membrane association and dimerization of a cysteine-rich, 16-kilodalton polypeptide released from the c-terminal region of the coronavirus infectious bronchitis virus 1a polyprotein.more than 10 mature proteins processed from coronavirus gene 1-encoded polyproteins have been identified in virus-infected cells. here, we report the identification of the most c-terminal cleavage product of the 1a polyprotein as a 16-kda protein in infectious bronchitis virus-infected vero cells. indirect immunofluorescence demonstrated that the protein exhibits a distinct perinuclear punctate staining pattern, suggesting that it is associated with cellular membranes. positive staining observed ...200212021359
a single mutation in the e2 glycoprotein important for neurovirulence influences binding of sindbis virus to neuroblastoma cells.the amino acid at position 55 of the e2 glycoprotein (e2(55)) of sindbis virus (sv) is a critical determinant of sv neurovirulence in mice. recombinant virus strain te (e2(55) = histidine) differs only at this position from virus strain 633 (e2(55)= glutamine), yet te is considerably more neurovirulent than 633. te replicates better than 633 in a neuroblastoma cell line (n18), but similarly in bhk cells. immunofluorescence staining showed that most n18 cells were infected by te at a multiplicity ...200212021363
vector infection determinants of venezuelan equine encephalitis virus reside within the e2 envelope glycoprotein.epizootic subtype iab and ic venezuelan equine encephalitis viruses (veev) readily infect the epizootic mosquito vector aedes taeniorhynchus. the inability of enzootic subtype ie viruses to infect this mosquito species provides a model system for the identification of natural viral determinants of vector infectivity. to map mosquito infection determinants, reciprocal chimeric viruses generated from epizootic subtype iab and enzootic ie veev were tested for mosquito infectivity. chimeras containi ...200212021373
postsynaptic expression of a new calcium pathway in hippocampal ca3 neurons and its influence on mossy fiber long-term potentiation.long-term potentiation (ltp) in the ca1 region of the hippocampus is induced by postsynaptic ca(2+) influx via nmda receptors (nmdars). however, this synaptic plasticity occurs independently of nmdars when ca(2+)-permeable ampa receptors (ampars) are expressed at postsynaptic sites using various genetic techniques, indicating that an increase in ca(2+) level at critical postsynaptic sites, regardless of its entry pathway, triggers the induction of ltp at ca1 synapses. in contrast, nmdars are spa ...200212040036
multiple mechanisms for the potentiation of ampa receptor-mediated transmission by alpha-ca2+/calmodulin-dependent protein kinase ii.some forms of activity-dependent synaptic potentiation require the activation of postsynaptic ca(2+)/calmodulin-dependent protein kinase ii (camkii). activation of camkii has been shown to phosphorylate the glutamate receptor 1 subunit of the ampa receptor (ampar), thereby affecting some of the properties of the receptor. here, a recombinant, constitutively active form of alphacamkii tagged with the fluorescent marker green fluorescent protein (gfp) [alphacamkii(1-290)-enhanced gfp (egfp)] was e ...200212040047
contribution of t cells to mortality in neurovirulent sindbis virus encephalomyelitis.intranasal inoculation of c57bl/6 mice with a neurovirulent strain of sindbis virus (sv) results in fatal encephalomyelitis. mice with selective immune deficiencies were studied to determine the role of the immune response in fatal outcome. mortality was decreased in mice deficient in alphabeta, but not gammadelta, t cells demonstrating a contribution of alphabeta t cells. mice lacking either cd4+ or cd8+ t cells also had reduced mortality and mice lacking interferon (ifn)-gamma were completely ...200212044981
interferons mediate terminal differentiation of human cortical thymic epithelial the thymus, epithelial cells comprise a heterogeneous population required for the generation of functional t lymphocytes, suggesting that thymic epithelium disruption by viruses may compromise t-cell lymphopoiesis in this organ. in a previous report, we demonstrated that in vitro, measles virus induced differentiation of cortical thymic epithelial cells as characterized by (i) cell growth arrest, (ii) morphological and phenotypic changes, and (iii) apoptotis as a final step of this process. i ...200212050353
previously infected and recovered chimpanzees exhibit rapid responses that control hepatitis c virus replication upon rechallenge.responses in three chimpanzees were compared following challenge with a clonal hepatitis c virus (hcv) contained in plasma from an animal that had received infectious rna transcripts. two of the chimpanzees (ch1552 and chx0186) had recovered from a previous infection with hcv, while the third (ch1605) was a naïve animal. all animals were challenged by reverse titration with decreasing dilutions of plasma and became serum rna positive following challenge. ch1605 displayed a typical disease profil ...200212050371
asymmetric requirement for cholesterol in receptor-bearing but not envelope-bearing membranes for fusion mediated by ecotropic murine leukemia virus.we show that fusion mediated by ecotropic murine leukemia virus envelope is dependent on cholesterol in receptor-bearing membranes. the effect is >10 times larger in insect cells than mammalian cells, probably because the former can be more extensively depleted of cholesterol. the fact that cholesterol is apparently not needed in envelope-bearing membranes suggests that it plays a role in an asymmetric step in membrane fusion and argues against a class of models in which cholesterol is important ...200212050383
protein disulfide isomerase, a component of the estrogen receptor complex, is associated with chlamydia trachomatis serovar e attached to human endometrial epithelial cells.chlamydia trachomatis serovar e, the leading bacterial agent responsible for sexually transmitted diseases, is required to invade genital epithelial cells for its growth and survival, yet little is known about the adhesin-receptor interactions promoting its entry. in contrast, much has been published on the heparan sulfate receptor for binding c. trachomatis l2 elementary bodies (ebs) prior to entry into hela cells. using a different experimental approach in which a biotinylated apical membrane ...200212065480
inhibitor specificity of recombinant and endogenous caspase-9.apoptosis triggered through the intrinsic pathway by radiation and anti-neoplastic drugs is initiated by the activation of caspase-9. to elucidate control mechanisms in this pathway we used a range of synthetic and natural reagents. the inhibitory potency of acetyl-asp-glu-val-asp-aldehyde ('ac-devd-cho'), benzyloxycarbonyl-val-ala-asp-fluoromethylketone ('z-vad-fmk') and the endogenous caspase inhibitor x-chromosome-linked inhibitor of apoptosis protein ('xiap') against recombinant caspase-9 we ...200212067274
fusion of alphaviruses with liposomes is a non-leaky has been reported that low-ph-induced fusion of influenza virus with liposomes results in rapid and extensive release of both low- and high-molecular-weight substances from the liposomes [günther-ausborn et al., j. biol. chem. 270 (1995) 29279-29285; shangguan et al., biochemistry 35 (1996) 4956-4965]. here, we demonstrate retention of encapsulated water-soluble compounds during fusion of semliki forest virus (sfv) or sindbis virus with liposomes at low ph. under conditions allowing complete ...200212067727
mass spectrometry-based proteolytic mapping for rapid virus identification.a novel method is proposed for rapid identification of viruses and other organisms that show a low number of biomarkers, based on the construction of databases of organism-specific tryptic peptide masses. the peptide products of any protease that cuts at specific residues can be accommodated. experimentally, a sample of intact virus, e.g., one collected from the atmosphere, is digested with a selective protease for a short time, and the digestion products are analyzed by maldi-tof mass spectrome ...200212069233
the lipopolysaccharide and beta-1,3-glucan binding protein gene is upregulated in white spot virus-infected shrimp (penaeus stylirostris).pattern recognition proteins such as lipopolysaccharide and beta-1,3-glucan binding protein (lgbp) play an important role in the innate immune response of crustaceans and insects. random sequencing of cdna clones from a hepatopancreas cdna library of white spot virus (wsv)-infected shrimp provided a partial cdna (psest-289) that showed similarity to the lgbp gene of crayfish and insects. subsequently full-length cdna was cloned by the 5'-race (rapid amplification of cdna ends) technique and sequ ...200212072514
aura virus structure suggests that the t=4 organization is a fundamental property of viral structural proteins.aura and sindbis viruses are closely related alphaviruses. unlike other alphaviruses, aura virus efficiently encapsidates both genomic rna (11.8 kb) and subgenomic rna (4.2 kb) to form virus particles. previous studies on negatively stained aura virus particles predicted that there were two major size classes with potential t=3 and t=4 capsid structures. we have used cryoelectron microscopy and three-dimensional image reconstruction techniques to examine the native morphology of different classe ...200212072523
positional cloning of the murine flavivirus resistance gene.inbred mouse strains exhibit significant differences in their susceptibility to viruses in the genus flavivirus, which includes human pathogens such as yellow fever, dengue, and west nile virus. a single gene, designated flv, confers this differential susceptibility and was mapped previously to a region of mouse chromosome 5. a positional cloning strategy was used to identify 22 genes from the flv gene interval including 10 members of the 2'-5'-oligoadenylate synthetase gene family. one 2'-5'-ol ...200212080145
involvement of fes/fps tyrosine kinase in semaphorin3a signaling.collapsin response mediator proteins (crmps)/toad64/ulips/drps and cram have emerged as strong candidates for a role in semaphorin signaling. in this study we identified fes/fps (fes) tyrosine kinase in the crmp-cram complex and investigated whether fes was involved in semaphorin3a (sema3a) signaling. in cos-7 cells, the interaction between fes and plexina1 (plexa1) and the tyrosine phosphorylation of plexa1 by fes were observed; however, these events were significantly attenuated by co-expressi ...200212093729
prolonged arthritis associated with sindbis-related (pogosta) virus infection. 200212096239
matrix metalloproteinase expression correlates with virulence following neurotropic mouse hepatitis virus infection.the relationship(s) between viral virulence and matrix metalloproteinase (mmp) expression in the central nervous system (cns) of mice undergoing lethal and sublethal infections with neurotropic mouse hepatitis virus was investigated. lethal infection induced increased levels of mmp-3 and mmp-12 mrnas as well as that of tissue inhibitor of matrix metalloproteinases 1 (timp-1) compared to sublethal infection. increased induction of mmp, timp, and chemokine expression correlated with increased viru ...200212097550
generation of amyloid beta peptide with pyroglutamate at position 3 in primary cortical neurons.the majority of amyloid beta peptide (abeta) deposited in the brains of alzheimer's disease (ad) patients is n-truncated, especially abeta starting with pyroglutamate at position 3 (abeta(3(pe))). to develop a system in which abeta(3(pe)) is generated in primary neurons and to clarify the cyclization mechanism of n-terminal glutamate, we constructed amyloid precursor protein complementary dnas which encoded a potential precursor for abeta(3(pe)) by amino acid substitution and deletion. among the ...200212098492
alphavirus vectors for gene therapy applications.high-titer alphavirus vectors have been generated for efficient gene delivery both in vitro and in vivo. studies on cns infection via intranasal and peripheral injections with virulent and avirulent replication-competent semliki forest virus (sfv) strains has demonstrated the potential of gene delivery. replication-deficient alphavirus particles have shown high local transgene expression of a transient nature in rodent brain. alphavirus vectors have been demonstrated to induce apoptosis in infec ...200112109136
inactivation of lipid enveloped viruses by octanoic acid treatment of immunoglobulin solution.inactivation of lipid enveloped viruses by treatment with octanoic acid has been investigated for three intravenous immunoglobulin preparations, using human immunodeficiency virus, bovine viral diarrhoea virus, sindbis virus and pseudorabies virus as test viruses. at a concentration of 7.45 g octanoic acid per kg solution complete inactivation of lipid enveloped viruses to below detectable level (>5.36, >4.68, >6.25 and >5.55 log(10), respectively) was achieved within the first minutes of treatm ...200212127315
avian reoviruses cause apoptosis in cultured cells: viral uncoating, but not viral gene expression, is required for apoptosis induction.the cytopathic effect evidenced by cells infected with avian reovirus s1133 suggests that this virus may induce apoptosis in primary cultures of chicken embryo fibroblasts. in this report we present evidence that avian reovirus infection of cultured cells causes activation of the intracellular apoptotic program and that this activation takes place during an early stage of the viral life cycle. the ability of avian reoviruses to induce apoptosis is not restricted to a particular virus strain or t ...200212133997
mutations that affect the tropism of da and gdvii strains of theiler's virus in vitro influence sialic acid binding and pathogenicity.theiler's murine encephalomyelitis virus (tmev) is a natural pathogen of the mouse. the different strains of tmev are divided into two subgroups according to the pathology they provoke. the neurovirulent strains gdvii and fa induce an acute fatal encephalitis, while persistent strains, like da and bean, cause a chronic demyelinating disease associated with viral persistence in the central nervous system. different receptor usage was proposed to account for most of the phenotype difference betwee ...200212134019
critical role for protein tyrosine phosphatase shp-1 in controlling infection of central nervous system glia and demyelination by theiler's murine encephalomyelitis virus.we previously characterized the expression and function of the protein tyrosine phosphatase shp-1 in the glia of the central nervous system (cns). in the present study, we describe the role of shp-1 in virus infection of glia and virus-induced demyelination in the cns. for in vivo studies, shp-1-deficient mice and their normal littermates received an intracerebral inoculation of an attenuated strain of theiler's murine encephalomyelitis virus (tmev). at various times after infection, virus repli ...200212134038
heparan sulfate mediates infection of high-neurovirulence theiler's viruses.the mechanisms by which theiler's murine encephalomyelitis virus (tmev) binds and enters host cells and the molecules involved are not completely understood. in this study, we demonstrate that the high-neurovirulence tmev gdvii virus uses the glycosaminoglycan heparan sulfate (hs) as an attachment factor that is required for efficient infection. studies based on soluble hs-mediated inhibition of attachment and infection, removal of hs with specific enzymes, and blocking with anti-hs antibodies e ...200212134043
sphingolipid and cholesterol dependence of alphavirus membrane fusion. lack of correlation with lipid raft formation in target liposomes.semliki forest virus (sfv) and sindbis virus (sin) are enveloped viruses that infect their host cells by receptor-mediated endocytosis and subsequent fusion from within acidic endosomes. fusion of the viral envelope requires the presence of both cholesterol and sphingolipids in the target membrane. this is suggestive of a possible involvement of sphingolipid-cholesterol microdomains, or "lipid rafts," in the membrane fusion and cell entry process of the virus. in this study, large unilamellar ve ...200212138173
transmission studies of a european sindbis virus in the floodwater mosquito aedes vexans (diptera: culicidae).sindbis viruses are arthropod-borne viruses, which are maintained in nature in a culex mosquito-bird associated transmission cycle, but aedes species have been suspected as playing a role in infecting humans. in this study, we addressed the question whether or not germany's most abundant floodwater mosquito species aedes vexans (diptera, culicidae) can serve as an efficient vector for sindbis viruses. firstly, the overall susceptibility of ae. vexans was tested by intrathoracic inoculation of 40 ...200212141742
phylogenetic relationships of southern african west nile virus isolates.phylogenetic relationships were examined for 29 southern african west nile virus (formal name west nile virus [wnv]) isolates from various sources in four countries from 1958 to 2001. in addition, sequence data were retrieved from genbank for another 23 wnv isolates and kunjin and japanese encephalitis viruses. all isolates belonged to two lineages. lineage 1 isolates were from central and north africa, europe, israel, and north america; lineage 2 isolates were from central and southern africa a ...200212141968
axonal protein synthesis provides a mechanism for localized regulation at an intermediate axons grow past intermediate targets, they change their responsiveness to guidance cues. local upregulation of receptor expression is involved, but the mechanisms for this are not clear. here protein synthesis is traced within individual axons by introducing rnas encoding visualizable reporters. individual severed axons and growth cones can translate proteins and also export them to the cell surface. as axons reach the spinal cord midline, epha2 is among the receptors upregulated on at least ...200212150930
alphavirus minus-strand rna synthesis: identification of a role for arg183 of the nsp4 polymerase.a partially conserved region spanning amino acids 142 to 191 of the sindbis virus (sin) nsp4 core polymerase is implicated in host restriction, elongation, and promoter recognition. we extended the analysis of this region by substituting ser, ala, or lys for a highly conserved arg183 residue immediately preceding its absolutely conserved ser184-ala-val-pro-ser188 sequence. in chicken cells, the nsp4 arg183 mutants had a nonconditionally lethal, temperature-sensitive (ts) growth phenotype caused ...200212163582
modification of asn374 of nsp1 suppresses a sindbis virus nsp4 minus-strand polymerase mutant.our recent study (c. l. fata, s. g. sawicki, and d. l. sawicki, j. virol. 76:8632-8640, 2002) found minus-strand synthesis to be temperature sensitive in vertebrate and invertebrate cells when the arg183 residue of the sindbis virus nsp4 polymerase was changed to ser, ala, or lys. here we report the results of studies identifying an interacting partner of the region of the viral polymerase containing arg183 that suppresses the ser183 codon mutation. large-plaque revertants were observed readily ...200212163583
enhanced neurovirulence of borna disease virus variants associated with nucleotide changes in the glycoprotein and l polymerase genes.borna disease virus (bdv) infection produces a variety of clinical diseases, from behavioral illnesses to classical fatal encephalitis (i.e., borna disease [bd]). since the genomes of most bdv isolates differ by less than 5%, host factors are believed responsible for much of the reported variability in disease expression. the contribution of bdv genomic differences to variation in bd expression is largely unexplored. here we compared the clinical outcomes of rats infected with one of two related ...200212163584
[viral encephalitis caused by biowarfare agents].many viruses may cause encephalitis. three such viruses of the alpha genus (venezuelan equine encephalitis (vee), western equine encephalitis (wee) and eastern equine encephalitis (eee)) may be used as biological warfare agents. the clinical course of the diseases caused by these viruses is not specific, and resembles a broad range of bacterial and viral diseases. several attenuated and inactivated vaccines were developed, but their efficacy in the biological warfare scenario is questionable. th ...200212170555
in vivo gene transfer using a nonprimate lentiviral vector pseudotyped with ross river virus glycoproteins.vectors derived from lentiviruses provide a promising gene delivery system. we examined the in vivo gene transfer efficiency and tissue or cell tropism of a feline immunodeficiency virus (fiv)-based lentiviral vector pseudotyped with the glycoproteins from ross river virus (rrv). rrv glycoproteins were efficiently incorporated into fiv virions, generating preparations of fiv vector, which after concentration attain titers up to 1.5 x 10(8) tu/ml. after systemic administration, rrv-pseudotyped fi ...200212186920
epstein-barr virus ebna2 blocks nur77- mediated apoptosis.epstein-barr virus infection in vitro immortalizes primary b cells. ebna2 is an epstein-barr virus-encoded transcriptional transactivator that mimics the effects of activated notch signaling and is essential for this proliferative response. an assay using sindbis virus (sv) as a cell death inducer revealed that, like notch, ebna2 also has antiapoptotic activity. we show that nur77 is a mediator of sv-induced cell death and that ebna2 antiapoptotic activity results from interaction with nur77. eb ...200212195020
selective electrical silencing of mammalian neurons in vitro by the use of invertebrate ligand-gated chloride channels.selectively reducing the excitability of specific neurons will (1) allow for the creation of animal models of human neurological disorders and (2) provide insight into the global function of specific sets of neurons. we focus on a combined genetic and pharmacological approach to silence neurons electrically. we express invertebrate ivermectin (ivm)-sensitive chloride channels (caenorhabditis elegans glucl alpha and beta) with a sindbis virus and then activate these channels with ivm to produce i ...200212196558
acid-induced movements in the glycoprotein shell of an alphavirus turn the spikes into membrane fusion the icosahedral (t = 4) semliki forest virus, the envelope protomers, i.e. e1-e2 heterodimers, make one-to-one interactions with capsid proteins below the viral lipid bilayer, transverse the membrane and form an external glycoprotein shell with projections. the shell is organized by protomer domains interacting as hexamers and pentamers around shell openings at icosahedral 2- and 5-fold axes, respectively, and the projections by other domains associating as trimers at 3- and quasi 3-fold axes ...200212198142
bioprocess applications of a sindbis virus-based temperature-inducible expression system.the production and study of toxic proteins requires inducible expression systems with low basal level expression and high inducibility. here, we describe bioprocess applications of the pcytts temperature-regulatable sindbis virus replicon-based expression system. we used green fluorescent protein as a marker protein to optimize the selection of stable transfected clones with increased expression levels. using the optimized protocol, clones were constructed that produced the growth-inhibiting, an ...200212209807
effect of sample storage conditions on virus inactivation by solvent/detergent. 200212217349
coxiella burnetii localizes in a rab7-labeled compartment with autophagic characteristics.the obligate intracellular bacterium coxiella burnetii, the agent of q fever in humans and of coxiellosis in other animals, survives and replicates within large, acidified, phagolysosome-like vacuoles known to fuse homo- and heterotypically with other vesicles. to further characterize these vacuoles, hela cells were infected with c. burnetii phase ii; 48 h later, bacteria-containing vacuoles were labeled by lysotracker, a marker of acidic compartments, and accumulated monodansylcadaverine and di ...200212228312
in vitro analysis of factors involved in the disassembly of sindbis virus cores by 60s ribosomal subunits identifies a possible role of low ph.disassembly of alphavirus cores early in infection involves interaction of the core with 60s ribosomal subunits. this interaction might be subjected to regulatory processes. we have established an in vitro system of core disassembly in order to identify cellular proteins involved in the regulation of disassembly. no evidence for the existence of such proteins was found, but it became apparent that certain organic solvents and detergents or a high proton concentration (ph 6.0) stimulated core dis ...200212237423
adaptation of alphaviruses to heparan sulfate: interaction of sindbis and semliki forest viruses with liposomes containing lipid-conjugated heparin.passage of sindbis virus (sin) in bhk-21 cells has been shown to select for virus mutants with high affinity for the glycosaminoglycan heparan sulfate (hs). three loci in the viral spike protein e2 (e2:1, e2:70, and e2:114) have been identified that mutate during adaptation and independently confer on the virus the ability to bind to cell surface hs (w. b. klimstra, k. d. ryman, and r. e. johnston, j. virol. 72:7357-7366, 1998). in this study, we used hs-adapted sin mutants to evaluate a new mod ...200212239287
molecular genetic evidence that the hydrophobic anchors of glycoproteins e2 and e1 interact during assembly of alphaviruses.chimeric alphaviruses in which the 6k and glycoprotein e1 moieties of sindbis virus are replaced with those of ross river virus grow very poorly, but upon passage, adapted variants arise that grow >100 times better. we have sequenced the entire domain encoding the e2, 6k, and e1 proteins of a number of these adapted variants and found that most acquired two amino acid changes, which had cumulative effects. in three independent passage series, amino acid 380 of e2, which is in the transmembrane d ...200212239293
role for human immunodeficiency virus type 1 membrane cholesterol in viral internalization.the membrane of human immunodeficiency virus type 1 (hiv-1) virions contains high levels of cholesterol and sphingomyelin, an enrichment that is explained by the preferential budding of the virus through raft microdomains of the plasma membrane. upon depletion of cholesterol from hiv-1 virions with methyl-beta-cyclodextrin, infectivity was almost completely abolished. in contrast, this treatment had only a mild effect on the infectiousness of particles pseudotyped with the g envelope of vesicula ...200212239312
bcl-2 and bax protect adult mice from lethal sindbis virus infection but do not protect spinal cord motor neurons or prevent paralysis.cellular proteins that regulate apoptotic cell death can modulate the outcome of sindbis virus (sv) encephalitis in mice. both endogenous and overexpressed bcl-2 and bax proteins protect newborn mice from fatal sv infection by blocking apoptosis in infected neurons. to determine the effects of these cellular factors on the course of infection in older animals, a more neurovirulent sv vector (dsnsv) was constructed from a viral strain that causes both prominent spinal cord infection with hind-lim ...200212239316
influenza virus can enter and infect cells in the absence of clathrin-mediated endocytosis.influenza virus has been described to enter host cells via clathrin-mediated endocytosis. however, it has also been suggested that other endocytic routes may provide additional entry pathways. here we show that influenza virus may enter and infect hela cells that are unable to take up ligands by clathrin-mediated endocytosis. by overexpressing a dominant-negative form of the eps15 protein to inhibit clathrin-mediated endocytosis, we demonstrate that while transferrin uptake and semliki forest vi ...200212239322
[sindbis-related (pogosta) virus epidemics every seventh year--does the biblical cycle come true again?]. 200212271600
isolation of arboviruses from mosquitoes (diptera: culicidae) collected from the gulf plains region of northwest queensland, part of investigations into japanese encephalitis (je) virus and related flaviviruses in northern australia, 153,529 mosquitoes were collected and processed for virus isolation from the gulf plains region of northwest queensland. collections from within 30 km of each of the townships of croydon, normanton and karumba yielded 3,087 (2.0%), 66,009 (43.0%), and 84,433 (55.0%) mosquitoes, respectively, from which 16 viruses were isolated. four isolates of murray valley encephalitis (mve), two of ...200212349863
video complicates stem-cell debate. 200212357222
suppression of lipopolysaccharide-induced antiviral transcription factor (stat-1 and nf-kappa b) complexes by antibody-dependent enhancement of macrophage infection by ross river virus.subneutralizing concentrations of antibody may enhance virus infection by bringing the virus-antibody complex into contact with the cell surface fc receptors; this interaction facilitates entry of virus into the cell and is referred to as antibody-dependent enhancement (ade) of infection. northern analysis of macrophage rna demonstrated that ade infection by the indigenous australian alphavirus ross river (rrv-ade) ablated or diminished message for tumor necrosis factor alpha (tnf-alpha), nitric ...200212364588
engineered viruses to select genes encoding secreted and membrane-bound proteins in mammalian cells.we have developed a functional genomics tool to identify the subset of cdnas encoding secreted and membrane-bound proteins within a library (the 'secretome'). a sindbis virus replicon was engineered such that the envelope protein precursor no longer enters the secretory pathway. cdna fragments were fused to the mutant precursor and expression screened for their ability to restore membrane localization of envelope proteins. in this way, recombinant replicons were released within infectious viral ...200212364608
systematic assembly of a full-length infectious cdna of mouse hepatitis virus strain a59.a novel method was developed to assemble a full-length infectious cdna of the group ii coronavirus mouse hepatitis virus strain a59 (mhv-a59). seven contiguous cdna clones that spanned the 31.5-kb mhv genome were isolated. the ends of the cdnas were engineered with unique junctions and assembled with only the adjacent cdna subclones, resulting in an intact mhv-a59 cdna construct of approximately 31.5 kb in length. the interconnecting restriction site junctions that are located at the ends of eac ...200212368349
in vitro-assembled alphavirus core-like particles maintain a structure similar to that of nucleocapsid cores in mature vitro-assembled core-like particles produced from alphavirus capsid protein and nucleic acid were studied by cryoelectron microscopy. these particles were found to have a diameter of 420 a with 240 copies of the capsid protein arranged in a t=4 icosahedral surface lattice, similar to the nucleocapsid core in mature virions. however, when the particles were subjected to gentle purification procedures, they were damaged, preventing generation of reliable structural information. similarly, purif ...200212368355
alphaviral gene transfer in neurobiology.semliki forest virus (sfv), sindbis virus (sin), and venezuelan equine encephalitis virus are simple, enveloped plus-strand rna viruses belonging to the alphavirus genus of the togaviridae family. they have been developed into expression vectors that infect a wide host cell range and cause rapid and high-level transgene expression. their easy and fast generation, classification into biosafety levels 1 and 2, and preferential transduction of neurons in cell and tissue cultures makes them an incre ...200212372543
induction of cytolytic anti-gal antibodies in alpha-1,3-galactosyltransferase gene knockout mice by oral inoculation with escherichia coli o86:b7 bacteria.naturally occurring antibodies against [gal alpha-1,3-gal] structures (anti-gal antibodies) are the primary effectors of human hyperacute rejection (har) of nonhuman tissue. unlike most mammals, humans lack a functional alpha-1,3-galactosyltransferase (galt) gene and produce abundant anti-gal antibodies, putatively in response to galt(+) enteric bacteria. galt knockout (ko) mice have been generated as a small animal model of har but inconsistently express anti-gal antibodies. we hypothesized tha ...200212379700
roles of nonstructural protein nsp2 and alpha/beta interferons in determining the outcome of sindbis virus infection.alphaviruses productively infect a variety of vertebrate and insect cell lines. in vertebrate cells, sindbis virus redirects cellular processes to meet the needs of virus propagation. at the same time, cells respond to virus replication by downregulating virus growth and preventing dissemination of the infection. the balance between these two mechanisms determines the outcome of infection at the cellular and organismal levels. in this report, we demonstrate that a viral nonstructural protein, ns ...200212388685
role of the alfalfa mosaic virus methyltransferase-like domain in negative-strand rna synthesis.rnas 1 and 2 of the tripartite genome of alfalfa mosaic virus (amv) encode the replicase proteins p1 and p2, respectively. p1 contains a methyltransferase-like domain in its n-terminal half, which has a putative role in capping the viral rnas. six residues in this domain that are highly conserved in the methyltransferase domains of alphavirus-like viruses were mutated individually in amv p1. none of the mutants was infectious to plants. mutant rna 1 was coexpressed with wild-type (wt) rnas 2 and ...200212388692
reovirus-induced apoptosis requires mitochondrial release of smac/diablo and involves reduction of cellular inhibitor of apoptosis protein levels.many viruses belonging to diverse viral families with differing structure and replication strategies induce apoptosis both in cultured cells in vitro and in tissues in vivo. despite this fact, little is known about the specific cellular apoptotic pathways induced during viral infection. we have previously shown that reovirus-induced apoptosis of hek cells is initiated by death receptor activation but requires augmentation by mitochondrial apoptotic pathways for its maximal expression. we now sho ...200212388702
stable expression of primary human immunodeficiency virus type 1 structural gene products by use of a noncytopathic sindbis virus vector.efficient expression of the human immunodeficiency virus type 1 (hiv-1) structural gene products gag, pol, and env involves the regulation by viral rev and rev-responsive elements (rre). removal of multiple inhibitory sequences (ins) in the coding regions of these structural genes or modification of the codon usage patterns of hiv-1 genes to those used by highly expressed human genes has been found to significantly increase hiv-1 structural protein expression in the absence of rev and rre. in th ...200212388704
generation of a replication-competent, propagation-deficient virus vector based on the transmissible gastroenteritis coronavirus genome.replication-competent propagation-deficient virus vectors based on the transmissible gastroenteritis coronavirus (tgev) genome that are deficient in the essential e gene have been developed by complementation within e(+) packaging cell lines. cell lines expressing the tgev e protein were established using the noncytopathic sindbis virus replicon psinrep21. in addition, cell lines stably expressing the e gene under the cmv promoter have been developed. the sindbis replicon vector and the ectopic ...200212388713
placement of the structural proteins in sindbis virus.the structure of the lipid-enveloped sindbis virus has been determined by fitting atomic resolution crystallographic structures of component proteins into an 11-a resolution cryoelectron microscopy map. the virus has t=4 quasisymmetry elements that are accurately maintained between the external glycoproteins, the transmembrane helical region, and the internal nucleocapsid core. the crystal structure of the e1 glycoprotein was fitted into the cryoelectron microscopy density, in part by using the ...200212388725
age-dependent resistance to lethal alphavirus encephalitis in mice: analysis of gene expression in the central nervous system and identification of a novel interferon-inducible protective gene, mouse isg12.several different mammalian neurotropic viruses produce an age-dependent encephalitis characterized by more severe disease in younger hosts. to elucidate potential factors that contribute to age-dependent resistance to lethal viral encephalitis, we compared central nervous system (cns) gene expression in neonatal and weanling mice that were either mock infected or infected intracerebrally with a recombinant strain, dste12q, of the prototype alphavirus sindbis virus. in 1-day-old mice, infection ...200212388728
induction of cytotoxic t-lymphocytes specific for bovine herpesvirus-1 by dna immunization.cytotoxic t-lymphocytes (ctls) are critical for the defense against herpesvirus infections, in which cell-to-cell spread occurs earlier than the hematogenous spread. the ability of bovine herpesvirus-1 (bhv-1) to undergo latency, to induce apoptosis of cd4(+) t-lymphocytes, and to down-regulate the expression of major histocompatibility complex (mhc) class i molecules, necessitates the development of immunization strategies that do not involve the live virus. the objective of this study was to e ...200212399204
epidemiology of sindbis virus infections in finland 1981-96: possible factors explaining a peculiar disease pattern.pogosta disease (pd), an epidemic rash-arthritis occurring in late summer is caused by sindbis virus (sinv) and is transmitted to humans by mosquitoes. altogether 2183 pd cases were serologically confirmed 1981-96 in finland, with an annual incidence of 2.7/100000 (18 in the most endemic area of northern karelia). the annual average was 136 (varying from 1 to 1282) with epidemics occurring in august-september with a 7-year interval. studies on 6320 patients with suspected rubella (1973-89) revea ...200212403109
cell proteins tia-1 and tiar interact with the 3' stem-loop of the west nile virus complementary minus-strand rna and facilitate virus was reported previously that four baby hamster kidney (bhk) proteins with molecular masses of 108, 60, 50, and 42 kda bind specifically to the 3'-terminal stem-loop of the west nile virus minus-stand rna [wnv 3'(-) sl rna] (p. y. shi, w. li, and m. a. brinton, j. virol. 70:6278-6287, 1996). in this study, p42 was purified using an rna affinity column and identified as tiar by peptide sequencing. a 42-kda uv-cross-linked viral rna-cell protein complex formed in bhk cytoplasmic extracts incubat ...200212414941
the myxoma poxvirus protein, m11l, prevents apoptosis by direct interaction with the mitochondrial permeability transition pore.m11l, an antiapoptotic protein essential for the virulence of the myxoma poxvirus, is targeted to mitochondria and prevents the loss of mitochondrial membrane potential that accompanies cell death. in this study we show, using a cross-linking approach, that m11l physically associates with the mitochondrial peripheral benzodiazepine receptor (pbr) component of the permeability transition (pt) pore. close association of m11l and the pbr is also indicated by fluorescence resonance energy transfer ( ...200212417624
interfacial domains in sindbis virus 6k protein. detection and functional characterization.alphavirus 6k is a short, constitutive membrane protein involved in virus glycoprotein processing, membrane permeabilization, and the budding of virus particles. the amino-terminal region that immediately precedes the transmembrane anchor contains a conserved sequence motif consisting of two interfacial domains separated by asn and gln residues. the presence of this motif confers on the 6k pretransmembrane region the tendency to partition into the membrane interface. to study the functional impo ...200312424249
dissection of c-mos degron.c-mos, a map kinase kinase kinase, is a regulator of oocyte maturation. the concentration of c-mos is controlled in part through its conditional degradation. previous studies proposed the "second-codon rule", according to which the n-terminal proline (pro) of c-mos is a destabilizing residue that targets c-mos for degradation. we analyzed the degradation signal (degron) of c-mos in xenopus oocytes, found it to be a portable degron, and demonstrated that, contrary to the model above, the n-termin ...200212426378
alphaviral vectors for gene transfer into neurons.alphaviruses are small, enveloped positive-strand rna viruses that have been successfully transformed into expression vectors in the case of semliki forest virus (sfv), sindbis virus (sin), and venezuelan equine encephalitis virus. compared to other viral vectors, their advantages are easy and fast generation of recombinant viral particles, rapid onset, and high-level transgene expression. when applied to neuronal tissue, sfv and sin vectors possess the additional advantage of efficiently and pr ...200212428755
broad-spectrum virus reduction in red cell concentrates using inactine pen110 chemistry.the risk of transmission of blood-borne pathogens by transfusion is a persistent problem in medicine. to address this safety issue, inactine pen110 chemistry is being utilized to develop a process for preparing pathogen-reduced red blood cell concentrates (rbcc). the purpose of this study was to characterize the virucidal effectiveness of the inactine pen110 chemistry in full units of rbcc by using a panel of viruses with diverse properties in composition, size and shape.200212437518
effects of membrane potential and sphingolipid structures on fusion of semliki forest virus.cells expressing the e1 and e2 envelope proteins of semliki forest virus (sfv) were fused to voltage-clamped planar lipid bilayer membranes at low ph. formation and evolution of fusion pores were electrically monitored by capacitance measurements, and membrane continuity was tracked by video fluorescence microscopy by including rhodamine-phosphatidylethanolamine in the bilayer. fusion occurred without leakage for a negative potential applied to the trans side of the planar membrane. when a posit ...200212438595
novel mutations that control the sphingolipid and cholesterol dependence of the semliki forest virus fusion protein.the enveloped alphavirus semliki forest virus (sfv) infects cells via a membrane fusion reaction mediated by the e1 membrane protein. efficient sfv-membrane fusion requires the presence of cholesterol and sphingolipid in the target membrane. here we report on two mutants, srf-4 and srf-5, selected for growth in cholesterol-depleted cells. like the previously isolated srf-3 mutant (e1 proline 226 to serine), the phenotypes of the srf-4 and srf-5 mutants were conferred by single-amino-acid changes ...200212438597
endocytosis is a critical step in entry of subgroup b avian leukosis viruses.the avian leukosis virus (alv) entry mechanism is controversial, with evidence for and against a low-ph requirement for viral fusion. to further address this question, we tested the entry of human immunodeficiency virus type 1 (hiv-1) pseudotyped with the envelope protein of subgroup b alv (alv-b) in the presence of three different lysosomotropic agents. these lysosomotropic agents were able to block the entry of wild-type and pseudotyped alv-b in two different cell lines, strongly suggesting th ...200212438612
polysulfonates derived from metal thiolate complexes as inhibitors of hiv-1 and various other enveloped viruses in vitro.sodium 2-mercaptoethanesulfonate reacts with the metal ions pd(ii), pt(ii), ag(i), cd(ii) and zn(ii) to yield complexes containing multiple anionic sulfonate sites. on the basis of spectroscopic and other analytical data the complexes were assigned the tentative molecular formulas: pd6(sch2ch2so3na)12, ptn(sch2ch2so3na)2n+2, agn(sch2ch2so3na)n, na2zn4(sch2ch2so3na)10, and na2cd4(sch2ch2so3na)10. the complexes displayed a variety of differences in activity towards dna and rna viruses. the platinu ...200212448691
in vivo antitumor activity of sindbis viral vectors.sindbis virus, a blood-borne virus transmitted by mosquitoes, has been used as a vector to efficiently express exogenous genes in vitro and in vivo and to induce apoptosis. because sindbis virus infects mammalian cells by interacting with the high-affinity laminin receptors, which are expressed at higher levels in several human cancers than in normal cells, we determined whether a sindbis viral vector could be used to target cancers in vivo.200212464651
study of caspase inhibitors for limiting death in mammalian cell culture.apoptosis in mammalian cell culture is associated with decreased bioproduct yields and can be inhibited through altering the intracellular signaling pathways mediating programmed cell death. in this study, we evaluated the capacity to inhibit caspases to maintain high viable cell numbers in cho and 293 cultures. two genetic caspase inhibitors, xiap and crma, were examined along with a mutant of each, xiap-bir123nc, which contains three bir domains but lacks the ring finger, and crma-dqmd, which ...200312474256
transcription strategy in a closterovirus: a novel 5'-proximal controller element of citrus tristeza virus produces 5'- and 3'-terminal subgenomic rnas and differs from 3' open reading frame controller elements.citrus tristeza virus (ctv) produces more than thirty 3'- or 5'-terminal subgenomic rnas (sgrnas) that accumulate to various extents during replication in protoplasts and plants. among the most unusual species are two abundant populations of small 5'-terminal sgrnas of approximately 800 nucleotides (nt) termed low-molecular-weight tristeza (lmt1 and lmt2) rnas. remarkably, ctv replicons with all 10 3' genes deleted produce only the larger lmt1 rnas. these 5'-terminal positive-sense sgrnas do not ...200312477839
poliovirus-induced apoptosis is reduced in cells expressing a mutant cd155 selected during persistent poliovirus infection in neuroblastoma cells.poliovirus (pv) can establish persistent infections in human neuroblastoma imr-32 cells. we previously showed that during persistent infection, specific mutations were selected in the first extracellular domain of the pv receptor (cd155) of these cells (n. pavio, t. couderc, s. girard, j. y. sgro, b. blondel, and f. colbère-garapin, virology 274:331-342, 2000). these mutations included the ala 67 --> thr substitution, corresponding to a previously described allelic form of the pv receptor. the m ...200312477887
small interfering rna-mediated inhibition of hepatitis c virus replication in the human hepatoma cell line huh-7. 200312477890
enhanced immunogenicity to mycobacterium tuberculosis by vaccination with an alphavirus plasmid replicon expressing antigen 85a.the immunogenicity of a plasmid dna vaccine incorporating sindbis virus rna replicase functions (psincp) and expressing antigen 85a (ag85a) from mycobacterium tuberculosis was compared with a conventional plasmid dna vector encoding ag85a. psincp-85a was highly immunogenic in mice and gave enhanced long-term protection against m. tuberculosis compared with the conventional vector.200312496215
alphavirus-based dna vaccine breaks immunological tolerance by activating innate antiviral pathways.cancer vaccines targeting 'self' antigens that are expressed at consistently high levels by tumor cells are potentially useful in immunotherapy, but immunological tolerance may block their function. here, we describe a novel, naked dna vaccine encoding an alphavirus replicon (self-replicating mrna) and the self/tumor antigen tyrosinase-related protein-1. unlike conventional dna vaccines, this vaccine can break tolerance and provide immunity to melanoma. the vaccine mediates production of double- ...200312496961
antiviral effect and virus-host interactions in response to alpha interferon, gamma interferon, poly(i)-poly(c), tumor necrosis factor alpha, and ribavirin in hepatitis c virus subgenomic replicons.the recently developed hepatitis c virus (hcv) subgenomic replicon system was utilized to evaluate the efficacy of several known antiviral agents. cell lines that persistently maintained a genotype 1b replicon were selected. the replicon resident in each cell line had acquired adaptive mutations in the ns5a region that increased colony-forming efficiency, and some replicons had acquired ns3 mutations that alone did not enhance colony-forming efficiency but were synergistic with ns5a mutations. a ...200312502825
an attenuating mutation in nsp1 of the sindbis-group virus s.a.ar86 accelerates nonstructural protein processing and up-regulates viral 26s rna synthesis.the sindbis-group alphavirus s.a.ar86 encodes a threonine at nonstructural protein 1 (nsp1) 538 that is associated with neurovirulence in adult mice. mutation of the nsp1 538 thr to the consensus ile found in nonneurovirulent sindbis-group alphaviruses attenuates s.a.ar86 for adult mouse neurovirulence, while introduction of thr at position 538 in a nonneurovirulent sindbis virus background confers increased neurovirulence (m. t. heise et al., j. virol. 74:4207-4213, 2000). since changes in the ...200312502831
glycosaminoglycan binding properties of natural venezuelan equine encephalitis virus isolates.equine-virulent, epidemic/epizootic strains of venezuelan equine encephalitis (vee) virus (veev) arise via mutation of progenitor enzootic strains that replicate poorly in equines. sequencing studies have implicated positively charged amino acids on the surface of the e2 envelope glycoprotein in the acquisition of equine virulence and viremia potential, suggesting that changes in binding to cell surface glycosaminoglycans (gags) may mediate vee emergence. therefore, we evaluated the binding of n ...200312502837
hepatitis c virus f protein is a short-lived protein associated with the endoplasmic reticulum.hepatitis c virus (hcv) f protein is a newly discovered hcv gene product that is expressed by translational ribosomal frameshift. little is known about the biological properties of this protein. by performing pulse-chase labeling experiments, we demonstrate here that the f protein is a labile protein with a half-life of <10 min in huh7 hepatoma cells and in vitro. the half-life of the f protein could be substantially increased by proteasome inhibitors, suggesting that the rapid degradation of th ...200312502871
alphavirus cdna-based expression vectors: effects of rna transcription and nuclear export.the construction of layered dna-rna replicons has facilitated and expanded the use of alphavirus vectors to vaccine development, construction of packaging cell lines and long-term heterologous gene expression. in these vector systems, the alphavirus replicon is under the control of a strong rna polymerase ii promoter and replicon rna is transcribed from dna before transport to the cytoplasm. efficient rna amplification catalyzed by the viral replicase results in high levels of mrna and the recom ...200312514804
anti-sindbis activity of flavanones hesperetin and naringenin.the effect of hesperetin, naringenin and its glycoside form on the sindbis neurovirulent strain (nsv) replication in vitro was studied. all flavanones tested were not cytotoxic on baby hamster cells 21 clone 15 (bhk-21). antiviral effect was evaluated by a colorimetric assay using mtt (3-(4,5 dimethylthiazol-2-yl)-2,5-dipheyl-tetrazolium bromide) and by plaque reduction assay. hesperetin and naringenin had inhibitory activity on nsv infection. the 50% inhibitory doses (id(50%)) of both compounds ...200312520185
properly folded nonstructural polyprotein directs the semliki forest virus replication complex to the endosomal compartment.the late rna synthesis in alphavirus-infected cells, generating plus-strand rnas, takes place on cytoplasmic vacuoles (cpvs), which are modified endosomes and lysosomes. the cytosolic surface of cpvs consists of regular membrane invaginations or spherules, which are the sites of rna synthesis (p. kujala, a. ikäheimonen, n. ehsani, h. vihinen, p. auvinen, and l. kääriäinen j. virol. 75:3873-3884, 2001). to understand how cpvs arise, we have expressed the individual semliki forest virus (sfv) nons ...200312525603
alphavirus minus-strand synthesis and persistence in mouse embryo fibroblasts derived from mice lacking rnase l and protein kinase r.we report our studies to probe the possible role of the host response to double-stranded rna in cessation of alphavirus minus-strand synthesis. mouse embryo fibroblasts (mef) from mx1-deficient mice that also lack either the protein kinase r (pkr) or the latent rnase l or both pkr and rnase l were screened. in rnase l-deficient but not wild-type or pkr-deficient mef, there was continuous synthesis of minus-strand templates and the formation of new replication complexes producing viral plus stran ...200312525614
antibody-mediated targeting of an adenovirus vector modified to contain a synthetic immunoglobulin g-binding domain in the capsid.adenovirus vectors have been targeted to different cell types by genetic modification of the capsid or by using recombinant or chemically engineered adaptor molecules. however, both genetic capsid modifications and bridging adaptors have to be specifically tailored for each particular targeting situation. here, we present an efficient and versatile strategy allowing the direct use of monoclonal antibodies against cell surface antigens for targeting of adenovirus vectors. a synthetic 33-amino-aci ...200312525644
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 ...200312525663
entry of alphaviruses at the plasma membrane converts the viral surface proteins into an ion-permeable pore that can be detected by electrophysiological analyses of whole-cell membrane currents.alphaviruses are small enveloped viruses that have been used extensively as model enveloped viruses. during infection, virus particles are taken up into endosomes, where a low ph activates the viral fusion protein, e1. fusion of the viral and the endosomal membranes releases the viral core into the cytoplasm where cores are disassembled by interaction with 60s ribosomal subunits. recently, we have shown that in vitro this disassembly is strongly stimulated by low ph. we have proposed that after ...200312533714
long-term potentiation in the hippocampal ca1 area and dentate gyrus plays different roles in spatial learning.nmda receptor-dependent long-term potentiation (ltp) at hippocampal synapses has been considered a crucial component of the cellular basis for learning and memory. this form of ltp occurs in excitatory synapses in both the ca1 area and the dentate gyrus in the hippocampus. however, differential roles of ltp in these areas have not yet been identified. to address this issue, we enhanced the degree of ltp by expressing ca2+-permeable ampa receptors at either hippocampal ca1 or dentate gyrus synaps ...200312542671
modification of the 5' terminus of sindbis virus genomic rna allows nsp4 rna polymerases with nonaromatic amino acids at the n terminus to function in rna replication.we have previously shown that sindbis virus rna polymerase requires an n-terminal aromatic amino acid or histidine for wild-type or pseudo-wild-type function; mutant viruses with a nonaromatic amino acid at the n terminus of the polymerase, but which are otherwise wild type, are unable to produce progeny viruses and will not form a plaque at any temperature tested. we now show that such mutant polymerases can function to produce progeny virus sufficient to form plaques at both 30 and 40 degrees ...200312551967
kinetics of virus-specific cd8+ -t-cell expansion and trafficking following central nervous system infection.cd8+ t cells control acute infection of the central nervous system (cns) by neurotropic mouse hepatitis virus but do not suffice to achieve sterile immunity. to determine the lag between t-cell priming and optimal activity within the cns, the accumulation of virus-specific cd8+ t cells in the cns relative to that in peripheral lymphoid organs was assessed by using gamma interferon-specific elispot assays and class i tetramer staining. virus-specific cd8+ t cells were first detected in the cervic ...200312552021
individual expression of sindbis virus glycoproteins. e1 alone promotes cell fusion.the envelope of alphavirus particles contains two major glycoproteins, e1 and e2, that participate in virus entry and assembly of new virus particles. interactions between these glycoproteins determine their correct functioning. the expression of each glycoprotein in the absence of the other counterpart was achieved by means of electroporation of modified sindbis virus (sv) genomes. in addition, in trans coexpression of both glycoproteins was also tested in bhk cells. synthesis of the e1 glycopr ...200312573591
the avian retrovirus avian sarcoma/leukosis virus subtype a reaches the lipid mixing stage of fusion at neutral ph.we previously showed that the envelope glycoprotein (enva) of avian sarcoma/leukosis virus subtype a (aslv-a) binds to liposomes at neutral ph following incubation with its receptor, tva, at >or=22 degrees c. we also provided evidence that aslv-c fuses with cells at neutral ph. these findings suggested that receptor binding at neutral ph and >or=22 degrees c is sufficient to activate env for fusion. a recent study suggested that two steps are necessary to activate avian retroviral envs: receptor ...200312584331
cellular proteins from human monocytes bind to dengue 4 virus minus-strand 3' untranslated region rna.the synthesis of plus and minus rna strands of several rna viruses requires as a first step the interaction of some viral regulatory sequences with cellular and viral proteins. the dengue 4 virus genome, a single-stranded, positive-polarity rna, is flanked by two untranslated regions (utr) located in the 5' and 3' ends. the 3'utr in the minus-strand rna [3'utr (-)] has been thought to function as a promoter for the synthesis of plus-strand rna. to study the initial interaction between this 3'utr ...200312584332
subcellular localization of herpes simplex virus type 1 ul51 protein and role of palmitoylation in golgi apparatus targeting.the herpes simplex virus type 1 (hsv-1) ul51 gene products are virion-associated phosphoproteins with apparent molecular masses of 27, 29, and 30 kda in hsv-1-infected cells. in this study, we have investigated the intracellular localization and distribution of ul51 protein both in infected cells and in transfected cells expressing only ul51. we found that this protein colocalized closely with golgi marker proteins such as the golgi-58k protein and gm130 in transfected cells expressing only ul51 ...200312584344
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