TitleAbstractYear(sorted ascending)
dna sequence (h) curves of the human immunodeficiency virus 1 and some related viral genomes.the complete nucleotide sequences of several human immunodeficiency virus 1 (hiv-1) genomes were converted by computer to respective h curves. these three-dimensional space curves embody all the information contained in the sequence due to their abstract vectorial structure. for one sequence (hiv-1 isolate bru) special efforts were made to maximize the available resolution (the number of nucleotides visually discernible within a unit length of the curve) when making a hard, master copy of the h ...19883402311
a quantitative bioassay for hiv-1 based on trans-activation.a bioassay that is based on trans-activation has been developed for the detection and quantitation of the human immunodeficiency virus type 1 (hiv-1). indicator cell lines were constructed that contain the hiv-1 long terminal repeat ligated to the chloramphenicol acetyltransferase (cat) gene. infection of these cells by hiv activates the expression of cat protein. isolates of hiv-1 with divergent nucleotide sequences activated the indicator cell lines to a similar extent, approximately 500- to 1 ...19883422113
antigenic mapping of the envelope proteins of equine infectious anemia virus: identification of a neutralization domain and a conserved region on glycoprotein 90.monoclonal antibodies (mcabs) were used to dissect the antigenic sites of the surface glycoproteins of the prototype cell-adapted wyoming strain of equine infectious anemia virus (eiav). serologic reactivities of these mcabs were determined by elisa, additive elisa, competitive elisa, and western blot assays. the results indicated that antigenic reactivity of gp90 was localized on at least four distinct epitopes, two of which were important in neutralization. our studies also revealed that these ...19882450529
antigenic variation of equine infectious anemia virus as detected by virus neutralization. brief report.the antigenic structure of 16 viruses isolated from four horses which were inoculated with a clone of equine infectious anemia (eia) virus was compared by the neutralization test. the antigenic structure of viruses isolated after development of neutralizing antibody differed from virus to virus. back mutation of the antigenic structure was also demonstrated by serial passage of the virus in horses. these results suggest that eia virus is subject to multidirectional antigenic variation. the possi ...19882829799
lentivirus antigen purification and characterization: isolation of equine infectious anemia virus gag and env proteins in one step by reverse phase hplc and application to human immunodeficiency virus glycoproteins.we describe here a one step hplc technique for purifying the four gag proteins (p26, p15, p11 and p9) and two env glycoproteins (gp90 and gp45) from purified equine infectious anemia virus (eiav), a member of the lentivirus subfamily of retroviruses. the purification procedure employs a reverse-phase phenyl radial-pak cartridge contained in a high pressure radial compression chamber in which a shallow, multistep acetonitrile gradient is applied at ambient temperatures. the purified proteins are ...19882836462
antigenic variation in lentiviral diseases. 19882838047
characterization of the serological cross-reactivity between glycoproteins of the human immunodeficiency virus and equine infectious anaemia virus.the reported serological relatedness between the major glycoproteins of human immunodeficiency virus (hiv gp120) and equine infectious anaemia virus (eiav gp90) was examined using purified antigens in radioimmunoprecipitation (rip), radioimmunoassay (ria) and immunoblot assays with reference serum from acquired immunodeficiency syndrome (aids) patients, an anti-gp120 goat serum and eiav-infected horse serum. to assess the contributions of glycoprotein oligosaccharide and peptide components to an ...19882839603
identification of gag precursor of equine infectious anaemia virus with monoclonal antibodies to the major viral core protein, p26.monoclonal antibodies (mabs) against the major core protein p26 of equine infectious anaemia virus (eiav) were produced and characterized. sensitive enzyme-linked immunosorbent assay and western blot immunoassay were employed to confirm the specificity of these mabs. western blot analysis also indicated that mabs to p26 reacted with another eiav protein of 55,000 apparent mr (designated here as pr55gag) present in density gradient-purified virus preparations. rabbit antiserum prepared against p2 ...19882839604
immune responses are required to terminate viremia in equine infectious anemia lentivirus infection.six normal and four immunodeficient horses were injected with a cloned variant of equine infectious anemia virus (eiav). the six normal horses had detectable eiav in their plasma by 7 days postinjection. during their primary viremic episode, which was accompanied by fever and anemia, maximum titers of eiav in plasma ranged from 10(3.8) to 10(4.8) 50% tissue culture infective doses per ml. all six normal horses cleared detectable virus from their plasma by 21 to 35 days after injection. horses wi ...19882839723
cis- and trans-acting regulation of gene expression of equine infectious anemia virus.deletion analysis of the equine infectious anemia virus long terminal repeat revealed that sequences responsive to virus-specific transactivation are located within the region spanning the transcriptional start site (-31 to +22). in addition, an active exon of a trans-acting factor (tat) was identified downstream of pol and overlapping env (nucleotides 5264 to 5461). activation by tat is accompanied by an increase in the steady-state levels of mrna directed by the equine infectious anemia virus ...19882841502
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 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
localization of sequences responsible for trans-activation of the equine infectious anemia virus long terminal repeat.we used the escherichia coli chloramphenicol acetyltransferase gene (cat) to study sequences that influence expression of the equine infectious anemia virus (eiav) genome. the eiav long terminal repeat (ltr) directed cat activity in a canine cell line, but at levels much lower than those achieved with other eucaryotic viral promoters. in the same cells infected with eiav or cotransfected with molecularly cloned eiav genomic dna, ltr-directed activity was markedly enhanced. comparison of cat mrna ...19882824840
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
qualitative analyses of cellular immune functions in equine infectious anemia show homology with aids.equine infectious anemia (eia) is a disease caused by a lymphocytotropic lentivirus which belongs to the same subfamily as hiv. because of the very close relationship of their predicted gag and pol gene products and similarities in clinical manifestations of the disease, eia served as a model to study immunological events involved in the host defence against lymphocytotropic viral infections. the existence of antibody dependent cell-mediated cytotoxicity against autologous eia virus infected lym ...19892523215
[a western blot test for the serological diagnosis of equine infectious anemia].after electrophoretic separation in sds-page structural proteins of the virus of equine infectious anemia (eia) were easily blotted by the semi-dry-blotting method onto nitrocellulose filters. strips of these filters were used for antibody demonstration, and positive reactions thereof were intensified by a biotin-avidin-peroxidase system. sensitivity of this system was so high as to allow readable interpretation of bands up to the dilution of 1:6,400 of a strongly positive serum. frequently this ...19892538978
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
development of an enzyme-linked immunosorbent assay for equine infectious anemia virus detection using recombinant provide more sensitive and convenient methods for the detection of equine infectious anemia virus (eiav), we developed an enzyme-linked immunosorbent assay (elisa) employing the eiav gag precursor (pr55gag) produced by using recombinant dna techniques. the antigenic reactivity of the recombinant eiav pr55gag was found to be equivalent to that of the virion p24gag and elicited high-titered antiserum in rabbits. when a large number of horse sera were analyzed for the presence of antibodies to e ...19892546970
occurrence of equine infectious anaemia in india. 19892547265
feline immunodeficiency virus infection.feline immunodeficiency virus (fiv) (formerly feline t-lymphotropic lentivirus or ftlv) was first isolated from a group of cats in petaluma, california in 1986. the virus is a typical lentivirus in gross and structural morphology. it replicates preferentially but not exclusively in feline t-lymphoblastoid cells, where it causes a characteristic cytopathic effect. the major structural proteins are 10, 17 (small gag), 28 (major core), 31 (endonuclease?), 41 (transmembrane?), 52 (core precursor pol ...19892549690
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
viral dna in horses infected with equine infectious anemia virus.the amount and distribution of viral dna were established in a horse acutely infected with the wyoming strain of equine infectious anemia virus (eiav). the highest concentration of viral dna were found in the liver, lymph nodes, bone marrow, and spleen. the kidney, choroid plexus, and peripheral blood leukocytes also contained viral dna, but at a lower level. it is estimated that at day 16 postinoculation, almost all of the viral dna was located in the tissues, with the liver alone containing ab ...19892555550
progress in vaccines against aids. 19892555922
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
nucleotide sequence analysis of feline immunodeficiency virus: genome organization and relationship to other lentiviruses.we determined the complete nucleotide sequence of an infectious proviral molecular clone (fiv-14) of the feline immunodeficiency virus (fiv). fiv-14 has a genome organization similar in complexity to other lentiviruses. in addition to three large open reading frames representing the gag, pol, and env genes, at least four small open reading frames are present in the pol-env intergenic, env, and env-3' long terminal repeat regions. nucleotide and deduced amino acid sequence alignments of the fiv c ...19892813380
comparative features of retroviral infections of livestock.retroviral infections of livestock have become of increasing importance due to their usefulness as comparative models for human retroviral infections and their effects upon animal health and marketability of animals and animal products nationally and internationally. this paper presents a perspective on the retroviruses of economic concern in veterinary medicine with emphasis on the importance of understanding the modes of virus transmission and the species specificity of the viruses. the retrov ...19901963391
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
cdna sequence of the env gene of a pathogenic equine infectious anemia lentivirus variant. 19902155398
equine infectious anemia virus tat: insights into the structure, function, and evolution of lentivirus trans-activator proteins.equine infectious anemia virus (eiav) contains a tat gene which is closely related to the trans-activator genes of the human and simian immunodeficiency viruses. nucleotide sequence analysis of eiav cdna clones revealed that the tat mrna is composed of three exons; the first two encode tat and the third may encode a rev protein. interestingly, eiav tat translation is initiated at a non-aug codon in exon 1 of the mrna, perhaps allowing an additional level of gene regulation. the deduced amino aci ...19902157047
pattern of transcription of the genome of equine infectious anemia virus.the pattern of expression of the equine infectious anemia virus (eiav) genome in a persistently infected canine cell line was determined. five eiav-specific transcripts (8.2, 5.0, 4.0, 2, and 1.8 kilobases [kb]) were detected by using subgenomic restriction enzyme fragments of eiav dna and eiav-specific oligonucleotides as probes. the 8.2-kb mrna could be shown to represent viral genomic rna, whereas the smaller transcripts were generated by splicing events. evidence was obtained that indicated ...19902157066
analysis of antibody reactivities in elisa using protein blots as antigen substrates: s-elisa.we describe here a novel immunoassay procedure, designated strip-elisa (s-elisa), in which specific antigens are purified by sds-page, transferred to support membranes, and utilized in situ as substrate in routine elisa procedures. using two different lentivirus systems, simian immunodeficiency virus and equine infectious anemia virus, we demonstrate the utility of s-elisa for screening hybridoma supernatants during production of monoclonal antibodies and for the dissection of polyclonal antibod ...19902157766
identification of sequences encoding the equine infectious anemia virus tat gene.equine infectious anemia virus (eiav), a lentivirus, encodes a trans-activator (tat) which stimulates gene expression directed by the viral long terminal repeat (ltr). this function has been previously shown by us and others to be encoded by sequences within the middle region of the eiav genome in which two short open reading frames, s1 and s2, reside. in the present study, by using in vitro mutagenesis, we show that disruption of s1, but not s2, completely abolished trans-activation. addition o ...19902158694
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
synthesis and processing of the transmembrane envelope protein of equine infectious anemia virus.the transmembrane (tm) envelope protein of lentiviruses, including equine infectious anemia virus (eiav), is significantly larger than that of other retroviruses and may extend in the c-terminal direction 100 to 200 amino acids beyond the tm domain. this size difference suggests a lentivirus-specific function for the long c-terminal extension. we have investigated the synthesis and processing of the eiav tm protein by immune precipitation and immunoblotting experiments, by using several envelope ...19902164597
comparative evaluation of the agar gel immunodiffusion test and two commercial elisa kits for the serodiagnosis of equine infectious anemia.selected sets of serum samples of horses were tested blindly in a comparative investigation for antibodies against equine infectious anemia (eia) virus. three commercial kits were used, a well-established agar-gel immuno-diffusion kit which our laboratory has been using routinely for 14 years on one hand, a competitive elisa kit (celisa) and a non-competitive elisa kit on the other hand. the american eia reference laboratory in ames cotested 56 serum samples with the same 3 products, with highes ...19902169689
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
distribution of equine infectious anemia in equids in southeastern united states.state veterinarians in 11 southeastern states completed a questionnaire designed to determine the proportion of equids in the region that were seropositive for equine infectious anemia (eia). cases of eia were diagnosed in each of the states surveyed. distinct geographic clusters of cases were apparent in tennessee and kentucky adjacent to the mississippi river, in the piedmont of north carolina at the virginia border, in north central georgia, and throughout the florida peninsula. it is suggest ...19902173692
equine infectious anemia virus derived from a molecular clone persistently infects horses.a full-length molecular clone of equine infectious anemia virus (eiav) was isolated from a persistently infected canine fetal thymus cell line (cf2th). upon transfection of equine dermis cells, the clone, designated cl22, yielded infectious eiav particles (cl22-v) that replicated in vitro in both cf2th cells and an equine dermis cell strain. horses infected with cl22-v developed an antibody response to viral proteins and possessed viral dna in peripheral blood mononuclear cells, as determined by ...19902173767
the open reading frame orf s3 of equine infectious anemia virus is expressed during the viral life cycle.the genome of equine infectious anemia virus (eiav) contains several small open reading frames (orfs), the importance of which in the development of the virus is not clear. we investigated the possibility that the largest of these orfs (orf s3) is expressed during the course of the viral infection. the orf s3 information was expressed in escherichia coli, and the antigen was used to raise monospecific antiserum. a 20-kda protein expressed in cells producing eiav was identified as the gene produc ...19902173797
topoisomerase i activity associated with human immunodeficiency virus (hiv) particles and equine infectious anemia virus 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
structure and expression of the equine infectious anemia virus transcriptional trans-activator (tat).equine infectious anemia virus (eiav) encodes a tat gene which is closely related to the trans-activators encoded by the human and simian immunodeficiency viruses. nucleotide sequence analysis of eiav cdna clones revealed that the tat message is composed of three exons; the first two encode tat and the third may encode rev.. interestingly, eiav tat translation is initiated at a non-aug codon in the first exon of the message, perhaps allowing an additional level of gene regulation. the deduced am ...19902178129
equine infectious anemia: prospects for control.equine infectious anemia has been managed in most countries by the imposition of testing and quarantine regulations. in the united states, about 700,000 of the more than 7,000,000 horses are tested annually. as long as the status of greater than 90% of the horse population remains unknown and horses are transported and congregate in a relatively unrestricted manner, eia will continue to exact its toll. therefore, it is incumbent on the scientific community to continue to develop and refine pract ...19902178130
studies on the regulation and pattern of expression of the equine infectious anemia virus genome. 19902178131
the viral hypothesis of alzheimer's disease. absence of antibodies to evaluate the possible role of lentiviruses in alzheimer's disease we searched for cross-reactive antibodies to human immunodeficiency virus type 1, caprine arthritis encephalitis virus, and equine infectious anemia virus in alzheimer's disease, down's syndrome, and related dementing illnesses in serum samples and cerebrospinal fluid samples and in healthy age-matched control subjects. no cross-reactive antibodies were detected.19902302089
intracellular proteins of feline immunodeficiency virus and their antigenic relationship with equine infectious anaemia virus proteins.feline immunodeficiency virus (fiv) grown in cat lymphocyte and thymocyte cultures was labelled with l-[35s]methionine or [3h]glucosamine and virus-coded proteins were identified using immunoprecipitation. polypeptides with apparent mr values of 15k, 24k, 43k, 50k, 120k and 160k were detected. an additional polypeptide of 10k was detected by western blot analysis. the two highest mr species sometimes appeared as one band, of which only the 120k polypeptide was glycosylated. in the presence of tu ...19901690264
in vitro isolation of a neutralization escape mutant of equine infectious anemia virus (eiav).a neutralization escape mutant (a/1 e) of equine infectious anemia virus was isolated after 13 passages in cell culture in the presence of serum containing antibodies to type- and group-specific determinants of eiav envelope glycoproteins. loss of neutralization by the selecting serum correlated with loss of two epitopes in the major envelope glycoprotein gp90 of a/1 e which were present in a parallel variant isolated from a persistently infected pony.19901693846
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
the characterization of eiav reverse transcriptase and its inhibition by 5'-triphosphates of 2'-deoxyuridine analogs, pfa and paa.a characterization of equine infectious anemia virus reverse transcriptase (eiav rt) and its inhibition by 5'-triphosphate analogs was undertaken to explore the possibility of using eiav rt as an in vitro model for studying human immunodeficiency virus (hiv). eiav rt activity was found to be dependent on the bivalent cations mg++ and mn++. the optimal ph for enzyme reaction was ph 8.2. eiav rt preferred a 70 mmol/l concentration of monovalent salts. phosphonoformic acid (pfa) was an active inhib ...19901711694
characterization of eiav immunogenicity during persistent infections: humoral responses and antigen targets. 19901704323
characterization of the antigenic domains of the major core protein (p26) of equine infectious anemia virus.a panel of recombinant trple-gag fusion proteins and synthetic peptides was used in western immunoblot and enzyme-linked immunosorbent assays to identify segments of the major core protein (p26) of equine infectious anemia virus that are antigenic in horses during experimental and natural infections with the virus. the predominant humoral immune response was directed toward a highly immunogenic domain composed of 83 amino acids from the carboxy terminus of p26. the observed immunogenicity of p26 ...19911702839
in situ processing of a retroviral nucleocapsid protein by the viral proteinase.the proteolytic processing pathway of the nucleocapsid protein (nc) by the viral proteinase within intact capsids of equine infectious anemia virus (eiav) is presented. the cleavage sites are located at the carboxyl side of the first cysteine residue within the zinc-finger domains. eiav is used as a model to predict similar nc cleavages in other retroviruses, including human immunodeficiency virus (hiv). the observed cleavages suggest a previously unrecognized function of the retroviral proteina ...19911658777
a minimal lentivirus tat.transcriptional regulatory mechanisms found in lentiviruses employ rna enhancer elements called trans-activation responsive (tar) elements. these nascent rna stem-loops are cis-acting targets of virally encoded tat effectors. interactions between tat and tar increase the processivity of transcription complexes and lead to efficient copying of viral genomes. to study essential elements of this trans activation, peptide motifs from tats of two distantly related lentiviruses, equine infectious anem ...19911658392
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
identification of lentivirus tat functional domains through generation of equine infectious anemia virus/human immunodeficiency virus type 1 tat gene chimeras.the structural regions that comprise the functional domains of lentivirus tat proteins were examined. chimeric tat genes and chimeric viral promoters were constructed between the distantly related human immunodeficiency virus type 1 (hiv-1) and equine infectious anemia virus (eiav). these exchange experiments revealed that the eiav tat-responsive element recognition domain is formed by two distinct structural regions. activation domains of both hiv-1 and eiav tat contain a conserved core element ...19911645777
equine infectious anemia virus and human immunodeficiency virus dna synthesis in vitro: characterization of the endogenous reverse transcriptase reaction.the endogenous reverse transcriptase reaction of equine infectious anemia virus (eiav) has been studied, and conditions allowing synthesis of full-length minus-strand dna have been determined. in contrast to results reported for other retroviruses, synthesis of eiav full-length minus-strand dna was not impaired by high concentrations of nonidet p-40, a nonionic detergent used to make the virion envelope permeable. all components of the reaction were titrated for maximum synthesis of complete min ...19911705993
photosensitization is required for inactivation of equine infectious anemia virus by hypericin.hypericin, a photoreactive polycyclic quinone, was found to dramatically reduce infectivity of cell-free stocks of equine infectious anemia virus. however, the antiviral activity of hypericin was completely dependent on the presence of light. short periods of photosensitization resulted in a partial loss of reverse transcriptase activity and complete inhibition of viral infectivity. these results suggest that the photodynamic effect of hypericin interferes with more than one stage in the virus r ...19911707176
neutralization of hiv-1: a paradox of humoral proportions.the production of immunoglobulin capable of neutralizing the infectivity of a virus represents one of the most remarkable molecular accomplishments of the host's available immune defenses. it should be no surprise that a virus that has existed in the parenchyma of the immune system has evolved as an equally dynamic molecule (i.e., viral envelope) for survival. neutralizing immunoglobulin (ig) can best serve the host under conditions where the invading pathogen requires a well-defined cell-free s ...19911712328
immune-mediated thrombocytopenia in horses infected with equine infectious anemia adult horse infected with a virulent, cell culture-adapted strain of equine infectious anemia virus (eiav) developed cyclical thrombocytopenia in which the nadir of platelet counts coincided with peak febrile responses. in order to investigate the mechanism of thrombocytopenia during acute febrile episodes, four adult horses were experimentally infected with the wild-type wyoming strain of eiav. platelet counts decreased from baseline as rectal temperature increased. serum reverse transcripta ...19911717720
purification and characterization of recombinant equine infectious anemia virus reverse transcriptase.a 1.67-kb segment of the equine infectious anemia virus pol gene, encoding a 66-kda reverse transcriptase (rt), was cloned and expressed in escherichia coli. recombinant rt, purified by a combination of metal chelate affinity chromatography and ion-exchange chromatography, displays both rna-dependent dna polymerase and rnase h activity. the affinity of purified rt for its replication primer, trna(3lys) was equivalent to that observed for human immunodeficiency virus rt. our data suggest that an ...19911719238
the topoisomerase i inhibitor, camptothecin, inhibits equine infectious anemia virus replication in chronically infected cf2th cells.camptothecin (cpt), a topoisomerase i-specific inhibitor, was found in this study to inhibit the replication of equine infectious anemia virus (eiav) in chronically infected cf2th cells (designated cf2th/eiav). by measuring viral reverse transcriptase activity in the culture medium, we demonstrated that treatment for 1 h with noncytotoxic doses of this drug inhibited production by 32 to 52%, whereas continuous exposure to this drug resulted in an 85 to 92% inhibition. no effect on the viability ...19911649321
characterization of variable regions in the envelope and s3 open reading frame of equine infectious anemia virus.the polymerase chain reaction was used to amplify and clone parts of the envelope gene and overlapping s3 open reading frame, thought to encode rev, of the virulent in vivo-derived th-1 isolate of equine infectious anemia virus (eiav). the results indicated that eiav consists of a heterogeneous mixture of genotypes present at the first febrile cycle after initial infection. we showed that the th-1 isolate apparently contains nondefective genotypes as well as types which have transmembrane protei ...19911649329
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
the tat protein of equine infectious anemia virus is encoded by at least three types of transcripts.nucleotide sequence analysis of a cdna library of eiav-infected canine cells established a complex pattern of gene expression, characterized by alternatively spliced polycistronic transcripts. the eiav tat gene product was shown to be encoded by at least three species of mrna which differed in their ability to trans-activate the eiav ltr upon expression in canine cells. the most active cdna was monocistronic, consisting of three exons. the most abundant cdna in the library contained four exons a ...19911653485
rna pseudoknots downstream of the frameshift sites of retroviruses.rna pseudoknot structural motifs could have implications for a wide range of biological processes of rnas. in this study, the potential rna pseudoknots just downstream from the known and suspected retroviral frame-shift sites were predicted in the rous sarcoma virus, primate immunodeficiency viruses (hiv-1, hiv-2, and siv), equine infectious anemia virus, visna virus, bovine leukemia virus, human t-cell leukemia virus (types i and ii), mouse mammary tumor virus, mason-pfizer monkey virus, and si ...19911663382
use of western blot and radioimmunoprecipitation for diagnosis of feline leukemia and feline immunodeficiency virus infections.the uses and limitations of the western blot (wb) and radioimmunoprecipitation assay (ripa) techniques for study of feline immunodeficiency virus (fiv) and felv were evaluated. western blot analysis was used to detect antigenic relatedness between the 2 lentiviruses. using a rabbit serum directed against p26 of the equine infectious anemia virus (eiav) and anti-eiav horse serum obtained from an infected horse, cross-reactivity with p24 of fiv was revealed. cat sera obtained late after experiment ...19911666078
epidemiologic importance of interstate transport of equids infected with equine infectious anemia virus. 19912061145
purification and kinetic characterization of equine infectious anemia virus reverse transcriptase.the reverse transcriptase of equine infectious anemia virus (eiav) was partially purified from virus particles and appeared to be a heterodimer with subunit molecular masses of 70 kdal and 59 kdal. the polymerase activity of this enzyme had an absolute requirement for a divalent cation, preferring mg++ over mn++. addition of a monovalent cation to the reaction mixture enhanced, but was not required for enzyme activity. kinetically, the reverse transcriptase of eiav is similar to the reverse tran ...19911719980
purification and partial characterization of equine infectious anemia virus reverse transcriptase.previously we raised a rabbit monospecific antibody (c2003) against a synthetic peptide derived from a sequence within the c-terminal portion of the reverse transcriptase (rt) of the human immunodeficiency virus type 1 (hiv-1). this sequence is found to be conserved in the predicted amino acid sequence of a related lentivirus, the equine infectious anemia virus (eiav). it was previously determined that the c2003 antibody could cross-react with native eiav rt and directly inhibit the dna polymera ...19911718086
analysis of equine humoral immune responses to the transmembrane envelope glycoprotein (gp45) of equine infectious anemia virus.defined segments of the transmembrane envelope glycoprotein (gp45) of equine infectious anemia virus were expressed as trple fusion proteins and examined for their reactivity in western immunoblots against a diverse panel of equine immune sera. the most immunogenic region of gp45 was localized to its amino terminus, positioned between the hydrophobic fusion and the transmembrane domains. a series of overlapping synthetic peptides were used in enzyme-linked immunosorbent assays to define an immun ...19911846180
identification of a hypervariable region in the long terminal repeat of equine infectious anemia avirulent, field-derived isolate of equine infectious anemia virus (eiav), designated ma-1, was molecularly cloned, and the complete nucleotide sequence was determined for the 3' half of the viral genome. comparisons between ma-1 and the prototype wyoming strain of eiav identified a 66-nucleotide stretch between caat (-91) and tataa (-25) in the u3 region of the long terminal repeat, where sequence divergence was as high as 39.3%. the polymerase chain reaction was used to amplify and clone lo ...19911847479
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
use of bacterial trpe fusion vectors to express and characterize the bovine immunodeficiency-like virus core protein.the gag coding region from bovine immunodeficiency-like virus (biv) was cloned into e. coli and expressed as a bacterial fusion protein. six different clones spanning various regions of the gag open reading frame were generated. the resulting fusion proteins were expressed at high concentrations and readily purified. a panel of bovine immune sera specifically recognized the recombinant gag proteins, as did immune sera from animals infected or immunized with lentiviruses related to biv, such as e ...19921372612
tightly bound zinc in human immunodeficiency virus type 1, human t-cell leukemia virus type i, and other retroviruses.human immunodeficiency virus type 1 (hiv-1) and human t-cell leukemia virus type i (htlv-i) were purified by sucrose density gradient centrifugation in the presence of 1 mm edta. pelleted gradient fractions were analyzed for total protein, total gag capsid protein, and total zinc. zinc was found to copurify and concentrate with the virus particles. through successive cycles of resuspending in buffer containing edta and repelleting, the zinc content remained constant at about 1.7 mol of zinc per ...19921731111
detecting single base substitutions as heteroduplex polymorphisms.we have developed a sensitive technique for detecting single base substitutions in polymerase chain reaction (pcr) products from individuals heterozygous for polymorphisms or new mutations. this technique takes advantage of the formation of heteroduplexes in the pcr between different alleles from heterozygous individuals. these heteroduplexes can be detected on polyacrylamide gels because they migrate slower than their corresponding homoduplexes. using pcr, we have generated a series of point mu ...19921740339
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
detailed mapping of the antigenicity of the surface unit glycoprotein of equine infectious anemia virus by using synthetic peptide strategies.we describe here a detailed analysis of the antigenic determinants of the surface unit glycoprotein (gp90) of equine infectious anemia virus (eiav), using a comprehensive panel of synthetic peptides in enzyme-linked immunosorbent assays with immune serum from naturally and experimentally infected horses and with a panel of gp90-specific neutralizing and nonneutralizing monoclonal antibodies. the results of these studies identify immunoreactive segments throughout the conserved and variable domai ...19921370556
wild-type equine infectious anemia virus replicates in vivo predominantly in tissue macrophages, not in peripheral blood situ hybridization of tissues from two horses infected with the wild-type wyoming strain of equine infectious anemia virus (eiav) identified the liver, spleen, lymph nodes, kidney, lung, and adrenal gland as the primary host tissue sites for viral transcription during acute infection. combined immunohistochemistry, with a monoclonal antibody recognizing a cytoplasmic antigen of equine mononuclear phagocytes, and in situ hybridization for viral rna identified most infected cells as mature tiss ...19921382143
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