viral and cellular determinants of productive infection. comparison of density-arrested and cycling c6/36 aedes albopictus cells infected with a low-passage den2 isolate revealed that cycling c ... | 2005 | 16227245 |
| communicable diseases network australia: national arbovirus and malaria advisory committee annual report 2004-05. | this report describes the epidemiology of mosquito-borne disease in australia for the mosquito-borne disease season 1 july 2004 to 30 june 2005. ross river virus (rrv) infections (45%), barmah forest virus (bfv) infections (30%) and malaria (19%) were the most common mosquito-borne diseases reported in 2004-05. the northern territory had the highest rate of rrv notifications and the peak notification rate (in february 2005) was 54 per cent less than the previous season. the northern territory al ... | 2005 | 16465923 |
| epidemiology and transmission dynamics of west nile virus disease. | from 1937 until 1999, west nile virus (wnv) garnered scant medical attention as the cause of febrile illness and sporadic encephalitis in parts of africa, asia, and europe. after the surprising detection of wnv in new york city in 1999, the virus has spread dramatically westward across the united states, southward into central america and the caribbean, and northward into canada, resulting in the largest epidemics of neuroinvasive wnv disease ever reported. from 1999 to 2004, >7,000 neuroinvasiv ... | 2005 | 16102302 |
| virology, pathology, and clinical manifestations of west nile virus disease. | west nile virus (wnv) causes epidemics of febrile illness, meningitis, encephalitis, and flaccid paralysis. since it was first detected in new york city in 1999, and through 2004, >16,000 wnv disease cases have been reported in the united states. over the past 5 years, research on wnv disease has expanded rapidly. this review highlights new information regarding the virology, clinical manifestations, and pathology of wnv disease, which will provide a new platform for further research into diagno ... | 2005 | 16102303 |
| west nile virus detection in urine. | we report west nile virus (wnv) rna in urine collected from a patient with encephalitis 8 days after symptom onset. viral rna was detected by reverse transcriptase-polymerase chain reaction (rt-pcr). sequence and phylogenetic analysis confirmed the pcr product to have > or = 99% similarity to the wnv strain ny 2000-crow3356. | 2005 | 16102323 |
| inhibition of interferon signaling by the new york 99 strain and kunjin subtype of west nile virus involves blockage of stat1 and stat2 activation by nonstructural proteins. | the interferon (ifn) response is the first line of defense against viral infections, and the majority of viruses have developed different strategies to counteract ifn responses in order to ensure their survival in an infected host. in this study, the abilities to inhibit ifn signaling of two closely related west nile viruses, the new york 99 strain (ny99) and kunjin virus (kun), strain mrm61c, were analyzed using reporter plasmid assays, as well as immunofluorescence and western blot analyses. w ... | 2005 | 15650219 |
| 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 ... | 2005 | 15752439 |
| development of immunoglobulin m capture enzyme-linked immunosorbent assay to differentiate human flavivirus infections occurring in australia. | we report the development of a flavivirus immunoglobulin m (igm) capture enzyme-linked immunosorbent assay (mac-elisa) which improves the determination of an infecting flavivirus serotype over that by current serological methods. a panel of 165 igm-positive sera from flavivirus patients with specific diagnostic results was tested by the flavivirus mac-elisa using a panel of 10 antigens. for 134 of these sera (81.2%), the highest reactivity was demonstrated against the infecting virus, which was ... | 2005 | 15753249 |
| the microbial rosetta stone database: a compilation of global and emerging infectious microorganisms and bioterrorist threat agents. | thousands of different microorganisms affect the health, safety, and economic stability of populations. many different medical and governmental organizations have created lists of the pathogenic microorganisms relevant to their missions; however, the nomenclature for biological agents on these lists and pathogens described in the literature is inexact. this ambiguity can be a significant block to effective communication among the diverse communities that must deal with epidemics or bioterrorist ... | 2005 | 15850481 |
| molecular typing of west nile virus, dengue, and st. louis encephalitis using multiplex sequencing. | we report the development of an assay to simultaneously identify three of the clinically important flaviviruses (west nile virus, dengue, and st. louis encephalitis). this assay is based on the nucleotide sequence variations within a 266-bp region of the non-structural protein 5. further, based on the nucleotide variations in the same region of the non-structural protein 5, four of the present dengue serotypes were identified. to identify some of the subtypes of wnv we have developed a second as ... | 2005 | 15858138 |
| chimeric dengue 2 pdk-53/west nile ny99 viruses retain the phenotypic attenuation markers of the candidate pdk-53 vaccine virus and protect mice against lethal challenge with west nile virus. | chimeric dengue serotype 2/west nile (d2/wn) viruses expressing prm-e of wn ny99 virus in the genetic background of wild-type d2 16681 virus and two candidate d2 pdk-53 vaccine variants (pdk53-e and pdk53-v) were engineered. the viability of the d2/wn viruses required incorporation of the wn virus-specific signal sequence for prm. introduction of two mutations at m-58 and e-191 in the chimeric cdna clones further improved the viability of the chimeras constructed in all three d2 carriers. two d2 ... | 2005 | 15919884 |
| inhibition of alpha/beta interferon signaling by the ns4b protein of flaviviruses. | flaviviruses are insect-borne, positive-strand rna viruses that have been disseminated worldwide. their genome is translated into a polyprotein, which is subsequently cleaved by a combination of viral and host proteases to produce three structural proteins and seven nonstructural proteins. the nonstructural protein ns4b of dengue 2 virus partially blocks activation of stat1 and interferon-stimulated response element (isre) promoters in cells stimulated with interferon (ifn). we have found that t ... | 2005 | 15956546 |
| envelope protein glycosylation status influences mouse neuroinvasion phenotype of genetic lineage 1 west nile virus strains. | the introduction of west nile virus (wnv) into north america has been associated with relatively high rates of neurological disease and death in humans, birds, horses, and some other animals. previous studies identified strains in both genetic lineage 1 and genetic lineage 2, including north american isolates of lineage 1, that were highly virulent in a mouse neuroinvasion model, while other strains were avirulent or significantly attenuated (d. w. c. beasley, l. li, m. t. suderman, and a. d. t. ... | 2005 | 15956579 |
| actively replicating west nile virus is resistant to cytoplasmic delivery of sirna. | west nile virus is an emerging human pathogen for which specific antiviral therapy has not been developed. recent studies have suggested that rna interference (rnai) has therapeutic potential as a sequence specific inhibitor of viral infection. here, we examine the ability of exogenous small interfering rnas (sirnas) to block the replication of west nile virus in human cells. | 2005 | 15985182 |
| long-range rna-rna interactions circularize the dengue virus genome. | secondary and tertiary rna structures present in viral rna genomes play essential regulatory roles during translation, rna replication, and assembly of new viral particles. in the case of flaviviruses, rna-rna interactions between the 5' and 3' ends of the genome have been proposed to be required for rna replication. we found that two rna elements present at the ends of the dengue virus genome interact in vitro with high affinity. visualization of individual molecules by atomic force microscopy ... | 2005 | 15890901 |
| histidine at residue 99 and the transmembrane region of the precursor membrane prm protein are important for the prm-e heterodimeric complex formation of japanese encephalitis virus. | the formation of the flavivirus prm-e complex is an important step for the biogenesis of immature virions, which is followed by a subsequent cleavage of prm to m protein through cellular protease to result in the production and release of mature virions. in this study, the intracellular formation of the prm-e complex of japanese encephalitis virus was investigated by baculovirus coexpression of prm and e in trans in sf9 insect cells as analyzed by anti-e antibody immunoprecipitation and sucrose ... | 2005 | 15956595 |
| variation in virulence of west nile virus strains for house sparrows (passer domesticus). | the observation of avian mortality associated with west nile virus (wnv) infection has become a hallmark epidemiologic feature in the recent emergence of this pathogen in israel and north america. to determine if phenotypic differences exist among different wnv isolates, we exposed house sparrows (passer domesticus) to low passage, lineage 1 wnv strains from north america (ny99), kenya (ken), and australia (kun; also known as kunjin virus). house sparrows inoculated with the ny99 and ken strains ... | 2005 | 15728874 |
| the transcriptome of hcv replicon expressing cell lines in the presence of alpha interferon. | we have used dna microarray analysis of human hepatoma and epithelial carcinoma cells expressing hepatitis c virus (hcv) subgenomic replicons to test whether hcv replication alters gene expression and influences the alpha interferon (ifn-alpha) response. we directly compared the hcv replicon system with a similar system based on a subgenomic replicon of the west nile virus (wnv) subtype kunjin virus. we found that in contrast to wnv replicons, persistent replication of hcv replicons did not sign ... | 2005 | 15840525 |
| nuclear localization of japanese encephalitis virus core protein enhances viral replication. | japanese encephalitis virus (jev) core protein was detected in both the nucleoli and cytoplasm of mammalian and insect cell lines infected with jev or transfected with the expression plasmid of the core protein. mutation analysis revealed that gly(42) and pro(43) in the core protein are essential for the nuclear and nucleolar localization. a mutant m4243 virus in which both gly(42) and pro(43) were replaced by ala was recovered by plasmid-based reverse genetics. in c6/36 mosquito cells, the m424 ... | 2005 | 15731239 |
| sentinel chicken surveillance program in australia, july 2003 to june 2004. | detection of flavivirus seroconversions in sentinel chicken flocks located in four australian states are used to provide an early warning of increased levels of murray valley encephalitis virus (mvev) and kunjin virus (kunv) activity in the region. during the 2003-2004 season low levels of flavivirus activity were detected in northern australia with both mvev and kunv virus activity detected in the kimberley and pilbara regions of western australia and in the northern territory. a single case of ... | 2005 | 15966677 |
| the src family kinase c-yes is required for maturation of west nile virus particles. | the role of cellular genes in west nile virus (wnv) replication is not well understood. examination of cellular transcripts upregulated during wnv infection revealed an increase in the expression of the src family kinase (sfk) c-yes. wnv-infected cell lines treated with the sfk inhibitor pp2 demonstrated a 2- to 4-log decrease in viral titers, suggesting that sfk activity is required for completion of the viral replication cycle. rna interference mediated knock-down of c-yes, but not c-src, and ... | 2005 | 16140770 |
| control of translation by the 5'- and 3'-terminal regions of the dengue virus genome. | the genomic rnas of flaviviruses such as dengue virus (den) have a 5' m7gpppn cap like those of cellular mrnas but lack a 3' poly(a) tail. we have studied the contributions to translational expression of 5'- and 3'-terminal regions of the den serotype 2 genome by using luciferase reporter mrnas transfected into vero cells. dcld rna contained the entire den 5' and 3' untranslated regions (utrs), as well as the first 36 codons of the capsid coding region fused to the luciferase reporter gene. capp ... | 2005 | 15956576 |
| semliki forest virus and kunjin virus rna replicons elicit comparable cellular immunity but distinct humoral immunity. | rna replicons offer a number of qualities which make them attractive as vaccination vectors. both alphavirus and flavivirus replicon vaccines have been investigated in preclinical models yet there has been little direct comparison of the two vector systems. to determine whether differences in the biology of the two vectors influence immunogenicity, we compared two prototypic replicon vectors based on semliki forest virus (sfv) (alphavirus) and kunjin virus (kun) (flavivirus). both vectors when d ... | 2005 | 16005737 |
| high-throughput assays using a luciferase-expressing replicon, virus-like particles, and full-length virus for west nile virus drug discovery. | many flaviviruses cause significant human disease worldwide. the development of flavivirus chemotherapy requires reliable high-throughput screening (hts) assays. although genetic systems have been developed for many flaviviruses, their usage in antiviral hts assays has not been well explored. here we compare three cell-based hts assays for west nile virus (wnv) drug discovery: (i) an assay that uses a cell line harboring a persistently replicating subgenomic replicon (containing a deletion of vi ... | 2005 | 16304161 |
| 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 ... | 2005 | 15650200 |
| ns1 protein secretion during the acute phase of west nile virus infection. | the west nile virus (wnv) nonstructural protein ns1 is a protein of unknown function that is found within, associated with, and secreted from infected cells. we systematically investigated the kinetics of ns1 secretion in vitro and in vivo to determine the potential use of this protein as a diagnostic marker and to analyze ns1 secretion in relation to the infection cycle. a sensitive antigen capture enzyme-linked immunosorbent assay (elisa) for detection of wnv ns1 (polyclonal-ace) was developed ... | 2005 | 16254328 |
| sucrose density gradient centrifugation and cross-flow filtration methods for the production of arbovirus antigens inactivated by binary ethylenimine. | sucrose density gradient centrifugation and cross-flow filtration methods have been developed and standardised for the safe and reproducible production of inactivated arbovirus antigens which are appropriate for use in diagnostic serological applications. | 2004 | 14720306 |
| mimicking live flavivirus immunization with a noninfectious rna vaccine. | flaviviruses are human pathogens of world-wide medical importance. they have recently received much additional attention because of their spread to new regions (such as west nile virus to north america), highlighting their potential as newly emerging disease agents. using tick-borne encephalitis virus, we have developed and evaluated in mice a new genetic vaccine based on self-replicating but noninfectious rna. this rna contains all of the necessary genetic information for establishing its repli ... | 2004 | 14769933 |
| west nile virus: a growing concern? | west nile virus was first detected in north america in 1999 and has subsequently spread throughout the united states and canada and into mexico and the caribbean. this review describes the epidemiology and ecology of west nile virus in north america and the prospects for effective treatments and vaccines. | 2004 | 15085186 |
| enzyme-linked immunosorbent assays using recombinant envelope protein expressed in cos-1 and drosophila s2 cells for detection of west nile virus immunoglobulin m in serum or cerebrospinal fluid. | humans infected with west nile virus (wnv) develop immunoglobulin m (igm) antibodies soon after infection. the microtiter-based assays for wnv igm antibody detection used by most state public health and reference laboratories utilize wnv antigen isolated from infected vero cells or recombinant envelope protein produced in cos-1 cells. recombinant antigen produced in cos-1 cells was used to develop a wnv igm capture enzyme immunoassay (eia). a supplementary eia using wnv envelope protein expresse ... | 2004 | 15242936 |
| comparisons of physical separation methods of kunjin virus-induced membranes. | the two sets of connected membranes induced in kunjin virus-infected cells are characterized by the presence of ns3 helicase/protease in both, and by rna-dependent rna polymerase (rdrp) activity plus the associated double-stranded rna (dsrna) template in vesicle packets (vp), or by the absence of both the vp-specific markers in the convoluted membranes/paracrystalline arrays (cm/pc). attempts were made to separate flavivirus-induced membranes by sedimentation or flotation analyses in density gra ... | 2004 | 15288961 |
| 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. | 2004 | 15324558 |
| 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 ... | 2004 | 15331694 |
| trans-packaged west nile virus-like particles: infectious properties in vitro and in infected mosquito vectors. | a trans-packaging system for west nile virus (wnv) subgenomic replicon rnas (reprnas), deleted for the structural coding region, was developed. wnv reprnas were efficiently encapsidated by the wnv c/prm/e structural proteins expressed in trans from replication-competent, noncytopathic sindbis virus-derived rnas. infectious virus-like particles (vlps) were produced in titers of up to 10(9) infectious units/ml. wnv vlps established a single round of infection in a variety of different cell lines w ... | 2004 | 15479801 |
| genetic interactions between hepatitis c virus replicons. | to investigate interactions between hepatitis c virus (hcv) rna replication complexes, a system was developed to simultaneously select different hcv subgenomic replicons within the same cell. transcomplementation of defective replicons was not observed, suggesting an isolated and independent nature of the hcv rna replication complex. in contrast, a high level of competition between replicons was observed, such that the presence and increased fitness of one replicon reduced the capacity of a seco ... | 2004 | 15479852 |
| 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 ... | 2004 | 15507609 |
| development and evaluation of fluorogenic taqman reverse transcriptase pcr assays for detection of dengue virus types 1 to 4. | the fluorogenic taqman reverse transcriptase pcr (rt-pcr) assay was developed for detecting each of the dengue virus (dv) types 1 to 4. dv genome was detected in all the 35 serum samples from confirmed dengue cases by the taqman rt-pcr, although it was not detected in 13 and 21% by conventional type-specific and cross-reactive rt-pcr, respectively. | 2004 | 15583346 |
| tetracycline-inducible packaging cell line for production of flavivirus replicon particles. | we have previously developed replicon vectors derived from the australian flavivirus kunjin that have a unique noncytopathic nature and have been shown to direct prolonged high-level expression of encoded heterologous genes in vitro and in vivo and to induce strong and long-lasting immune responses to encoded immunogens in mice. to facilitate further applications of these vectors in the form of virus-like particles (vlps), we have now generated a stable bhk packaging cell line, tetkuncprme, carr ... | 2004 | 14671135 |
| alterations of pr-m cleavage and virus export in pr-m junction chimeric dengue viruses. | during the export of flavivirus particles through the secretory pathway, a viral envelope glycoprotein, prm, is cleaved by the proprotein convertase furin; this cleavage is required for the subsequent rearrangement of receptor-binding e glycoprotein and for virus infectivity. similar to many furin substrates, prm in vector-borne flaviviruses contains basic residues at positions p1, p2, and p4 proximal to the cleavage site; in addition, a number of charged residues are found at position p3 and be ... | 2004 | 14963133 |
| recombinant kunjin virus replicon vaccines induce protective t-cell immunity against human papillomavirus 16 e7-expressing tumour. | the persistence of the e7 oncoprotein in transformed cells in human papillomavirus (hpv)-associated cervical cancer provides a tumour-specific antigen to which immunotherapeutic strategies may be directed. self-replicating rna (replicon) vaccine vectors derived from the flavivirus kunjin (kun) have recently been reported to induce t-cell immunity. here, we report that inclusion of a ctl epitope of hpv16 e7 protein into a polyepitope encoded by a kun vector induced e7-directed t-cell responses an ... | 2004 | 14980484 |
| detection of australasian flavivirus encephalitic viruses using rapid fluorogenic taqman rt-pcr assays. | the development of single, sensitive, fluorogenic reverse transcriptase-polymerase chain reaction (taqman) assays were required for the rapid and specific detection of three encephalitic viruses found in the australasian region, namely; japanese encephalitis virus (jev), murray valley encephalitis virus (mvev), and kunjin virus (kunv). primers and a fluorogenic probe were individually designed to be complementary to a nucleotide region encompassing the 3' terminus of the nonstructural (ns) 5 gen ... | 2004 | 15041213 |
| sybr green-based real-time quantitative pcr assay for detection of west nile virus circumvents false-negative results due to strain variability. | real-time quantitative pcr is used routinely for the high-throughput diagnosis of viral pathogens, such as west nile virus (wnv). rapidly evolving rna viruses present a challenge for diagnosis because they accumulate mutations that may render them undetectable. to explore the effect of sequence variations on assay performance, we generated every possible single point mutation within the target region of the widely used taqman assay for wnv and found that the taqman assay failed to detect 47% of ... | 2004 | 15070997 |
| common e protein determinants for attenuation of glycosaminoglycan-binding variants of japanese encephalitis and west nile viruses. | natural isolates and laboratory strains of west nile virus (wnv) and japanese encephalitis virus (jev) were attenuated for neuroinvasiveness in mouse models for flavivirus encephalitis by serial passage in human adenocarcinoma (sw13) cells. the passage variants displayed a small-plaque phenotype, augmented affinity for heparin-sepharose, and a marked increase in specific infectivity for sw13 cells relative to the respective parental viruses, while the specific infectivity for vero cells was not ... | 2004 | 15254199 |
| 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 ... | 2004 | 15507646 |
| 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 ... | 2004 | 15564480 |
| west nile virus vaccines. | west nile virus (wnv) is a mosquito-borne flavivirus that is emerging as a global pathogen. in the last decade, virulent strains of the virus have been associated with significant outbreaks of human and animal disease in europe, the middle east and north america. efforts to develop human and veterinary vaccines have taken both traditional and novel approaches. a formalin-inactivated whole virus vaccine has been approved for use in horses. dna vaccines coding for the structural wnv proteins have ... | 2004 | 15268663 |
| inefficient signalase cleavage promotes efficient nucleocapsid incorporation into budding flavivirus membranes. | the mechanism for efficient nucleocapsid (nc) uptake into flavivirus particles which form by budding through the membranes of the endoplasmic reticulum (er) was investigated by using murray valley encephalitis virus as a model. budding of flavivirus membranes is driven by the viral transmembrane proteins prm and e independently of nc interaction. we show that control of signalase cleavage of the multimembrane-spanning flavivirus polyprotein by the catalytic function of the viral protease is crit ... | 2004 | 14671099 |
| de novo synthesis of negative-strand rna by dengue virus rna-dependent rna polymerase in vitro: nucleotide, primer, and template parameters. | by using a purified dengue virus rna-dependent rna polymerase and a subgenomic 770-nucleotide rna template, it was shown previously that the ratio of the de novo synthesis product to hairpin product formed was inversely proportional to increments of assay temperatures (20 to 40 degrees c). in this study, the components of the de novo preinitiation complex are defined as atp, a high concentration of gtp (500 micro m), the polymerase, and the template rna. even when the 3'-terminal sequence of tem ... | 2003 | 12885902 |
| incorporation of tick-borne encephalitis virus replicons into virus-like particles by a packaging cell line. | rna replicons derived from flavivirus genomes show considerable potential as gene transfer and immunization vectors. a convenient and efficient encapsidation system is an important prerequisite for the practical application of such vectors. in this work, tick-borne encephalitis (tbe) virus replicons and an appropriate packaging cell line were constructed and characterized. a stable cho cell line constitutively expressing the two surface proteins prm/m and e (named cho-me cells) was generated and ... | 2003 | 12885909 |
| flavivirus isolations from mosquitoes collected from western cape york peninsula, australia, 1999-2000. | after the 1st appearance of japanese encephalitis virus (je) on mainland australia in 1998, a study was undertaken to investigate whether je had become established in enzootic transmission cycles on western cape york peninsula. adult mosquitoes were collected during the late wet season from kowanyama and pormpuraaw in april 1999, and pormpuraaw and barr's yard in april 2000. despite processing 269,270 mosquitoes for virus isolation, no isolates of je were obtained. however, other flaviviruses co ... | 2003 | 14710742 |
| nonstructural protein precursor ns4a/b from hepatitis c virus alters function and ultrastructure of host secretory apparatus. | the nonstructural proteins of hepatitis c virus (hcv) have been shown previously to localize to the endoplasmic reticulum (er) when expressed singly or in the context of other hcv proteins. to determine whether the expression of hcv nonstructural proteins alters er function, we tested the effect of expression of ns2/3/4a, ns4a, ns4b, ns4a/b, ns4b/5a, ns5a, and ns5b from genotype 1b hcv on anterograde traffic from the er to the golgi apparatus. only the nominal precursor protein ns4a/b affected t ... | 2003 | 12829824 |
| a system of protein target sequences for anti-rna-viral chemotherapy by a vitamin b6-derived zinc-chelating trioxa-adamantane-triol. | the synthesis of the structurally unusual heterotricyclic compound 1-[3-hydroxy-5-(hydroxymethyl)-2-methyl-4-pyridinyl]-2,8,9-trioxaadamantane-3,5,7-triol (trivially named bananin, bn) from pyridoxylidenephloroglucinol and a theoretical prospect on possible biological activities of bn are presented in this report. pyridoxylidenephloroglucinol is synthesized by knoevenagel condensation of the vitamin b6 aldehyde pyridoxal with phloroglucinol. pyridoxylidenephloroglucinol rearranges to light-yello ... | 2003 | 14527557 |
| dengue 2 pdk-53 virus as a chimeric carrier for tetravalent dengue vaccine development. | attenuation markers of the candidate dengue 2 (d2) pdk-53 vaccine virus are encoded by mutations that reside outside of the structural gene region of the genome. we engineered nine dengue virus chimeras containing the premembrane (prm) and envelope (e) genes of wild-type d1 16007, d3 16562, or d4 1036 virus within the genetic backgrounds of wild-type d2 16681 virus and the two genetic variants (pdk53-e and pdk53-v) of the d2 pdk-53 vaccine virus. expression of the heterologous prm-e genes in the ... | 2003 | 14557629 |
| dynamics of hepatitis c virus replication in human liver. | hepatitis c virus (hcv) replication at the cellular level is not fully understood. this study describes an optimized system for quantifying replication of hcv in hepatocytes and in liver tissues. a digital image analysis method was developed to quantify signal intensities of hcv genomic and replicative-intermediate rnas in infected human liver tissues and to examine their spatial distribution. the average number of viral genomes per productively infected hepatocyte ranged from 7 to 64 rna molecu ... | 2003 | 12875965 |
| origin and evolution of japanese encephalitis virus in southeast asia. | since it emerged in japan in the 1870s, japanese encephalitis has spread across asia and has become the most important cause of epidemic encephalitis worldwide. four genotypes of japanese encephalitis virus (jev) are presently recognized (representatives of genotypes i to iii have been fully sequenced), but its origin is not known. we have determined the complete nucleotide and amino acid sequence of a genotype iv indonesian isolate (jkt6468) which represents the oldest lineage, compared it with ... | 2003 | 12584335 |
| sindbis virus vectors designed to express a foreign protein as a cleavable component of the viral structural polyprotein. | alphavirus-based expression vectors commonly use a duplicated 26s promoter to drive expression of a foreign gene. here we describe an expression strategy in which the foreign sequences are linked to the gene encoding the 2a protease of foot-and-mouth disease virus and then inserted in frame between the capsid and e3 genes of sindbis virus. during replication, the 2a fusion protein is synthesized as a component of the viral structural polyprotein that is then released by intramolecular cleavages ... | 2003 | 12719552 |
| australia's notifiable diseases status, 2001: annual report of the national notifiable diseases surveillance system. | in 2001 there were 104,187 notifications of communicable diseases in australia reported to the national notifiable diseases surveillance system (nndss). the number of notifications in 2001 was an increase of 16 per cent of those reported in 2000 (89,740) and the largest annual total since the nndss commenced in 1991. in 2001, nine new diseases were added to the list of diseases reported to nndss and four diseases were removed. the new diseases were cryptosporidiosis, laboratory-confirmed influen ... | 2003 | 12725505 |
| tick-borne encephalitis with hemorrhagic syndrome, novosibirsk region, russia, 1999. | eight fatal cases of tick-borne encephalitis with an unusual hemorrhagic syndrome were identified in 1999 in the novosibirsk region, russia. to study these strains, we sequenced cdna fragments of protein e gene from six archival formalin-fixed brain samples. phylogenetic analysis showed tick-borne encephalitis variants clustered with a far eastern subtype (homology 94.7%) but not with the siberian subtype (82%). | 2003 | 12781020 |
| epitope-blocking enzyme-linked immunosorbent assays for detection of west nile virus antibodies in domestic mammals. | we evaluated the ability of epitope-blocking enzyme-linked immunosorbent assays (elisas) to detect west nile virus (wnv) antibodies in domestic mammals. sera were collected from experimentally infected horses, cats, and pigs at regular intervals and screened in elisas and plaque reduction neutralization tests. the diagnostic efficacies of these techniques were similar. | 2003 | 12791902 |
| kunjin rna replication and applications of kunjin replicons. | the kunjin virus (kunv) has provided a useful laboratory model for flavivirus rna replication. the synthesis of progeny rna(+) strands occurs via asymmetric and semiconservative replication on a template of recycling double-stranded rna (dsrna) or replicative form (rf). kinetics of viral rna synthesis indicated a cycle period of about 15 min during which, on average, a single nascent rna (+) strand displaces the pre-existing rna(+) strand in the replicative intermediate. data on the composition ... | 2003 | 14696328 |
| fine mapping of a cis-acting sequence element in yellow fever virus rna that is required for rna replication and cyclization. | we present fine mapping of a cis-acting nucleotide sequence found in the 5' region of yellow fever virus genomic rna that is required for rna replication. there is evidence that this sequence interacts with a complementary sequence in the 3' region of the genome to cyclize the rna. replicons were constructed that had various deletions in the 5' region encoding the capsid protein and were tested for their ability to replicate. we found that a sequence of 18 nucleotides (residues 146 to 163 of the ... | 2003 | 12525663 |
| functional analysis of mosquito-borne flavivirus conserved sequence elements within 3' untranslated region of west nile virus by use of a reporting replicon that differentiates between viral translation and rna replication. | we have developed a reporting replicon of west nile virus (wnv) that could be used to quantitatively distinguish viral translation and rna replication. a renilla luciferase (rluc) gene was fused in-frame with the open reading frame of a subgenomic replicon in the position where the viral structural region was deleted, resulting in rlucrep. transfection of bhk cells with rlucrep rna yielded two distinctive rluc signal peaks, one between 2 and 10 h and the other after 26 h posttransfection. by con ... | 2003 | 12941911 |
| epitope-blocking enzyme-linked immunosorbent assays for the detection of serum antibodies to west nile virus in multiple avian species. | we report the development of epitope-blocking enzyme-linked immunosorbent assays (elisas) for the rapid detection of serum antibodies to west nile virus (wnv) in taxonomically diverse north american avian species. a panel of flavivirus-specific monoclonal antibodies (mabs) was tested in blocking assays with serum samples from wnv-infected chickens and crows. selected mabs were further tested against serum samples from birds that represented 16 species and 10 families. serum samples were collecte ... | 2003 | 12624027 |
| hepatitis c virus rna replication occurs on a detergent-resistant membrane that cofractionates with caveolin-2. | the mechanism and machinery of hepatitis c virus (hcv) rna replication are still poorly understood. in this study, we labeled de novo-synthesized viral rna in situ with bromouridine triphosphate (brutp) in huh7 cells expressing an hcv subgenomic replicon. by immunofluorescence staining using an anti-brutp antibody and confocal microscopy, we showed that the newly synthesized hcv rna was localized to distinct speckle-like structures, which also contain all of the hcv nonstructural (ns) proteins. ... | 2003 | 12634374 |
| intracellular assembly and secretion of recombinant subviral particles from tick-borne encephalitis virus. | it is believed that flavivirus assembly occurs by intracellular budding of the nucleocapsid into the lumen of the endoplasmic reticulum (er). recombinant expression of tick-borne encephalitis (tbe) virus envelope proteins prm and e in mammalian cells leads to their incorporation into enveloped recombinant subviral particles (rsps), which have been used as a model system for studying assembly and entry processes and are also promising vaccine candidates. in this study, we analyzed the formation a ... | 2003 | 12634393 |
| cytoskeletal requirements for hepatitis c virus (hcv) rna synthesis in the hcv replicon cell culture system. | hepatitis c virus (hcv) induces microtubule aggregates in infected hepatocytes. to determine if cytoskeletal elements are important for hcv rna synthesis, we examined the effect of cytoskeleton inhibitors on hcv replicon transcription in huh7 cells. the data demonstrate that hcv replication complex-mediated rna synthesis requires microtubule and actin polymerization. | 2003 | 12634397 |
| dna vaccine coding for the full-length infectious kunjin virus rna protects mice against the new york strain of west nile virus. | a plasmid dna directing transcription of the infectious full-length rna genome of kunjin (kun) virus in vivo from a mammalian expression promoter was used to vaccinate mice intramuscularly. the kun viral cdna encoded in the plasmid contained the mutation in the ns1 protein (pro-250 to leu) previously shown to attenuate kun virus in weanling mice. kun virus was isolated from the blood of immunized mice 3-4 days after dna inoculation, demonstrating that infectious rna was being transcribed in vivo ... | 2003 | 12917491 |
| potential high-throughput assay for screening inhibitors of west nile virus replication. | prevention and treatment of infection by west nile virus (wnv) and other flaviviruses are public health priorities. we describe a reporting cell line that can be used for high-throughput screening of inhibitors against all targets involved in wnv replication. dual reporter genes, encoding renilla luciferase (rluc) and neomycin phosphotransferase (neo), were engineered into a wnv subgenomic replicon, resulting in rluc/neorep. geneticin selection of bhk-21 cells transfected with rluc/neorep yielde ... | 2003 | 14610212 |
| association of japanese encephalitis virus ns3 protein with microtubules and tumour susceptibility gene 101 (tsg101) protein. | previously reported findings by our group showed that non-structural protein 3 (ns3) of japanese encephalitis virus (jev) was localized mainly in the jev-induced convoluted membrane (cm), which has been proposed to originate from rough endoplasmic reticulum (rer), golgi apparatus or the trans-golgi network (tgn), and serves as a reservoir for viral proteins during virus assembly. earlier findings indicated that ns3 of kunjin virus interacts with microtubules. in addition, one of the golgi-associ ... | 2003 | 13679614 |
| cytopathic and noncytopathic interferon responses in cells expressing hepatitis c virus subgenomic replicons. | hepatitis c virus (hcv) is the only known positive-stranded rna virus that causes persistent lifelong infections in humans. accumulation of hcv rna can be inhibited with alpha interferon (ifn-alpha) in vivo and in culture cells. we used cell-based assay systems to investigate the mechanisms responsible for the cytokine-induced inhibition of hcv replication. the results showed that ifn-alpha could suppress the accumulation of viral rna by a noncytopathic pathway and could also induce apoptosis of ... | 2003 | 14512527 |
| significance in replication of the terminal nucleotides of the flavivirus genome. | point mutations that resulted in a substitution of the conserved 3'-penultimate cytidine in genomic rna or the rna negative strand of the self-amplifying replicon of the flavivirus kunjin virus completely blocked in vivo replication. similarly, substitutions of the conserved 3'-terminal uridine in the rna negative or positive strand completely blocked replication or caused much-reduced replication, respectively. the same preference for cytidine in the 3'-terminal dinucleotide was noted in report ... | 2003 | 12970446 |
| west nile virus encephalomyelitis in horses in ontario: 28 cases. | west nile virus encephalomyelitis was diagnosed in 28 horses presented to the ontario veterinary college veterinary teaching hospital between august 20 and october 15, 2002. the age range of affected horses was 5 months to 20 years (mean 6.9 years, median 6 years). clinical signs were highly variable. duration of hospitalization ranged from < 1 to 12 days (mean 5 days, median 5.4 days). overall, 16 of the 28 (57%) horses were discharged and, of the 14 from which follow-up information was availab ... | 2003 | 12839240 |
| molecular and functional analyses of kunjin virus infectious cdna clones demonstrate the essential roles for ns2a in virus assembly and for a nonconservative residue in ns3 in rna replication. | a number of full-length cdna clones of kunjin virus (kun) were previously prepared; it was shown that two of them, pakun and flsdx, differed in specific infectivities of corresponding in vitro transcribed rnas by approximately 100,000-fold (a. a. khromykh et al., j. virol. 72:7270-7279, 1998). in this study, we analyzed a possible genetic determinant(s) of the observed differences in infectivity initially by sequencing the entire cdnas of both clones and comparing them with the published sequenc ... | 2003 | 12829820 |
| polymerase chain reaction tests for the identification of ross river, kunjin and murray valley encephalitis virus infections in horses. | to develop and validate specific, sensitive and rapid diagnostic tests using rt-pcr for the detection of ross river virus (rrv), kunjin virus (kv) and murray valley encephalitis virus (mvev) infections in horses. | 2003 | 15084017 |
| topology of the membrane-associated hepatitis c virus protein ns4b. | hepatitis c virus (hcv) belongs to the hepacivirus genus in the flaviviridae family. among the least known viral proteins in this family is the nonstructural protein ns4b, which has been suggested to be a part of the replication complex. hydrophobicity plots indicate a common profile among the ns4b proteins from different members of the flaviviridae family, suggesting a common function. in order to gain a deeper understanding of the nature of hcv ns4b, we have determined localization and topolog ... | 2003 | 12692244 |