| oligodendrocyte infection and demyelination produced in mice by the m9 mutant of semliki forest virus. | intraperitoneal inoculation with the m9 mutant of semliki forest virus caused focal demyelinating encephalomyelitis in weanling balb/c and c57bl/6 mice. demyelination was more severe in balb/c than in c57bl/6 mice. virus particles were seen in oligodendrocytes in areas of myelin vacuolation 5 and 7 days post inoculation (dpi). oligodendrocytes containing virus in balb/c mice showed hypertrophy and vacuolar degeneration. there was a mononuclear cell infiltrate and lymphocytes and necrotic cells w ... | 1983 | 6310927 |
| antiviral activity released from aedes albopictus cells persistently infected with semliki forest virus. | aedes albopictus (mosquito) cells persistently infected with semliki forest virus released an agent which inhibited virus production by a. albopictus cells infected with homologous virus. inhibition of virus production was accompanied by a marked reduction in the synthesis of viral rna and viral proteins. expression of the antiviral effect was prevented by pretreatment of cells with actinomycin. no analogous antiviral activity was detected in culture fluids of a. albopictus cells persistently in ... | 1983 | 6312089 |
| chemical synthesis and molecular cloning of a stop oligonucleotide encoding an uga translation terminator in all three reading frames. | we have chemically synthesized an oligonucleotide 5'd(tgattgattga)3' 3'd(actaactaact)5' that encodes the translation termination codon tga in all three reading frames. after ligation of appropriate restriction endonuclease linkers to the ends, the double-stranded oligonucleotide (stop-oligonucleotide) was joined to the plasmid pbr322 between the ecori and bamhi, or hindiii and bamhi sites, and the hybrid plasmids were transformed into escherichia coli hb101. four different constructions were obt ... | 1983 | 6313480 |
| delayed-type hypersensitivity in mice after infection with avirulent semliki forest virus. brief report. | after subcutaneous infection of mice with semliki forest virus, a delayed-type hypersensitivity (dh) could be demonstrated by footpad swelling. pretreatment with cyclophosphamide resulted in enhanced dh if neutralizing antibodies were undetectable in serum. | 1983 | 6316872 |
| physiological deficits in the visual system of mice infected with semliki forest virus and their correlation with those seen in patients with demyelinating disease. | electrophysiological recordings were made from the superior colliculus of mice infected with semliki forest virus (sfv) which produced patchy demyelination in many different locations within the central nervous system including the optic nerve. over a wide range of light intensities, the visual latencies of both single cell and field potential responses from the superior colliculi of infected mice were longer than those of the corresponding control mice, and there was a greater interocular diffe ... | 1983 | 6317139 |
| expression of viral membrane proteins from cloned cdna by microinjection into eukaryotic cell nuclei. | | 1983 | 6318022 |
| protein synthesis in semliki forest virus-infected cells is not controlled by permeability changes. | the uptake of the gtp analogue guanylyl(beta,gamma-methylene)diphosphonate (gppch2p) is the same in semliki forest virus (sfv)-infected bhk cells as in mock-infected cells, in spite of the fact that protein synthesis is inhibited by gppch2p more markedly in sfv-infected cells than in control cells. a possible explanation for this difference is that infected cells have a lower concentration of gtp and a lower ratio of gtp:gdp than uninfected cells, and the analogue may thus be a more effective co ... | 1983 | 6319551 |
| the pathogenicity of the m9 mutant of semliki forest virus in immune-compromised mice. | the role of immune mechanisms in the pathogenicity of the m9 mutant of semliki forest virus (sfv) has been examined by the use of immune-deficient and immune-suppressed mice. in immune-competent balb/c and c57bl/6 mice, the lesions in the central nervous system (cns) were characterized by acute demyelinating meningoencephalomyelitis. myelin vacuolation and demyelination were more severe in balb/c mice than in mice with a c57bl background. the mortality was 12% and 29% respectively. treatment wit ... | 1984 | 6319575 |
| action of human lymphoblastoid interferon on hela cells infected with rna-containing animal viruses. | protein synthesis in interferon-treated hela cells infected by different animal rna viruses has been studied. synthesis of vesicular stomatitis virus (vsv) proteins was not detected in cells treated with concentrations of huifn-alpha (ly) above 10 iu/ml. no specific inhibition of glycosylation of the g protein was observed. in addition, inhibition of host protein synthesis in ifn-treated cells occurred when high multiplicities of vsv were used, even though no viral protein synthesis was detected ... | 1984 | 6319580 |
| the identification and role of cells involved in cns demyelination in mice after semliki forest virus infection: an ultrastructural study. | | 1983 | 6320269 |
| didemnins a and b. effectiveness against cutaneous herpes simplex virus in mice. | the antiviral activity of didemnin a and didemnin b against a lethal semliki forest virus (sfv) infection of mice and a cutaneous herpes type 1 infection in hairless mice was evaluated. both compounds significantly decreased the severity of herpesvirus lesions if topical treatment with either didemnin a or didemnin b was started 2 days prior to infection. the survival rate was significantly greater (p = 0.03) in the didemnin b treated group than in controls. if initiation of treatment was delaye ... | 1983 | 6320719 |
| pathogenesis of in utero infections with abortogenic and non-abortogenic alphaviruses in mice. | the initial stages of infection of pregnant mice at gestation day 11 with either the t48 strain of ross river virus or avirulent semliki forest virus are similar. with both infections, a hematogenous spread of virus to the placenta occurs. the viruses subsequently replicate to high titer in all placentas and are able to persist in the presence of specific maternal antiviral antibodies. there is a delay of at least 1 to 2 days between the initial detection of virus in the placenta and the onset o ... | 1984 | 6321801 |
| effect of pregnancy on stimulation of alphavirus immunity in mice. | the state of pregnancy was associated with a marked enhancement of both proliferative and cytotoxic t cell antiviral immune responses after infection of mice with avirulent semliki forest virus. strong responses were obtained from the spleen and the para-aortic lymph nodes that drain the uterus. this immune enhancement seemed to be in response to the increased antigenic challenge that originated from infected placental and fetal tissue and was released during the process of abortion. immune enha ... | 1984 | 6321802 |
| binding, endocytosis, and degradation of enveloped animal viruses. | | 1983 | 6321902 |
| cryo-electron microscopy of viruses. | thin vitrified layers of unfixed, unstained and unsupported virus suspensions can be prepared for observation by cryo-electron microscopy in easily controlled conditions. the viral particles appear free from the kind of damage caused by dehydration, freezing or adsorption to a support that is encountered in preparing biological samples for conventional electron microscopy. cryo-electron microscopy of vitrified specimens offers possibilities for high resolution observations that compare favourabl ... | 1984 | 6322001 |
| antiviral activity of tetrahydro-2(1h)-pyrimidinones and related compounds. | 24 derivatives of tetrahydro-2(1h)-pyrimidinone and related compounds were tested in vitro for antiviral activity against representatives of six viral taxonomic groups. the screening was carried out by a two-stage procedure including the agar-diffusion plaque-inhibition test and the one-step growth cycle setup. a distinct activity of three mono- and bis-morpholinomethyl derivatives of tetrahydro-2(1h)-pyrimidinone (thp), 1,3-bis(piperidinomethyl)-thp, the 1-morpholinomethyl derivative of tetrahy ... | 1984 | 6322812 |
| regulated expression of genes injected into early drosophila embryos. | dna of cloned genes injected into 15-30 min drosophila embryos reaches nearly all the cells of the later embryo and its expression can be detected by northern blot hybridisation. the injected dna continues to be expressed at least up to the first instar larval stage and some developmental control of expression is retained. genes normally expressed in the embryo are strongly transcribed upon injection while genes characteristic of later stages are not, or only very weakly expressed. some transcri ... | 1984 | 6323163 |
| comparison of protein a-gold and ferritin immunoelectron microscopy of semliki forest virus in mouse brain using a rapid processing technique. | processing tissue for transmission electron microscopy by standard laboratory methods can take two to three days. this makes the development of new techniques time consuming and generally restricts the use of the electron microscope in routine diagnostic work. the possibility of viewing tissue with the electron microscope five hours after sampling using rapid processing techniques is presented. the morphology of the tissue appears undamaged with cell and organelle ultrastructures being readily r ... | 1984 | 6323573 |
| gamma interferon production and cytotoxicity of spleen cells from mice infected with semliki forest virus. | interferon (ifn) production by spleen cells from normal mice, mice acutely infected with semliki forest virus (sfv) or mice immune to sfv was measured after stimulation in vitro with either infectious or inactivated sfv. all three classes of spleen cells made ifn-alpha beta in response to infectious sfv. spleen cells taken from mice late, but not early, after infection, or from immune mice, made ifn-gamma in response to inactivated sfv. amounts of inf-gamma and ifn-alpha beta were similar. norma ... | 1984 | 6327889 |
| immunological reaction of the demyelinating semliki forest virus with immune serum to glycolipids and its possible importance to central nervous system viral auto-immune disease. | the avirulent demyelinating strain a7(74) of semliki forest virus after passage through mouse brain in vivo and mouse brain cell cultures has been shown to react immunologically with immune sera against galactocerebroside, glucocerebroside, total ganglioside and gt1b ganglioside but not against myelin or sulphatide . semliki forest virus is known to take host membrane glycolipid into its coat. the importance of the findings is discussed in relation to the production of a possible anti-brain cell ... | 1984 | 6328340 |
| [human immune interferon: production and action]. | the most marked production of immune interferon by human peripheral blood leukocytes and splenocytes stimulated with phytohemagglutinin (pha) and staphylococcal enterotoxin a (sea) was shown to be achieved when lymphoid cells are propagated under conditions of constant sparing mixing on roller apparatus at a temperature of 37 degrees +/- 0.5 degrees c. the resulting interferon was sensitive to low ph, thermolabile, inactivated by treatment with trypsin, and not neutralised by antisera to human a ... | 1984 | 6328769 |
| a simple methodology for the routine production and partial purification of human lymphoblastoid interferon. | we report a methodology suitable for the large scale production and partial purification of human lymphoblastoid interferon with a minimum expense and reasonable (10%) degree of purity of product. the cells used were namalwa lymphoblastoid cells, which have the advantage of being both easy to grow and well characterized. they were grown in rpmi 1640 containing 10% fetal calf serum to a density of 1.5 - 2 x 10(6) cells/ml and then diluted 50% by the addition of serum free medium containing 2mm so ... | 1984 | 6328906 |
| translation of capped viral mrnas in poliovirus-infected hela cells. | hela cells doubly infected with semliki forest virus (sfv) and poliovirus synthesize either more poliovirus proteins or more sfv late proteins depending on the time of super-infection with poliovirus. under some conditions, the infected cells translate uncapped poliovirus mrna and capped 26s mrna from sfv simultaneously, even though host protein synthesis has been shut down. vesicular stomatitis virus (vsv) protein synthesis is depressed drastically when vsv-infected cells are super-infected wit ... | 1982 | 6329715 |
| can viral envelope glycolipids produce auto-immunity, with reference to the cns and multiple sclerosis? | many viruses, with lipid envelopes derived from the host cell membranes, have been implicated in the aetiology of multiple sclerosis (ms), and epidemiological studies support an infectious agent. alternatively the disease is thought by other workers to be auto-immune in nature, and recently much attention has been focused on immunological sensitivity to glycolipids in ms patients. in this paper it is proposed that cns demyelination could arise in susceptible individuals (hla type) from an immune ... | 1984 | 6330601 |
| properties of host and virus which influence defective interfering virus mediated-protection of mice against semliki forest virus lethal encephalitis. brief report. | variation of the mouse strain, the amount of defective interfering (di) virus and the amount of infectious semliki forest virus (sfv) are all factors which affect the efficiency with which di sfv prevents the sfv-mediated lethal encephalitis. | 1984 | 6331348 |
| immunohistochemical demonstration of glial fibrillary acidic protein in scrapie. | although little is known about its metabolism, glial fibrillary acidic (gfa) protein has become widely used as a cell-specific, species-non-specific antigenic marker for normal or pathologically altered astroglia. so far there have been few investigations on gfa protein in relation to scrapie and analogous spongiform encephalopathies although there has been a need for an unequivocal method for the discrimination of different types of glia in these diseases. in the present studies, a commercially ... | 1983 | 6345602 |
| transport of virus membrane glycoproteins, use of temperature-sensitive mutants and organelle-specific lectins. | | 1983 | 6361459 |
| envelope proteins of semliki forest virus synthesized in xenopus oocytes are transported to the cell surface. | the mrna coding for the structural proteins of semliki forest virus, the 26s rna, was injected into xenopus oocytes. synthesis of the capsid protein and the three envelope glycoproteins e1, e2 and e2 was observed. the proteins, which are normally incorporated into the plasma membrane of infected cells, are transported to the surface of the oocytes. the transport of the membrane proteins takes place in the presence of tunicamycin. the results show that the proteins foreign to the oocyte reach the ... | 1984 | 6373249 |
| semliki forest virus: a probe for membrane traffic in the animal cell. | | 1984 | 6382965 |
| detection of semliki forest virus in cell culture by use of an enzyme immunoassay with peroxidase-labeled monoclonal antibodies specific for glycoproteins e1 and e2. | four noncompeting monoclonal antibodies (ma) directed against either the e1 (um 8.64 and 8.139) or e2 (um 8.55 and 8.73) glycoprotein of semliki forest virus were purified and labeled with horseradish peroxidase. each enzyme-labeled ma was tested alone and in combination with others for its sensitivity to detect virus-infected cells. semliki forest virus-infected l cells seeded as monolayers in 96-well plates were screened for the virus after incubation with enzyme-labeled ma and a substrate. in ... | 1984 | 6386855 |
| dissection of the golgi complex. ii. density separation of specific golgi functions in virally infected cells treated with monensin. | in the accompanying paper (griffiths, g., p. quinn, and g. warren, 1983, j. cell biol., 96:835-850), we suggested that the golgi stack could be divided into functionally distinct cis, medial, and trans compartments, each comprising one or two adjacent cisternae. these compartments were identified using baby hamster kidney (bhk) cells infected with semliki forest virus (sfv) and treated with monensin. this drug blocked intracellular transport but not synthesis of the viral membrane proteins that ... | 1983 | 6403555 |
| effect of myocrisin (sodium auro-thio-malate) on the morphogenesis of avirulent semliki forest virus in mouse brain: an electron microscopical study. | adult mice, infected intracerebrally or intraperitoneally with avirulent semliki forest virus, do not show mature virus or advanced stages of viral replication in the brain. if myocrisin is given intraperitoneally 3 h before the virus there is enhancement of all stages of viral replication and budding of virus and mature virions are seen. compared with controls many intracytoplasmic smooth membrane vesicles were seen in the parenchymal cells of the brain treated with myocrisin or with myocrisin ... | 1983 | 6413876 |
| pre- and post-golgi vacuoles operate in the transport of semliki forest virus membrane glycoproteins to the cell surface. | the effect of reduced temperature on synchronized transport of sfv membrane proteins from the er via the golgi complex to the surface of bhk-21 cells revealed two membrane compartments where transport could be arrested. at 15 degrees c the proteins could leave the er but failed to enter the golgi cisternae and accumulated in pre-golgi vacuolar elements. at 20 degrees c the proteins passed through golgi stacks but accumulated in trans-golgi cisternae, vacuoles, and vesicular elements because of a ... | 1984 | 6432345 |
| semliki forest virus entry and the endocytic pathway. | | 1984 | 6442239 |
| role of cholesterol in fusion of semliki forest virus with membranes. | the low ph-triggered membrane fusion activity of semliki forest virus is dependent on the presence of cholesterol in the target membrane. when liposomes containing phospholipids and cholesterol analogs were used, fusion activity was observed with steroids which did not have a planar nucleus or an isooctyl side chain at c-17, but fusion activity was not observed when analogs which lacked the 3 beta-oh group were used. binding of virus to liposomes at low ph was similarly, but not totally, depende ... | 1984 | 6481854 |
| defective interfering particles of semliki forest virus are smaller than particles of standard virus. | by electron microscopy, particles of defective interfering semliki forest virus (di sfv) had a mean diameter of 46.8 nm compared with 55.9 nm for standard virus particles, a decrease of 16%. the difference was confirmed by measurements of the two-dimensional projected areas of di and standard virus particles. we examined nine different di virus preparations produced by four to 13 undiluted passages in bhk cells and all were found to contain a majority of the smaller type of particle. calculation ... | 1984 | 6512506 |
| infection of rat brain primary cell cultures with an avirulent a7 strain of semliki forest virus. | the ability of a7 semliki forest virus (sfv) to infect primary brain cell cultures has been examined using cultures prepared from 1-2-day neonatal rat cerebral hemispheres. these cultures, characterised immunocytochemically using cell-specified markers, contain mainly gfap+ protoplasmic astrocytes and smaller multiprocessed a2b5+ cells, probably fibrous astrocytes. 10% of the cells are gc+ oligodendrocytes and some neurones are also present. these cultures support virus growth and a cytopathic e ... | 1984 | 6520614 |
| density of newly synthesized plasma membrane proteins in intracellular membranes. i. stereological studies. | as the spike proteins of semliki forest virus (sfv) pass from their site of synthesis in the endoplasmic reticulum (er) to the cell surface, they must be concentrated and freed from endogenous proteins. to determine the magnitude of this sorting process we have measured the density of spike proteins in membranes of the intracellular transport pathway. in this first paper, using stereological procedures, we have estimated the surface areas of the er, golgi complex, and plasma membrane of infected ... | 1984 | 6563037 |
| density of newly synthesized plasma membrane proteins in intracellular membranes ii. biochemical studies. | using two independent methods, incorporation of radioactive amino-acid and quantitative immunoblotting, we have determined that the rate of synthesis of each of the semliki forest virus (sfv) proteins in infected baby hamster kidney (bhk) cells is 1.2 x 10(5) copies/cell/min. given the absolute surface areas of the endoplasmic reticulum and golgi complex presented in the companion paper (griffiths, g., g. warren, p. quinn , o. mathieu - costello , and a. hoppeler , 1984, j. cell biol. 98:2133-21 ... | 1984 | 6563038 |
| production of type i (alpha/beta) interferon after virus infection of cloned, alloantigen-sensitized mouse t lymphocytes. | mouse t lymphocytes sensitized to alloantigens were cloned by limiting dilution in the presence of interleukin 2. clones were tested for surface markers thy-1, lyt-1 and lyt-2, and for cytotoxic function. production of interferon (ifn) by clones either (a) stimulated with allogeneic cells; (b) activated with concanavalin a (con a); or (c) infected with semliki forest virus or newcastle disease virus were assayed. all clones produced ifn upon con a stimulation and most after virus infection. anal ... | 1984 | 6609825 |
| nonstructural proteins of semliki forest virus: synthesis, processing, and stability in infected cells. | the synthesis of the nonstructural (ns) proteins of semliki forest virus was studied in vivo. the fourth ns protein, ns60, was identified and isolated. the order of translation (nh2-ns70-ns86-ns60-ns72-cooh) was determined by using various labeling procedures after or in the presence of a hypertonic block of translation initiation. a sequential labeling procedure was devised to specifically label defined segments of the polyprotein. the specific labeling procedures allowed isolation of the four ... | 1983 | 6620462 |
| defective viral rnas in aedes albopictus c6/36 cells persistently infected with semliki forest virus. | a persistent infection of semliki forest virus (sfv) has been established in aedes albopictus c6/36 cells. only a small number of cells survived the initial infection with this rna virus and gave rise to a persistently infected culture which produced continuously small amounts of infectious virus. to investigate whether defective viral rna was analyzed early and late after infection by blot hybridizations. several defective viral rnas were detected with a common sequence corresponding to the 3' ... | 1983 | 6623928 |
| intracellular vesicles involved in the transport of semliki forest virus membrane proteins to the cell surface. | the route of transport of semliki forest virus (sfv) membrane glycoproteins to the plasma membrane was studied using immunoperoxidase electron microscopy. sfv glycoproteins were localized in cultured bhk-21 fibroblasts infected with a temperature-sensitive mutant ts-1 of sfv, which shows a temperature-dependent, reversible defect in the transport of membrane glycoproteins to the cell surface. at 39 degrees c (restrictive temperature) the viral proteins were retained in the endoplasmic reticulum ... | 1983 | 6641709 |
| identification of a unique guanine-7-methyltransferase in semliki forest virus (sfv) infected cell extracts. | the methylation of the 5' terminal guanosine residue of the cap structure of semliki forest virus (sfv) mrnas has been shown to occur in vitro concomitantly with their synthesis (r. k. cross and p. j. gomatos, virology, 114, 542-554, 1981). the enzyme responsible for this methylation, a guanine-7-methyltransferase, is associated with the sfv replication complex which contains both the virus-specified polymerase and rna template in a mitochondrial pellet fraction, p-15, from infected cell lysates ... | 1983 | 6649413 |
| disproportionate synthesis of semiliki forest virus 42s and 26s rnas in polyamine-depleted baby hamster kidney cells. | the role of polyamines in viral rna synthesis has been studied using semliki forest virus-infected, polyamine-depleted baby hamster kidney cells as a model system. the synthesis of viral 42s rna, which corresponds to the viral genome, was markedly inhibited, while the synthesis of viral 26s rna, which acts as a messenger for viral structural proteins, was reduced much less or not at all. the decreased total viral rna synthesis and the ratio of 42s to 26s rna were rapidly returned to normal by ad ... | 1983 | 6656320 |
| immunoelectron microscopy using thin, frozen sections: application to studies of the intracellular transport of semliki forest virus spike glycoproteins. | | 1983 | 6656640 |
| dissection of the golgi complex. i. monensin inhibits the transport of viral membrane proteins from medial to trans golgi cisternae in baby hamster kidney cells infected with semliki forest virus. | baby hamster kidney (bhk) cells were infected with semliki forest virus (sfv) and, 2 h later, were treated for 4 h with 10 microm monensin. each of the four to six flattened cisternae in the golgi stack became swollen and separated from the others. intracellular transport of the viral membrane proteins was almost completely inhibited, but their synthesis continued and they accumulated in the swollen golgi cisternae before the monensin block. in consequence, these cisternae bound large numbers of ... | 1983 | 6682112 |
| expression of semliki forest virus proteins from cloned complementary dna. i. the fusion activity of the spike glycoprotein. | a complementary (cdna) molecule encoding the structural proteins of semliki forest virus (sfv) has been inserted into a simian virus 40-derived eucaryotic expression vector lacking introns. introduction of the recombinant dna into nuclei of baby hamster kidney cells results in the synthesis of authentic sfv membrane glycoproteins e1 and e2. the glycoproteins are both transported to the cell surface and induce cell-cell fusion after a brief treatment of the cells with low ph medium. the ph depend ... | 1983 | 6688423 |
| expression of semliki forest virus proteins from cloned complementary dna. ii. the membrane-spanning glycoprotein e2 is transported to the cell surface without its normal cytoplasmic domain. | the e2 protein (422 amino acid residues long) of semliki forest virus is a spanning membrane protein which is made in the rough endoplasmic reticulum of the infected cell and transported to the cell surface. the cytoplasmic domain of this protein comprises 31 amino acid residues. we introduced deletions of various sizes into the gene region encoding this part of the protein molecule and analyzed the transport behavior of the mutant proteins. the deletions were made using exonuclease digestions o ... | 1983 | 6688424 |
| infection of neuroblastoma cells by semliki forest virus. the interference of viral capsid protein with the binding of host messenger rnas into initiation complexes is the cause of the shut-off of host protein synthesis. | from ribosomal washes of neuroblastoma cells infected with semliki forest virus (sfv) a protein of mr 33000 was purified, which comigrated with the viral capsid protein on sodium dodecyl sulfate/polyacrylamide gels and was recognized by antibodies against the capsid protein of sfv. this protein selectively inhibits the translation of host and early viral 42s mrna in vitro, but has no effect on late viral 26s and encephalomyocarditis virus mrna translation. eukaryotic initiation factor 4b and cap ... | 1984 | 6692830 |
| identification of immunologically cross-reactive proteins of sindbis virus: evidence for unique conformation of e1 glycoprotein from infected cells. | hyperimmune antisera to purified sindbis (sin) or semliki forest (sf) virus were used to identify alphavirus-specific and cross-reactive proteins in virions and infected cells. the hyperimmune sera participated in homologous and cross-cytolysis of alphavirus-infected cells, and the use of monospecific antisera to sin structural proteins suggested that e1 and e2 could serve as target proteins in cytolysis. proteins from purified virions or infected cells were extracted with nonidet p-40, denature ... | 1984 | 6694261 |
| la crosse bunyavirus can mediate ph-dependent fusion from without. | lipid binding properties which are dependent on exposure to acid ph are an important mechanism for the cellular entry pathway for some enveloped viruses and for other macromolecules. cell-to-cell fusion can be used to demonstrate this function. la crosse virus, a member of the family bunyaviridae, fused bhk-21 cells from without (ffwo) upon exposure of the absorbed virus to ph 6.3 or below. a high multiplicity of infection and temperature of 37 degrees were necessary for optimum fusion. the ph r ... | 1984 | 6695500 |
| delayed type hypersensitivity against semliki forest virus in mice: local transfer of delayed type hypersensitivity with thioglycollate-induced peritoneal exudate cells. | in mice, a strong delayed type hypersensitivity (dh) without detectable neutralizing antibodies in serum could be obtained after intracutaneous injection of inactivated semliki forest virus (sfv) mixed with the adjuvant dimethyl dioctadecyl ammonium bromide (dda). thioglycollate-induced peritoneal exudate cells (pec) from these mice were highly effective in passive transfer of dh against sfv locally in footpads of naive recipient mice. dh reactions were measured with a footpad swelling test. by ... | 1984 | 6698625 |
| membrane fusion mutants of semliki forest virus. | previous reports have indicated that the entry of semliki forest virus (sfv) into cells depends on a membrane fusion reaction catalyzed by the viral spike glycoproteins and triggered by the low ph prevailing in the endosomal compartment. in this study the in vitro ph-dependent fusion of sfv with nuclease-filled liposomes has been used to select for a new class of virus mutants that have a ph-conditional defect. the mutants obtained had a threshold for fusion of ph 5.5 as compared with the wild-t ... | 1984 | 6707081 |
| identification of acyl donors and acceptor proteins for fatty acid acylation in bhk cells infected with semliki forest virus. | the modification of viral glycoproteins through the covalent attachment of fatty acids was studied in baby hamster kidney (bhk) cells infected with semliki forest virus (sfv). comparative pulse-chase experiments with [3h]palmitic acid and [35s]methionine revealed that a precursor polypeptide, designated p62, of the structural sfv glycoprotein and e1 serve as the primary acceptors of acyl chains. acylation of p62 occurs immediately prior to its proteolytical cleavage to e2 and e3 emphasizing the ... | 1984 | 6723626 |
| cell-free fatty acid acylation of semliki forest viral polypeptides with microsomal membranes from eukaryotic cells. | using [14c]palmitoyl-coa as donor and deacylated (fatty acid-free) structural proteins of semliki forest virus as exogenous acceptors, palmitic acid was incorporated into polypeptide in a cell-free system with microsomes of baby hamster kidney cells, chicken embryo fibroblasts, and rat liver cells. out of the four viral proteins (e1, e2, e3, and c) only e1 becomes acylated enzymatically. the protein bound fatty acids of the in vitro product are resistant to detergents and to organic extractions ... | 1984 | 6725287 |
| variation in homotypic and heterotypic interference by defective interfering viruses derived from different strains of semliki forest virus and from sindbis virus. | there was strong interference between various virulent and avirulent strains of semliki forest virus (sfv) and their respective defective interfering (di) viruses but in other combinations interference was variable: it could be equally strong, weak or could not be demonstrated. on passage, this spectrum of interfering activity changed, some combinations showing greater interference than before and others less. heterotypic interference between di sfv, di sindbis virus and standard viruses was cle ... | 1984 | 6726189 |
| ultraviolet-crosslinking reveals specific affinity of eukaryotic initiation factors for semliki forest virus mrna. | eukaryotic initiation factors (eif) associate readily with 32p-labeled semliki forest virus (sfv) mrna in vitro, forming complexes which can be crosslinked by 254 nm ultraviolet irradiation. after ribonuclease digestion, the initiation factors were released and analysed by gel electrophoresis. autoradiography revealed proteins by virtue of crosslinked 32p-labeled mrna fragments. eif-4a, -4b and -4c as well as three subunits of eif-3 could be crosslinked with sfv mrna. none of these proteins boun ... | 1984 | 6733107 |
| defective interfering semliki forest virus populations are biologically and physically heterogeneous. | this study demonstrates that populations of defective interfering semliki forest virus (di sev) are heterogeneous particularly in respect of their interference properties. interference was quantified by two assays, one measuring inhibition of the yield of infectious progeny virus, and the other measuring reduction in virus-directed rna synthesis; for 11 different di sfv preparations a ratio of the two interference titres was calculated. these ratios varied up to 46-fold indicating that each di v ... | 1984 | 6747604 |
| biosynthesis and assembly of membrane proteins. | | 1982 | 6764630 |
| temperature-dependent internalization of virus glycoproteins in cells infected with a mutant of semliki forest virus. | when the ts-1 mutant of semliki forest virus (sfv) was grown in chick embryo or bhk 21 cells at the restrictive temperature (39 degrees c), its membrane glycoproteins were arrested in the endoplasmic reticulum, but started to migrate to the cell surface once the cultures were shifted to the permissive temperature (28 degrees c). if the temperature of infected cells was raised back to 39 degrees c, ts-1 glycoproteins disappeared from the cell surface as evidenced by loss of surface immunofluoresc ... | 1982 | 6765172 |
| short-lived minus-strand polymerase for semliki forest virus. | semliki forest virus (sfv)-infected bhk-21, vero, and hela cells incorporated [3h]uridine into 42s and 26s plus-strand rna and into viral minus-strand rna (complementary to the 42s virion rna) early in the infectious cycle. between 3 and 4 h postinfection, the synthesis of minus-strand rna ceased in these cultures, although the synthesis of plus-strand rna continued at a maximal rate. at the time of cessation of minus-strand rna synthesis, two changes in the pattern of viral protein synthesis we ... | 1980 | 6768898 |
| fusion and haemolysis of erythrocytes caused by three togaviruses: semliki forest, sindbis and rubella. | semliki forest, sindbis and rubella viruses can fuse erythrocytes from several different species. large fusion vesicles consisting of tens to hundreds of red blood cells were seen under optical conditions. for the haemagglutination and cell fusion to occur the adsorption of virus and further incubation had to be carried out at ph 5.8. haemagglutination took place over a wide temperature range (0 to 40 degrees c) whereas fusion required temperatures between 37 and 42 degrees c. haemolysis of red ... | 1980 | 6770037 |
| further studies of macrophages in relationship to avirulent semliki forest virus infections. | the amount of virus in macrophages from normal mice infected in vivo and in vitro with avirulent semliki forest virus a7(74)c1 and virulent l10/c1 has been compared to that in macrophages infected similarly from mice given myocrisin (colloidal gold) before inoculation. very high titres of virus were found in all macrophages which had been "blockaded" with myocrisin up to 10(8.5)/icld50/ml with the avirulent strain and up to 10(7.2)/icld50/ml with the virulent strain. "blockade" of the macrophage ... | 1980 | 6775662 |
| brain glycosidases in creutzfeldt-jakob disease. | several glycosidase activities were measured in frontal gray matter of 4 brains from subjects affected by creutzfeldt-jakob disease. the changes of n-acetyl-beta-glucosaminidase, n-acetyl-beta-galactosaminidase, beta-glucosidase, alpha-fucosidase and alpha-mannosidase were not statistically significant but significant increases of beta-glucuronidase and beta-galactosidase activities were found. these results are in accordance with several reports on brain glycosidases in scrapie and semliki fore ... | 1981 | 6783737 |
| synthesis of semliki-forest virus in polyamine-depleted baby-hamster kidney cells. | the role of polyamines in macromolecular synthesis has been studied using the synthesis of semliki-forest virus (sf virus) in normal and alpha-difluoromethylornithine-treated baby-hamster kidney (bhk21) cells as a model system. the activities of ornithine decarboxylase and s-adenosylmethionine decarboxylase, the rate-limiting enzymes in polyamine biosynthesis, decreased rapidly in mock- and sf-virus-infected cells, indicating that virus production in bhk21 cells was not dependent on polyamines f ... | 1982 | 6812570 |
| penetration of semliki forest virus from acidic prelysosomal vacuoles. | to identify and characterize the intracellular site from which the penetration of semliki forest virus (sfv) to the cytosolic compartment of the host cell occurs, we determined the time course and temperature dependence of nucleocapsid uncoating and infection in bhk-21 cells. at 37 degrees c the genome release to the cytosol was detected within 5-7 min after virus endocytosis, whereas delivery of the virus particles to secondary lysosomes occurred within 15-20 min. at temperatures of 15 degrees ... | 1983 | 6831562 |
| interactions of semliki forest virus spike glycoprotein rosettes and vesicles with cultured cells. | semliki forest virus (sfv)-derived spike glycoprotein rosettes (soluble octameric complexes), virosomes (lipid vesicles with viral spike glycoproteins), and liposomes (protein-free lipid vesicles) have been used to investigate the interaction of subviral particles with bhk-21 cells. cell surface binding, internalization, degradation, and low ph-dependent membrane fusion were quantitatively determined. electron microscopy was used to visualize the interactions. virosomes and rosettes, but not lip ... | 1983 | 6833365 |
| structural proteins of western equine encephalitis virus: amino acid compositions and n-terminal sequences. | the structural proteins of western equine encephalitis virus, a member of the alphavirus group, have been characterized by the determination of their amino acid compositions and by n-terminal sequence analysis. more than 60 residues of the n-terminal sequences of each of the envelope glycoproteins have been determined. a comparison of these sequences with the previously determined sequences of two related alphaviruses. sindbis virus and semliki forest virus, strongly supports the view that all t ... | 1983 | 6834471 |
| the core protein of alphaviruses. 1. purification of peptides and complete amino-acid sequence of semliki forest virus core protein. | the primary structure of the core protein of semliki forest virus has been established by protein chemical characterization of 102 peptides, generated by digestion with trypsin, pepsin, thermolysin, and by partial acid cleavage of the protein. besides a difference in one position, the sequence as established by these experiments is in agreement with the sequence predicted from the nucleotide sequence of the mrna [garoff et al. (1980) proc. natl acad. sci. usa, 77, 6376-6380]. the core protein ha ... | 1983 | 6852050 |
| the avirulent a7 strain of semliki forest virus has reduced cytopathogenicity for neuroblastoma cells compared to the virulent l10 strain. | molecular and host range properties of the virulent l10 strain of semliki forest virus were compared to those of the avirulent a7 strain. no difference could be detected between the two strains in adsorption, nucleocapsid synthesis, protein synthesis, ratio of 42s:26s rna, particle infectivity, interferon induction and susceptibility, or defective interfering particle production. a7 showed lower total rna synthesis than l10 in bhk, g26-24 (oligodendroglioma) and c1300 (neuroblastoma) cells. cyto ... | 1983 | 6854273 |
| neutralizing and non-neutralizing monoclonal antibodies to the e2 glycoprotein of semliki forest virus can protect mice from lethal encephalitis. | two monoclonal antibodies (um 4.2 and um 5.1) directed against the glycoprotein e2 of semliki forest virus (sfv) are described; both belong to the igg2a isotype but are of different idiotype. analysis employing isoelectric focusing resulted in different focusing patterns for both monoclonals (um 4.2, pi 8; um 5.1, pi 7.2). they further differed in their ability to neutralize virus. the um 4.2 antibodies were inactive in neutralization, while the um 5.1 antibodies exceeded conventional mouse hype ... | 1983 | 6854274 |
| protein synthesis in cells infected with semliki forest virus is not controlled by intracellular cation changes. | treatment of bhk cells with 1 microm nigericin results in a 55% decrease in k+ and a 3.3-fold increase in intracellular na+; protein synthesis under these conditions is depressed by 35%. in bhk cells infected with semliki forest virus (sfv), protein synthesis is depressed by 76% 6.5 h after infection; intracellular k+ is unchanged, and intracellular na+ is increased 1.8-fold at this time. these results suggest that the increase in intracellular na+ in sfv-infected bhk cells does not adequately a ... | 1983 | 6884366 |
| another violation of nih guidelines. | | 1980 | 6893357 |
| the effects of octylglucoside on the semliki forest virus membrane. evidence for a spike-protein--nucleocapsid interaction. | evidence is presented for a non-covalent interaction between the spike glycoprotein and the nucleocapsid of semliki forest virus. when isolated viruses were treated with the non-ionic detergent beta-d-octylglucoside at neutral ph and low ionic strength the lipid bilayer membrane could be removed leaving most of the spike glycoproteins attached to the nucleocapsids. the interaction between capsids and membrane protein was sensitive to elevated ph and ionic strength, but at least partially reversi ... | 1980 | 6901662 |
| viral membrane proteins acquire galactose in trans golgi cisternae during intracellular transport. | frozen, thin sections of baby hamster kidney (bhk) cells were incubated with either concanavalin a (con a) or ricinus communis agglutinin i (rca) to localize specific oligosaccharide moieties in endoplasmic reticulum (er) and golgi membranes. these lectins were then visualized using an anti-lectin antibody followed by protein a conjugated to colloidal gold. all golgi cisternae and all er membranes were uniformly labeled by con a. in contrast, rca gave a uniform labeling of only half to three-qua ... | 1982 | 6924936 |
| the capsid protein of semliki forest virus has clusters of basic amino acids and prolines in its amino-terminal region. | the amino acid sequence of the capsid (c) protein was deduced from the nucleotide sequence of the c gene. this part of the viral 42s rna genome was transcribed into double-stranded cdna. the cdna was cloned in the escherichia coli chi 1776-pbr322 host-vector system and then the base sequence was determined with the technique described by maxam and gilbert. the amino acid sequence of the c protein shows a clustering of basic amino acids and prolines within the first 110 amino acids. | 1980 | 6935652 |
| 5'-terminal nucleotide sequence of semliki forest virus 18s defective interfering rna is heterogeneous and different from the genomic 42s rna. | an 18s defective interfering (di) rna population was isolated from the cytoplasm of baby hamster kidney (bhk-21) cells infected with semliki forest virus from the 10th undiluted passage. the rna was approximately 2000 nucleotides long and contained a 5'-terminal cap with the structure 7mgpppap and a poly(a) tract. the di rna contained large ti oligonucleotides derived from both the 42s rna-specific region and the 3' one-third of the genome common to 42s and 26s rna. several of the large oligonuc ... | 1981 | 6941239 |
| 18s defective interfering rna of semliki forest virus contains a triplicated linear repeat. | the nucleotide sequence of a nearly full-length cloned cdna copy of an 18s defective interfering (di) rna of semliki forest virus has been determined. this corresponded to a major virus-specific cytoplasmic rna species at the 11th undiluted passage of the virus in bhk cells. the 1652-nucleotide-long sequence consists of a unique 5'-terminal sequence followed by three tandem 484-nucleotide repeat units derived from the 5' two-thirds of the viral genome and a unique sequence of 106 nucleotides pre ... | 1981 | 6946476 |
| expression of the structural proteins of semliki forest virus from cloned cdna microinjected into the nucleus of baby hamster kidney cells. | the three structural proteins of semliki forest virus--i.e., the capsid, p62, and e1 proteins--were expressed in baby hamster kidney cells from cloned dna transcribed from the virus-specific 4.1-kilobase mrna. the cdna was engineered into an expression vector developed by others [mulligan, r. c. & berg, p. (1980) science 209, 1422--1427] downstream from the simian virus 40 early promoter and was introduced into cell nuclei by microneedle injection. immunofluorescence analysis of injected cells ... | 1982 | 6956877 |
| monensin inhibits semliki forest virus penetration into culture cells. | the carboxylic ionophores monensin and nigericin, at concentrations higher than 10 and 6 mum, respectively, prevent the penetration of the semliki forest virus (sfv) genome into the cytosol of baby hamster kidney (bhk-21) cells and thereby inhibit viral replication. in the absence of inhibitors, the entry of sfv is known to proceed by adsorptive endocytosis in coated vesicles, followed by acid-triggered membrane fusion in intracellular vacuoles or lysosomes. the results show that binding of the ... | 1982 | 6957864 |
| the responses of normal an athymic mice to infections by togaviruses: strain differentiation in active and adoptive immunization. | strains of yellow fever virus (yfv), venezuelan equine encephalomyelitis virus (veev) and semliki forest virus (sfv) have been used to compare the stimulations of regulatory immunity (pre-challenge), antibody synthesis and protective immunity (post-challenge) in athymic-nude and normal mice. similarly, direct assessments have been extended to athymic recipients of normal spleen cells and to adoptively immunized mice. the results indicate that the responses of mice to different togaviruses or str ... | 1980 | 6966674 |
| asymmetric and symmetric membrane reconstitution by detergent elimination. studies with semliki-forest-virus spike glycoprotein and penicillinase from the membrane of bacillus licheniformis. | the dissociation and reconstitution of the semliki forest virus membrane using the nonionic detergent octyl beta-d-glucoside was studied by sucrose density gradient centrifugation. the dissociation occurred in three stages: lysis at a free equilibrium octyl glucoside concentration of 14--18 mm, solubilization at 18--20 mm, and delipidation of the spike glycoproteins at the critical micellar concentration (22 mm) or higher. after solubilization the spike glycoproteins were present as soluble comp ... | 1981 | 6972870 |
| nucleotide sequence of cdna coding for semliki forest virus membrane glycoproteins. | the genes coding for the three membrane polypeptides of semliki forest virus have been sequenced and the primary structures of the proteins deduced. the amino acid sequence gives further insight into how the transmembrane structure of the three-chain virus membrane glycoprotein is generated in the infected cell. | 1980 | 6985476 |
| on the entry of semliki forest virus into bhk-21 cells. | the pathway by which semliki forest virus (sfv), a membrane-containing animal virus, enters bhk-21 cells was studied morphologically and biochemically. after attaching to the cell surface, the majority of viruses was rapidly trapped into coated pits, internalized by endocytosis in coated vesicles, and sequestered into intracellular vacuoles and lysosomes. direct penetration of viruses through the plasma membrane was never observed. to assess the possible involvement of lysosomes in the release o ... | 1980 | 6991511 |
| ph-dependent fusion between the semliki forest virus membrane and liposomes. | semliki forest virus was mixed with liposomes containing phosphatidylcholine,phosphatidylethanolamine, sphingomyelin, and cholesterol. when the ph of the mixture was dropped to 6 or below, rapid fusion between the membranes of the virus and the liposomes occurred, resulting in the transfer of viral nucleocapsids into the liposomes. fusion was demonstrated biochemically by trapping rnase or trypsin within the liposomes. trapped rnase digested the viral rna into acid-soluble form, providing a simp ... | 1980 | 6997876 |
| ucsd gene splicing incident ends unresolved. | | 1980 | 7001622 |
| synthesis and processing of semliki forest virus-specific nonstructural proteins in vivo and in vitro. | a large short-lived virus-specific nonstructural protein with an apparent molecular weight of about 250000 (nsp250) has been isolated from cells infected with the temperature-sensitive mutants ts-4 and ts-6 of the semliki forest virus. nsp250 contained all peptides characteristic of the two previously identified nonstructural precursor proteins, nsp155 and nsp135, as revealed by limited proteolysis with staphylococcus aureus v8 protease. thus nsp250 is probably the translational product of the 5 ... | 1980 | 7007047 |
| passage of viral membrane proteins through the golgi complex. | | 1981 | 7038131 |
| the use of red cells with fused semliki forest virus envelope proteins in antibody determinations by hemolysis in gel. | chicken red blood cells with fused semliki forest virus (sfv) proteins on the cell membrane were used in the hemolysis-in-gel (hig) plates. optimally the plate contained a 1.5 mm thick gel of 1% agarose with 1% red cells and 1 unit/ml gel of complement. 400 ng of sfv was fused to the red cells in 1 ml of the gel (about 20 virions fused to one red cell). five microliters of inactivated (56 degrees c, 30 min) serum samples were pipetted into wells in the gel. after 20 h of incubation at 37 degrees ... | 1982 | 7042724 |
| how an animal virus gets into and out of its host cell. | | 1982 | 7058321 |
| a procedure to verify an amino acid sequence which has been derived from a nucleotide sequence: application to the 26s rna of semliki forest virus. | we describe a peptide sequencing procedure which can be used to verify an amino acid sequence which is derived from a nucleotide sequence. one first labels the protein with a 3h- and a 14c-labelled amino acid and then cleaves the protein into a set of peptides using a cleavage reaction specific for a particular amino acid residue. finally one performs edman degradations on the whole mixture of peptides. the released amino acids reflect the combined aminoterminal amino acid sequences of all the p ... | 1982 | 7063412 |
| association of sindbis virion glycoproteins and their precursors. | | 1982 | 7077663 |
| nucleotide sequence at the junction between the nonstructural and the structural genes of the semliki forest virus genome. | the nucleotide sequence at the junction between the nonstructural and the structural genes of the semliki forest virus 42s rna genome has been determined from cloned cdna. with the aid of s1-mapping, we have located the 5' end of the viral 26s rna on this sequence. the 26s rna is homologous to the 3' end of the 42s rna and is used as a messenger for the structural proteins of the virus. the nucleotide sequence in the noncoding 5' region of the 26s rna (51 bases) was thus established, completing ... | 1982 | 7086974 |
| poly(a):poly(u); poly(o8a):poly(u); poly(a):poly(menh5u) and poly(o8a):poly(menh5u) versus bida semliki forest virus in chick embryos. | poly(a):poly(u) (polyadenylic acid:polyuridylic acid hybrid); poly(o8a):poly(u) (poly-8-oxy-adenylic acid:polyuridylic acid hybrid); poly(a):poly(menh5u) (polyadenylic acid-5-methylamino uridylic acid hybrid) and poly(o8a):poly(menh5u) (poly-8-oxyadenylic acid:poly-5-methylamino uridylic acid hybrid) were studied in chick embryos to compare the protection offered against semliki forest virus (the nigerian strain) an 49809. the modified polymers showed a higher activity index but were more toxic ... | 1982 | 7112601 |
| extreme ends of the genome are conserved and rearranged in the defective interfering rnas of semliki forest virus. | | 1982 | 7120391 |
| incomplete complex oligosaccharides in semliki forest virus envelope proteins arrested within the cell in the presence of monensin. | | 1982 | 7120410 |
| inhibition of semliki forest virus penetration by lysosomotropic weak bases. | the effect of five lysosomotropic weak bases (chloroquine, amantadine, tributylamine, methylamine and nh4c1) on semliki forest virus (sfv) infection has been studied in bhk-21 cells. when present at concentrations equal to or greater than 0.1, 0.5, 2, 15 and 15 mm respectively, the agents inhibited sfv infection by more than 90%. the effect was reversible and involved a process occurring within the first 60 min of virus-cell contact. the agents did not have a direct virucidal effect nor did they ... | 1982 | 7142969 |
| a kinetic and ultrastructural comparison of alphavirus infection of cultured mosquito and vertebrate cells. | vero cells and aedes pseudoscutellaris cells showed rapid production of semliki forest virus (sfv) whereas in aedes aegypti and anopheles stephensi cells no rapid production of sfv was observed. ultrastructurally the only virally induced cell inclusion in early infection was the cytopathic vacuole type 1. later in infection, in mosquito cells, electron-dense bodies appear and budding of new virions appears to be very efficient. in vero cells large accumulations of envelope proteins and nucleocap ... | 1982 | 7154145 |
| [passive hemagglutination test for semliki-forest virus (author's transl)]. | several methods of coupling immunoglobulins onto sheep erythrocytes have been examined with a view to demonstrate semliki-forest virus by use of a passive hemagglutination tests. with the exception of the carbodiimid coupling reaction, most methods could be used to couple goat anti sfv igg to erythrocytes. best results were obtained when anti sfv goat igg was coupled to sheep red blood cells by using 0.25% glutaraldehyde. sheep red blood cells treated after that method could be used to identify ... | 1980 | 7191609 |