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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
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
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
synthesis of long complementary dna in the endogenous reaction by equine infectious anemia virus.in 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
mechanism of viral persistence in equine infectious anemia. 1975165036
[latest results in the research of infectious anemia in perissodactyla]. 1975174243
viral antigen production in horse kidney cell cultures infected persistently with equine infectious anemia virus. 1976177893
equine infectious anaemia. 1976181892
eia research. 1977189175
equine infectious anemia: current knowledge. 1979218920
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
serologic survey for equine infectious anemia virus in louisiana.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
equine infectious anemia virus: development of a simple reproducible method for titrating infectivity of the cell-adapted strain.an 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
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
responses in horses infected with equine infectious anemia virus adapted to tissue culture. 1979228570
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
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
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
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
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
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
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
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
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
immune-mediated thrombocytopenia in horses infected with equine infectious anemia virus.an 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
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
identification of a hypervariable region in the long terminal repeat of equine infectious anemia virus.an 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
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
proviral dna integration and transcriptional patterns of equine infectious anemia virus during persistent and cytopathic infections.the structure and integration patterns of equine infectious anemia virus (eiav) proviral dna and the patterns of viral transcription were examined in persistent and cytopathic infections of cultured cells. the results of southern blot analyses indicated that, in persistently infected cells, about 30% of the eiav provirus exists as randomly integrated dna, while the remaining 70% is equally divided between unintegrated linear and closed circular forms. the cytopathic infection, in contrast, is ch ...19902152836
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
equine infectious anemia virus (eiav) humoral responses of recipient ponies and antigenic variation during persistent infection.three ponies were inoculated with plasma containing 10(4.8) tcid50 of equine infectious anemia virus (eiav) and observed for 165 to 440 days. each pony developed a febrile response within 3 weeks of infection during which a plasma viremia greater than or equal to 10(3.5) tcid50/ml was observed. analyses of four isolates from sequential febrile episodes in a single pony were conducted by two-dimensional tryptic peptide maps and with monoclonal antibodies in immunoblots. structural and antigenic a ...19902162160
cloning and characterization of cdnas encoding equine infectious anemia virus tat and putative rev proteins.we isolated and characterized six cdna clones from an equine infectious anemia virus-infected cell line that displays a rev-defective phenotype. with the exception of one splice site in one of the clones, all six cdnas exhibited the same splicing pattern and consisted of four exons. exon 1 contained the 5' end of the genome; exon 2 contained the tat gene from mid-genome; exon 3 consisted of a small section of env, near the 5' end of the env gene; and exon 4 contained the putative rev open readin ...19902164593
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
topoisomerase i activity associated with human immunodeficiency virus (hiv) particles and equine infectious anemia virus core.in the present study, we found a topoisomerase i (topo i) activity in two strains of human immunodeficiency virus type 1 (hiv-1) and equine infectious anemia virus (eiav) particles. the topo i activity was located in the eiav cores and differed from the cellular topo i in its ionic requirements and response to atp, indicating that these were two distinct forms of this enzyme. topo i activity was removed from the viral lysates and viral cores by anti-topo i antiserum. the only protein recognized ...19902174357
immunopathogenesis of equine infectious anemia lentivirus disease.virus replication and subsequent viremia are clearly correlated with clinical disease in eiav infected horses. termination of viremia is the result of specific immune responses. recurrences of viremia are associated with antigenic variation of neutralization-sensitive epitopes. immunosuppression experiments indicate that the eventual control of eiav and development of carriers is mediated by the immune system. even though the immune response to eiav has a protective effect, immune responses also ...19902178127
human t-cell lymphotropic virus type iii: immunologic characterization and primary structure analysis of the major internal protein, p24.the major internal structural protein of human t-cell lymphotropic virus type iii (htlv-iii), a virus etiologically implicated in acquired immunodeficiency syndrome (aids), was purified to homogeneity. this 24,000-molecular-weight protein (p24) was shown to lack immunologic cross-reacting antigenic determinants shared by other known retroviruses, including htlv-i and htlv-ii, with the exception of equine infectious anemia virus (eiav). a broadly reactive competition immunoassay was developed in ...19852410630
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
hybridoma cell lines secreting monoclonal antibodies against equine infectious anemia virus.a monoclonal anti-equine infectious anemia virus (anti-eiav) antibody (1b15) has been generated by fusion of x63 ag 8.653 myeloma cells and spleen cells from mice hypersensitized with viral antigen p29. ouchterlony double-diffusion analysis indicated that antibody 1b15 is of the igg class. the specificity of the immune reaction for p29 was confirmed by cross-over immunoelectrophoresis and disc-gel electrophoresis. mab 1b15 was used to devise a solid-phase 'capture' ria for eiav-p29 antigen. the ...19872435751
lav/htlv-iii gag gene product p24 shares antigenic determinants with equine infectious anemia virus but not with visna virus or caprine arthritis encephalitis virus.antigenic cross-reactivity of the human acquired immunodeficiency disease syndrome virus lav/htlv-iii with the lentiviruses visna virus, caprine arthritis encephalitis virus (caev), and equine infectious anemia virus (eiav) was determined with indirect enzyme-linked immunosorbent assays, immunoblot analysis, and virus-specific polyclonal antisera. nonreciprocal cross-reactivity was seen between the gag gene products p24 of lav/htlv-iii and p28 of eiav. reciprocal cross-reactivity was seen betwee ...19862438251
change in host cell tropism associated with in vitro replication of equine infectious anemia virus.similar to other human and animal lentiviruses, equine infectious anemia virus (eiav) is detectable in vivo in cells of the monocyte-macrophage lineage. owing to their short-lived nature, horse peripheral blood macrophage cultures (hmc) are rarely used for in vitro propagation of eiav, and equine dermal (ed) or kidney cell cultures, which can be repeatedly passed in vitro, are used in most studies. however, wild-type isolates of eiav will not grow in these cell types without extensive adaptation ...19892470916
animal lentivirus replication and reverse transcriptase inhibitors.we summarize the pathogenesis of animal lentiviruses (visna-maedi virus, caprine arthritis and encephalitis virus, and equine infectious anemia virus), which have raised considerable interest since the discovery of human lentiviruses. the human lentiviruses possess structural, genetic, and clinical properties similar to those of animal lentiviruses. we describe the different mechanisms of and the principal work on reverse transcriptase inhibitors of animal lentiviruses, such as hpa-23, phosphono ...19892479076
the preparation and biochemical characterization of intact capsids of equine infectious anemia virus.capsids of equine infectious anemia virus have been isolated as cone-shaped particles 60 x 120 nm in size. detergent treatment of whole virus followed by two cycles of rate-zonal centrifugation in ficoll produces these capsids in a yield of approximately 10%. the major protein components are the gag-encoded p11 nucleocapsid protein and p26 capsid protein, which are present in equimolar amounts. substantial cleavage of p11 to p6 and p4 can be observed under conditions where the viral protease pac ...19892541703
occurrence of equine infectious anaemia in india. 19892547265
analysis of regulatory elements of the equine infectious anemia virus and caprine arthritis-encephalitis virus long terminal repeats.we analyzed the equine infectious anemia virus (eiav) long terminal repeat (ltr) for sequences that influence its promoter activity and ability to be trans-activated by the eiav tat gene product. a series of ltr deletion mutants and recombinants between ltr and simian virus 40 (sv40) regulatory sequences were used for these studies. we were able to identify the eiav promoter region and showed that sequences within the u3 region significantly inhibited ltr-directed transcription. however, when pl ...19892552171
localization of conserved and variable antigenic domains of equine infectious anemia virus envelope glycoproteins using recombinant env-encoded protein fragments produced in escherichia coli.previous characterizations of equine infectious anemia virus (eiav) glycoprotein variation by dna sequence analysis and epitope mapping using monoclonal antibodies (mabs) have revealed the presence of conserved and variable regions within the eiav env gene. to extend these studies, fragments of the eiav envelope proteins gp90 and gp45 were expressed in escherichia coli and used in western blot analysis with a diverse panel of equine immune sera to identify antigenic segments. all sera from eiav- ...19892552661
cross-neutralizing and subclass characteristics of antibody from horses with equine infectious anemia virus.antibody responses in horses with equine infectious anemia virus (eiav) were examined to determine their cross-neutralizing capacity. antibodies induced by infection with any of six biologically cloned variants of eiav cross-neutralized multiple variants from the group. anti-eiav antibody was found in both the igg and igg(t) subclasses in plasmas with virus-neutralizing activity and the majority of antiviral antibody was of the igg(t) subclass. depletion of igg(t) did not increase the neutraliza ...19892559537
comparison of diagnostic tests for the detection of equine infectious anemia antibody.two diagnostic tests are approved for detecting antibody to equine infectious anemia virus: the agar-gel immunodiffusion (agid) test and the competitive enzyme-linked immunosorbent assay (elisa). a total of 420 sera from national veterinary services laboratories check sets were tested with the agid and competitive elisa. a 100% correlation was obtained. the agid and competitive elisa were further used to test difficult samples with low levels of equine infectious anemia antibody (weak positives) ...19892562211
the visna virus genome: evidence for a hypervariable site in the env gene and sequence homology among lentivirus envelope proteins.the complete nucleotide sequence of the visna virus 1514 genome was determined. our sequence confirms the relationship of visna virus and other lentiviruses to human immunodeficiency virus (hiv) both at the level of sequence homology and of genomic organization. sequence homology is shown to extend to the transmembrane proteins of lentivirus env genes; this homology is strongest in the extracellular domain, suggesting that close structural and functional similarities may also exist among these e ...19872824836
antigenic variation and lentivirus persistence: variations in envelope gene sequences during eiav infection resemble changes reported for sequential isolates of hiv.the extent and nature of genomic variation among nine antigenically distinct eiav isolates recovered during sequential clinical episodes from two experimentally infected ponies were examined by restriction fragment analysis and nucleotide sequencing. only minor variations in restriction enzyme patterns were observed among the viral genomes. in contrast, env gene sequences of four isolates from one pony revealed numerous clustered base substitutions. divergence in env gene nucleotide and deduced ...19872825406
rapid detection of viral-specific antibodies by enzyme-linked immunosorbent assay (elisa).the development of three separate rapid elisas for detecting antibodies in host serum to three different viruses is described. these include: 1. a direct antigen assay using enzyme labelled anti-canine ig for detecting antibodies to canine parvovirus, 2. a competitive elisa using a feline infectious peritonitis virus-specific monoclonal antibody labelled with enzyme, and 3. a competitive elisa using an equine infectious anemia virus-specific monoclonal antibody and enzyme labelled antigen, p. 26 ...19872829416
antigenic variation in lentiviral diseases. 19882838047
eiav genomic organization: further characterization by sequencing of purified glycoproteins and cdna.nucleotide sequence analyses of two different proviral clones of equine infectious anemia virus (eiav), designated lambda 12 (k. rushlow et al., 1986, virology 155, 309-321) and 1369 (t. kawakami et al., 1987, virology 158, 300-312), indicate significant differences in the organization of two critical regions of the viral genome, i.e., in the short open reading frames in the pol-env intergenic region and in the 5'-end of the env gene. to determine the correct structure of the eiav genome, we hav ...19882841805
the lentiviruses: maedi/visna, caprine arthritis-encephalitis, and equine infectious anemia. 19882843016
a perspective on equine infectious anemia with an emphasis on vector transmission and genetic analysis. 19882847392
a propagating epizootic of equine infectious anemia on a horse farm.an epizootic of equine infectious anemia (eia) involved 35 horses on a farm in south georgia. during a 126-day period, 21 of these horses became seropositive for eia. after the initial diagnosis in july, the horses were tested every 7 to 10 days. at least one additional horse was found to be seropositive on each testing day. as soon as they were determined to be seropositive, the horses were removed from the herd and sent to slaughter. the removal of the seropositive horses, however, did not sto ...19882848789
equine infectious anemia virus: immunopathogenesis and persistence.equine infectious anemia (eia) is a chronic, relapsing infectious disease of horses caused by a nononcogenic retrovirus. virus persists in infected animals for life and can be reliably detected by serologic tests that measure levels of antibody to the major structural protein of the virus. periodic virus replication in macrophages leads to an immunologically mediated acute disease characterized primarily by severe anemia. recrudescence of acute eia is the result of antigenic variation of the sur ...19852984759
rapid solid-phase radioimmunoassay for detection of equine infectious anemia viral antigen and antibodies: parameters involved in standardization.solid-phase radioimmunoassays (spria) are described for the detection of equine infectious anemia (eia) viral antigen and antibodies. protein-antigen p29 currently used in the agar-gel immunodiffusion (agid) test was used as antigen in the spria. rabbit sera selected from positive agid test data were used to standardize the method. briefly, wells of flexible microtitre plates coated with antigen were incubated with antiserum followed by a secondary labelled antibody. the radioactivity remaining ...19853001113
rapid emergence of novel antigenic and genetic variants of equine infectious anemia virus during persistent infection.previous results from our laboratory have demonstrated that equine infectious anemia virus displays structural variations in its surface glycoproteins and rna genome during passage and chronic infections in experimentally infected shetland ponies (montelaro et al., j. biol. chem. 259:10539-10544, 1984; payne et al., j. gen. virol. 65:1395-1399, 1984). the present study was undertaken to obtain an antigenic and biochemical characterization of equine infectious anemia virus isolates recovered from ...19863001367
characterization of equine infectious anemia virus long terminal repeat.the long terminal repeats (ltrs) of equine infectious anemia virus (eiav) were examined with respect to their ability to function as transcriptional promoters in various cellular environments. nucleotide sequence analyses of the ltrs derived from two unique proviral clones revealed the requisite consensus transcription and processing signals. one of the proviruses possessed a duplication of a 16-base-pair sequence in the ccaat box region of the ltr which was absent in the other provirus. to asse ...19873027401
phagocytosis of horse erythrocytes treated with equine infectious anemia virus by cultivated horse leukocytes.horse erythrocytes treated with equine infectious anemia virus hemagglutinin were phagocytized by cultivated horse leukocytes (mainly macrophage-like cells and partly polymorphonuclear cells) after incubation with fresh horse serum but not with inactivated horse serum. the phagocytosis began as soon as the erythrocytes were added to the leukocyte cultures, and the majority of the reaction proceeded within 30 minutes. addition of antiserum showed a slightly suppressing but no enhancing effect on ...19873036046
a review of antigenic variation by the equine infectious anemia virus. 19873040337
studies on viral-induced anemia in horses infected with equine infectious anemia virus. 19883386089
preparation of equine infectious anemia antigens for diagnosis. 19734128832
pathological studies on bone marrow in equine infectious anemia. 3. cytlogical findings of bone marrow aspirates. 19684182535
[the development of petechial hemorrhages on the under-surface of the tongue in the horse and its relation to infection with the virus of equine infectious anemia]. 19674299474
[myocardium infarct in horses with infectious anemia]. 19684300496
equine infectious anemia: preliminary investigation of the complement-fixation test for the demonstration of antibodies and antigen.clinical field cases of equine infectious anemia were studied and the disease was reproduced experimentally in horses. attempts were made to adapt the complement-fixation test to the detection of antibodies in the serum of infected animals and to the demonstration of antigens in tissue extracts.a moderate complement-fixing antibody response was demonstrated in the serum of horses shortly after primary exposure to the infectious agent. however, this reactivity was of short duration and occurred w ...19694305760
viremia and immunological responses in horses infected with equine infectious anemia virus. 19694306393
immunofluorescent localization of equine infectious anemia virus in tissue. 19714322275
[cultivation of equine infectious anemia virus]. 19704325782
characterization of precipitating antibody in equine infectious anemia. 19714328472
detection of equine infectious anemia virus in vitro by immunofluorescence. 19714330258
titration of equine infectious anemia virus. effect of dosage on incubation time and clinical signs. 19714330637
diagnosis of equine infectious anemia by immunodiffusion test. 19724333633
passive immunity in the foal: measurement of immunoglobulin classes and specific antibody. 19734355952
role of horse fly (tabanus fuscicostatus hine) and stable fly (stomoxys calcitrans l.) in transmission of equine infectious anemia to ponies in louisiana. 19734357708
spontaneous autoimmune diseases of domestic animals. 19744367527
equine infectious anemia virus from infected horse serum.equine infectious anemia virus was purified from infected horse serum samples. electron microscope observation on negatively stained preparations of purified virus showed roughly spherical particles sized between 100 and 200 nm in diameter. in disrupted particles, an envelope was visible but no internal structure could be resolved. since the purified virus fraction had a strong antigenic activity to antiserum in immunodiffusion reaction, these particles are thought to be the causative virus of e ...19744372175
demonstration of antigenic identity between purified equine infectious anemia virus and an antigen extracted from infected horse spleen.antigenic relationship between purified equine infectious anemia (eia) virus and spleen-derived antigen from eia-infected horses was examined by immunodiffusion. identical antigenicity of these two antigens has been proven because precipitation lines formed between the two antigens and eia antiserum connected with each other. the results indicate that the antigenic substance derived from infected spleen is a component of eia virus.19724629262
the role of stable flies and mosquitoes in the transmission of equine infectious anemia virus. 19806118874
studies with equine infectious anemia virus: transmission attempts by mosquitoes and survival of virus on vector mouthparts and hypodermic needles, and in mosquito tissue culture.biological and mechanical transmission trials with psorophora columbiae (dyar and knab) and aedes sollicitans (walker) and ponies acutely infected with equine infectious anemia virus (eiav) were negative. the eiav antigen was detected by radioimmunoassay in ae sollicitans immediately after the mosquitoes had fed on an acutely ill pony, but not 14 days after feeding. psorophora columbiae mosquitoes had detectable eiav antigen as determined by radioimmunoassay 24 hours after they fed on an acutely ...19816119953
isolation and characterization of low-molecular-weight dna-binding proteins from retroviruses. 19806249039
hemagglutination of several strains of equine infectious anemia virus.six strains of equine infectious anemia (eia) virus propagated in equine leukocyte cultures were found to agglutinate horse erythrocytes. concentrated virus material containing about 20 units of complement fixation (cf) titer showed hemagglutinating (ha) titers ranging from 4 to 8 units. the ha activity remained stable after ether treatment and was reduced by trypsin, formaldehyde and kio4. cesium chloride equilibrium density gradient centrifugation revealed two populations of hemagglutinin, one ...19816263225
transmission of equine infectious anaemia virus from a horse negative to agar gel immunodiffusion testing. 19816265206
transmission of equine infectious anemia virus from horses without clinical signs of disease.twenty seven adult horses positive to the agar gel immunodiffusion (agid) test for equine infectious anemia (eia), but with no history of clinical eia, were used in transfusion studies to determine whether infectious eia virus was present in 1 to 5 ml of their blood. of 27 recipients, 21 (78%) became agid test-positive at an average of 24 days after inoculation. two horses that were initially negative when screened were retested and found to carry infectious virus in 5-300 ml of whole blood; the ...19826276353
antigenic stimulation of t lymphocytes in chronic nononcogenic retrovirus infection: equine infectious anemia.equine infectious anemia is a chronic disease of horses caused by a nononcogenic retrovirus. studies were undertaken to determine the types of cells involved in the in vitro lymphoproliferative response to viral antigens and the dynamics of this reaction. it was observed that reactive lymphocytes were present at unpredictable times in the peripheral blood of infected horses. this reaction was shown to be specific for the interaction of equine infectious anemia virus and t lymphocytes. enriched b ...19826281191
equine infectious anaemia: detection of antibodies using an immunofluorescence test.an indirect immunofluorescence test for detecting antibodies to equine infectious anaemia virus is presented. using monolayers of equine dermal cells within a defined period after infection, discrete fluorescent spots were observed in the cytoplasm of as many as 95 per cent of the cells. these inclusions appeared as ring-like structures when high titred sera were employed but became spots when the sera were diluted. cells showing optimal antigen fluorescence were used immediately or after storag ...19826296954
mechanical transmission of equine infectious anemia virus by deer flies (chrysops flavidus) and stable flies (stomoxys calcitrans). 19836297339
studies on equine infectious anemia virus transmission by insects.there are several factors involved in the mechanical transmission of equine infectious anemia (eia) virus by insects. large hematophagous insects, especially tabanids, which feed from extravascular sites (ie, pool feeding) appear to be the most efficient vectors. the biology of the host-seeking and blood-feeding behavior of the vectors are important variables that have been overlooked in the mechanical transmission of pathogens like eia virus. the biology, population levels, and diversity of the ...19846321420
structural proteins of equine infectious anemia virus and their antigenic activity.using purified equine infectious anemia (eia) virus labeled with 3h-glucosamine or 14c-protein hydrolysate, structural proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. as a result, 2 glycoproteins and 10 proteins with molecular weights (mol wt) ranging from 12,000 to 115,000 daltons were demonstrated. of 12 structural proteins, 3 proteins, namely a glycoprotein with mol wt of 76,000 (gp76) and 2 proteins with mol wt of 25,000 (p25) and 12,000 (p12), respective ...19846322625
effects of common radioiodination procedures on the binding of glycoproteins to immobilized lectins.representative glycoproteins including fetuin, protein a, ovalbumin, alpha 1 acid glycoprotein, and the major glycoprotein of equine infectious anemia virus were labelled with 125i by the chloramine-t or bolton-hunter procedure and their binding to immobilized con a or lentil lectin compared to untreated samples of each glycoprotein. glycoprotein modification was no greater than one substituted residue per protein molecule. yet the radioiodinated glycoproteins typically displayed only 0-50% of t ...19836838504
nmr analysis of the trans-activation response (tar) rna element of equine infectious anemia virus.transcription of lentiviral dna in the host cell is regulated by an interaction between the viral tar rna stem-loop and the viral tat protein. here we present a model of the three-dimensional structure of the tar rna stem-loop of the equine infectious anemia virus (eiav), derived from two- and three-dimensional nmr data. this 25 nucleotide rna consists of an a-form helical stem capped by two u-g base pairs and a four-nucleotide loop. two loop cytidines are stacked into the loop interior and like ...19957479065
production of monoclonal antibodies in horses. 19957550692
expression and mutational analysis of the reverse transcriptase of the lentivirus equine infectious anemia virus.the reverse transcriptase of equine infectious anemia virus (eiav) shows sequence similarity with the reverse transcriptases of other lentiviruses, particularly with those of human immunodeficiency viruses types 1 and 2 (hiv-1 and hiv-2). we have constructed a plasmid that when introduced into e. coli induces the synthesis of substantial quantities of the nearly authentic eiav reverse transcriptase. the viral and bacterially expressed reverse transcriptases are similar in their molecular weights ...19937694581
structural studies of hiv-1 tat protein.tat (trans-activator) proteins are early rna binding proteins regulating lentiviral transcription. these proteins are necessary components in the life cycle of all known lentiviruses, such as the human immunodeficiency viruses (hiv) or the equine infectious anemia virus (eiav). tat proteins are thus ideal targets for drugs intervening with lentiviral growth. the consensus rna binding motif (tar, trans-activation responsive element) of hiv-1 is well characterized. structural features of the 86 am ...19957723010
structural analysis of the principal immunodominant domain of the feline immunodeficiency virus transmembrane glycoprotein.in the transmembrane envelope glycoprotein (tm) of lentiviruses, including human immunodeficiency virus type 1 (hiv-1) and feline immunodeficiency virus (fiv), two cysteine residues, conserved in most retroviruses, are thought to form a loop containing five to seven amino acids. these elements make up a b-cell epitope recognized by nearly 100% of sera from infected patients or animals, designated the principal immunodominant domain (pid). the pid amino acid sequences are highly conserved between ...19957884857
delineating minimal protein domains and promoter elements for transcriptional activation by lentivirus tat proteins.lentivirus tat proteins comprise a novel class of rna-binding transcriptional activators that are essential for viral replication. in this study, we performed a series of protein fusion experiments to delineate the minimal protein domains and promoter elements required for tat action. we show that a 15-amino-acid region of equine infectious anemia virus (eiav) tat protein, when fused to the gal4 or lexa dna binding domain, can activate transcription in appropriate promoter contexts. in the natur ...19957884911
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