TitleAbstractYear(sorted descending)
is eiav tat protein a homeodomain? 19968658146
lymphoid leukosis viruses, their recognition as 'persistent' viruses and comparisons with certain other retroviruses of veterinary importance.diseases caused by lymphoid leukosis virus (llv), a retrovirus, take a long time after infection to develop and have a wide variety of pathological manifestations. this long latent period is characteristic of 'persistent virus infections'. disease produced by llv infection and its underlying mechanisms is compared with 'persistent' infections caused by other retroviruses in birds and mammals of veterinary importance. the diseases considered for comparison are those caused by reticuloendotheliosi ...19968693704
detection of equine infectious anemia viral rna in plasma samples from recently infected and long-term inapparent carrier animals by pcr.control of equine infectious anemia (eia) is currently based on detection of anti-eia virus (eiav) antibodies. however, serologic diagnostic methods may give false-negative results in infected horses that fail to respond adequately or are in the early stages of infection. we developed a reverse transcriptase nested pcr (rt-npcr) assay for the detection of viral gag gene sequences in plasma from eiav-infected horses. the ability of rt-npcr to detect field strains of eiav was investigated by assay ...19968735102
inhibition of hiv-1 replication by uridine-3'-spiroxirane, a new type of reverse transcriptase inhibitor. 19968736903
rna structure is a critical determinant of poly(a) site recognition by cleavage and polyadenylation specificity factor.sequence conservation among mammalian poly(a) sites is limited to the sequence aauaaa, coupled with an amorphous downstream u- or gu-rich region. since these sequences may also occur within the coding region of mrnas, additional information must be required to define authentic poly(a) sites. several poly(a) sites have been shown to contain sequences outside the core elements that enhance the efficiency of 3' processing in vivo and in vitro. the human immunodeficiency virus type 1, equine infecti ...19968756653
structural studies of the equine infectious anemia virus trans-activator protein.trans-activator (tat) proteins are necessary components for the completion of the t replication cycle of lentiviruses. the three-dimensional structure of the equine infectious anemia virus (eiav) tat protein (e-tat) was studied with cd spectroscopy, nmr spectroscopy, and restrained molecular-dynamics calculations. no stable elements of regular secondary structure were detected, but the sequence regions responsible for nucleic acid binding showed helix-forming tendency, e-tat exhibits a flexible ...19968797834
a morphometric study of bone marrow megakaryocytes in foals infected with equine infectious anemia virus.morphometric evaluation of bone marrow core biopsies was used to determine megakaryocyte (mk) numbers and mk size in nine foals with equine infectious anemia virus (eiav)-induced thrombocytopenia. both immunocompetent normal foals and foals with severe combined immunodeficiency (scid) were used. platelet counts were made three times weekly following viral infection. bone marrow core biopsies were taken from the ilium of each foal prior to experimental infection, immediately after the onset of th ...19968801716
initiation of (-) strand dna synthesis from trna(3lys) on lentiviral rnas: implications of specific hiv-1 rna-trna(3lys) interactions inhibiting primer utilization by retroviral reverse transcriptases.initiation of minus (-) strand dna synthesis was examined on templates containing r, u5, and primer-binding site regions of the human immunodeficiency virus type 1 (hiv-1), feline immunodeficiency virus (fiv), and equine infectious anemia virus (eiav) genomic rna. dna synthesis was initiated from (i) an oligoribonucleotide complementary to the primer-binding sites, (ii) synthetic trna(3lys), and (iii) natural trna(3lys), by the reverse transcriptases of hiv-1, fiv, eiav, simian immunodeficiency ...19968816751
stability of equine infectious anemia virus in aedes aegypti (diptera: culicidae), stomoxys calcitrans (diptera:muscidae), and tabanus fuscicostatus (diptera:tabanidae) stored at -70 degrees c.equine infectious anemia virus (eiav) was injected intrathoracically into aedes aegypti, stomoxys calcitrans, and tabanus fuscicostatus, and fed to ae. aegypti in suspensions of either artificial blood of eagle's minimum essential medium. insects were stored at -70 degrees c for up to 9 months before testing for the presence of eiav. the viral tissue culture titers detected from stored insects were similar to those from insects tested at time 0.19968827617
structure of equine infectious anemia virus proteinase complexed with an inhibitor.equine infectious anemia virus (eiav), the causative agent of infectious anemia in horses, is a member of the lentiviral family. the virus-encoded proteinase (pr) processes viral polyproteins into functional molecules during replication and it also cleaves viral nucleocapsid protein during infection. the x-ray structure of a complex of the 154g mutant of eiav pr with the inhibitor hby-793 was solved at 1.8 a resolution and refined to a crystallographic r-factor of 0.136. the molecule is a dimer ...19968844837
characterization of protective and enhancing immune responses to equine infectious anemia virus resulting from experimental vaccines. 19968882322
a primary production deficit in the thrombocytopenia of equine infectious anemia.the purpose of this study was to identify the mechanisms responsible for the thrombocytopenia that develops following infection of horses by the lentivirus equine infectious anemia virus (eiav). immunocompetent arabian foals and arabian foals with severe combined immunodeficiency (scid), which lack functional b and t lymphocytes, were experimentally infected with eiav. levels of viremia and a number of clinical and hematologic parameters were examined prior to and following infection. thrombocyt ...19968892906
aqueous solution structure of a hybrid lentiviral tat peptide and a model of its interaction with hiv-1 tar rna.human immunodeficiency virus, type 1, (hiv-1) encodes a transactivating regulatory protein, called tat, which is required for efficient transcription of the viral genome. tat acts by binding to a specific rna stem-loop element, called tar, on nascent viral transcripts. the specificity of binding is principally determined by residues in a short, highly basic domain of tat. the structure in aqueous solution of a biologically active peptide, comprised of the ten-amino acid hiv-1 tat basic domain li ...19968906885
expression, characterisation and mutagenesis of the aspartic proteinase from equine infectious anaemia virus.the gene encoding the proteinase from equine infectious anaemia virus (eiav) was cloned and expressed in escherichia coli. the recombinant eiav proteinase was purified to homogeneity and shown to have the ability to process polyprotein and synthetic peptide substrates of human immunodeficiency virus (hiv) origin with an efficiency that can approach that exhibited by hiv proteinase. eiav proteinase, however, was not susceptible to inhibition by a wide variety of inhibitors of hiv-1 proteinase, in ...19968917470
analysis of the long terminal repeat from a cytopathic strain of equine infectious anemia virus.sequential passage of the tissue culture-adapted prototype strain of eiav in fetal donkey dermal (fdd) cell cultures generated a virus stock which exhibits cytopathic effects in fdd cell cultures. in this study, the effects of the long terminal repeat (ltr) region on virus replication and cytopathogenicity were examined. the fdd-adapted virus ltr was found to contain a number of base pair mutations and a large insertion within the u3 region in comparison with the previously characterized ltr, la ...19968918926
retroviruses and systemic lupus some animal models of autoimmune diseases the roles of exogenous and endogenous retroviruses are clearly defined. in ungulates caprine arthritis encephalitis virus, equine infectious anemia virus or maedi-visna virus infections cause a well-defined autoimmune disease and the appearance of seropositivity of the animals is of diagnostic value. likewise, in mrl lpr/lpr mice insertion of a retrotransposon into the fas gene could clearly be shown to cause survival of autoreactive lymphocytes. desp ...19968930671
biochemical characterization of recombinant equine infectious anemia virus integrase.the integrase from equine infectious anemia virus (elav) was expressed in escherichia coli as a polyhistidine fusion protein. the protein was purified under native and denaturing conditions using one-step nickel-affinity chromatography. the purified denatured protein was refolded in the presence of detergent. in vitro 3' processing and dna strand transfer activities were analyzed under mg(2+)- and mn(2+)-dependent reaction conditions. both protein preparations were similarly active. only one vir ...19968936591
phorbol ester stimulation of equine macrophage cultures alters expression of equine infectious anemia virus.equine infectious anemia virus (eiav) is a lentivirus that replicates predominantly in mature tissue macrophages. viral expression is strongly influenced by the state of differentiation of the host cell. while blood monocytes can be infected, viral transcription is limited until the cell differentiates into a mature macrophage. activation of mature macrophages infected with eiav might also alter viral expression, presumably through binding of cellular transcription factors to viral nucleic acid ...19968972047
mechanism of inhibition of hiv reverse transcriptase by toxiusol, a novel general inhibitor of retroviral and cellular dna polymerases.toxiusol, a natural product isolated from the red sea sponge toxiclona toxius, has been shown to be a potent inhibitor of various viral reverse transcriptases (rt) [i.e., of human immunodeficiency virus (hiv-1), equine infectious anemia virus, and murine leukemia virus] and cellular dna polymerases (i.e., of dna polymerases alpha and beta and escherichia coli dna polymerase i). a thorough investigation of the mode of inhibition was conducted with hiv-1 rt-associated dna polymerase activity. the ...19957532006
incorporation of uracil into viral dna correlates with reduced replication of eiav in macrophages.the retrovirus equine infectious anemia virus (eiav) encodes a dutpase situated between reverse transcriptase and integrase. we have described the inability of eiav with a 270-bp dutpase deletion, delta du eiav, to replicate to wild-type (wt) levels in equine macrophages (d. s. threadgill, w. k. steagall, m. t. flaherty, f. j. fuller, s. t. perry, k. e. rushlow, s. f. j. legrice, and s. l. payne, j. virol. 67, 2592-2600, 1993). here we describe the construction of a second dutpase-deficient viru ...19957542416
production of monoclonal antibodies in horses. 19957550692
analysis of cross reactivity of retrovirus proteases using a vaccinia virus-t7 rna polymerase-based expression system.we have used the vaccinia virus-t7 rna polymerase-based expression system for studies on the activity of proteases from various retroviruses on homologous and heterologous gag polyproteins in eukaryotic cells. proteases from human immunodeficiency virus (hiv) types 1 and 2, equine infectious anaemia virus, human t cell leukaemia virus type 1 and human spumavirus were produced and were shown to cleave their cognate gag substrates produced in trans. analysis of cross reactivity revealed that lenti ...19957561754
helix-stabilizing agent, cc-1065, enhances suppression of translation by an antisense oligodeoxynucleotide.the antitumor antibiotic cc-1065 is known to bind at selected sequences in the minor groove of duplex nucleic acids and to hyperstabilize the duplexes against thermal melting. these properties suggested that cc-1065 may enhance translation inhibition by antisense oligonucleotides directed against a specific mrna. a 585 bp mrna transcript containing the equine infectious anemia virus (eiav) s2 gene and a portion of the env gene was prepared. also, a complementary 20 mer antisense oligodeoxynucleo ...19957580119
dutpase from the retrovirus equine infectious anemia virus: high-level expression in escherichia coli and purification.deoxyuridine 5'-triphosphate nucleotidohydrolase (dutpase, ec catalyzes the hydrolysis of dutp to dump and pyrophosphate, and plays important roles in nucleotide metabolism and dna replication. the dutpase gene of the retrovirus equine infectious anemia virus (eiav) was cloned and overexpressed in escherichia coli using the t7 rna polymerase expression system. the recombinant vector (pet-3a/edu), constructed by mutagenic pcr, was transformed into e. coli bl21 (de3) plyss cells, resulti ...19957663176
the tendency of lentiviral open reading frames to become a-rich: constraints imposed by viral genome organization and cellular trna availability.human immunodeficiency virus type 1 (hiv-1) and other lentiviridae demonstrate a strong preference for the a-nucleotide, which can account for up to 40% of the viral rna genome. the biological mechanism responsible for this nucleotide bias is currently unknown. the increased a-content of these viral genomes corresponds to the typical use of synonymous codons by all members of the lentiviral family (hiv, siv, biv, fiv, caev, eiav, visna) and the human spuma retrovirus, but not by other retrovirus ...19957666442
replication in vitro and in vivo of an equine infectious anemia virus mutant deficient in dutpase an important enzyme in dna synthesis, dutpase is present in a wide variety of organisms and viruses and has been identified as a component of the equine infectious anemia virus (eiav) pol gene. the role of eiav dutpase, designated du, in virus replication in vitro and in vivo was investigated with a recently described infectious molecular clone of eiav. a deletion mutant that was deficient in dutpase activity was constructed, and its replication kinetics was examined in fetal equine kidney (f ...19957707512
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
identification of a novel human zinc finger protein that specifically interacts with the activation domain of lentiviral tat proteins.transcriptional activation of hiv-1 gene expression by the viral tat protein requires the interaction of a cellular cofactor with the tat activation domain. this domain has been shown to consist of the cysteine-rich and core motifs of hiv-1 tat and is functionally conserved in the distantly related tat proteins of hiv-2 and eiav. using the yeast two-hybrid system, we have identified a novel human gene product, termed ht2a, that specifically and precisely binds to the activation domain of hiv-1 t ...19957778269
enhanced sensitivity to neutralizing antibodies in a variant of equine infectious anemia virus is linked to amino acid substitutions in the surface unit envelope glycoprotein.serial passage of the prototype (pr) cell-adapted wyoming strain of equine infectious anemia virus (eiav) in fetal donkey dermal (fdd) rather than fetal horse (designated fetal equine kidney [fek]) cell cultures resulted in the generation of a variant virus strain which produced accelerated cytopathic effects in fdd cells and was 100- to 1,000-fold more sensitive to neutralizing antibodies than its parent. this neutralization-sensitive variant was designated the fdd strain. although there were d ...19957853482
lentivirus tat proteins specifically associate with a cellular protein kinase, tak, that hyperphosphorylates the carboxyl-terminal domain of the large subunit of rna polymerase ii: candidate for a tat cofactor.efficient replication of human immunodeficiency virus types 1 and 2 (hiv-1 and hiv-2) requires the virus transactivator proteins known as tat. in order to understand the molecular mechanisms involved in tat transactivation, it is essential to identify the cellular target(s) of the tat activation domain. using an in vitro kinase assay, we previously identified a cellular protein kinase activity, tat-associated kinase (tak), that specifically binds to the activation domains of tat proteins. here i ...19957853496
structural analysis of the principal immunodominant domain of the feline immunodeficiency virus transmembrane 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
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
the catalytic properties of the reverse transcriptase of the lentivirus equine infectious anemia virus.the reverse transcriptase (rt) of equine infectious anemia virus (eiav) shares sequence similarity with the rts of other lentiviruses, particularly with the rts of human immunodeficiency viruses types 1 and 2 (hiv-1 and hiv-2, respectively), the causative agents of acquired immunodeficiency syndrome (aids). there is a 41-42% sequence identity between eiav rt and both hiv rts (which have 61% sequence identity to each other). we have compared the enzymic properties of eiav rt with those of hiv-1 r ...19947509281
lentivirus cross-reactive determinants present in the capsid protein of equine infectious anaemia this study we used immune sera from equine infectious anaemia virus (eiav)-infected horses which uniquely display broad reactivity with different lentivirus capsid proteins (ca) to characterize the cross-reactive determinants of lentivirus ca proteins. in particular, the role of the major homology region (mhr) of lentivirus ca proteins in this serological cross-reactivity was evaluated using both equine immune serum and murine monoclonal antibodies (mabs) directed against the mhr segment of d ...19947510329
alternative modes of polymerization distinguish the subunits of equine infectious anemia virus reverse transcriptase.a comparative study of recombinant 51- and 66-kda subunits comprising equine infectious anemia virus reverse transcriptase (eiav rt) is reported. both polypeptides sedimented as stable homodimers (molecular mass, 102 and 132 kda, respectively) when analyzed by rate sedimentation through glycerol gradients. consistent with their dimer composition, each preparation displayed considerable levels of both rna- and dna-dependent dna polymerase activity on different homopolymeric template/primer combin ...19947510690
a versatile synthetic peptide-based elisa for identifying antibody epitopes.a simple, versatile and very inexpensive procedure for cross-linking synthetic peptides to the polystyrene surfaces of micro-well assay plates for use in elisa was developed. the method is based on the use of poly-l-lysine (pll) as the anchor protein for synthetic peptides which were then easily and covalently linked to the pll using glutaraldehyde. the synthetic peptides used for the study were based on the amino acid sequence of the equine infectious anemia virus (eiav) envelope sequence and e ...19947513733
screening anti-hiv chinese materia medica with hiv and equine infectious anemic virus reverse transcriptase.the inhibitory activities of human immunodeficiency virus reverse transcriptase (hiv-rt) inhibitors pfa and suramin against hiv-rt and equine infectious anemic virus reverse transcriptase (eiav-rt) were studied in this paper. the 50% inhibitory concentration (ic50) of hiv-rt and eiav-rt treated by pfa and suramin were 0.2 mumol, 9.8 mumol and 17 mumol, 19.9 mumol, respectively. more than thirty chinese medicines, including recipes, herbs, extracts of traditional materia medica and isolated compo ...19947515133
structure of the equine infectious anemia virus tat protein.trans-activator (tat) proteins regulate the transcription of lentiviral dna in the host cell genome. these rna binding proteins participate in the life cycle of all known lentiviruses, such as the human immunodeficiency viruses (hiv) or the equine infectious anemia virus (eiav). the consensus rna binding motifs [the trans-activation responsive element (tar)] of hiv-1 as well as eiav tat proteins are well characterized. the structure of the 75-amino acid eiav tat protein in solution was determine ...19947515512
envelope sequence variation, neutralizing antibodies, and primate lentivirus persistence.studies in ungulate lentivirus systems clearly indicate that neutralization escape variants emerge over time in chronically infected animals. studies in the eiav system, in particular, have provided strong evidence that the humoral branch of the immune system is at least one selective force acting on an array of viral variants. in previous studies with the ungulate lentiviruses, molecularly cloned virus was never used, and plaque-purified virus was only sometimes used; the genetic determinants r ...19947523031
use of an elisa test in the eradication of an equine infectious anaemia enzyme linked immunosorbent assay (elisa) test and the classic agar gel immunodiffusion (agid) test were used as diagnostic methods in the eradication of a focus of equine infectious anaemia from a herd of 86 horses. the elisa test proved to be more sensitive, detecting positive animals earlier than the agid test. a group of 16 animals positive only by elisa also became positive to the agid when retested one month later, except for 2 animals which showed clinical signs of the disease and died ...19947941030
trifluoroethanol stabilizes a helix-turn-helix motif in equine infectious-anemia-virus trans-activator protein.the solution structure of the 75-amino-acid trans-activator (tat) protein of the equine infectious-anemia virus in trifluoroethanol-containing solution was determined by two-dimensional and three-dimensional nuclear magnetic resonance spectroscopy, resulting in a total of 838 nuclear-over-hauser-enhancement distance restraints, and restrained molecular-dynamics simulations. in contrast to the recently determined structure of this protein in trifluoroethanol-free ph 6.3 solution, the hydrophobic ...19947957222
chemiluminescent activation of the antiviral activity of hypericin: a molecular flashlight.hypericin is a naturally occurring photosensitizer that displays potent antiviral activity in the presence of light. the absence of light in many regions of the body may preclude the use of hypericin and other photosensitizers as therapeutic compounds for the treatment of viral infections in vivo. the chemiluminescent oxidation of luciferin by the luciferase from the north american firefly photinus pyralis was found to generate sufficiently intense and long-lived emission to induce antiviral act ...19947991618
nmr structure of a biologically active peptide containing the rna-binding domain of human immunodeficiency virus type 1 tat.the tat protein of human immunodeficiency virus type 1 enhances transcription by binding to a specific rna element on nascent viral transcripts. binding is mediated by a 10-amino acid basic domain that is rich in arginines and lysines. here we report the three-dimensional peptide backbone structure of a biologically active 25-mer peptide that contains the human immunodeficiency virus type 1 tat basic domain linked to the core regulatory domain of another lentiviral tat--i.e., that from equine in ...19948058789
the immunopathogenesis of equine infectious anemia virus. 19948067050
monocyte maturation controls expression of equine infectious anemia vivo, equine infectious anemia virus (eiav) replicates in tissues rich in macrophages, and it is widely believed that the tissue macrophage is the principal, if not sole, cell within the host that replicates virus. no viral replication has been detected in circulating peripheral blood monocytes. however, proviral dna can be detected in these cells, and monocytes may serve as a reservoir for the virus. in this study, an in vitro model was developed to clarify the role of monocyte maturation in ...19948083967
major histocompatibility complex-restricted cd8+ cytotoxic t lymphocytes from horses with equine infectious anemia virus recognize env and gag/pr proteins.cytotoxic t lymphocytes (ctl) can control some viral infections and may be important in the control of lentiviruses, including human immunodeficiency virus type 1. since there is limited evidence for an in vivo role of ctl in control of lentiviruses, dissection of immune mechanisms in animal lentiviral infections may provide needed information. horses infected with equine infectious anemia virus (eiav) a lentivirus, have acute plasma viremia which is terminated in immunocompetent horses. viremic ...19948107209
posttranscriptional effector domains in the rev proteins of feline immunodeficiency virus and equine infectious anemia systematically dissecting the rev proteins of feline immunodeficiency virus (fiv) and equine infectious anemia virus (eiav), we have identified within each a short peptide that is functionally interchangeable with the effector domains found in rev-like proteins from other retroviruses. the active sequences from fiv and eiav differ in several respects from other known effectors and may represent a distinct class of effector domain.19948107262
characterization of infectious molecular clones of equine infectious anaemia virus.we have recovered five infectious molecular clones of the lentivirus equine infectious anaemia virus (eiav). the clones were recovered from fetal equine kidney (fek) cells infected with a virulent, cell culture-adapted virus stock (designated pv) and have been characterized at a molecular level. each clone has unique envelope and long terminal repeat (ltr) sequences. we further investigated ltr sequence variation in the pv stock using pcr amplification to obtain additional ltr clones from infect ...19948113766
enhancement of eiav replication and disease by immunization with a baculovirus-expressed recombinant envelope surface glycoprotein.the potential for antibody-dependent enhancement of replication of macrophage/monocyte tropic viruses has posed a significant problem in the development of vaccines for several animal and human viruses and has raised significant concern in the design of potential aids vaccines. using the previously described equine infectious anemia virus/shetland pony system as a model for hiv-1 vaccine development, we have evaluated the efficacy of a recombinant subunit vaccine containing a baculovirus-express ...19948116252
in vivo replicative status and envelope heterogeneity of equine infectious anemia virus in an inapparent carrier.the distribution and replicative status of equine infectious anemia virus (eiav) dna in the tissues of a well-characterized inapparent carrier horse were established by using the pcr technique. the eiav pol region could be amplified in all of the tissues tested, including the cerebellum and periventricular tissue, at concentrations approximately 10(5)-fold less than in the same tissue from an acutely infected horse. further analysis of the eiav genome, with primer pairs diagnostic for sequential ...19948139056
expression of functional protease and subviral particles by vaccinia virus containing equine infectious anaemia virus gag and 5' pol genes.cells infected with vaccinia viruses expressing the equine infectious anaemia virus (eiav) gag gene (vgag) or gag plus the 5' pol encoding protease (vgag/pr) were evaluated with monoclonal antibody to a p26 capsid protein linear epitope (qeiskfltd). both recombinant viruses expressed gag precursor protein (55k) whereas only vgag/pr expressed a detectable gag-pol fusion protein (82k) with a functional protease, shown by subviral particles containing processed p26. horses inoculated with vgag/pr p ...19948151302
equine infectious anemia virus trans-regulatory protein rev controls viral mrna stability, accumulation, and alternative splicing.the cis- and trans-acting components of the rev regulatory pathway employed by equine infectious anemia virus (eiav) to regulate and coordinate viral gene expression were examined in complementation experiments. viral protein expression and mrna expression were compared in cells transiently transfected with wild-type or mutant proviruses in combination with rev expression plasmids. mutation of the predicted rev gene abolished gag protein synthesis, and this defect was complemented, in trans, by ...19948151775
cellular and viral specificity of equine infectious anemia virus tat transactivation.lentiviruses vary in their dependence on a functional tat gene during their viral life cycle. to begin to understand the viral and cellular parameters controlling equine infectious anemia virus (eiav) transactivation, we investigated tat function and tat and ltr structural requirements necessary for successful transactivation. eiav tat expression was required for detection of viral antigens from a full-length provirus. the level of transactivation by eiav tat as measured by ltr-cat assays correl ...19948178449
application of cycle dideoxy fingerprinting to screening heterogeneous populations of the equine infectious anemia virus.nucleotide sequence heterogeneity in a population of the equine infectious anemia virus (eiav) was investigated using a modification of the dideoxy fingerprinting (ddf) technique. pcr-amplified regions of the gag gene from eiav isolates were ligated into plasmid vectors and used to transform bacteria. the single dideoxynucleotide sequencing step was performed using plasmid dna prepared from individual bacterial colonies using an 35s end-labeled primer and taq dna polymerase. analysis of the prod ...19947818901
the aspartic proteinase of equine infectious anaemia virus. 19947821563
biological activity and intracellular location of the tat protein of equine infectious anemia virus.the tat protein of equine infectious anemia virus (eiav) was synthesized in escherichia coli using the inducible expression plasmid, pet16b, which contains a his.tag leader, thus allowing for rapid and efficient enrichment of the histidine-tagged protein by metal affinity chromatography. yields of up to 20 mg of tat were obtained from 10(11) bacterial cells. the recombinant tat protein was shown to potently trans-activate the eiav long terminal repeat (ltr) following its introduction into canine ...19947821797
phosphorothioate oligonucleotides inhibit the replication of lentiviruses and type d retroviruses, but not that of type c retroviruses.phosphorothioate analogs of oligodeoxynucleotides at a concentration of 2 microm protected himalayan tahr cells from infection by caprine arthritis encephalitis virus (caev) and equine dermis cells from infection by equine infectious anemia virus (eiav). the characteristics of this inhibition against these lentiviruses are similar to those previously described for the inhibition of hiv-1 in ath8 cells [17]. thus, the 28-mer homo-oligomer of cytidine [s-(dc)28] was at least as effective as three ...19947826217
molecular dynamics simulation of equine infectious anemia virus tat protein in water and in 40% trifluoroethanol.two molecular dynamics (md) simulations were performed in order to increase the understanding of the dependence of protein conformation on solvent environment. the protein used for these simulations is the transcriptional activator of the equine infectious anemia virus (eiav-tat). the structure of this protein has been determined by nuclear magnetic resonance (nmr) in aqueous solution (willbold et al., science 264, 1584 (1994)) and in 40% (v/v) trifluoroethanol (tfe) (sticht et al., eur. j. bioc ...19947848558
the origin of human immunodeficiency virus type-1 rev gene. an evolutionary hypothesis.the rev protein of human immunodeficiency virus type-1 is an rna-binding posttranscriptional transregulator encoded by an accessory gene that is distinct from retroviral oncogenes and whose origin is unclear. we hypothesize that the rev gene was generated by duplication of a viral rna segment having a secondary-structure that evolved into the rev-responsive element (rre). this hypothesis is based on the following findings. first, accumulated data on functional mapping of rev, tat, and the transm ...19948307167
development of the coggins test. 19948313705
molecular dynamics simulation of equine infectious anemia virus tat protein in water and in 40% trifluoroethanol.abstract two molecular dynamics (md) simulations were performed in order to increase the understanding of the dependence of protein conformation on solvent environment. the protein used for these simulations is the transcriptional activator of the equine infectious anemia virus (eiav-tat). the structure of this protein has been determined by nuclear magnetic resonance (nmr) in aqueous solution (willbold et al., science 264, 1584 (1994)) and in 40% (v/v) trifluoroethanol (tfe) (sticht et al., eur ...199422671906
structural features of the trans-activation response rna element of equine infectious anemia virus.a 25-nucleotide rna with the sequence of the trans-activation response (tar) element of equine infectious anemia virus (eiav) was analyzed by biochemical methods and by one- and two-dimensional nmr spectroscopy. nmr, nuclease probing, and polyacrylamide gel migration rates show that the rna consists of an a-helical stem capped by two non-watson-crick u-g base pairs and a compact four-nucleotide loop. the loop is stabilized by base stacking, with loop nucleotides c12 and c15 stacked upon u11 and ...19938381023
translation of equine infectious anemia virus bicistronic tat-rev mrna requires leaky ribosome scanning of the tat ctg initiation codon.we have examined the translational regulation of the equine infectious anemia virus (eiav) bicistronic tat-rev mrna. site-directed mutagenesis of the tat leader region followed by expression of the tat-rev cdna both in vitro and in transiently transfected cells established that tat translation is initiated exclusively at a ctg codon. increasing the efficiency of tat translation by altering the ctg initiator to atg resulted in a dramatic decrease in translation of the downstream (rev) cistron, in ...19938382305
lentivirus envelope sequences and proviral genomes are stabilized in escherichia coli when cloned in low-copy-number plasmid vectors.a promoter-selection vector (pkk232-8) was used to identify sequences with strong escherichia coli promoter activity positioned near the start of the envelope-encoding genes (env) of two lentiviruses, simian immunodeficiency virus (siv) and equine infectious anemia virus (eiav). for eiav, cloning the cryptic promoter sequences together with downstream sequences encoding the envelope glycoprotein (gp90) in moderate- to high-copy-number (hcn) plasmid vectors, such as pbr322 or puc, resulted in rea ...19938382658
physical and functional characterization of transcriptional control elements in the equine infectious anemia virus promoter.equine infectious anemia virus (eiav) is a lentivirus that causes a chronic disease of horses characterized by cyclic episodes of fever, anemia, and viremia. although the genome and promoter of eiav are much less complex than those of its relatives the primate immunodeficiency viruses, the cellular proteins that activate and regulate transcription of eiav have not yet been identified. in this report, we show by electrophoretic mobility shift assays and dnase i footprinting that the eiav promoter ...19938383228
a comparison of elisa, fast-elisa and gel diffusion tests for detecting antibody to equine infectious anaemia virus.sera of sixteen horses with clinical signs of eia from six different outbreaks and sera of 100 uninfected horses were used to validate an elisa for eia diagnosis. the antigen used was a recombinant protein derived from the amino-terminal portion of the transmembrane envelope protein of eia (gp45). reactivity between positive and negative sera could be clearly distinguished. comparison with the traditional agar gel immunodiffusion test (commonly called the coggins test) showed that the elisa was ...19938383374
studies on the substrate specificity of the proteinase of equine infectious anemia virus using oligopeptide substrates.the proteinase of the equine infectious anemia virus (eiav), a lentivirus closely related to human immunodeficiency virus (hiv), was purified from concentrated virus. the specificity of the enzyme was characterized using oligopeptides representing naturally occurring cleavage sites in the gag and gag-pol polyproteins. the length of the substrate binding pocket was found to be 1-2 residues longer than that of hiv proteinases. although the eiav and hiv proteinases cleaved most of the peptides at t ...19938384879
molecular model of equine infectious anemia virus proteinase and kinetic measurements for peptide substrates with single amino acid substitutions.a molecular model has been built of the equine infectious anemia virus (eiav) proteinase on the basis of the crystal structures of the related rous sarcoma virus (rsv) and human immunodeficiency virus (hiv) proteinases. the 104 residue long eiav proteinase has 30 identical and 11 similar amino acids compared to those in hiv-1 proteinase and 25 identical and 18 similar amino acids compared to rsv proteinase. the overall structure is predicted to be close to that of hiv-1 proteinase. two regions s ...19938384880
a review of techniques for the serologic diagnosis of equine infectious anemia. 19938385498
characterization of equine infectious anemia virus dutpase: growth properties of a dutpase-deficient mutant.the putative dutpase domain was deleted from the polymerase (pol) gene of equine infectious anemia virus (eiav) to produce a recombinant delta dupol escherichia coli expression cassette and a delta du proviral clone. expression of the recombinant delta dupol polyprotein yielded a properly processed and enzymatically active reverse transcriptase, as determined by immunoblot analysis and dna polymerase activity gels. transfection of delta du provirus into feline (fea) cells resulted in production ...19938386267
mutagenesis of eiav tat reveals structural features essential for transcriptional activation and tar element recognition.certain members of the lentivirus subfamily of retroviruses encode unique transcriptional activator (tat) proteins that modify the transcription complex after binding to the 5' end of nascent viral mrna. the tat proteins are modular, containing rna-binding and activation domains that can be exchanged between different tat proteins or replaced with heterologous protein fragments. while there is considerable sequence conservation among the divergent tat proteins, there are also some structural dif ...19938389074
genetic analysis of the cofactor requirement for human immunodeficiency virus type 1 tat function.the tat protein of human immunodeficiency virus type 1 is a potent transcriptional trans activator of the viral long terminal repeat promoter element. tat function requires the direct interaction of tat with a cis-acting viral rna target sequence termed the trans-activation response (tar) element and has also been proposed to require at least one cellular cofactor. we have used a genetic approach to attempt to experimentally define the role of the cellular cofactor in tat function and tar bindin ...19938389901
the pu.1/spi-1 proto-oncogene is a transcriptional regulator of a lentivirus promoter.the enhancer unit present in the retrovirus equine infectious anemia virus (eiav) was previously shown to contain binding sites for proteins belonging to mdbp, pea2, ap-1, and ets families. the eiav ets motif matches the consensus sequence for both pea3- and pu.1-binding sites. here, we show by gel shift analysis that pu.1, present in nuclear extracts from monocyte and b-lymphocyte cell lines, binds to oligonucleotides containing the eiav ets element. hela cells transiently transfected with a pu ...19938389910
structural and functional characterization of rev-like transcripts of equine infectious anemia virus.three cdna clones representing structurally distinct transcripts were isolated from a cdna library prepared from cells infected with equine infectious anemia virus (eiav) by using a probe representing the s3 open reading frame, which is thought to encode rev. one species, designated p2/2, contained four exons and was identical to a previously described polycistronic mrna that encodes tat. this transcript was predicted to also direct the synthesis of a truncated form of the transmembrane protein ...19938394464
sequence-specific resonance assignments of the 1h-nmr spectra of a synthetic, biologically active eiav tat protein.the equine infectious anemia virus (eiav) trans-activating (tat) protein is a close homologue of the human immunodeficiency virus (hiv) tat protein. both of these proteins bind to an rna trans-activation responsive element (tar). we synthesized chemically a protein with the sequence of the 75 amino acid tat protein from eiav. the chemically synthesized protein was shown to be biologically active. circular dichroism (cd) and 1h nuclear magnetic resonance (nmr) spectroscopy were used to structural ...19938395203
equine infectious anemia.the ability of eiav to persistently infect horses in the face of a profound immune response by the host makes it a potentially devastating disease for the horse population of the united states. its ability to evade host immune defenses by lying dormant in apparently healthy animals and by rapidly changing its antigenic determinants is proving to be a major obstacle to vaccine development. because most infected horses appear clinically normal and a large proportion of horses in this country remai ...19938395326
protein interactions with dna elements in variant equine infectious anemia virus enhancers and their impact on transcriptional activity.the long terminal repeats (ltrs) from various cloned equine infectious anemia virus (eiav) proviruses differ significantly, but all contain cis-acting dna elements identical to mdbp-, pea2-, ap-1-, and pu.1 (ets)-binding sites. a prototype eiav ltr would contain one of each of these conserved elements. the ltr variations originate from the insertion of novel sequences between the pea2 and ap-1 elements in the transcriptional enhancer unit. viewed in this way, the ltr from provirus clone lambda 1 ...19938411361
analysis of multiple mrnas from pathogenic equine infectious anemia virus (eiav) in an acutely infected horse reveals a novel protein, ttm, derived from the carboxy terminus of the eiav transmembrane protein.transcription of pathogenic equine infectious anemia virus (eiav) in an acutely infected horse was examined by using the polymerase chain reaction and nucleotide sequencing. four spliced transcripts were identified in liver tissue, in contrast to the multiplicity of alternatively spliced messages reported for in vitro-propagated human immunodeficiency virus, simian immunodeficiency virus, and, to a lesser extent, eiav. nucleotide sequence analysis demonstrated that three of these mrnas encode kn ...19938419648
high prevalence of serum antibodies to equine infectious anemia virus reverse transcriptase.the immunogenicity of the equine infectious anemia virus (eiav) reverse transcriptase (rt) was examined by immunoblot assay with recombinant eiav rt. all of the 19 sera from eiav-infected horses tested contained antibodies that recognized eiav rt and directly inhibited the polymerase activity of the enzyme. an examination of sera obtained sequentially from two experimentally infected animals revealed that anti-rt antibodies arise early in infection and increase in level. the appearance of the an ...19937678974
fidelity of dna synthesis exhibited in vitro by the reverse transcriptase of the lentivirus equine infectious anemia virus.the lentivirus equine infectious anemia virus (eiav) shows high genetic variations. to gain insight into the relative contribution of the reverse transcription process to the eiav mutation rate, the accuracy of dna synthesis catalyzed in vitro by the reverse transcriptase (rt) of eiav was determined. since the rt of eiav shows a relatively high sequence homology with other lentiviral rts, most notable being the rts of human immunodeficiency viruses (hivs), type 1 and type 2, it was of interest t ...19937687876
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
identification of the activation domain of equine infectious anemia virus rev.several members of the lentivirus family of complex retroviruses have been shown to encode proteins that are functionally equivalent to the rev posttranscriptional regulatory protein of human immunodeficiency virus type 1 (hiv-1). furthermore, the domain organization of hiv-1 rev, featuring a highly basic n-terminal rna binding domain and a leucin-rich c-terminal effector domain, has also been shown to be highly conserved among rev proteins derived from not only the primate but also the ovine an ...19938230455
equine infectious anemia virus tat is a predominantly helical protein.nuclear magnetic resonance (nmr) spectroscopy revealed features of the secondary structure of the equine infectious anemia virus (eiav) tat protein in solution. we could show that this protein, which is required in the replication cycle of lentiviruses, forms a predominantly helical structure in trifluoroethanol/water (40% by vol.) solution. in particular, the basic rna-binding region and the adjacent core domain, which are highly conserved among lentiviral tat proteins, show helix-type secondar ...19937506657
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
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 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
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
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
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 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
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
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
african horse sickness and equine infectious anaemia serology in the gambia. 19921339038
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