PMID(sorted ascending)
kunjin virus replicon vaccine vectors induce protective cd8+ t-cell immunity.the ability of self-replicating rna (replicon) vaccine vectors derived from the australian flavivirus kunjin (kun) to induce protective alphabeta cd8+ t-cell responses was examined. kun replicons encoding a model immunogen were delivered by three different vaccine modalities: (i) as naked rna transcribed in vitro, (ii) as plasmid dna constructed to allow in vivo transcription of replicon rna by cellular rna polymerase ii (dna based), and (iii) as replicon rna encapsidated into virus-like particl ...200211907219
heat shock cognate protein 70 is involved in rotavirus cell this work, we have identified the heat shock cognate protein (hsc70) as a receptor candidate for rotaviruses. hsc70 was shown to be present on the surface of ma104 cells, and antibodies to this protein blocked rotavirus infectivity, while not affecting the infectivity of reovirus and poliovirus. preincubation of the hsc70 protein with the viruses also inhibited their infectivity. triple-layered particles (mature virions), but not double-layered particles, bound hsc70 in a solid-phase assay, a ...200211907249
infection of glioma cells with sindbis virus induces selective activation and tyrosine phosphorylation of protein kinase c delta. implications for sindbis virus-induced apoptosis.sindbis virus (sv) is an alpha virus used as a model for studying the role of apoptosis in virus infection. in this study, we examined the role of protein kinase c (pkc) in the apoptosis induced by svni, a virulent strain of sv. infection of c6 cells with svni induced a selective translocation of pkcdelta to the endoplasmic reticulum and its tyrosine phosphorylation. the specific pkcdelta inhibitor rottlerin and a pkcdelta kinase-dead mutant increased the apoptosis induced by svni. to examine th ...200211927579
isolation of west nile and sindbis viruses from mosquitoes collected in the nile valley of egypt during an outbreak of rift valley part of an evaluation of potential vectors of arboviruses during a rift valley fever (rvf) outbreak in the nile valley of egypt in august 1993, we collected mosquitoes in villages with known rvf viral activity. mosquitoes were sorted to species, pooled, and processed for virus isolation both by intracerebral inoculation into suckling mice and by inoculation into cell culture. a total of 33 virus isolates was made from 36,024 mosquitoes. viruses were initially identified by indirect fluorescen ...200211931267
involvement of the matrix protein in attachment of porcine reproductive and respiratory syndrome virus to a heparinlike receptor on porcine alveolar macrophages.the porcine reproductive and respiratory syndrome virus (prrsv) has a very restricted tropism for well-differentiated cells of the monocyte-macrophage lineage, which is probably determined by specific receptors on these cells. in this study, the importance of heparinlike molecules on porcine alveolar macrophages (pam) for prrsv infection was determined. heparin interacted with the virus and reduced infection of pam up to 92 or 88% for the american and european types of prrsv, respectively. other ...200211932397
immune-mediated protection from measles virus-induced central nervous system disease is noncytolytic and gamma interferon dependent.neurons of the mammalian central nervous system (cns) are an essential and largely nonrenewable cell population. thus, virus infections that result in neuronal depletion, either by virus-mediated cell death or by induction of the cytolytic immune response, could cause permanent neurological impairment of the host. in a transgenic mouse model of measles virus (mv) infection of neurons, we have previously shown that the host t-cell response was required for resolution of infection in susceptible a ...200211932415
bak and bax function to limit adenovirus replication through apoptosis induction.adenovirus infection and expression of e1a induces both proliferation and apoptosis, the latter of which is blocked by the adenovirus bcl-2 homologue e1b 19k. the mechanism of apoptosis induction and the role that it plays in productive infection are not known. unlike apoptosis mediated by death receptors, infection with proapoptotic e1b 19k mutant viruses did not induce cleavage of bid but nonetheless induced changes in bak and bax conformation, bak-bax interaction, caspase 9 and 3 activation, ...200211932420
adeno-associated virus capsids displaying immunoglobulin-binding domains permit antibody-mediated vector retargeting to specific cell surface receptors.recombinant adeno-associated virus type 2 (raav2) is a promising vector for human somatic gene therapy. however, its broad host range is a disadvantage for some applications, because it reduces the specificity of the gene transfer. to overcome this limitation, we sought to create a versatile raav vector targeting system which would allow us to redirect raav binding to specific cell surface receptors by simple coupling of different ligands to its capsid. for this purpose, an immunoglobulin g (igg ...200211932421
poly(adp-ribose) polymerase impairs early and long-term experimental stroke recovery.poly(adp-ribose) polymerase (parp-1; enzyme commission 2.4.30) is a nuclear dna repair enzyme that mediates early neuronal ischemic injury. using novel 3-dimensional, fast spin-echo-based diffusion-weighted imaging, we compared acute (21 hours) and long-term (3 days) ischemic volume after middle cerebral artery (mca) occlusion in parp-1-null mutants (parp-/-) versus genetically matched wild-type mice (wt mice). parp-/- mice were also treated with viral transfection of wild-type parp-1 to determi ...200211935067
effects of pkr/rnase l-dependent and alternative antiviral pathways on alphavirus replication and pathogenesis.type i interferons (ifn-alpha/beta) rapidly confer resistance to alphavirus infection in macrophages and dendritic cells (dc) as evidenced by the dramatically increased susceptibility of these cells in mice with the ifnar1 subunit of the ifn-alpha/beta receptor ablated (ifnar1-/-). normal adult mice develop only a subclinical sindbis virus infection, whereas infected ifnar1-/- mice rapidly succumb to a fatal disease. here, we investigated the individual and combined contributions of the two best ...200211952147
human immunodeficiency virus type 1 uses lipid raft-colocalized cd4 and chemokine receptors for productive entry into cd4(+) t this report, we describe a crucial role of lipid raft-colocalized receptors in the entry of human immunodeficiency virus type 1 (hiv-1) into cd4(+) t cells. we show that biochemically isolated detergent-resistant fractions have characteristics of lipid rafts. lipid raft integrity was required for productive hiv-1 entry as determined by (i) semiquantitative pcr analysis and (ii) single-cycle infectivity assay using hiv-1 expressing the luciferase reporter gene and pseudotyped with hiv-1 hxb2 e ...200211967288
mutations in the yellow fever virus nonstructural protein ns2a selectively block production of infectious particles.little is known about the function of flavivirus nonstructural protein ns2a. two forms of ns2a are found in yellow fever virus-infected cells. full-length ns2a (224 amino acids) is the product of cleavage at the ns1/2a and ns2a/2b sites. ns2aalpha, a c-terminally truncated form of 190 amino acids, results from partial cleavage by the viral ns2b-3 serine protease at the sequence qk /t within ns2a. exchange of serine for lysine at this site (qkt-->qst) blocks the production of both ns2aalpha and i ...200211967294
introduction of west nile virus in the middle east by migrating white storks.west nile virus (wnv) was isolated in a flock of 1,200 migrating white storks that landed in eilat, a town in southern israel, on august 26, 1998. strong, hot westerly winds had forced the storks to fly under considerable physical stress before reaching the agricultural land surrounding the town. most of the flock were fledglings, <1 year old, which had hatched in europe. thirteen dead or dying storks were collected 2 days after arrival and submitted to the laboratory for examination. four wnv i ...200211971773
predominance of six different hexanucleotide recoding signals 3' of read-through stop codons.redefinition of uag, uaa and uga to specify a standard amino acid occurs in response to recoding signals present in a minority of mrnas. this 'read-through' is in competition with termination and is utilized for gene expression. one of the recoding signals known to stimulate read-through is a hexanucleotide sequence of the form caryya 3' adjacent to the stop codon. the present work finds that of the 91 unique viral sequences annotated as read-through, 90% had one of six of the 64 possible codons ...011972340
differential palmitoylation directs the ampa receptor-binding protein abp to spines or to intracellular clusters.long-term changes in excitatory synapse strength are thought to reflect changes in synaptic abundance of ampa receptors mediated by receptor trafficking. ampa receptor-binding protein (abp) and glutamate receptor-interacting protein (grip) are two similar pdz (postsynaptic density 95/discs large/zona occludens 1) proteins that interact with glutamate receptors 2 and 3 (glur2 and glur3) subunits. both proteins have proposed roles during long-term potentiation and long-term depression in the deliv ...200211978826
n-methyl-d-aspartate receptor signaling results in aurora kinase-catalyzed cpeb phosphorylation and alpha camkii mrna polyadenylation at synapses.activity-dependent local translation of dendritic mrnas is one process that underlies synaptic plasticity. here, we demonstrate that several of the factors known to control polyadenylation-induced translation in early vertebrate development [cytoplasmic polyadenylation element-binding protein (cpeb), maskin, poly(a) polymerase, cleavage and polyadenylation specificity factor (cpsf) and aurora] also reside at synaptic sites of rat hippocampal neurons. the induction of polyadenylation at synapses ...200211980711
phosphorylation of cucumber mosaic virus rna polymerase 2a protein inhibits formation of replicase complex.the 2a (polymerase) protein of cucumber mosaic virus (cmv) was shown to be phosphorylated both in vivo and in vitro. in vitro assays using 2a protein mutants and tobacco protein kinases showed that the 2a protein has at least three phosphorylation sites, one of which is located within the n-terminal 126 amino acid region. this region is essential and sufficient for interaction with the cmv 1a protein. when phosphorylated in vitro, the 2a protein n-terminal region failed to interact with the 1a p ...200211980726
l1 mediated homophilic binding and neurite outgrowth are modulated by alternative splicing of exon 2.the neural cell adhesion molecule (cam) l1 is a member of the immunoglobulin superfamily that has been implicated in neuronal adhesion, neurite outgrowth, and axon guidance. the clinical importance of l1 is illustrated by pathological mutations that lead to hydrocephalus, mental retardation, motor defects, and early mortality. the l1 gene is composed of 28 exons, including exons 2 and 27 that are spliced alternatively, and mutations in exon 2 are associated with severe neurological abnormalities ...200211984840
rous sarcoma virus gag protein-oligonucleotide interaction suggests a critical role for protein dimer formation in assembly.the structural protein gag is the only viral product required for retrovirus assembly. purified gag proteins or fragments of gag are able in vitro to spontaneously form particles resembling immature virions, but this process requires nucleic acid, as well as the nucleocapsid domain of gag. to examine the role of nucleic acid in the assembly in vitro, we used a purified, slightly truncated version of the rous sarcoma virus gag protein, delta mbd delta pr, and dna oligonucleotides composed of the ...200211991973
langat flavivirus protease ns3 binds caspase-8 and induces apoptosis.the flavivirus ns3 protein plays an important role in the cleavage and processing of the viral polyprotein and in the synthesis of the viral rna. ns3 recruits ns2b and ns5 proteins to form complexes possessing protease and replicase activities through protease and nucleoside triphosphatase/helicase domains. we have found that ns3 also induces apoptosis. expression of the langat (lgt) virus ns3 protein resulted in a cleavage of cellular dna and reduced the viability of cells. coexpression of ns3 ...200211991998
inhibition of rotavirus replication by a non-neutralizing, rotavirus vp6-specific iga mab.rotaviruses are the leading cause of severe diarrheal disease in young children. intestinal mucosal iga responses play a critical role in protective immunity against rotavirus reinfection. rotaviruses consist of three concentric capsid layers surrounding a genome of 11 segments of double-stranded rna. the outer layer proteins, vp4 and vp7, which are responsible for viral attachment and entry, are targets for protective neutralizing antibodies. however, iga mab's directed against the intermediate ...200211994409
ribozyme inhibition of alphavirus replication.a model system to examine the expression and antiviral activity of trans-acting ribozymes in mammalian cells has been developed and evaluated. hairpin ribozymes were engineered to cleave a specific site, identified by a combinatorial activity-based selection method, within genomic and subgenomic rna species of sindbis virus. transiently transfected cells expressed moderate levels of ribozyme (approximately 50,000 molecules/cell) with predominant nuclear localization and a short half-life (23 min ...200212006558
differential roles for nsf and grip/abp in ampa receptor cycling.alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor (ampar) stability and movement at synapses are important factors controlling synaptic strength. here, we study the roles of proteins [n-ethylmaleimide-sensitive fusion protein (nsf), glutamate receptor ampar binding protein (abp)-interacting protein (grip)/(abp), and protein interacting with c-kinase-1 (pick1) that interact with the glur2 subunit in the control of the surface expression and cycling of ampars. epitope-tagged glur2 ...200212011465
[the relationship between protein synthesis of sindbis virus and host cytoskeletons].in our experiments, protein synthesis of host cells were inhibited quickly at the early stage of infection by sindbis virus. polysome and mrna of host cell fell off from cytoskeletons, whereas virus rna bound up. we also found it was via 3'-terminal that virus rna bound with cytoskeleton. after studying on the virus nonstructural proteins, we found the synthesis and processing of virus protein in vitro were far slowly than in vivo, and most of proteins were premature. so, the cytoskeletons may p ...199812016969
antiviral effects of pyrrolidine dithiocarbamate on human rhinoviruses.human rhinoviruses (hrvs) are the predominant cause of the common cold. the frequency of hrv infections in industrial countries and the lack of effective therapeutical treatment underline the importance of research for new antiviral substances. as viral infections are often accompanied by the generation of oxidative stress inside the infected cells, several redox-active substances were tested as potential antivirals. in the course of these studies it was discovered that pyrrolidine dithiocarbama ...200212021333
comparison of two aquatic alphaviruses, salmon pancreas disease virus and sleeping disease virus, by using genome sequence analysis, monoclonal reactivity, and cross-infection.cell culture isolates of salmon pancreas disease virus (spdv) of farmed atlantic salmon and sleeping disease virus (sdv) of rainbow trout were compared. excluding the poly(a) tracts, the genomic nucleotide sequences of spdv and sdv rnas include 11,919 and 11,900 nucleotides, respectively. phylogenetic analysis places spdv and sdv between the new world viruses of venezuelan equine encephalitis virus and eastern equine encephalitis virus and the old world viruses of aura virus and sindbis virus. w ...200212021349
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
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