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sequence analysis of the e2 gene of a hyperglycosylated, host restricted mutant of sindbis virus and estimation of mutation rate from frequency of revertants.svap15/21, a strain of sindbis virus (sv) derived from our standard laboratory strain of sv (svstd) after repeated passage on aedes albopictus cells, grows normally in mosquito cells but is host restricted (hr) in vertebrate cells. it is also temperature sensitive (ts) and produces pinpoint plaques on vertebrate cells (sp). e2 glycoprotein of svstd differs from that of the more widely used svhr (from which svstd was derived) by an additional (i.e., third) n-linked glycan. the e2 of svap15/21, in ...19863750843
[mechanism of action of remantadine hydrochloride on sindbis virus reproduction: inhibition of virus penetration into the cell].the effect of rimantadine and ammonium chloride on the rna synthesis of sindbis virus, added in different times of infection cycle, was studied. when compounds were presented in period of adsorption and first hour post-infection, the maximal inhibitory effect was found. the step blocked by rimantadine was identified as uncoating process (deprotainization). this connection was confirmed by the finding that rimantadine markedly reduced the change of the virus rna into the nuclease-sensitive form.19863811275
sindbis virus infection increases hexose transport in quiescent cells.sindbis virus infection of baby hamster kidney cells or chick embryo cells resulted in a significant increase in the rate of uptake of [2-3h]deoxy-d-glucose ([3h]dglu). stimulation of hexose transport in sindbis virus-infected cells occurred only if the cells were rendered quiescent by culturing at high density or by serum starvation. in contrast, sindbis virus-induced inhibition of potassium transport, measured as a decrease in the uptake of 86rb+, was independent of cell growth state. stimulat ...19863024395
dominance of the cpe(+) phenotype in hybrid aedes albopictus cells infected with sindbis virus.the effect of sindbis virus (sv) infection was analyzed in hybrid aedes albopictus cells formed by fusing ouabain-resistant cpe(+) cells to cpe(-) alpha-amanitin resistant cells. although the 24-h yields of virus from the parental cpe(+) and cpe(-) clones were similar, the rates of viral rna synthesis and virus release at early times post-infection were higher in the cpe(+) cells. in all eight hybrid clones studied, the cpe(+) phenotype was dominant. in addition, the kinetics of viral rna synthe ...19863765819
scanning fluorescence correlation spectroscopy. ii. application to virus glycoprotein aggregation.scanning fluorescence correlation spectroscopy is a new approach to measuring changes in the state of aggregation of cell membrane proteins. measurements of the mean number of aggregates of virus glycoproteins from sindbis virus and vesicular stomatitis virus agree with the findings of a recent fluorescence photobleaching recovery study on the same systems (johnson, d.c., m.j. schlesinger, and e.l. elson, 1981, cell, 23:423-431). sindbis virus glycoproteins are immobilized and cannot be induced ...19863013328
expression of genes encoding vesicular stomatitis and sindbis virus glycoproteins in yeast leads to formation of disulfide-linked oligomers.saccharomyces cerevisiae strains transformed with plasmids containing cdnas coding for the glycoproteins of vesicular stomatitis or sindbis viruses can be induced to produce large amounts of glycosylated virus glycoproteins. studies reported here show that these proteins from high molecular weight disulfide-linked oligomers in the yeast endoplasmic reticulum. oligomers were also found for two genetically altered forms of vsv g; one of these was lacking the membrane anchor domain and the other ha ...19863016985
experimental assessment of the vector competence of culex (culex) neavei theobald with west nile and sindbis viruses in south africa.culex univittatus is the maintenance vector of west nile (wn) and sindbis (sin) viruses on the inland plateau of south africa and also transfers infection to man. both viruses have frequently been isolated from this mosquito and human immunity is high on the plateau. in the natal lowlands where cx univittatus is replaced by cx neavei, apparently the main vector there, immune rates are low and few isolations have been made from this species. vector competence experiments were carried out with cx ...19863024364
rna virus genomes hybridize to cellular rrnas and to each other.in this communication we show that the rna genomes of vesicular stomatitis, sindbis, and reoviruses can specifically hybridize under stringent conditions to the large rrnas present in hela cell cytoplasmic extracts. in addition, we show that some virus genome rnas can also hybridize to each other. on the basis of our previous detailed studies identifying specific regions of hybridization between the poliovirus genome and 28s rrna, we suggest that a similar phenomenon of "patchy complementary" ma ...19863005635
sindbis virus mutant ts20 of complementation group e contains a lesion in glycoprotein e2.a technique has been devised to readily obtain the entire structural protein region of sindbis virus cloned into a plasmid vector. this method uses the fact that the nearest site for restriction enzyme hindiii to the 3' terminal poly(a) occurs at nucleotides 6266-6271 in the genomic rna. inserts extending from the poly(a) tract to this hindiii site are 5438 nucleotides long (excluding the poly a tract) and contain the entire 4106-nucleotide structural protein region. using an oligo(dt)-tailed ve ...19863008426
ockelbo disease: arthralgia 3-4 years after infection with a sindbis virus related agent. 19862871323
synergistic anticellular and antiviral activities of human recombinant interferon-gamma and -beta.the synergism of anticellular and antiviral activities of recombinant human interferon-gamma (reifn-gamma) and recombinant human interferon-beta (reifn-beta) was examined in vitro using human melanoma sk-mel-28 cells. some differences were detected in the kinetics of anticellular activity between both ifns, namely the inhibitory effect of reifn-beta occurred earlier than that of reifn-gamma. significant synergism was detected in the anticellular activity of both ifns when growth curves and isobo ...19863031263
sindbis virus-mediated cell fusion from without is a two-step event.the process by which sindbis virus induces the fusion of bhk-21 cells in monolayer cultures after exposure to low ph was examined. the fusion process was found to require an exposure to low ph followed by a return to conditions closer to neutral ph. the rate at which cells fused was affected by the ph to which the monolayers were exposed, subsequent to the initial exposure to acid conditions. virus-mediated cell fusion was not observed if the virus-cell complexes were maintained at the acid ph r ...19863944588
sindbis and west nile virus infections in the witwatersrand-pretoria region.from mid-december 1983 until mid-april 1984, there was an epidemic of sindbis (sin) virus infection in the witwatersrand-pretoria region in which hundreds of human cases were diagnosed clinically. twenty-eight of these diagnoses were confirmed in the laboratory by seroconversion as being infections with sin virus, and 5 cases of infection with west nile (wn) virus were also found. attempts to isolate virus from 66 patients, mainly from serum specimens, were unsuccessful. infection rates for the ...19863016922
the effect of loss of regulation of minus-strand rna synthesis on sindbis virus replication.during the replication cycle of sindbis virus minus-strand synthesis stops normally at the time that plus-strand synthesis reaches a maximum rate. we have isolated and characterized revertants of ts24, a member of the a complementation group of sindbis hr mutants, that we had demonstrated previously to have a temperature-sensitive defect in the regulation of minus-strand synthesis. these revertants of ts24 replicated efficiently at 40 degrees but nevertheless retained the temperature sensitive d ...19863705466
effect of concanavalin a on early interactions of sindbis virus with goose erythrocytes and bhk 21 cells.the role of mannose containing molecules in sindbis virus envelope glycoproteins and cell membrane receptors was investigated by means of concanavalin a (con a). treatment of virus or bhk 21 cells with the lectin before infection reduced viral infectivity. hemagglutination and hemolysis showed a different sensitivity to con a. hemagglutination was not affected by the lectin and treatment of erythrocytes with con a produced an enhancement of agglutinability by the virus. hemolytic activity was, o ...19863747853
novel preparation of functional sindbis virosomes.lipid and protein factors important for the preparation and stability of reconstituted membranes prepared by the insertion of detergent-solubilized sindbis virus glycoproteins into preformed lipid vesicles have been defined. it was found that both the state of aggregation of the membrane protein and the phase of the lipid are critical for the insertion of proteins into preformed lipid vesicles. the membranes prepared with the insertion technique were characterized in terms of residual detergent, ...19863756136
circulation of mosquito-borne viruses in large-scale sheep farms in eastern slovakia.samples of blood sera collected from 608 sheep in large farms of the districts of trebisov, michalovce, vranov nad toplou and humenné were investigated in hemagglutination-inhibition test for the presence of mosquito-borne viruses sindbis, west nile, tahyna and calovo. antibodies to arboviruses tahyna (11.5%) and calovo (10.9%) were detected most frequently, while a lower sero-positivity was recorded to the sindbis (2.3%) and west-nile (1.0%) viruses. certain differences were found in the infect ...19863758873
effect of interferon on vero cells persistently infected with sspe virus and lytically infected with measles virus.the effect of lymphoblastoid interferon (ifn) on viral polypeptides synthesized in a vero cell culture persistently infected with subacute sclerosing panencephalitis virus (sspe-vero) was compared to that of vero cells infected with exogenous measles virus. after ifn treatment there was no significant decrease in the synthesis of sspe viral proteins, but inhibition of synthesis of measles polypeptides was readily seen. in vero and sspe-vero cells ifn was able to inhibit replication of sindbis vi ...19863729726
characterization of sindbis virus epitopes important for penetration in cell culture and pathogenesis in animals.two anti-glycoprotein e2 monoclonal (mc) antibodies, designated r6 and r13, prepared against an attenuated mutant (sb-rl) of sindbis virus, preferentially neutralize attenuated, rapidly penetrating strains of sindbis as opposed to virulent, more slowly penetrating strains. an antigenic variant of sb-rl which displayed reduced reactivity with r6 and r13, demonstrated virulence in suckling mice and slow penetration in baby hamster kidney cells. anti-e2 mc antibodies to sb-rl and to an independentl ...19862417415
pretreatment of human lymphocytes with interferon enhances the synthesis of interferon in cocultures with allogeneic cells.human lymphocytes pretreated with interferon (ifn) alpha, beta, or gamma produced 17 times more ifn alpha (600-10,000 units/ml) than nontreated lymphocytes when cocultivated with allogeneic cells. significant increases in ifn production (500-3,000 units/ml) were observed when lymphocytes were treated with ifn for just 2 h, and peak levels (10,000 units/ml) were produced after a 4-h treatment. the amount of ifn required to show the maximum priming effect was between 100 and 1,000 units; higher le ...19862427629
analysis of receptors, cell surface antigens, and proteins in human melanoma cell lines resistant to human recombinant beta- or gamma-interferon.we studied the mechanisms of resistance to interferon (ifn) in two human melanoma cell lines, sk-mel-28/beta cells resistant to human recombinant beta-interferon (reifn-beta) and sk-mel-28/gamma cells resistant to human recombinant gamma-interferon (reifn-gamma). sk-mel-28/beta cells were resistant to both reifn-beta and ifn-alpha, but not reifn-gamma or natural gamma-interferon (ifn-gamma), and sk-mel-28/gamma cells were resistant to both reifn-gamma and ifn-gamma, but not reifn-beta or ifn-alp ...19862430691
cells with natural killer activity in the cerebrospinal fluid of normal mice and athymic nude mice with acute sindbis virus encephalitis.sindbis virus causes an acute, nonfatal inflammatory encephalitis in weanling balb/c mice. mononuclear inflammatory cells are present in the cerebrospinal fluid (csf) as well as in the parenchyma of the brain. both aspects of this inflammatory response were eliminated by treatment with cyclophosphamide. athymic nude (nu/nu) mice developed no inflammation in the brain, but did develop a csf pleocytosis that peaked on day 2 after infection. the time course of the appearance of cells in the csf was ...19862419416
antibody-selected variation and reversion in sindbis virus neutralization epitopes.sindbis virus variants evidencing a complex and bidirectional tendency toward spontaneous antigenic change were isolated and characterized. variants were selected on the basis of their escape from neutralization by individual monoclonal antibodies to either of the two envelope glycoproteins, e2 and e1. multisite variants, including one altered in three neutralization sites, were obtained by selecting mutants consecutively in the presence of different neutralizing monoclonal antibodies. two pheno ...19862419586
monoclonal antibody cure and prophylaxis of lethal sindbis virus encephalitis in mice.neuroadapted sindbis virus (nsv) causes acute encephalitis and paralyzes and kills adult mice unless they are treated with primary immune serum after infection. to study the nature and specificity of curative antibodies, we gave mice 30 different monoclonal antibodies (mabs) against sindbis virus (sv) 24 h after lethal intracerebral inoculation of nsv. by the time of mab treatment, nsv replication in the brain had been well established (7.5 x 10(7) pfu/g). seventeen mabs directed against multipl ...19862419592
[interferon production in lymph nodes draining breast carcinoma and its augmentation by ok-432].in breast cancer patients on whom modified radical mastectomy is performed, relatively more of the regional lymph nodes draining the breast carcinoma remain in comparison with standard radical mastectomy. therefore, investigation of the functions of lymph nodes draining breast carcinoma has become important. lymphocyte subsets of 33 axillary lymph nodes from 19 breast cancer patients were analysed using flow cytometry. in axillary lymph nodes, both okt-3(+) cells and okt-8(+) cells were decrease ...19862428312
alphavirus replication in cultured cells and infected animals is inhibited by antiproteinase agents.the influence of different antiproteinase agents on alphavirus replication was examined. sindbis virus multicycle replication in cultured cells was suppressed by n-tosyl-phenylalanine chloromethyl ketone (tpck), an inhibitor of chymotrypsin-like proteinases, and by aprotinin, an inhibitor of a wide spectrum of proteinases. antiviral activity of tpck was also demonstrated in sindbis virus-infected animals. parenteral injections of tpck in infected mice reduced virus titers in brain and blood. the ...19862429615
translation of homologous and heterologous messenger rnas in a yeast cell-free system.a stable mrna-dependent cell-free translation system from saccharomyces cerevisiae, prepared by a modification of the method of hofbauer et al. [eur. j. biochem. 122 (1982) 199-203] was active in translation of exogenous homologous and heterologous mrnas. optimal translational activity required the addition of polyamines and yeast trna. the m transcript of the m segment of double-stranded rna, synthesized in vitro using the killer virus-associated rna polymerase, directed the synthesis of prepro ...19862433189
deletion mapping of sindbis virus di rnas derived from cdnas defines the sequences essential for replication and packaging.defective-interfering (di) genomes of a virus contain sequence information essential for their replication and packaging. they need not contain any coding information and therefore are a valuable tool for identifying cis-acting, regulatory sequences in a viral genome. to identify these sequences in a di genome of sindbis virus, we cloned a cdna copy of a complete di genome directly downstream of the promoter for the sp6 bacteriophage dna dependent rna polymerase. the cdna was transcribed into rn ...19863753584
identification of the inflammatory cells present in the central nervous system of normal and mast cell-deficient mice during sindbis virus encephalitis. 19863742614
alternative forms of a strain-specific neutralizing antigenic site on the sindbis virus e2 glycoprotein.experiments with monoclonal antibodies raised against two laboratory strains of sindbis virus, sb and sin, suggested the existence of a strain-specific neutralizing antigenic site (e2-b) on the e2 glycoprotein. a comparison of monoclonal antibody binding patterns and e2 glycoprotein gene sequences of six laboratory strains distinguished three different configurations of e2-b that correlated with specific amino acid substitutions at position 216 of the e2 glycoprotein. further study of neutraliza ...19872445100
induction of the stress response: alterations in membrane-associated transport systems and protein modification in heat shocked or sindbis virus-infected cells.heat shock or sindbis virus infection of chick embryo (ce) or baby hamster kidney (bhk) cells resulted in a decrease in the uptake of 86rubidium+, a k+ tracer. both stressful treatments decreased 86rb+ uptake by inhibition of the ouabain-sensitive na+/k+ atpase. alterations in the intracellular levels of monovalent ions may be involved in translational or transcriptional control of the stress response. heat shock or sindbis virus infection also resulted in an increase in rate of uptake of [3h]de ...19872825445
interactions of target-sensitive immunoliposomes with herpes simplex virus. the foundation of a sensitive immunoliposome assay for the virus.interactions between target-sensitive (ts) immunoliposomes and herpes simplex virus (hsv) were investigated. target sensitivity of phosphatidylethanolamine (pe) immunoliposomes is a result of the ability of acylated monoclonal anti-hsv glycoprotein d (gd) to stabilize the bilayer phase of pe, whereas by itself, pe does not form stable liposomes (ho, r. j. y., rouse, b. t., and huang, l. (1986) biochemistry 25, 5500-5506). upon binding of these immunoliposomes to hsv antigen-containing gd, destab ...19872820988
engineered defective interfering rnas of sindbis virus express bacterial chloramphenicol acetyltransferase in avian cells.we are investigating the feasibility of using the positive-strand rna virus sindbis virus and its defective interfering (di) particles as vectors for introducing foreign genes into cells. in previous work we showed by deletion mapping of a cloned cdna derived from one of the di rnas that only nucleotides at the 3' and 5' termini of the rna are essential for the di rna to be amplified after it is transfected into cells in the presence of helper virus. as a first step in developing a vector we rep ...19872440030
loss of (2'-5')oligoadenylate synthetase activity by production of antisense rna results in lack of protection by interferon from viral infections.an expression vector was constructed that carries part of the human bk papovavirus with 0.5 kilobases of (2'-5')oligoadenylate (2-5a) synthetase cdna inserted in inverted orientation downstream from the virion proteins (vp) promoter and the neomycin-resistance gene neo under the control of a simian virus 40 promoter. cells transfected with this vector and selected for resistance to the neomycin derivative g418 synthesized rna complementary to 2-5a synthetase mrna. these cells lacked 2-5a synthet ...19872433688
microcarriers as a culturing system of insect cells and insect viruses.there is an increasing interest in culturing of insect cells, which are host for arthropod-born (arbo) viruses. the potential applications of arbo viruses are in the following two main fields: 1. medical applications (e.g. preparation of viral vaccines and viral antigens for diagnostic purposes). 2. as bioinsecticides in pest control in horticulture, agriculture and forestry. one of the potential cell substrates for these applications is an anchorage-dependent-mosquito cell line established from ...19872438174
is sindbis a simple picornavirus with an envelope?a three-dimensional image reconstruction was performed from cryo-electron micrographs of isolated sindbis (snv) nucleocapsids. the isolated capsid is a smooth but fenestrated t = 3 structure. comparison with the nucleocapsid seen within the whole virion indicated that the structure resembles the swollen forms which some non-enveloped viruses adopt after removal of divalent cations. a sensitive comparison method was used to align snv capsid protein sequences with those of picornavirus vp3 capsid ...19873595557
production of infectious rna transcripts from sindbis virus cdna clones: mapping of lethal mutations, rescue of a temperature-sensitive marker, and in vitro mutagenesis to generate defined mutants.we constructed full-length cdna clones of sindbis virus that can be transcribed in vitro by sp6 rna polymerase to produce infectious genome-length transcripts. viruses produced from in vitro transcripts are identical to sindbis virus and show strain-specific phenotypes reflecting the source of rna used for cdna synthesis. the cdna clones were used to confirm the mapping of the causal mutation of ts2 to the capsid protein. a general strategy for mapping sindbis virus mutations is described and wa ...19873479621
the t=4 envelope of sindbis virus is organized by interactions with a complementary t=3 capsid.the three-dimensional structure of sindbis virus, an enveloped animal virus, has been determined to a resolution of 35 a by using a common lines procedure to combine cryoelectron micrographs of vitrified particles. the spikes of the virus appear as columnar trimers arranged on a t=4 lattice. the lipid bilayer of the virus envelope is polyhedral and surrounds a smooth t=3 nucleocapsid. hence, a complete sindbis virion (molecular weight 46.4 x 10(6)) contains 240 copies of each of the spike protei ...19873829124
regional distribution of sindbis virus glycoproteins on the plasma membrane of infected baby hamster kidney cells.sindbis virus-infected baby hamster kidney (bhk) cells were analysed in surface replicas or conventional thin sections after specific immunolabelling with antiviral glycoprotein antibodies in conjunction with colloidal gold-conjugated protein a. newly synthesized viral glycoproteins were detected, beginning 1 1/2 h after infection, while the virus maturation started 3 h after infection. the glycoproteins appeared to be inserted on the plasma membrane in large spots located mainly in the central ...19873780874
free diffusion to and from the inner nuclear membrane of newly synthesized plasma membrane glycoproteins.sindbis virus-infected baby hamster kidney (bhk) cells were analyzed by thin section fracture-label. specific immunolabel with antiviral glycoprotein antibodies was used in conjunction with colloidal gold-conjugated protein a. as we previously reported (torrisi, m. r., and s. bonatti, 1985, j. cell biol., 101:1300-1306), sindbis transmembrane glycoproteins are present in the inner nuclear membrane as well as in the outer nuclear membrane, endoplasmic reticulum, golgi stacks and vesicles, and pla ...19873818797
the pathogenesis of spinal cord involvement in the encephalomyelitis of mice caused by neuroadapted sindbis virus infection.weanling mice develop an acute encephalomyelitis with high mortality after intracerebral inoculation of neuroadapted sindbis virus. the mice develop kyphoscoliosis and hindlimb paralysis. immunohistochemical and in situ hybridization studies have demonstrated virus in the gray matter of the brain and spinal cord. ventral horn cells are prominently infected, providing an anatomical basis for the clinical poliomyelitis. a novel route of spread of inoculated virus within the central nervous system ...19873031369
synergistic action of quercetin and murine alpha/beta interferon in the treatment of mengo virus infection in mice.abd2f1 mice were infected intraperitoneally (i.p.) or intranasally (i.n.) with mengo or sindbis virus and treated with either crude murine alpha/beta interferon (muifn-alpha/beta) or quercetin, or both. muifn-alpha/beta given i.p. or intramuscularly (i.m.) 1-3 h before the infection had a dose-dependent protective effect regardless of the route of administration. when given after the infection, ifn did not show any effect. oral quercetin, capable of protecting cardio, i.e. mengo virus-infected m ...19873038013
reduction in antiviral activity of human interferon-gamma in acidic media with reference to structural change.the fluorescence intensity of a unique tryptophan 36 in human interferon-gamma was drastically decreased below ph 4 with a concomitant decrease of antiviral activity. the region of residues 32-42 of human interferon-gamma was found by calculation to have a low hydrophobicity together with a high helical hydrophobic moment, and the net electric charge of this region having an amphiphilic helical structure changed significantly near ph 4. these results suggest that the region of residues 32-42 pla ...19873118958
passive protection across subgroups of alphaviruses by hyperimmune non-cross-neutralizing anti-sindbis serum.extended hyperimmunization of rabbits with sindbis (sin) or semliki forest (sf) viruses causes the production of antisera that are cross-reactive with virus-infected cells in antibody-dependent, complement-mediated cytotoxicity assays but that do not cross-neutralize viruses in vitro. c3h/hej mice given gamma globulin fractionated from the extended hyperimmune antiserum against sin, but not control sera, were protected from challenge by 100 ld50 of sf, a virus which is in a different subgroup th ...19873025890
organization of the sindbis virus nucleocapsid as revealed by bifunctional cross-linking agents.purified sindbis virus nucleocapsids were reacted with a variety of bifunctional protein-specific cross-linking agents. the products were analyzed in concentration-gradient polyacrylamide gels and amounts of various products determined. these studies indicated that available lysine residues within adjacent capsid proteins in purified intact nucleocapsids are separated by 6 a. the capsid proteins in intact nucleocapsids are cross-linked in a pattern predicted for discrete monomeric entities, rath ...19873656418
antiviral effects of melia azedarach l. leaves extracts on sindbis virus-infected cells.partially purified extracts from leaves of melia azedarach l. (ma) exert a broad range of antiviral effects on dna and rna viruses. the effect of ma on different stages of sindbis virus replicative cycle in bhk cells was investigated. under one-step growth conditions ma afforded a greater than 90% inhibition in virus yield if added to the cell cultures 2 h before or after infection, and when added 4 h after infection ma still caused a greater than 80% inhibition. analysis of early events followi ...19873688841
fusion of sindbis virus with model membranes containing phosphatidylethanolamine: implications for protein-induced membrane fusion.the ph-induced fusion of sindbis virus with model lipid membranes containing phosphatidylethanolamine has been studied using a quantitative fluorescence technique. the headgroup and acyl chain domains of the lipids have been altered systematically to determine their effect on fusion. unsaturated phosphatidylethanolamines (pe) have been found to promote fusion, either by themselves, or in combination with phosphatidylcholines (pc). cholesterol added to a mixture of unsaturated pe and pc was also ...19873580364
topological organization of sindbis virus capsid protein in isolated nucleocapsids.sindbis virus nucleocapsids were isolated from mature virions by a two-step purification method. detergent-treated virions were sedimented in sucrose gradients and the nucleocapsid peaks chromatographed on rnase-free sephadex g-200. the purified nucleocapsids displayed several morphologies when examined in the electron microscope. these morphologies, and the results of double-angle shadowing, suggest that the core of this enveloped virus has the shape of a regular icosahedron with a triangulatio ...19873590962
inactivation of 12 viruses by heating steps applied during manufacture of a hepatitis b vaccine.the efficacy of two heating cycles (90 sec at 103 degrees c and 10 hr at 65 degrees c) used during manufacture of a plasma-derived hepatitis-b vaccine was validated for the inactivation of 12 virus families. a period of 15 min warming up to 65 degrees c had already completely inactivated representatives of nine virus families, ie, poxvirus (vaccinia), picornavirus (encephalomyocarditis virus), togavirus (sindbis virus), coronavirus (mouse hepatitis virus), orthomyxovirus (influenza virus), rhabd ...19872828525
use of enzyme immunoassay and nucleic acid hybridization for detecting sindbis virus in infected mosquitoes.aedes aegypti mosquitoes were inoculated intrathoracically with prototype sindbis virus, held at 26.7 degrees c for from 0-95 h and placed at -70 degrees c. individual mosquitoes were tested for virus by plaque assay in vero cells, for viral rna by nucleic acid hybridization using a cloned cdna probe, and for viral protein by enzyme-linked immunosorbent assay. virus was detected by plaque assay as early as 8 h after infection. sindbis virus rna was detected by nucleic acid hybridization 18 h aft ...19872890652
approaches to the study of vector specificity for arboviruses--model systems using cultured mosquito cells. 19872884833
overwintering of culex mosquitoes in sweden and their potential as reservoirs of human pathogens.1. culex pipiens l. and cx torrentium martini are suspected enzootic vectors in sweden of sindbis virus causing ockelbo disease in man. to estimate their potential as virus reservoirs over the winter, mosquitoes were collected from august to may from a cellar in a rural area, central sweden. the mosquitoes were dissected and examined for blood content, gonotrophic stage, parity and insemination, and tested for fructose. 2. cx pipiens, cx torrentium and cx territans walker constituted 94% of 887 ...19872856507
the effect of gold sodium thiomalate in adult swiss/a2g mice infected with togaviruses and flaviviruses.treatment of adult mice with gold sodium thiomalate made the normally non-lethal semliki forest virus and sindbis virus infections lethal and increased the virulence of langat and west nile viruses. these changes were associated with an enhanced virus invasion of the brain. depression of the humoral antibody response was not observed.19872822844
elimination of viruses (human immunodeficiency, hepatitis b, vesicular stomatitis and sindbis viruses) from an intravenous immunoglobulin preparation.more than 10(4) plaque-forming units (pfu)/ml of hiv are inactivated during the alcohol fractionation step from plasma to fraction (fr)-ii+iii, greater than 10(4) pfu/ml is inactivated from fr-ii+iii to fr-ii and greater than 10(4) pfu/ml is inactivated during the polyethylene glycol (peg) fractionation process from fr-ii+iii to intravenous igg (ivig). the total inactivation rate from plasma to ivig via fr-ii+iii or fr-ii was calculated to be greater than 10(8) or 10(12), respectively. the peg f ...19872825431
antiviral activity of uridine 5'-diphosphate glucose analogues against some enveloped viruses in cell culture.twenty five analogues of uridine 5'-diphosphate glucose were screened against herpes simplex type 2, vaccinia virus, sindbis virus and african swine fever virus. after screening, the compound 5'-[[[[(2",3",4",6"-tetra-o-benzoyl-alpha-d- glucopyranosyl)oxi]carbonyl]amino]sulfonyl]uridine (2), the synthesis of which has been reported (camarasa et al., j. med. chem. 28, 40-46, 1985), was selected for further study. this compound showed in vitro activity against all viruses tested. the replication o ...19872837144
differential effects of oncogenic transformation on n-linked oligosaccharide processing at individual glycosylation sites of viral glycoproteins.hamster sarcoma virus (hsv) transformation of nil-8 fibroblasts is associated with an increase in the average size of n-acetyllactosamine (complex) type n-linked glycans due to an increase in both the average number of branches/chain and in the fraction of n-linked glycans containing poly(glcnac(beta 1,3) gal-(beta 1,4)) (polylactosaminylglycan) chains. analysis of glycopeptides from the envelope glycoproteins of sindbis virus and vesicular stomatitis virus (vsv) grown in nil-8 and nil/hsv cells ...19872824491
characterization of a murine cytomegalovirus-induced immunosuppressive factor.murine cytomegalovirus infection in spleen cultures resulted in the production of a soluble factor, visf (virus-induced suppressive factor), which inhibited concanavalin a mitogenesis in fresh spleen cells. its production was specific for mcmv, since infection of spleen cultures by sindbis virus, or bacteriophages pm 2 and t 4, and the phagocytosis of latex beads, all failed to elicit visf. maximum appearance of the factor occurred within 24 hours p.i. in spleen cultures, and its source was iden ...19872821959
replication of the genome of alphaviruses.the genome of semliki forest virus (sfv) is 11,442 nucleotides with a 5' cap-structure and a 3' poly(a) tail of about 100 residues. the genome of the closely relate sindbis virus (sin) is slightly longer (11,703 nucleotides). the parental rna is first translated from the 5' two thirds to yield; nsp1, nsp2, nsp3 and nsp4, which are cleaved from a polyprotein of 2431 amino acids (sfv). the parental genome is copied to a full-length minus strand with poly(u) at the 5' end. the minus strand is used ...19872846593
sindbis virus mutants resistant to mycophenolic acid and ribavirin.previous work from this laboratory has demonstrated a correlation between the inhibition by ribavirin (rbv), mycophenolic acid (mpa), or 2-amino thiadiazole (tda) of sindbis virus replication in aedes albopictus mosquito cells and a reduction in cellular gtp levels. this reduction in gtp results from the inhibition by these drugs of inosine monophosphate dehydrogenase (impdh), the first enzyme specific for the de novo synthesis of gmp. by serial passage of sv in a. albopictus cells in the presen ...19873033882
glucose trimming and mannose trimming affect different phases of the maturation of sindbis virus in infected bhk cells.the roles of glucose and mannose trimming in the maturation of sindbis virus in bhk cells have been investigated using inhibitors of glycoprotein oligosaccharide processing. in the presence of the glucosidase inhibitor n-methyl-1-deoxynojirimycin the viral glycoproteins were equipped with oligosaccharides of the composition glc3man8,9(glcnac)2 and the yield of virus in the extracellular medium was reduced as a result of a block in the proteolytic cleavage of the precursor (pe2) of the e2 viral e ...19872960074
[immunofluorescent detection of viral antigens in the enzymatic processing of histological and cytological matter]. 19873314146
effects of 5'-terminal modifications on the biological activity of defective interfering rnas of sindbis virus.we have been studying defective interfering (di) genomes of the rna enveloped virus sindbis virus. deletion mapping of a di cdna demonstrated that only sequences at the 3' and 5' termini of the genome are required for the di rna to be biologically active. we constructed a series of cdnas that transcribe di rnas differing only in 5'-terminal sequences. two of the 5' termini identical to ones found in naturally occurring di rnas are the 5' terminus of the virion rna (di-549) and the first 142 nucl ...19883334750
selection for accelerated penetration in cell culture coselects for attenuated mutants of venezuelan equine encephalitis virus.previous studies with sindbis virus (sb) suggested that a single point mutation in glycoprotein e2 (serine 114 to arginine 114) conferred three phenotypic alterations: attenuation in neonatal mice, accelerated penetration of cultured cells, and efficient neutralization by two e2-specific monoclonal antibodies (davis, fuller, dougherty, olmsted, and johnston (1986) proc. natl. acad. sci. usa 83, 6771-6775). moreover, selection for rapidly penetrating mutants of sb coselected for attenuation in vi ...19883341117
svlm21, a mutant of sindbis virus able to grow in aedes albopictus cells in the absence of methionine, shows increased sensitivity to s-adenosylhomocysteine hydrolase inhibitors such as neplanocin a.inhibition of s-adenosylhomocysteine (adohcy) hydrolase by compounds such as neplanocin a (npa) leads to the build-up of adohcy and the inhibition of methyltransferase enzymes. whether assayed by efficiency of plaquing or virus yield, svlm21, a mutant of sindbis virus resistant to methionine deprivation, was more sensitive to npa than was the standard virus (svstd) from which it was derived. for example, whereas 10 micrograms npa/ml depressed the yield of svlm21 by more than 30-fold, the yield o ...19883347999
[ecology of mosquito-borne infections in fennoscandia--a review]. 19882898578
human gamma interferon induction by staphylococcal protein a: effector cells, kinetics and the effect of prostaglandin, indomethacin, ibuprofen and aspirin.soluble staphylococcal protein a (spa) induces the synthesis of gamma-interferon (gamma-ifn) by human peripheral blood lymphocytes (pbl). to investigate the kinetics of this gamma-ifn induction and the effector cells involved, we used a highly purified spa preparation, pbl from healthy volunteers, and a cpe-inhibition gamma-ifn assay with sindbis virus in human fibroblasts. the production of spa-induced gamma-ifn (spa-gamma-ifn) peaked 48 h after the addition of spa to cultures of pbl and decrea ...19882966775
immunogenicity, pathogenicity, and transmissibility of a recombinant vaccinia virus in calves.experiments concerned with the immunogenicity, pathogenicity, and transmissibility of a recombinant vaccinia:sindbis virus were conducted. the wr strain of the recombinant vaccinia:sindis virus was found to be infective for calves and mildly pathogenic, resulting in local tissue reaction. it was not transmissible to other calves. also, it was found to be immunogenic when inoculated intradermally into calves, and antibody was produced against the parent vector virus (vaccinia) and the sindbis ant ...19883239835
identity of karelian fever and ockelbo viruses determined by serum dilution-plaque reduction neutralization tests and oligonucleotide mapping.the causative agents of ockelbo disease in sweden, pogosta disease in finland, and karelian fever in the ussr have been attributed to alphaviruses (family togaviridae) related to sindbis virus. we compared prototypes sindbis, ockelbo, and karelian fever viruses by neutralization tests. we also analyzed oligonucleotide fingerprint maps of prototypes ockelbo and karelian fever viruses and a strain of sindbis virus from czechoslovakia. the results indicate that ockelbo and karelian fever viruses ar ...19882849885
inactivation of lipid-enveloped viruses in labile blood derivatives by unsaturated fatty acids.virus sterilization of blood plasma derivatives by addition of several naturally occurring fatty acids was evaluated using vesicular stomatitis virus and sindbis virus as markers for lipid-enveloped virus inactivation and human immunodeficiency virus (hiv). inactivation of greater than or equal to 10(4) tissue culture infectious doses (tcid50) of marker viruses added to antihemophilic factor (ahf) concentrates, with 60-100% retention of ahf activity, was achieved with oleic, 11-eicosenoic, linol ...19882831669
genome sequences of a mouse-avirulent and a mouse-virulent strain of ross river virus.the nucleotide sequence of the genomic rna of a mouse-avirulent strain of ross river virus, rrv nb5092 (isolated in 1969), has been determined and the corresponding sequence for the prototype mouse-virulent strain, rrv t48 (isolated in 1959), has been completed. the rrv nb5092 genome is approximately 11,674 nucleotides in length, compared with 11,853 nucleotides for rrv t48. rrv nb5092 and rrv t48 have the same genome organization. for both viruses an untranslated region of 80 nucleotides at the ...19882833022
reevaluation of the western equine encephalitis antigenic complex of alphaviruses (family togaviridae) as determined by neutralization tests.fourteen viruses closely related to the fleming strain of western equine encephalitis (wee) virus were cross-tested by serum dilution-plaque reduction neutralization. the results demonstrate that strains mcmillan, r-43738, ag80-646, bear 102091, and y62-33 are subtypes or varieties of western equine encephalitis virus strain fleming. ockelbo, kyzylagach, and babanki are subtypes of the prototype strain (egar 339) of sindbis virus. fort morgan and buggy creek viruses are closely related to each o ...19882833129
interaction of alphaviruses with the serum complement system is a function of method of purification.the interaction of sindbis and ross river viruses with the serum complement system in vitro was influenced by the type of density gradient used to purify them. sindbis virus purified on sucrose gradients activated the alternate serum complement pathway while ross river virus prepared in an identical manner had no effect on c3 turnover in non-immune serum. both viruses purified on tartrate gradients inhibited the spontaneous cleavage of c3 in normal serum. at least some of this inhibition appeare ...19882850782
sindbis virus infection decreases intracellular ph: alkaline medium inhibits processing of sindbis virus polyproteins.infection of baby hamster kidney cells by sindbis virus, an alphavirus, resulted in a decrease in the intracellular ph of approximately 0.5 units within the first 1-2 hr after infection as measured either by equilibrium labeling with [14c]benzoic acid or by use of a ph-sensitive fluorescent probe, 2,7-bis-carboxyethyl-5,6-carboxyfluorescein-acetooxymethyl ester. in contrast, intralysosomal ph, as measured using an endocytized ph-sensitive probe, fluorescein isothiocyanate-labeled dextran, was no ...19882842937
[changes in cellular microfilaments in viral infection].the effect of disorders in actin microfilament polymerization by cytochalasin b (cb) on the development of cytopathic changes was studied in two models. cb in concentrations of 0.1-1.0 microgram/ml enhanced 3-5-fold the formation of symplasts in a line of kidney cells from green monkey 4647 infected with carnivore distemper virus and inhibited this process in higher concentrations (2.5-5.0 micrograms/ml). the addition of cb in concentrations 5-10 micrograms/ml into the medium of a line of chines ...19882854678
characterization of b cells and ia expression in sindbis virus encephalitis. 19882849900
effect of interferon on vero cells persistently infected with sendai virus compared to vero cells persistently infected with sspe virus.persistent infections with sendai and sspe virus were established in vero cells. sequential passages of these cells were monitored by immunofluorescence and for their sensitivity to the antiviral and antiproliferative effects of interferon (ifn). the cells rapidly developed resistance to the antiviral effect of ifn as judged by the inability of ifn to inhibit the replication of exogenous sindbis virus. this decrease was accompanied by a reduction in the induction of the 2'-5' oligo a synthetase. ...19882831857
absence of antiviral activity in recombinant b cell stimulatory factor 2 (bsf-2).recombinant b cell stimulatory factor 2 (rbsf-2) did not display any detectable level of antiviral activity when using human diploid fibroblasts, dip-2, fs-4, fs-7, amnion-derived wish and fl cells with vesicular stomatitis virus (vsv) and sindbis virus as challenging agents (less than 2.5 x 10(2) iu/mg). furthermore anti-ifn-beta could not neutralize the immunoglobulin-inducing activity of bsf-2. moreover anti-bsf-2 could not neutralize the antiviral activity of ifn-beta. the data indicate that ...19882832321
molecular basis of sindbis virus neurovirulence in mice.we examined a variety of strains of sindbis virus for the genetic changes responsible for differences in neurovirulence in mice. sv1a (a low passage of the ar339 strain of sindbis virus), a neuroadapted sindbis virus (nsv), and two laboratory strains of sindbis virus (hrsp and toto1101) were examined. nsv causes severe encephalomyelitis with hind-limb paralysis and high mortality after intracerebral inoculation in weanling mice. in contrast, sv1a causes only mild, nonfatal disease in weanling mi ...19882836615
alpha-(-)-peltatin, an antiviral constituent of amanoa aff. oblongifolia. 19882836661
virus removal or inactivation in hemoglobin solutions by ultrafiltration or detergent/solvent treatment.two procedures to eliminate virus infectivity from hemoglobin solutions at ambient temperature were evaluated. in the first, virus removal was assessed during the ultrafiltration of hemoglobin solutions through a membrane with a nominal molecular weight cut-off of 100,000 daltons. the results of this study demonstrated that less than 0.1% of any virus originally spiked into the solution was detectable in the ultrafiltrate. in the second procedure the inactivation of viruses in hemoglobin solutio ...19882846096
virus inactivation in hemoglobin solutions by heat.to determine the feasibility of heat treating hemoglobin solutions to inactivate viruses, we performed experiments on the thermal stability of this protein and found that the structure and function of deoxyhemoglobin are well preserved during incubation at 60 degrees c for 10 hours at a ph of 7.5. model viruses and the human immunodeficiency virus were rapidly inactivated under these conditions. the results imply that incubation at 60 degrees c is a practical method for inactivating viruses in h ...19882846097
molecular analysis of sindbis virus pathogenesis in neonatal mice by using virus recombinants constructed in vitro.genetic loci affecting sindbis virus pathogenesis in neonatal mice have been examined by using a full-length cdna clone of the virus (toto1101). the full-length cdna is linked to a bacteriophage sp6 promoter to facilitate the synthesis of infectious rna transcripts in vitro. virus derived from toto1101 showed reduced virulence (attenuation) in neonatal mice. replacement of the e1 glycoprotein and 6k genes of toto1101 with cloned e1 and 6k genes derived from a virulent sindbis virus strain, ar339 ...19882835514
viral neurovirulence. 19882835547
nonstructural proteins nsp3 and nsp4 of ross river and o'nyong-nyong viruses: sequence and comparison with those of other alphaviruses.we have sequenced the nsp3 and nsp4 region of two alphaviruses, ross river virus and o'nyong-nyong virus, in order to examine these viruses for the presence or absence of an opal termination codon present between nsp3 and nsp4 in many alphaviruses. we found that ross river virus possesses an in-phase opal termination codon between nsp3 and nsp4, whereas in o'nyong-nyong virus this termination codon is replaced by an arginine codon. previous studies have shown that two other alphaviruses, sindbis ...19882834873
diel activity patterns of blood-seeking anthropophilic mosquitoes in central sweden.1. blood-seeking diel activity cycles of mosquitoes are described from 24 h landing catches on human bait in a field and a forest habitat during june-august in central sweden. 2. daytime activity in the field was low or absent, whilst in the forest activity was relatively even throughout the diel. 3. in both habitats, activity peaks generally occurred about sunset and sunrise and were more distinct in the field than in the forest. 4. data from this and other studies show that, in general, aedes ...19882908783
polyamine depletion of cells reduces the infectivity of herpes simplex virus but not the infectivity of sindbis virus.the effect of polyamines on the viral growth was examined using cell strains that could be effectively depleted of polyamines. in order to avoid the polyamines present in serum we used a polyamine auxotrophic chinese hamster ovary cell line p22 growing in serum-free medium and vero cells growing in low serum medium. the final yield of an enveloped rna virus, sindbis, in p22 cells was not decreased by depletion of cellular polyamines although the onset of the viral replication was delayed. in con ...19882835567
processing the nonstructural polyproteins of sindbis virus: study of the kinetics in vivo by using monospecific antibodies.plasmids were constructed which contained a large portion of each of the four nonstructural genes of sindbis virus fused to the n-terminal two-thirds of the trpe gene of escherichia coli. the large quantity of fusion protein induced from cells containing these plasmids was subsequently used as an antigen to generate polyclonal antisera in rabbits. each antiserum was specific for the corresponding nonstructural protein and allowed ready identification of each nonstructural protein and of precurso ...19883339717
t cell-mediated cytotoxicity against dengue-infected target cells.a cytotoxic t lymphocyte (ctl) response to dengue virus-infected target cells is described. effector cells were generated in an in vitro secondary culture and appeared to be t cells possessing both the lyt 1.1 and lyt 2.1 surface antigens. a stronger ctl response was noted with the h-2k haplotype compared to h-2d, and h-2 compatibility was required between ctl and target cells. ctl generated showed some cross-reactivity with target cells infected with japanese encephalitis virus (jev), another f ...19883262810
western equine encephalitis virus is a recombinant virus.the alphaviruses are a group of 26 mosquito-borne viruses that cause a variety of human diseases. many of the new world alphaviruses cause encephalitis, whereas the old world viruses more typically cause fever, rash, and arthralgia. the genome is a single-stranded nonsegmented rna molecule of + polarity; it is about 11,700 nucleotides in length. several alphavirus genomes have been sequenced in whole or in part, and these sequences demonstrate that alpha-viruses have descended from a common ance ...19883413072
antibody-mediated activation of sindbis virus.the biological activity of an anti-sindbis monoclonal antibody (mcab 49) has been explored. the antibody recognizes an epitope on the e2 glycoprotein of sindbis virus and, in the presence of complement (c'), neutralizes virus infectivity. in the absence of c', reaction of the antibody with our laboratory strain of sindbis, sb, increased the number of plaque-forming units (pfu) detected on baby hamster kidney (bhk) cells rather than neutralizing virus infectivity. the elevated titers of sb approa ...19883413988
regulation of glycosylation. the influence of protein structure on n-linked oligosaccharide processing.the sindbis virus glycoproteins, e1 and e2, comprise a useful model system for evaluating the effects of local protein structure on the processing of n-linked oligosaccharides by golgi enzymes. the conversion of oligomannose to n-acetyllactosamine (complex) oligosaccharides is hindered to different extents at the four glycosylation sites, so that the complex/oligomannose ratio decreases in the order e1-asn139 greater than e2-asn196 greater than e1-asn245 greater than e2-asn318. the processing st ...19883198629
differences in virion stability among sindbis virus pathogenesis mutants.the structure of closely related sindbis virus strains, which differ in their virulence for neonatal mice, has been probed by measuring the sensitivity of virions to heat, varying concentrations of dithiothreitol (dtt), phenylglyoxal or low ph. attenuated mutants (sb-rl and sb-fp) were much more sensitive to loss of infectivity after heat or dtt treatment than either the prototype virulent strain (sb) or same-site virulent revertants of sb-rl. incubation of sb-rl virions in the presence of dtt i ...19883414183
alphavirus rna replicase is located on the cytoplasmic surface of endosomes and lysosomes.using morphological and cell biological techniques, we have shown that the rna replicase of semliki forest and sindbis virus (two closely related alphaviruses) is located in complex ribonucleoprotein structures associated with the cytoplasmic surface of modified secondary lysosomes and endosomes. these nucleoprotein complexes often form a bridge between the membrane of the endocytic vacuole and the rough endoplasmic reticulum where the synthesis of the structural proteins of these viruses occurs ...19882904446
large-scale production and properties of a solvent-detergent-treated factor ix concentrate from human plasma.a human solvent-detergent (sd)-treated factor ix concentrate has been produced from cryoprecipitate-poor plasma using deae-sepharose cl-6b and heparin-sepharose cl-6b chromatography. the deae eluate was incubated with an sd mixture [0.3% tri(n-butyl) phosphate-1% tween 80, 6-h at 24 degrees c] which was found to inactivate, in less than 1 h, more than 3.8 log10 of vesicular stomatitis virus and more than 4.8 log10 of sindbis virus; the sd was removed by a subsequent heparin adsorption step. the ...19883265237
effect of actinomycin d and cycloheximide on replication of sindbis virus in aedes albopictus (mosquito) cells.production of sindbis virus in the presence of transcription and translation inhibitors was examined in three aedes albopictus cell lines. addition of cycloheximide to heat-resistant sindbis virus (svhr)-infected mosquito cells arrested viral rna synthesis completely, in contrast to the effects of this drug on virus-infected vertebrate cells. production of mature virus by both svhr (a variant commonly used as a wild-type virus) and sbamr (a mutant which is resistant to the effects of 18 h of pre ...19883392770
demonstration in vitro of temperature-sensitive elongation of rna in sindbis virus mutant ts6.characterization of conditionally lethal mutants of alphaviruses, sindbis virus and semliki forest virus, has indicated that in almost all the rna-negative mutants the temperature-sensitive (ts) defect prevents the formation of active transcription complexes at nonpermissive temperature (40 degrees c), but such complexes retain activity at 40 degrees c if formed first at permissive temperature (30 degrees c). our recent results have extended the characterization of one exception to this finding: ...19883418782
sindbis virus neutralization. 19883207286
basis of neurovirulence in sindbis virus encephalomyelitis of mice.neuroadapted sindbis virus (nsv) was selected by serial passage of wild-type sindbis virus (sv) in mouse brain. after intracerebral inoculation of weanling mice, nsv causes a severe encephalomyelitis with hindlimb paralysis and high mortality; sv causes nonfatal mild disease. in order to determine the biologic basis of neurovirulence in vivo, these viral infections have been compared by using infectivity assays, light and electron microscopy, in situ hybridization, immunohistochemistry, and doub ...19883367635
studies on the pharmacological activity of amazonian euphorbiaceae.plant material from 34 amazonian species of the family euphorbiaceae were collected and extracts prepared. sixteen of these species have a documented use as a medicinal agent. the extracts were tested for their ability to inhibit the growth of the bacteria, escherichia coli and staphylococcus aureus; the yeasts, saccharomyces cerevisiae and candida albicans; the dermatophytic fungi, microsporum canis, microsporum fulvum, microsporum gypseum and trichophyton gallinae; the viruses, sindbis virus a ...19883374150
location of a major antigenic site involved in ross river virus neutralization.the location of a major antigenic domain involved in the neutralization of an alphavirus, ross river virus, has been defined in terms of its position in the amino acid sequence of the e2 glycoprotein. the domain encompasses three topographically close epitopes which were identified using three e2-specific neutralizing monoclonal antibodies in competitive binding assays. nucleotide sequencing of the structural protein genes of monoclonal antibody-selected antigenic variants showed that for each v ...19882448952
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