rna-dependent dna polymerase associated with equine infectious anemia virus.equine infectious anemia (eiav) is shown to have an associated rna-instructed dna polymerase similar in its cofactor requirements and reaction conditions to the rna tumor virus dna polymerases. demonstrating this dna polymerase activity requires a critical concentration of a nonionic detergent, all four deoxyribonucleoside triphosphates, and a divalent metal ion. the reaction is sensitive to rnase, and a substantial fraction of the fna synthesized is complementary to viral rna. the detection of ...197767219
characterization of a retravirus isolated from squirrel monkeys.a new retravirus (smrv) isolated from a squirrel monkey, saimiri sciureus, has an mg2+-dependen reverse transcriptase and a buoyant density of 1.17 g/cm3 in sucrose and 1.21 g/cm3 in cesium chloride, similar to the mouse mammary tumor virus and the mason-pfizer monkey virus. the polypeptide patter of smrv as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis was distinct from the reported polypeptide patterns of known retraviruses. four major polypeptides of molecular weight ...197769728
immunology of a persistent retrovirus infection--equine infectious anemia. 197995154
equine infectious anaemia in czechoslovakia. 1975164712
mechanism of viral persistence in equine infectious anemia. 1975165036
monocyte activation in horses persistently infected with equine infectious anemia virus.the monocytes of horses infected with equine infectious anemia virus were shown by their failure to migrate from capillary tubes and their increased adherence to erythrocytes to be activated.1975172455
viral antigen production in horse kidney cell cultures infected persistently with equine infectious anemia virus. 1976177893
recrudescence of equine infectious anemia by treatment with immunosuppressive drugs.horses which had passed a few months to a few years asymptomatically after the last recurrence of equine infectious anemia (eia) showed a typical febrile response after treatment with the immunosuppressive agent, dexamethasone (dm) or cyclophosphamide (cy). in horses showing a febrile response, eia virus which had not been neutralized by neutralizing antibody previously produced was propagated. in dm-treated horses it disappeared from the blood soon after pyretolysis and antibody against the vir ...1976177894
equine infectious anaemia. 1976181892
apparent propagation of the equine infectious anemia virus in a mosquito (culex pipiens quinquefasciatus say) ovarian cell line.a tissue culture of culex pipiens quinquefasciatus say ovarian cells appeared to support the growth of equine infectious anemia (eia) virus. shetland ponies inoculated with 2nd, 7th, 9th, and 11th passages of mediums harvested from infected tissue culture had clinical signs of the disease and became eia positive on 11, 19, 23, and 43 days after inoculation, respectively.1976183574
inactivation of equine infectious anemia virus by chemical disinfectants.twelve chemicals and commercial disinfectants were tested for inactivation of equine infectious anemia virus. in the presence of 10% bovine serum, all chemicals inactivated 4 log10 (based on 0.1 ml) of the virus within 5 minutes at 23 c. a reduction of at least 4 log10 was observed when the virus was exposed for 1 minute to substituted phenolic disinfectants (3 commercial preparations and sodium orthophenylphenate), halogen derivatives (iodophor and sodium hypochlorite), chlorhexidine, and 70% e ...1977199094
characterization of rna from equine infectious anemia virus.the genome of equine infectious anemia virus, a nononcogenic retrovirus, has been characterized by velocity sedimentation, electrophoresis in polyacrylamide gels, buoyant density in cs2so4, and susceptibility to nuclease digestion. the nucleic acid of purified virus was resolved by sedimentation analysis into a fast-sedimenting genome component, which comprises about two-thirds of the virion rna, and a slow-sedimenting rna, which is probably comprised of host-derived trna and a trace amount of 5 ...1977199735
demonstration of equine infectious anemia virus in primary leukocyte cultures by electron microscopy.electron microscopy was used to demonstrate the presence of viral particles in primary cultures of leukocytes taken from a horse after sc inoculation with the wyoming strain of equine infectious anemia virus. unlike previous studies, the exposure virus was not passaged through cell culture prior to horse inoculation. cultures were begun approximately 1 week before and 1 week after the 1st pyrexic period after inoculation. in both samples, viral particles and cytoplasmic alterations were observed ...1977202180
the structural polypeptides of equine infections anemia virus.the structural polypeptides and glycoproteins of equine infectious anemia virus were identified following electrophoresis in sds-page. the major non-glycosylated polypeptides had molecular weights of 25,000, 14,000 and 11,000 daltons. two glycoproteins of 80,000 and 40,000 daltons were also detected. the relationship of these components to the structural elements of mammalian c-type oncoviruses is discussed.1978202575
induction of a cell membrane antigen by equine infectious anemia virus.equine fibroblasts persistently infected with equine infectious anemia virus acquire a new cell membrane antigen demonstrable by indirect radioimmunoassay, using infected horse serum as an antibody source.1978205145
preparation of hemagglutinating antigen of equine infectious anemia virus from infected equine leukocyte cultures. 1978206841
scanning and transmission electron microscopic study of equine infectious anemia virus.scanning and transmission electron microscopy were used to study in detail the morphogenesis and replication of equine infectious anemia virus (eiav) in cultured, persistently infected equine fetal kidney fibroblasts. the eiav was shown by thin-section electron microscopy to resemble morphologically more closely the members of the genus lenti-virus in the family retroviridae than other genera. scanning electron microscopy demonstrated budding virus on only about 5% of the equine fetal kidney fib ...1978215061
structural proteins of equine infectious anemia virus.equine infectious anemia virus was found to be comprised of fourteen polypeptides of molecular weight ranging from 10,000 to 79,000. eighty percent of the virion protein was accounted for by five polypeptides, including two non-glycosylated components (p29 and p13) comprising one-half of the virion protein and three glycoproteins (gp77/79, gp64, and gp40).1978215790
simple method for preparation of specific antisera against viral proteins: rabbit antisera against equine infectious anemia virus proteins p26 and p16.a simple method for preparation of highly specific antisera against equine infectious anemia virus proteins p26 and p16 is described. viral proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. the motility of the viral proteins in the gel was compared with standards. unstained portions of the slab gel were sliced into 5-mm bands, emulsified with freund's complete adjuvant, and injected into rabbits to produce specific antisera.1978216292
prevalence of antibodies to equine viruses in the netherlands.the prevalence of antibodies to various viruses was investigated in a series of serum samples collected from horses in the netherlands between 1963 and 1966 and from 1972 onwards. neutralizing antibodies to equine rhinopneumonitis virus, equine arteritis virus and to equine rhinovirus types 1 and 2 were detected in respectively 76%, 14%, 66% and 59% of the equine serum samples tested. the observed incidence of serum samples positive to equine adenovirus in the complement fixation test was 39%. p ...1979219560
equine infectious anemia virus: development of a simple reproducible method for titrating infectivity of the cell-adapted equine dermal cell line between the 14th and 30th subpassages was used to develop a reproducible method of titrating the infectivity of the cell-adapted strain of equine infectious anemia virus (eiav). cells inoculated with eiav were subcultured or fed once each week and were monitored for the production of p26 antigen of eiav in supernatant fluids. ultrathin sections were prepared once each week and were examined for the detection of budding virus-like particles (vlp). the vlp could not be d ...1979223479
serologic survey for equine infectious anemia virus in 1975, a survey was conducted in east baton rouge parish, louisiana, to determine the prevalence of equine infectious anemia. using the agar gel immunodiffusion test, 94 of 1,398 horses (6.7%) were found to be infected. infection rates were especially high in areas where clinical cases of equine infectious anemia had been diagnosed. clinical signs compatible with the disease were noted in 1 of the 94 seropositive horses. the sample set of 1,398 horses represented 22% of the census population o ...1979221447
distinct subsets of retroviruses encode dutpase.the nonprimate lentiviruses feline immunodeficiency virus, equine infectious anemia virus, visna virus, and caprine encephalitis virus contain a gene segment in the polymerase gene that is lacking in the primate lentiviruses. a related sequence has been noted in other retroviruses, most notably the type d retroviruses. computer searches have indicated a relatedness between this unique gene segment, termed proteaselike element and elements of both the aspartate proteinase and the dutpase enzyme f ...19921310783
equine infectious anemia: current knowledge. 1979218920
specificity of response to viral proteins in horses infected with equine infectious anemia virus.three structural proteins of equine infectious anemia virus were purified, labeled with 125i, and utilized in radioimmunoassays with horse sera and antisera to heterologous retroviruses. whereas radioimmunoassay titers for the major protein, p25, were 500- to 1,000-fold higher than titers in immunodiffusion, for clinical purposes these two procedures were equivalent. antibodies to two low-molecular-weight proteins, p12 and p10, were also found in infected horses, but with a lower frequency and l ...1979217831
detection of proviral dna in horse cells infected with equine infectious anemia virus.equine infectious anemia virus (eiav) recently has been shown to possess a high-molecular-weight rna genome and a virion reverse transcriptase. we completed the demonstration that eiav is a retrovirus by showing the presence of proviral dna in equine cells infected in vitro, but not in normal horse dna. these studies were performed by using a highly representative cdna probe synthesized by the virion polymerase. it was found that this cdna reassociated extensively, and with high thermal stabilit ...1978209211
[cytomorphological aspects of the blood experimentally induced with inoculation of equine infectious anemia virus]. 1978208135
electron microscopic studies on equine infectious anemia virus (eiav). brief report.morphological studies of eiav reveal knobs on the surface of the particles, conically and tubularly shaped cores, budding particles with dense crescents directly underlying the plasma membrane, and distinct intracytoplasmic structures in infected cells.1977202230
genomic variation and segregation of equine infectious anemia virus during acute infection.equine infectious anemia virus (eiav) is a lentivirus that infects and persists in the monocyte/macrophage populations of blood and tissues. we employed polymerase chain reaction to investigate the distribution and the level of genome variability of eiav dna in different tissues of a horse infected with a highly virulent variant of the wyoming strain of the virus. long terminal repeat, gag, and pol primer pairs were used to direct the amplification of eiav dna from the peripheral blood mononucle ...19921316487
the surface envelope protein gene region of equine infectious anemia virus is not an important determinant of tropism in vitro.virulent, wild-type equine infectious anemia virus (eiav) is restricted in one or more early steps in replication in equine skin fibroblast cells compared with cell culture-adapted virus, which is fully competent for replication in this cell type. we compared the sequences of wild-type eiav and a full-length infectious proviral clone of the cell culture-adapted eiav and found that the genomes were relatively well conserved with the exception of the envelope gene region, which showed extensive se ...19921318398
immunoglobulin g subclass [igg and igg(t)] interaction with the p26 group specific antigen of equine infectious anemia virus: immunodiffusion and complement-fixation reactions.isolated equine immunoglobulin (ig)g(t) antibodies to equine infectious anemia virus p26 antigen did not precipitate with antigen when the ratio of antibody to antigen was high. however, at lower ratios of antibody to antigen precipitation occurred. in addition, complement-fixation by igg and p26 antigen was inhibited by high concentrations of igg(t). the unusual reaction pattern noted with igg(t) antibodies was still detectable by the immunodiffusion test for equine infectious anemia virus. in ...1977195493
effects of equine infectious anemia virus on hematopoietic progenitors in effects of equine infectious anemia virus (eiav) on hematopoiesis in vitro were studied. bone marrow mononuclear cells from clinically normal horses were incubated with 100 tcid50 of eiav/10(7) cells. these cells were cultured to assay for colonies derived from erythroid progenitors, granulocyte/monocyte progenitors, and fibroblastic progenitors. the eiav had a selective suppressive effect on the erythroid progenitors. colony-forming units-erythroid were suppressed to 80% of that for medi ...19921323227
extended x-ray absorption fine structure studies of a retrovirus: equine infectious anemia virus cysteine arrays are coordinated to zinc.zinc finger arrays have been established as a critical structural feature of proteins involved in dna recognition. retroviral nucleocapsid proteins, which are involved in the binding of viral rna, contain conserved cysteine-rich arrays that have been suggested to coordinate zinc. we provide metalloprotein structural data from an intact virus preparation that validate this hypothesis. extended x-ray absorption fine structure (exafs) spectroscopy of well-characterized and active preparations of eq ...19921332027
equine antibody to bovine serum induced by several equine vaccines as a source of extraneous precipitin lines in the agar gel immunodiffusion test for equine infectious anemia.precipitin lines not associated with equine infectious anemia (eia) were observed in routine agar gel immunodiffusion (agid) testing for the infection. the serums which produced these lines were obtained from horses which had been given multiple vaccinations with commercially available cell culture-origin equine virus vaccines as part of a comprehensive herd health program. the lines formed against cell culture-derived, but not spleen-derived eia viral antigens. investigation revealed that bovin ...1977192111
identification and evaluation of new primer sets for the detection of lentivirus proviral dna.we have developed sets of degenerate oligonucleotides designed to detect pol gene sequences from any member of the lentivirus subfamily when used as primers in amplification techniques such as the polymerase chain reaction (pcr). this pan-lentivirus-specific primer set (plsps) consists of primers, lv1, lv2, and lv3, based on conserved regions common to lentiviruses only. our protocol is based on primary amplification with lv1 and lv2 followed by secondary amplification with a nested primer set b ...19921337258
eia research. 1977189175
purification and characterization of equine infectious anemia virus.eia virus was purified from equine fetal kidney cell cultures by peg-precipitation, two sucrose-gradient sedimentations (5-30 per cent) and (25 to 60 per cent) centrifugation, using the immunodiffusion test to follow the procedure. purified eia virus had a density (20 degrees c) of 1.162 and a sedimentation constant of s20w=656. electron microscopy revealed a particle of about 100 nm in diameter with a very flexible but usually spherical shape. the dense core may be at various locations inside t ...1976183628
[purification and study of equine infectious anemia virus antigens, produced in vivo or in cultured cells].the g and c antigens of equine infectious anemia virus have been produced in vivo and in infected cell culture, then they have been purified. their physico-chemical properties have been determined, particularly their molecular weight, their sedimentation coefficient, their density and the iso electric point.1975174831
equine infectious anemia. 1975174411
use of bacterial trpe fusion vectors to express and characterize the bovine immunodeficiency-like virus core protein.the gag coding region from bovine immunodeficiency-like virus (biv) was cloned into e. coli and expressed as a bacterial fusion protein. six different clones spanning various regions of the gag open reading frame were generated. the resulting fusion proteins were expressed at high concentrations and readily purified. a panel of bovine immune sera specifically recognized the recombinant gag proteins, as did immune sera from animals infected or immunized with lentiviruses related to biv, such as e ...19921372612
[latest results in the research of infectious anemia in perissodactyla]. 1975174243
investigation of equine infectious anaemia in queensland using gel antigen for the gel diffusion test for equine infectious anaemia (eia) was prepared from the spleen of a horse experimentally infected with the cq strain of the virus. the antigen produced a single, distinct line of precipitation when tested against a range of known positive serums, and did not react with pre-inoculation and known negative serums. extracts prepared from uninfected spleens displayed no reaction when similarly tested. serum from 34 of 451 queensland horses contained detectable ...1975173275
identification of multiple equine infectious anemia antigens by immunodiffusion reactions.equine infectious anemia (eia) cell antigens prepared from infected equine spleen, equine leukocyte cultures or a persistently infected equine dermis cell line contained at least two serologically reacting components. for convenience one component was designated as soluble antigen (sa) and the other as cell-associated antigen (caa). the sa appeared as a single component when it was prepared from eia virus precipitated from infectious tissue culture fluid with polyethylene glycol and ether treate ...1975169969
synthesis of long complementary dna in the endogenous reaction by equine infectious anemia the endogenous reverse transcriptase reaction, equine infectious anemia virus is able to synthesize complementary dna (cdna) of 8,000 nucleotides in high yield. after 2 h in 50 mum dntp, about 2.8 mug of cdna per mg of protein is produced, almost 30% of which is long cdna. the system thus compares favorably with the other two well-characterized endogenous reaction systems, moloney murine leukemia virus and avian sarcoma virus. elongation rates of 100 to 150 nucleotides per min have been obser ...197987522
purification of equine infectious anemia virus antigen by affinity chromatography.affinity chromatography was performed to obtain highly purified antigen from equine infectious anemia (eia) virus. after crude antigen was concentrated by polyethylene glycol precipitation of culture fluids from equine dermal cells persistently infected with eia virus, and after the virus was disrupted with ether, it was added to a column of cyanogen bromide-activated sepharose 4b to which eia-specific antibody had been conjugated. the antigen was effectively released from the column with 5m mgc ...197769631
equine infectious anemia virus: evidence favoring classification as a retravirus.equine infectious anemia virus (eiav) has a density of 1.154 g/cm3 in sucrose a high-molecular-weight rna similar in size to rauscher murine leukemia virus, and an internal virion reverse transcriptase that utilizes the synthetic rna template poly(ra) but not the synthetic dna template poly(da), both with (dt)12 as primer. although capable of utilizing manganese at low concentrations (approximately 0.1 mm), eiav reverse transcriptase showed highest activity in the presence of 9 mm magnesium. the ...197661283
failure to propagate equine infectious anemia virus in mosquitoes and culicoides variipennis.laboratory-colonized mosquitoes, culex tarsalis, aedes aegypti, culiseta inornata, and anopheles free-borni, and the biting gnat, culicoides variipennis, were exposed to equine infectious anemia virus. exposure to the virus was by intrathoracic inoculation for mosquitoes and by oral ingestion of an infective blood meal through a membrane for c variipennis. after various intervals, groups of 15 to 20 insects were homogenized and inoculated into susceptible ponies. positive immunodiffusion test r ...197831831
hemagglutination by equine infectious anemia virus.equine infectious anemia (eia) virus which was propagated on an equine dermal cell line agglutinated guinea pig erythrocytes. viral fluids containing about 10(7.5) mean tissue culture infective doses/ml showed hemagglutinating (ha) titers ranging from 16 to 32 units/0.05 ml. results of cesium chloride equilibrium density gradient centrifugation revealed that the hemagglutinin was inseparable from the virus particles. the hemagglutination reaction persisted over a wide range of temperature and ph ...19769361
transmission of equine infectious anemia virus by tabanus fuscicostatus.the mechanical transmission of equine infectious anemia (eia) virus by tabanus fuscicostatus was investigated. in 1 of 7 transmission trials, a single horsefly transmitted eia virus from an acutely infected pony to a susceptible pony. groups of horseflies isolated for 3, 10, or 30 minutes before refeeding transmitted eia virus, whereas those isolated for 4 or 24 hours did not. data from field studies indicate that the home range or flight distance of horseflies may exceed 4 miles. that informati ...1976942712
role of horse flies in transmission of wquine infectious anemia from carrier ponies.equine infectious anemia virus was transmitted from an acutely ill and an inapparently infected pony to uninfected ponies by the interrupted feeding of horse flies (tabanids). transmission from acutely ill ponies was not accomplished following: (1) the interrupted feeding of a single horse fly, (2) bites of horse flies that had fed on an acutely affected pony 24 hours earlier, (3) bites of horse flies that had oviposited after feeding on an acutely affected pony, or (4) the inoculation of larval ...1978621184
characterization of the infection of equine fibroblasts by equine infectious anemia virus.equine dermal fibroblasts persistently infected with equine infectious anemia virus (eiav) show no alterations in cell morphology or growth kinetics when compared to uninfected cells. the percentage of cells immunofluorescent positive for viral proteins fluctuated, depending upon the stage of the cell cycle, while production of extracellular virus was uniform throughout the cell cycle, increasing only as the cell number increased. this was shown in log versus stationary phase cultures as well as ...1979228638
responses in horses infected with equine infectious anemia virus adapted to tissue culture. 1979228570
leukocyte cytotoxicity in a persistent virus infection: presence of direct cytotoxicity but absence of antibody-dependent cellular cytotoxicity in horses infected with equine infectious anemia virus.antibody-dependent cellular cytotoxicity and direct cytotoxicity assays were performed with equine infectious anemia virus-infected target cells, equine leukocytes, and equine anti-equine infectious anemia virus antibody to determine whether these mechanisms play a role in controlling viral replication in equine infectious anemia. direct cytotoxicity was observed by using peripheral blood mononuclear cells from 7 of 10 infected horses. antibody-dependent cellular cytotoxicity was not observed. t ...1979223981
in vitro isolation of a neutralization escape mutant of equine infectious anemia virus (eiav).a neutralization escape mutant (a/1 e) of equine infectious anemia virus was isolated after 13 passages in cell culture in the presence of serum containing antibodies to type- and group-specific determinants of eiav envelope glycoproteins. loss of neutralization by the selecting serum correlated with loss of two epitopes in the major envelope glycoprotein gp90 of a/1 e which were present in a parallel variant isolated from a persistently infected pony.19901693846
inhibition of human immunodeficiency virus type 1 tat activity by coexpression of heterologous trans activators.we examined the mechanism of tat-mediated trans activation through competition experiments employing tat proteins of human immunodeficiency virus type 1 (hiv-1) and equine infectious anemia virus (eiav). eiav tat, as well as chimeric eiav/hiv-1 tat proteins, inhibited hiv-1 tat-mediated trans activation in a cell-type-dependent fashion. furthermore, these proteins inhibited trans activation by tat-bacteriophage r17 coat protein chimeras. inhibition resulted from competition between activation do ...19921312617
conservation of amino-acid sequence motifs in lentivirus vif proteins.the nonstructural/regulatory genes of human immunodeficiency virus type 1 (hiv-1) and other lentiviruses are believed to play an important role in the replication and pathogenesis of these viruses. in hiv-1 and other lentiviruses, the vif (viral infectivity factor) open reading frame (orf) (also termed sor or q in some lentivirus genomes) is located in the central region, overlapping the 3' end of the pol orf, but in a different reading frame. among the lentiviruses, only equine infectious anemi ...19921312756
expression of the protease gene of equine infectious anemia virus in escherichia coli: formation of the mature processed enzyme and specific cleavage of the gag precursor.a 620-bp bg/ii restriction fragment containing the putative protease coding sequence from equine infectious anemia virus (eiav) proviral dna was cloned and expressed in e. coli as a pol precursor protein. in contrast to the 25-kda fusion protein predicted from the expressed pol sequence, a protein of approximately 10 kda was generated by apparent autocatalytic processing of the pol precursor. this mature processed protein was detected in transformed cells using an antisera raised against synthet ...19921314466
efficacy of inactivated whole-virus and subunit vaccines in preventing infection and disease caused by equine infectious anemia virus.we report here on a series of vaccine trials to evaluate the effectiveness of an inactivated equine infectious anemia virus (eiav) whole-virus vaccine and of a subunit vaccine enriched in eiav envelope glycoproteins. the inactivated vaccine protected 14 of 15 immunized ponies from infection after challenge with at least 10(5) 50% tissue culture-infective doses of the homologous prototype strain of eiav. in contrast, it failed to prevent infection in any of 15 immunized ponies that were challenge ...19921316455
equine infectious anemia virus and human immunodeficiency virus dna synthesis in vitro: characterization of the endogenous reverse transcriptase reaction.the endogenous reverse transcriptase reaction of equine infectious anemia virus (eiav) has been studied, and conditions allowing synthesis of full-length minus-strand dna have been determined. in contrast to results reported for other retroviruses, synthesis of eiav full-length minus-strand dna was not impaired by high concentrations of nonidet p-40, a nonionic detergent used to make the virion envelope permeable. all components of the reaction were titrated for maximum synthesis of complete min ...19911705993
equine infectious anemia virus gene expression: characterization of the rna splicing pattern and the protein products encoded by open reading frames s1 and s2.the utilization of predicted splice donor and acceptor sites in generating equine infectious anemia virus (eiav) transcripts in fetal donkey dermal cells (fdd) was examined. a single splice donor site identified immediately upstream of the gag coding region joins the viral leader sequence to all downstream exons of spliced eiav transcripts. the predominant 3.5-kb transcript synthesized in eiav-infected fdd cells appears to be generated by a single splicing event which links the leader sequence t ...19921316461
the characterization of eiav reverse transcriptase and its inhibition by 5'-triphosphates of 2'-deoxyuridine analogs, pfa and paa.a characterization of equine infectious anemia virus reverse transcriptase (eiav rt) and its inhibition by 5'-triphosphate analogs was undertaken to explore the possibility of using eiav rt as an in vitro model for studying human immunodeficiency virus (hiv). eiav rt activity was found to be dependent on the bivalent cations mg++ and mn++. the optimal ph for enzyme reaction was ph 8.2. eiav rt preferred a 70 mmol/l concentration of monovalent salts. phosphonoformic acid (pfa) was an active inhib ...19901711694
a soluble recombinant fusion protein of the transmembrane envelope protein of equine infectious anaemia virus for elisa.the use of the bacterial expression vector, pgex, to produce an abundant, soluble fusion protein of gp45 from equine infectious anaemia virus is described. purification of the recombinant protein was achieved by one step affinity chromatography on immobilized glutathione using competitive elution so no harsh conditions were required. this provides a readily available antigen that is defined, plentiful and cheap. yields of 3.5 mg of purified soluble protein/litre of bacterial culture were obtaine ...19921320787
equine lentivirus, comparative studies on four serological tests for the diagnosis of equine infectious anaemia.serological diagnosis of equine infectious anemia is of necessity group-reactive, i.e. based on viral core protein p26, because viral envelope components as well as the host's immune response to them undergo rapid antigenic change. since 1970 the agar gel-immunodiffusion test ("coggins-test") has been the diagnostic method of choice. recently, elisa tests have been introduced for faster and theoretically more sensitive serodiagnosis, while western blots have been used to clarify doubtful results ...19921336247
purification and partial characterization of equine infectious anemia virus reverse transcriptase.previously we raised a rabbit monospecific antibody (c2003) against a synthetic peptide derived from a sequence within the c-terminal portion of the reverse transcriptase (rt) of the human immunodeficiency virus type 1 (hiv-1). this sequence is found to be conserved in the predicted amino acid sequence of a related lentivirus, the equine infectious anemia virus (eiav). it was previously determined that the c2003 antibody could cross-react with native eiav rt and directly inhibit the dna polymera ...19911718086
african horse sickness and equine infectious anaemia serology in the gambia. 19921339038
detailed mapping of the antigenicity of the surface unit glycoprotein of equine infectious anemia virus by using synthetic peptide strategies.we describe here a detailed analysis of the antigenic determinants of the surface unit glycoprotein (gp90) of equine infectious anemia virus (eiav), using a comprehensive panel of synthetic peptides in enzyme-linked immunosorbent assays with immune serum from naturally and experimentally infected horses and with a panel of gp90-specific neutralizing and nonneutralizing monoclonal antibodies. the results of these studies identify immunoreactive segments throughout the conserved and variable domai ...19921370556
wild-type equine infectious anemia virus replicates in vivo predominantly in tissue macrophages, not in peripheral blood situ hybridization of tissues from two horses infected with the wild-type wyoming strain of equine infectious anemia virus (eiav) identified the liver, spleen, lymph nodes, kidney, lung, and adrenal gland as the primary host tissue sites for viral transcription during acute infection. combined immunohistochemistry, with a monoclonal antibody recognizing a cytoplasmic antigen of equine mononuclear phagocytes, and in situ hybridization for viral rna identified most infected cells as mature tiss ...19921382143
a nonradioactive micro-assay for released reverse transcriptase activity of a lentivirus.a nonradioactive micro-assay procedure for detection of released reverse transcriptase activity from cells infected with equine infectious anemia virus is described. this procedure utilizes biotinylated-dutp in conjunction with a streptavidin-alkaline phosphatase conjugate. detection of alkaline phosphatase is by autoradiography of the chemiluminescence produced during enzymatic dephosphorylation of lumi phos 530. this method, as with reverse transcriptase micro-assays employing 32p-labeled nucl ...19921382469
in situ processing of a retroviral nucleocapsid protein by the viral proteinase.the proteolytic processing pathway of the nucleocapsid protein (nc) by the viral proteinase within intact capsids of equine infectious anemia virus (eiav) is presented. the cleavage sites are located at the carboxyl side of the first cysteine residue within the zinc-finger domains. eiav is used as a model to predict similar nc cleavages in other retroviruses, including human immunodeficiency virus (hiv). the observed cleavages suggest a previously unrecognized function of the retroviral proteina ...19911658777
identification of a hypervariable region in the long terminal repeat of equine infectious anemia avirulent, field-derived isolate of equine infectious anemia virus (eiav), designated ma-1, was molecularly cloned, and the complete nucleotide sequence was determined for the 3' half of the viral genome. comparisons between ma-1 and the prototype wyoming strain of eiav identified a 66-nucleotide stretch between caat (-91) and tataa (-25) in the u3 region of the long terminal repeat, where sequence divergence was as high as 39.3%. the polymerase chain reaction was used to amplify and clone lo ...19911847479
rna pseudoknots downstream of the frameshift sites of retroviruses.rna pseudoknot structural motifs could have implications for a wide range of biological processes of rnas. in this study, the potential rna pseudoknots just downstream from the known and suspected retroviral frame-shift sites were predicted in the rous sarcoma virus, primate immunodeficiency viruses (hiv-1, hiv-2, and siv), equine infectious anemia virus, visna virus, bovine leukemia virus, human t-cell leukemia virus (types i and ii), mouse mammary tumor virus, mason-pfizer monkey virus, and si ...19911663382
use of western blot and radioimmunoprecipitation for diagnosis of feline leukemia and feline immunodeficiency virus infections.the uses and limitations of the western blot (wb) and radioimmunoprecipitation assay (ripa) techniques for study of feline immunodeficiency virus (fiv) and felv were evaluated. western blot analysis was used to detect antigenic relatedness between the 2 lentiviruses. using a rabbit serum directed against p26 of the equine infectious anemia virus (eiav) and anti-eiav horse serum obtained from an infected horse, cross-reactivity with p24 of fiv was revealed. cat sera obtained late after experiment ...19911666078
intracellular proteins of feline immunodeficiency virus and their antigenic relationship with equine infectious anaemia virus proteins.feline immunodeficiency virus (fiv) grown in cat lymphocyte and thymocyte cultures was labelled with l-[35s]methionine or [3h]glucosamine and virus-coded proteins were identified using immunoprecipitation. polypeptides with apparent mr values of 15k, 24k, 43k, 50k, 120k and 160k were detected. an additional polypeptide of 10k was detected by western blot analysis. the two highest mr species sometimes appeared as one band, of which only the 120k polypeptide was glycosylated. in the presence of tu ...19901690264
antiretroviral activity of synthetic hypericin and related analogs.hypericin and pseudohypericin are naturally occurring polycyclic quinones which have recently been shown to inhibit the infectivity of several retroviruses, including human immunodeficiency virus. to better understand the antiviral mechanisms of these compounds, hypericin and a series of analogous quinones were synthesized and tested for anti-retroviral activity against equine infectious anemia virus (eiav). treatment of eiav-infected cells with hypericin reduced the production of infectious vir ...19901699534
photosensitization is required for inactivation of equine infectious anemia virus by hypericin.hypericin, a photoreactive polycyclic quinone, was found to dramatically reduce infectivity of cell-free stocks of equine infectious anemia virus. however, the antiviral activity of hypericin was completely dependent on the presence of light. short periods of photosensitization resulted in a partial loss of reverse transcriptase activity and complete inhibition of viral infectivity. these results suggest that the photodynamic effect of hypericin interferes with more than one stage in the virus r ...19911707176
immune-mediated thrombocytopenia in horses infected with equine infectious anemia adult horse infected with a virulent, cell culture-adapted strain of equine infectious anemia virus (eiav) developed cyclical thrombocytopenia in which the nadir of platelet counts coincided with peak febrile responses. in order to investigate the mechanism of thrombocytopenia during acute febrile episodes, four adult horses were experimentally infected with the wild-type wyoming strain of eiav. platelet counts decreased from baseline as rectal temperature increased. serum reverse transcripta ...19911717720
pattern of transcription of the genome of equine infectious anemia virus.the pattern of expression of the equine infectious anemia virus (eiav) genome in a persistently infected canine cell line was determined. five eiav-specific transcripts (8.2, 5.0, 4.0, 2, and 1.8 kilobases [kb]) were detected by using subgenomic restriction enzyme fragments of eiav dna and eiav-specific oligonucleotides as probes. the 8.2-kb mrna could be shown to represent viral genomic rna, whereas the smaller transcripts were generated by splicing events. evidence was obtained that indicated ...19902157066
analysis of antibody reactivities in elisa using protein blots as antigen substrates: s-elisa.we describe here a novel immunoassay procedure, designated strip-elisa (s-elisa), in which specific antigens are purified by sds-page, transferred to support membranes, and utilized in situ as substrate in routine elisa procedures. using two different lentivirus systems, simian immunodeficiency virus and equine infectious anemia virus, we demonstrate the utility of s-elisa for screening hybridoma supernatants during production of monoclonal antibodies and for the dissection of polyclonal antibod ...19902157766
retrovirus infections in non-domestic felids: serological studies and attempts to isolate a african lioness from the zoo of zurich had to be euthanized because of an inoperable tumor. the serum tested negative for feline leukemia virus (felv) p27 antigen by enzyme-linked immunosorbent assay (elisa) but was strongly positive for feline immunodeficiency virus (fiv) antibodies by elisa and western blot. when her only offspring and mate were tested for fiv, high antibody titers to fiv were also found in their serum. lymphocytes were prepared from these two lions on different occasions a ...19921337398
immunologic response to eiav offers hope for aids treatment. 19921338067
identification of lentivirus tat functional domains through generation of equine infectious anemia virus/human immunodeficiency virus type 1 tat gene chimeras.the structural regions that comprise the functional domains of lentivirus tat proteins were examined. chimeric tat genes and chimeric viral promoters were constructed between the distantly related human immunodeficiency virus type 1 (hiv-1) and equine infectious anemia virus (eiav). these exchange experiments revealed that the eiav tat-responsive element recognition domain is formed by two distinct structural regions. activation domains of both hiv-1 and eiav tat contain a conserved core element ...19911645777
mutational analysis of the equine infectious anemia virus tat-responsive element.a hairpinlike structure is predicted to exist at the 5' end of equine infectious anemia virus (eiav) rna which is similar in many ways to the human immunodeficiency type 1 (hiv-1) tat-responsive element (tar). in eiav, this structure has a shorter stem than in hiv-1 and lacks the uridine bulge. primer extension analysis of eiav rna was used to identify the transcriptional start site in the viral long terminal repeat. premature termination of primer elongation at the predicted double-stranded rna ...19911645778
the topoisomerase i inhibitor, camptothecin, inhibits equine infectious anemia virus replication in chronically infected cf2th cells.camptothecin (cpt), a topoisomerase i-specific inhibitor, was found in this study to inhibit the replication of equine infectious anemia virus (eiav) in chronically infected cf2th cells (designated cf2th/eiav). by measuring viral reverse transcriptase activity in the culture medium, we demonstrated that treatment for 1 h with noncytotoxic doses of this drug inhibited production by 32 to 52%, whereas continuous exposure to this drug resulted in an 85 to 92% inhibition. no effect on the viability ...19911649321
selection against cpg dinucleotides in lentiviral genes: a possible role of methylation in regulation of viral expression.extremely low frequencies of cpg dinucleotides are found in the genomes of the lentivirus subfamily of retroviruses, including the human, simian and feline immunodeficiency viruses (hiv1, hiv2, siv, and fiv, respectively), equine infectious anemia virus (eiav), and the ovine lentivirus, visna. the occurrence of cpg dinucleotides is greater in the 2-3 (ncg) than in the 1-2 (cgn) codon-defined frame, as well as in the gag and env genes, compared to the more conserved pol gene. these differences su ...19902170945
characterization of variable regions in the envelope and s3 open reading frame of equine infectious anemia virus.the polymerase chain reaction was used to amplify and clone parts of the envelope gene and overlapping s3 open reading frame, thought to encode rev, of the virulent in vivo-derived th-1 isolate of equine infectious anemia virus (eiav). the results indicated that eiav consists of a heterogeneous mixture of genotypes present at the first febrile cycle after initial infection. we showed that the th-1 isolate apparently contains nondefective genotypes as well as types which have transmembrane protei ...19911649329
proviral sequences detected by polymerase chain reaction in peripheral blood cells of horses with equine infectious anemia lentivirus.proviral sequences in the peripheral blood mononuclear cells of 3 horses with acute equine infectious anemia virus were monitored using the polymerase chain reaction. provirus was detected during the initial viremic episode in each horse and during each of 3 relapsing viremic cycles, although the appearance of provirus lagged behind the onset of viremia. following each viremic episode, provirus levels in the peripheral monocytes decreased to less than 1 copy in 5 x 10(6) cells.19911848747
comparative features of retroviral infections of livestock.retroviral infections of livestock have become of increasing importance due to their usefulness as comparative models for human retroviral infections and their effects upon animal health and marketability of animals and animal products nationally and internationally. this paper presents a perspective on the retroviruses of economic concern in veterinary medicine with emphasis on the importance of understanding the modes of virus transmission and the species specificity of the viruses. the retrov ...19901963391
epidemiologic importance of interstate transport of equids infected with equine infectious anemia virus. 19912061145
cdna sequence of the env gene of a pathogenic equine infectious anemia lentivirus variant. 19902155398
equine monoclonal antibodies recognize common epitopes on variants of equine infectious anaemia virus.equine-murine xenohybridoma cells were produced using sp2/0 murine myeloma cells and splenic lymph node cells obtained from horses infected with 10(6) tcid50 of single cloned variants of equine infectious anaemia virus (eiav). the xenohybridomas secreted equine igg monoclonal antibodies reactive with eiav in enzyme immunoassays employing purified virus. seven antibodies were studied in detail. they bound to viral glycoproteins (gp90 or gp45) in radioimmunoprecipitation assays, and reacted with h ...19901703988
characterization of eiav immunogenicity during persistent infections: humoral responses and antigen targets. 19901704323
equine infectious anemia virus tat: insights into the structure, function, and evolution of lentivirus trans-activator proteins.equine infectious anemia virus (eiav) contains a tat gene which is closely related to the trans-activator genes of the human and simian immunodeficiency viruses. nucleotide sequence analysis of eiav cdna clones revealed that the tat mrna is composed of three exons; the first two encode tat and the third may encode a rev protein. interestingly, eiav tat translation is initiated at a non-aug codon in exon 1 of the mrna, perhaps allowing an additional level of gene regulation. the deduced amino aci ...19902157047
neutralization of hiv-1: a paradox of humoral proportions.the production of immunoglobulin capable of neutralizing the infectivity of a virus represents one of the most remarkable molecular accomplishments of the host's available immune defenses. it should be no surprise that a virus that has existed in the parenchyma of the immune system has evolved as an equally dynamic molecule (i.e., viral envelope) for survival. neutralizing immunoglobulin (ig) can best serve the host under conditions where the invading pathogen requires a well-defined cell-free s ...19911712328
purification and characterization of recombinant equine infectious anemia virus reverse transcriptase.a 1.67-kb segment of the equine infectious anemia virus pol gene, encoding a 66-kda reverse transcriptase (rt), was cloned and expressed in escherichia coli. recombinant rt, purified by a combination of metal chelate affinity chromatography and ion-exchange chromatography, displays both rna-dependent dna polymerase and rnase h activity. the affinity of purified rt for its replication primer, trna(3lys) was equivalent to that observed for human immunodeficiency virus rt. our data suggest that an ...19911719238
purification and kinetic characterization of equine infectious anemia virus reverse transcriptase.the reverse transcriptase of equine infectious anemia virus (eiav) was partially purified from virus particles and appeared to be a heterodimer with subunit molecular masses of 70 kdal and 59 kdal. the polymerase activity of this enzyme had an absolute requirement for a divalent cation, preferring mg++ over mn++. addition of a monovalent cation to the reaction mixture enhanced, but was not required for enzyme activity. kinetically, the reverse transcriptase of eiav is similar to the reverse tran ...19911719980
shedding and interspecies type sero-reactivity of the envelope glycopolypeptide gp120 of the human immunodeficiency virus.two glycopolypeptides with molecular weights 160,000 and 120,000 (gp120) are regularly recognized by human immunodeficiency virus (hiv)-specific antisera in lysates of cells persistently infected with hiv. in the present study, gp120 was characterized as the major envelope glycopolypeptide of hiv. gp120 was identified as the external viral glycoprotein by radiosequencing and by its presence in purified virus. however gp120 was predominantly shed as a soluble protein into the culture fluid. furth ...19862431105
tightly bound zinc in human immunodeficiency virus type 1, human t-cell leukemia virus type i, and other retroviruses.human immunodeficiency virus type 1 (hiv-1) and human t-cell leukemia virus type i (htlv-i) were purified by sucrose density gradient centrifugation in the presence of 1 mm edta. pelleted gradient fractions were analyzed for total protein, total gag capsid protein, and total zinc. zinc was found to copurify and concentrate with the virus particles. through successive cycles of resuspending in buffer containing edta and repelleting, the zinc content remained constant at about 1.7 mol of zinc per ...19921731111
detecting single base substitutions as heteroduplex polymorphisms.we have developed a sensitive technique for detecting single base substitutions in polymerase chain reaction (pcr) products from individuals heterozygous for polymorphisms or new mutations. this technique takes advantage of the formation of heteroduplexes in the pcr between different alleles from heterozygous individuals. these heteroduplexes can be detected on polyacrylamide gels because they migrate slower than their corresponding homoduplexes. using pcr, we have generated a series of point mu ...19921740339
analysis of equine humoral immune responses to the transmembrane envelope glycoprotein (gp45) of equine infectious anemia virus.defined segments of the transmembrane envelope glycoprotein (gp45) of equine infectious anemia virus were expressed as trple fusion proteins and examined for their reactivity in western immunoblots against a diverse panel of equine immune sera. the most immunogenic region of gp45 was localized to its amino terminus, positioned between the hydrophobic fusion and the transmembrane domains. a series of overlapping synthetic peptides were used in enzyme-linked immunosorbent assays to define an immun ...19911846180
transient suppression of equine immune responses by equine infectious anemia virus (eiav).suppression of the immune system is a common aspect of the disease pathogenesis associated with retroviral infections in both man and animals. we have measured transient suppression of the equine immune system as a loss or decrease in antigen-specific and polyclonal lymphocyte proliferation following experimental infection of ponies with three variants of equine infectious anemia virus (eiav) with difference virulence characteristics. the transient suppression of proliferative responses was temp ...19911651604
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