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stability of viability and immunizing potency of lyophilized, modified equine arteritis live-virus vaccine.the bucyrus strain of equine arteritis virus, previously modified to avirulence and vaccinal virus by 131 serial passages in primary cell cultures of horse kidney followed by 111 passages in primary cell cultures of rabbit kidney, was further passaged in cultures of the e. derm (nbl-6) cell line, a continuous diploid cell line. pools of the 16th and 25th passages of the virus in this last equine dermal cell line were lyophilized and stored in lots at 37 c, 23 to 28 c, 4c, and -20 c. the viabilit ...19816275755
equine arteritis virus-infected cells contain six polyadenylated virus-specific rnas. 19826283728
effect of mycoplasma orale on growth of equine arteritis virus in vero cells. 19826304392
pathology of maternal genital tract, placenta, and fetus in equine viral arteritis.six pregnant mares were given equine viral arteritis virus intravenously. tissues from genital tracts, placentae, and fetuses were examined by light and electron microscopy to study the mechanism of abortion. four mares which died with acute disease had diffuse vacuolation of endometrial epithelium and systemic necrotizing vasculitis. two of these mares had dead fetuses and two had live fetuses; virus was isolated from tissues of one live fetus. placentae of mares dying from acute disease did no ...19846328724
equine arteritis virus subgenomic rna transcription: uv inactivation and translation inhibition studies.the expression of the genetic information of equine arteritis virus (eav), an arterivirus, involves the synthesis of six subgenomic (sg) mrnas. these are 5' and 3' coterminal since they are composed of a leader and a body sequence, which are identical to the 5' and 3' ends of the genome, respectively. previously, it has been suggested that cis-splicing of a genome-length precursor rna is involved in their synthesis. this was reevaluated in a comparative analysis of the sg rna synthesis of eav, t ...19957491761
a 29k envelope glycoprotein of equine arteritis virus expresses neutralization determinants recognized by murine monoclonal antibodies.a panel of six neutralizing murine monoclonal antibodies (mabs) to equine arteritis virus (eav) was produced. the mabs were characterized by western immunoblotting assay and competitive elisa. the six mabs identify a single neutralization site on a 29k envelope glycoprotein. deglycosylation of viral proteins prior to immunoblotting showed that the 29k protein is the glycosylated form of a 20k protein. equine anti-eav serum also strongly bound the 29k glycoprotein, as well as an unglycosylated pr ...19937504076
determination of the 5' end of the lactate dehydrogenase-elevating virus genome by two independent approaches.we have determined the 5' end of the lactate dehydrogenase-elevating virus (ldv) genome (strain ldv-p) using two independent approaches. in one approach, methylmercuric hydroxide-denatured genomic rna was reverse-transcribed using as primer an oligonucleotide complementary to the 5' end of open reading frame (orf) 1a. the first-strand cdna was ligated with t4 rna ligase to an oligonucleotide of which the 3' end was blocked. the ligated product was amplified by pcr, cloned and sequenced. in the s ...19947512122
identification of a neutralization site in the major envelope glycoprotein (gl) of equine arteritis virus.a panel of six neutralizing monoclonal antibodies (mabs), neutralization-resistant variant (escape mutant [em]) viruses, and individual viral proteins derived from a vaccinia virus expression system were used to identify the neutralizing determinants of equine arteritis virus (eav). the neutralizing mabs recognize a single neutralization site on the 29-kda envelope glycoprotein of eav (u. b. r. balasuriya et al., 1993, j. gen. virol., 74, 2525-2529). vaccinia virus recombinants which express eit ...19957533965
development and evaluation of an elisa using recombinant fusion protein to detect the presence of host antibody to equine arteritis virus.a recombinant glutathione-s-transferase fusion protein expressing amino acids 55-98 of equine arteritis virus (eav) gl (rgl 55-98) was tested in an elisa for its ability to detect serum antibodies to eav. host antibodies induced following eav infection bound the recombinant antigen by elisa. the elisa specificity and sensitivity were determined with a panel of equine sera including postinfection and postvaccination samples. a good correlation existed between eav neutralizing antibody titers and ...19957559853
comparison of equine arteritis virus isolates using neutralizing monoclonal antibodies and identification of sequence changes in gl associated with neutralization resistance.three murine monoclonal antibodies (mabs) that neutralize equine arteritis virus (eav) infectivity were identified and characterized. the antibodies, 93b, 74d(b) and 38f, recognized the major envelope glycoprotein (gl) encoded by open reading frame (orf) 5 in immunoblots and by immunoprecipitation. all three mabs were used to compare the bucyrus isolate of eav and mab neutralization-resistant (nr) escape mutants with the vaccine virus and 19 independent field isolates of eav by virus neutralizat ...19957561759
first recorded outbreak of equine viral arteritis in the united kingdom.equine viral arteritis was diagnosed for the first time in the united kingdom in 1993. the outbreak began on a non-thoroughbred stud in south nottinghamshire and spread to five other premises through chilled semen used for artificial insemination and from acutely and subclinically infected mares returning home. the outbreak was contained on these six premises by means of voluntary movement restrictions. the most commonly observed clinical signs were typical: pyrexia with depression, and conjunct ...19957604517
the two major envelope proteins of equine arteritis virus associate into disulfide-linked heterodimers.in a coimmunoprecipitation assay with monospecific antisera, the two major envelope proteins gl and m of equine arteritis virus were found to occur in heteromeric complexes in virions and infected cells. while the gl protein associated with m rapidly and efficiently, newly synthesized m protein was incorporated into complexes at a slower rate, which implies that it interacts with gl molecules synthesized earlier. analysis under nonreducing conditions revealed that the gl/m complexes consist of d ...19957609031
the arterivirus nsp2 protease. an unusual cysteine protease with primary structure similarities to both papain-like and chymotrypsin-like proteases.the replicase orf1a polyprotein of equine arteritis virus, a positive-stranded rna virus, is proteolytically processed into (at least) six nonstructural proteins (nsp). a papain-like cys protease in nsp1 and a chymotrypsin-like ser protease in nsp4 are involved in this process. in this paper we demonstrate that the nsp2/3 junction is not cleaved by either of these previously described proteases. comparative sequence analysis suggested that an additional cys protease resided in the n-terminal nsp ...19957622476
equine arteritis virus-neutralizing antibody in the horse is induced by a determinant on the large envelope glycoprotein gl.complementary dnas encoding orfs 2 to 7 equine arteritis virus (eav) have been cloned into the expression vector pgex to produce glutathione-s-transferase fusion proteins. recombinant proteins were affinity purified and screened in elisa with equine sera to identify immunoreactive polypeptides. the large envelope glycoprotein (gl) was identified as the most reactive to eav-positive equine sera and an immuno-dominant epitope was mapped between amino acids 55 and 98 by subcloning and expression. a ...19957636479
serological study of equine viral arteritis in standard-breds in the uk. 19957645189
ultrastructure and immuno-cytochemistry of bhk-21 cells infected with a modified bucyrus strain of equine arteritis virus.morphogenesis of a modified bucyrus strain of equine arteritis virus (eav) in bhk-21 cells was studied. bacillary tubules were first detected in the cytoplasm 8 h after infection, and mature virions 79 to 122 nm in diameter, 101 nm on average, were mostly observed in the cisternae of the rough endoplasmic reticulum (rer) at 12 h or later. they had isometrical cores and morphological subunits in the outer layer. budding occurred from the rer and the outer nuclear membrane, but not from the cell s ...19957646351
[rhinopneumonia and equine viral arteritis: seroepidemiological study in the northeast of tunisia].a seroepidemiological survey was realized in the nord-est tunisia to study the prevalence of complement fixing and neutralizing antibodies to equine rhinopneumonitis and viral arteritis of horse, respectively. four hundred sera were tested, using complement fixation reaction and seroneutralization test. the results show that 8.75% of sera have antibodies to viral arteritis and only 1.25% are positive for equine rhinopneumonitis.19947661652
comparison of the structural protein coding sequences of the vr-2332 and lelystad virus strains of the prrs virus.the 3'-portion of the genome of a u.s. isolate of the porcine reproductive and respiratory syndrome (prrs) virus, atccvr-2332, was cloned and sequenced. the resultant 3358 nucleotides contain 6 open reading frames (orfs) with homologies to orfs 2 through 7 of the european strain of the prrs virus and other members of the free-standing genus of arteriviruses. both vr-2332 and the european isolate (called the lelystad virus) have been identified as infectious agents responsible for the swine disea ...19957661696
detection of equine arteritis virus (eav) by polymerase chain reaction (pcr) and differentiation of eav strains by restriction enzyme analysis of pcr products.a polymerase chain reaction (pcr) based assay capable of detecting and differentiating seven strains of equine arteritis virus (eav) from around the world was developed. the primers for the pcr were chosen from the orf6 gene encoding the unglycosylated membrane protein (m). viral rna from cell culture fluids infected with each of the seven eav strains and rna from the live vaccine, arvac, was detected by pcr using four sets of primers. the sensitivity of detection was increased from 100 to 1,000 ...19957661700
the small envelope glycoprotein (gs) of equine arteritis virus folds into three distinct monomers and a disulfide-linked dimer.the small membrane glycoprotein (gs) of equine arteritis virus (eav) is a minor virion component but is abundantly expressed in eav-infected cells. in this study, we have analyzed its membrane topology, folding, oligomerization, and intracellular transport. we show that gs is a class i integral membrane protein with one functional n-glycosylation site. gel electrophoresis under nonreducing conditions revealed that gs occurs in eav-infected cells in four monomeric conformations and as disulfide-l ...19957745690
clinical, virological and serological responses of donkeys to intranasal inoculation with the ky-84 strain of equine arteritis virus.the clinical, virological and serological responses of seven female donkeys (equus asinus) to inoculation with the ky-84 strain of equine arteritis virus (eav), a strain that causes moderate to severe clinical signs in horses, was investigated. in the donkeys, the only clinical signs observed were fever (mainly 3-9 days after inoculation), mild depression in four animals, and a slight nasal or ocular discharge in three. all of the donkeys became infected with eav as shown by recovery of the viru ...19957769149
processing and evolution of the n-terminal region of the arterivirus replicase orf1a protein: identification of two papainlike cysteine proteases.two adjacent papainlike cysteine protease (pcp) domains, pcp alpha and pcp beta, were identified in the n-terminal region of the open reading frame 1a replicase proteins of the arteriviruses porcine reproductive and respiratory syndrome virus and lactate dehydrogenase-elevating virus. the replicase of the related virus equine arteritis virus contains only one active pcp in the corresponding region. sequence comparison revealed that the equine arteritis virus pcp alpha counterpart probably was in ...19957769711
equine viral arteritis in donkeys in south africa. 19947776331
phylogenetic analyses of the putative m (orf 6) and n (orf 7) genes of porcine reproductive and respiratory syndrome virus (prrsv): implication for the existence of two genotypes of prrsv in the u.s.a. and europe.the putative membrane (m) protein (orf 6) and nucleocapsid (n) protein (orf 7) genes of five u.s. isolates of porcine reproductive and respiratory syndrome virus (prrsv) with differing virulence were cloned and sequenced. to determine the genetic variation and the phylogenetic relationship of prrsv, the deduced amino acid sequences of the putative m and n proteins from these isolates were aligned, to the extent known, with other prrsv isolates, and also other members of the proposed arterivirus ...19957794115
hprs-103 (exogenous avian leukosis virus, subgroup j) has an env gene related to those of endogenous elements eav-0 and e51 and an e element found previously only in sarcoma viruses.the avian leukosis and sarcoma virus (alsv) group comprises eight subgroups based on envelope properties. hprs-103, an exogenous retrovirus recently isolated from meat-type chicken lines, is similar to the viruses of these subgroups in group antigen but differs from them in envelope properties and has been assigned to a new subgroup, j. hprs-103 has a wide host range in birds, and unlike other nontransforming alsvs which cause late-onset b-cell lymphomas, hprs-103 causes late-onset myelocytomas. ...19957815543
characterization of proteins encoded by orfs 2 to 7 of lelystad virus.the genome of lelystad virus (lv), a positive-strand rna virus, is 15 kb in length and contains 8 open reading frames (orfs) that encode putative viral proteins. orfs 2 to 7 were cloned in plasmids downstream of the sp6 rna polymerase promoter, and the translation of transcripts generated in vitro yielded proteins that could be immunoprecipitated with porcine anti-lv serum. synthetic polypeptides of 15 to 17 amino acids were selected from the amino acid sequences of orfs 2 to 7 and antipeptide s ...19957831770
resistance of castrated male horses to attempted establishment of the carrier state with equine arteritis virus.twelve geldings all became infected when inoculated intranasally with the ky-84 strain of equine arteritis virus (eav), a strain previously shown to be capable of establishing the carrier state in the stallion. with the exception of one animal that showed no effects other than pyrexia, all of the geldings developed clinical signs characteristic of equine viral arteritis (eva). the geldings were febrile for varying periods within the range of 2-10 days after inoculation. viraemia occurred from da ...19947884055
molecular characterization of the 3' terminus of the simian hemorrhagic fever virus genome.the 3' end of the simian hemorrhagic fever virus (shfv) single-stranded rna genome was cloned and sequenced. adjacent to the 3' poly(a) tract, we identified a 76-nucleotide noncoding region preceded by two overlapping reading frames (orfs). the ultimate 3' orf of the viral genome encodes the capsid protein, and the penultimate orf encodes the smallest shfv envelope protein. these two orfs overlap each other by 26 nucleotides. northern (rna) blot hybridization analyses of cytoplasmic rna extracts ...19957884922
analysis of simian hemorrhagic fever virus (shfv) subgenomic rnas, junction sequences, and 5' leader.full-length simian hemorrhagic fever virus (shfv) genome rna (about 15 kb in length) and six subgenomic rnas, ranging in size from 0.65 to 4.7 kb, were detected by northern blot hybridization in ma104 cytoplasmic extracts with a 3' genomic antisense probe. the 5' regions of the two smallest subgenomic rnas (rnas 6 and 7) were cloned and sequenced. sequence analysis indicated that these two rnas contained a common 5' leader sequence joined to the subgenomic rna bodies via a highly conserved junct ...19957886957
use of the serum neutralisation test for equine viral arteritis with different virus strains.serum cross neutralisation tests were conducted with a recent american isolate (84ky-a1) and a european isolate, (wroclaw-2) and compared with the prototype and modified viruses of the bucyrus strain of equine arteritis virus by using virus specific immune horse sera. the modified bucyrus strain was neutralised and showed high neutralisation titres with all the immune sera. the prototype bucyrus strain was also substantially neutralised, followed by the 84ky-a1 strain. as a result of the tests w ...19947941250
[equine infectious arteritis: molecular biology, epidemiology and preventative measures].after a brief historical account of the outbreak of infectious arteritis of horses which occurred in 1984 in kentucky (united states of america), the author reports on the present state of knowledge concerning the organisation of the genome of the virus. clinical signs of the disease are described, as well as modes and routes of transmission. finally, currently-available vaccination procedures are discussed and their value is assessed.19947949357
prevalence of antibodies against some equine viruses in zebra (zebra burchelli) in the kruger national park, 1991-1992.the presence of antibodies against equine encephalosis virus (eev) and equid herpesvirus 1 and 4 in zebra in the kruger national park (knp) was demonstrated. the ability of zebra to maintain immunity against eev is illustrated by the appearance of neutralizing antibodies in most zebra foals within months of losing their maternal immunity. this occurs in every month of the year, even in winter. the high proportion of serologically positive foals in winter is ascribed to the presence of large numb ...19937970572
enzymatic amplification of lactate dehydrogenase-elevating virus.to improve the detection of lactate dehydrogenase-elevating virus (ldv), we developed a pcr assay. primers were selected from orf7, encoding nucleocapsid protein vp1. no specific amplification was observed with any other common murine virus or with rnas from the closely related lelystad virus and equine arteritis virus. in experimentally infected mice, ldv could be detected in plasma in both the acute and the persistent phases. ldv was also detected by the pcr in contaminated pools of plasmodium ...19947989557
lelystad virus belongs to a new virus family, comprising lactate dehydrogenase-elevating virus, equine arteritis virus, and simian hemorrhagic fever virus.lelystad virus (lv) is an enveloped positive-stranded rna virus, which causes abortions and respiratory disease in pigs. the complete nucleotide sequence of the genome of lv has been determined. this sequence is 15.1 kb in length and contains a poly(a) tail at the 3' end. open reading frames that might encode the viral replicases (orfs 1a and 1b), membrane-associated proteins (orfs 2 to 6) and the nucleocapsid protein (orf7) have been identified. sequence comparisons have indicated that lv is di ...19948032274
proteolytic processing of the replicase orf1a protein of equine arteritis virus.to study the proteolytic processing of the equine arteritis virus (eav) replicase open reading frame 1a (orf1a) protein, specific antisera were raised in rabbits, with six synthetic peptides and a bacterial fusion protein as antigens. the processing of the eav orf1a product in infected cells was analyzed with western blot (immunoblot) and immunoprecipitation techniques. additional information was obtained from transient expression of orf1a cdna constructs. the 187-kda orf1a protein was found to ...19948057457
monoclonal antibodies to equine arteritis virus proteins identify the gl protein as a target for virus neutralization.monoclonal antibodies (mabs) to equine arteritis virus (eav) proteins were produced and characterized. the protein specificities of eight mabs were determined definitively by immunoprecipitation of eav proteins expressed from vaccinia virus recombinants (vvrs). included were two new vvrs produced for this study, expressing the m and the gl proteins, respectively. three mabs were determined to be n-specific and five mabs recognized the gl protein. one gl-specific mab, 17f5, of the iga class, effi ...19948077945
validation of virus inactivation and removal for the manufacturing procedure of two immunoglobulins and a 5% serum protein solution treated with beta-propiolactone.intravenous immunoglobulins and serum protein solutions are manufactured from human plasma pools of healthy, screened donors. a step-by-step validation of virus removal and/or inactivation was performed for the manufacturing process, which includes cold ethanol fractionation, beta-propiolactone (beta-pl) treatment, uv irradiation, thermal inactivation and other chemical and physical purification steps. the total viral clearance factors achieved for the entire manufacturing process were by severa ...19938117439
identification of major differences in the nucleocapsid protein genes of a québec strain and european strains of porcine reproductive and respiratory syndrome virus.the sequence of the 3'-terminal region of the genome of québec reference strain iaf-exp91 of porcine reproductive and respiratory syndrome virus (prrsv) was investigated by analysis of four cdna clones. the 3'-terminal 530 nucleotides (nt) encompassed a large open reading frame with a coding capacity of 123 amino acids (m(r) 13,649). the predicted protein was extremely basic and hence was considered to correspond to the nucleocapsid (n) protein gene. when compared to the homologous sequences of ...19948126467
export of stallions vaccinated against equine viral arteritis. 19948128564
detection of equine arteritis virus following amplification of structural and nonstructural viral genes by reverse transcription-pcr.a reverse transcription (rt)-pcr assay was developed for the detection of equine arteritis virus (eav) in cell culture supernatant and in horse semen. four different sets of oligonucleotide primers complementary to sequences located in the 3' end of the polymerase gene (open reading frame [orf] 1b) and to sequences representing the entire orfs 3, 4, and 7, which encode for nonstructural (orfs 3 and 4) or viral nucleocapsid (orf 7) proteins, were compared for their abilities to amplify the target ...19948195375
comparison of m and n gene sequences distinguishes variation amongst equine arteritis virus isolates.cdna copies of the m and n genes of equine arteritis virus (eav) isolates were synthesized by reverse transcription followed by polymerase chain reaction amplification. the cdna was subjected to a cycle sequencing strategy using taq polymerase, and the nucleotide and derived amino acid sequences of 10 virus isolates were compared. the m and n genes of all isolates had the same initiation and termination sites as the prototype bucyrus strain and the encoded proteins were conserved between viruses ...19948207415
proteolytic processing of the n-terminal region of the equine arteritis virus replicase.a papainlike cysteine protease (pcp) domain in the n-terminal region of the equine arteritis virus (eav) replicase was identified by in vitro translation and mutagenesis studies. the eav protease was found to direct an autoproteolytic cleavage at its c-terminus which leads to the production of an approximately 30k n-terminal replicase product (nsp1) containing the pcp domain. amino acid residues cys164 and his230 of the eav replicase polyprotein were identified as the most likely candidates for ...19938209735
the coronaviruslike superfamily. 19938209737
equine arteritis virus contains a unique set of four structural proteins. 19938209738
eva vaccine granted animal test certificate. 19938212469
molecular characterization of positive-strand rna viruses: pestiviruses and the porcine reproductive and respiratory syndrome virus (prrsv).molecular characterization has become an important tool for the analysis of viruses including their classification. the manuscript focuses on the molecular analysis of two members of the genus pestivirus (hog cholera virus, hcv and bovine viral diarrhea virus, bvdv) and of the recently discovered porcine reproductive and respiratory syndrome virus (prrsv). the first protein encoded within the single large pestivirus orf is a nonstructural protein with autoproteolytic activity. the cleavage site ...19938219812
equine viral arteritis--a challenge for the british horse industry. 19938221034
horserace betting levy board recommendation for the 1993 covering season. common code of practice for equine viral arteritis. 19938221035
association of microbiologic flora with clinical, endoscopic, and pulmonary cytologic findings in foals with distal respiratory tract infection.undifferentiated distal respiratory tract disease (nasal discharge, cough, pneumonia) in foals (1 to 8 months old) is a burdensome economic problem on breeding farms; yet, the infective agents associated with these episodes have not been well described. possible causes of these episodes of illness were investigated by culturing specimens of proximal and distal airways of clinically diseased foals (n = 101), prior to any treatment, for aerobic and anaerobic bacteria and viruses (rhinoviruses, equ ...19938250386
complement-dependent serum neutralization with virulent and avirulent bucyrus strains of equine arteritis virus.virulent and avirulent strains of bucyrus equine arteritis virus (eav) were used to raise antiserum in horses. serum neutralization (sn) tests were performed with and without the addition of guinea pig complement. the inclusion of ten percent guinea pig serum in the virus suspension was sufficient for optimal enhancement of sn titres at any immune stages after immunization. immune serum prepared against avirulent virus reacted only with homologous virus and there was no complement enhancement. i ...19938273282
[an outbreak of equine arteritis virus infection in a riding school].a major part of the residing horses and ponies of a riding school in noord-holland became affected by a febrile disorder that included anorexia, depression, conjunctivitis, urticaria, edema of the legs and laborious locomotion. all remaining horses fell ill within one week. based on the clinical symptoms the disorder was diagnosed as vasculitis. with serology the causative agent of the disorder appeared to be equine arteritis virus.19948296297
pathological changes associated with equine arteritis virus infection of the reproductive tract in prepubertal and peripubertal colts.the nature and extent of changes associated with equine arteritis virus (eav) infection of the reproductive tract was documented in 21 prepubertal and 15 peripubertal colts. this study was part of an investigation into the relationship between stage of reproductive tract maturity and susceptibility to the experimental establishment of persistent infection with eav. after intranasal challenge with a field isolate of eav, all colts developed clinical signs of equine viral arteritis (eva) from whic ...19938300916
the horserace betting levy board's code of practice for equine viral arteritis for the 1994 breeding season.the horserace betting levy board formulates codes of practice for the control of contagious equine metritis and other equine bacterial venereal diseases, and equine viral arteritis and equid herpesvirus 1. this year's codes have just been published and the code of practice for eva, reproduced below, has been substantially amended following the recent outbreak in the uk. the code is intended for use by veterinary surgeons and breeders of thoroughbred and non-thoroughbred horses. the hblb states t ...19938310626
research note: avian leukosis retroviral genes are not detected in geese.genomic dna from four strains of geese was analyzed for the presence of endogenous viral elements using a probe that can detect over 20 rous-associated endogenous viral genes (ev genes) in chickens, as well as a probe and protocol that detects endogenous avian viruses (eav). southern blot analysis of genomic dna did not reveal any ev genes in dna of 15 geese from chinese, synthetic, or two embden goose strains. even under low stringency conditions, using a probe that covered most of the polymera ...19938382817
sequences of 3' end of genome and of 5' end of open reading frame 1a of lactate dehydrogenase-elevating virus and common junction motifs between 5' leader and bodies of seven subgenomic mrnas.the sequences of the 3'-terminal 3.7 kb of the genome and of a 1.7 kb 5' end cdna clone of one isolate of lactate dehydrogenase-elevating virus (ldv) are reported. the 3' end sequence encodes six major independent open reading frames (orfs 2 to 7), which are overlapping by between one and 130 nucleotides. each orf is expressed at the 5' end of one of six 3'-coterminal subgenomic mrnas (mrnas 2 to 7, respectively; 3.5 to 0.8 kb). the smallest mrna, mrna 7, encodes the nucleocapsid protein, vp1; m ...19938385693
equine arteritis virus in an imported stallion. 19938387715
complete genomic sequence and phylogenetic analysis of the lactate dehydrogenase-elevating virus (ldv).the apparently complete sequence of the rna genome of the neurovirulent isolate of lactate dehydrogenase-elevating virus (ldv-c) has been determined. the ldv-c genome is at least 14,222 nucleotides in length and contains eight open reading frames (orfs). orf 1a, which encodes a protein of 242.8 kda and is located at the 5' end of the genome, contains at least two putative papain-like cysteine protease domains, and one putative chymotrypsin-like serine protease domain. this orf terminates with a ...19938389075
serological evidence of equine arteritis virus in donkeys in south africa.this paper reports the first serological evidence of exposure of donkeys to equine arteritis virus. seven hundred and thirty-four serum samples collected between 1989 and 1992 from donkeys in different areas of south africa were examined for the presence of antibodies against this virus by a microneutralization test. seventeen percent of serum samples tested positive. the distribution of seropositive animals varied from none in the western cape province and the transvaal highveld to 30% in the n ...19938392682
equine viral arteritis. 19938393224
equine viral arteritis in britain. 19938393227
equine viral arteritis.equine viral arteritis is an infrequently encountered contagious viral disease of equids that has assumed increased veterinary medical and economic significance since the 1984 epidemic in thoroughbreds in kentucky. the most important consequences of this infection are abortion in the mare and establishment of the carrier state in the stallion. equine arteritis virus becomes localized in the reproductive tract of a relatively high percentage of infected stallions which serve as very efficient tra ...19938395325
relationship between onset of puberty and establishment of persistent infection with equine arteritis virus in the experimentally infected colt.the relationship between stage of reproductive tract maturity and susceptibility to the experimental establishment of persistent infection with equine arteritis virus (eav) was investigated in 21 prepubertal and 15 peripubertal colts. five of six prepubertal colts inoculated intranasally remained infected in the reproductive tract from post-challenge day 28 to 93 and two of six from post-challenge day 120 to 180. no virus was detected in five of these animals killed on post-challenge day 210. ea ...19938408779
molecular characterization of porcine reproductive and respiratory syndrome virus, a member of the arterivirus group.porcine reproductive and respiratory syndrome virus (prrsv)-specific cdna clones spanning the 3' terminal 5 kb of the genomic rna were isolated, sequenced, and used as probes for identification of prrsv-specific rnas. the prrsv genome is a positive-stranded polyadenylated rna of about 15 kb. in infected cells, a 3' coterminal nested set of six major subgenomic mrnas could be demonstrated. within the 3' terminal 3.5 kb of the prrsv genome, six overlapping reading frames (orfs) were identified, ea ...19938438574
lelystad virus, the causative agent of porcine epidemic abortion and respiratory syndrome (pears), is related to ldv and eav.the genome of lelystad virus (lv), the causative agent of porcine epidemic abortion and respiratory syndrome (previously known as mystery swine disease), was shown to be a polyadenylated rna molecule. the nucleotide sequence of the lv genome was determined from a set of overlapping cdna clones. a consecutive sequence of 15,088 nucleotides was obtained. eight open reading frames (orfs) that might encode virus-specific proteins were identified. orf1a and orf1b are predicted to encode the viral rna ...19938517032
clinical features of the 1992 outbreak of equine viral arteritis in spain.during 1992, a widespread outbreak of equine viral arteritis (eva) occurred at a riding establishment near barcelona, spain. a total of 31 out of 186 horses on the premises displayed clinical signs, most frequently, fever, depression, mild ventral and limb oedema and a vesicular-erosive stomatitis, with hypersalivation, petechiations and small ulcerations. affected horses developed illness of varying severity with only a few exhibiting a severe form of the disease and no mortality was recorded. ...19958536667
phylogenetic analysis of open reading frame 5 of field isolates of equine arteritis virus and identification of conserved and nonconserved regions in the gl envelope glycoprotein.the variation and phylogenetic relationship of open reading frame 5 (orf5) of 3 different laboratory strains of the original prototype bucyrus strain of equine arteritis virus (eav), the modified live virus vaccine (arvac, fort dodge laboratories), and 18 field isolates of eav from north america and europe were determined by comparison of their gene sequences. the viruses differed from the published sequence by between 3 (99.6% homology) and 94 (87.8%) nucleotides and by between 3 (98.8%) and 24 ...19958553578
immunoperoxidase histochemistry as a diagnostic tool for detection of equine arteritis virus antigen in formalin fixed tissues. 19968565959
the phospholipid composition of enveloped viruses depends on the intracellular membrane through which they bud. 19958566406
sexual and in-contact transmission of asinine strain of equine arteritis virus among donkeys.two in a group of five naturally seropositive donkey stallions were found to shed equine arteritis virus (eav) in their semen as demonstrated by virus isolation. direct intramuscular inoculation of sonicated semen from one virus-shedding stallion (s3) caused clinical disease in two donkeys from which virus was recovered and in which seroconversion was detected. sexual transmission was confirmed in two mares mated to s3 when after a febrile response during which eav was isolated from huffy coats ...19958586720
equine viral arteritis with abortions: serological and virological evidence in germany.an outbreak of clinical disease with abortions, suspected to be equine viral arteritis in germany was examined serologically and virologically. three of five animals tested seroconverted to eav, and eav was isolated from an aborted fetus. in view of the significant increase in seropositive horses, the need for control measures is emphasized.19958592914
equine viral arteritis. 19958596181
the arterivirus nsp4 protease is the prototype of a novel group of chymotrypsin-like enzymes, the 3c-like serine proteases.the replicase of equine arteritis virus, an arterivirus, is processed by at least three viral proteases. comparative sequence analysis suggested that nonstructural protein 4 (nsp4) is a serine protease (sp) that shares properties with chymotrypsin-like enzymes belonging to two different groups. the sp was predicted to utilize the canonical his-asp-ser catalytic triad found in classical chymotrypsin-like proteases. on the other hand, its putative substrate-binding region contains thr and his resi ...19968617757
recognition of bronchopulmonary dysplasia in a newborn foal. 19958654357
intracellular synthesis, processing, and transport of proteins encoded by orfs 5 to 7 of porcine reproductive and respiratory syndrome virus.porcine reproductive and respiratory syndrome virus (prrsv), a small enveloped virus containing a positive-strand rna genome, possesses at least three major structural proteins designated n, m, and e. the n protein is considered as the major component of the nucleocapsid, whereas m and e are membrane-associated. previous studies using peptide-specific antibodies assigned these proteins to orfs 7, 6, and 5, respectively. in the present report, monospecific antisera raised against escherichia coli ...19968661418
equine arteritis virus subgenomic mrna synthesis: analysis of leader-body junctions and replicative-form rnas.in addition to the genomic rna, a 3' coterminal nested set of six subgenomic mrnas is produced in equine arteritis virus (eav)-infected cells. the seven viral rnas are also 5' coterminal, since they all contain a 206-nucleotide common leader sequence which is identical to the 5' end of the genome. a conserved penta-nucleotide sequence motif, 5' ucaac 3', was shown to be present at the junctions between the leader and body sequences in each of the mrnas. in addition, two alternative junction site ...19968676451
histopathological and immunofluorescent studies on transplacental infection in experimentally induced abortion by equine arteritis virus.five pregnant mares, at between 6 and 8 months gestation, were experimentally infected with the bucyrus strain of equine arteritis virus (eav). of the five mares, four aborted and one died. the pathogenesis of the abortions was studied, using histopathologic techniques, tissue immunofluorescence and virus isolation. common microscopic lesions in the maternal reproductive organs indicated myometritis with a degeneration of the myocytes and an infiltration of the mononuclear cells. epithelial cell ...19968693844
processing of the equine arteritis virus replicase orf1b protein: identification of cleavage products containing the putative viral polymerase and helicase domains.the replicase open reading frame lb (orf1b) protein of equine arteritis virus (eav) is expressed from the viral genome as an orf1ab fusion protein (345 kda) by ribosomal frameshifting. processing of the orf1b polyprotein was predicted to be mediated by the nsp4 serine protease, the main eav protease. several putative cleavage sites for this protease were detected in the orf1b polyprotein. on the basis of this tentative processing scheme, peptides were selected to raise rabbit antisera that were ...19968794297
genetic variation in open reading frame 2 of field isolates and laboratory strains of equine arteritis virus.the open reading frame 2 (orf2) of three laboratory strains, the live attenuated vaccine virus, and 18 field isolates of equine arteritis virus (eav) from europe and north america was sequenced. the orf2 of eav encodes the gs protein that is abundantly expressed in infected cells but constitutes less than 2% of the virion protein mass. variation of orf2 among the isolates facilitated phylogenetic analysis that largely confirmed results of an earlier study based on sequence divergence of orf5 of ...19968806173
reactions to strangles vaccination. 19958825322
expression cloning and antigenic analysis of the nucleocapsid protein of equine arteritis virus.a series of recombinant fusion proteins derived from equine arteritis virus (eav) open reading frame (orf) 7 have been used to define the immunoreactive region of the viral nucleocapsid (n) protein. reactivities of recombinant n fusion proteins with post-infection equine sera in immunoblots and elisas indicate that the major nucleocapsid protein epitope is located within amino acid residues 1-69. in elisas two recombinant nucleocapsid fusion proteins containing residues 1-69 (rn1-69) and 1-28 (r ...19958837890
detection of related positive-strand rna virus genomes by reverse transcription/polymerase chain reaction using degenerate primers for common replicase sequences.a set of degenerate sense and antisense primers were designed on the basis of short segments with identical amino acids in the predicted orf 1b replicase proteins of lactate dehydrogenase-elevating virus (ldv), equine arteritis virus (eav) and porcine reproductive and respiratory syndrome virus, strain lelystad virus (prrsv-lv), which are members of a new group of positive-strand rna viruses. reverse transcription/polymerase chain reaction amplification using this set of degenerate primers yield ...19958837898
fatal experimental equine arteritis virus infection of a pregnant mare: immunohistochemical staining of viral antigens. 19968844583
experimental pathological studies on mechanism of abortion caused by equine arteritis virus. 19968870395
sequence determination of the extreme 5' end of equine arteritis virus leader region.the extreme 5' end of the leader sequence of four equine arteritis virus (eav) strains was obtained by using rapid amplification of cdna end method (5' race), and sequenced. seventeen more nucleotides were added upstream of the 5' end of the eav published genomic sequence. a common feature among the analyzed eav isolates was the presence of an aug start codon within the added sequence and the appearance of an intraleader open reading frame (orf) of 111 nucleotides which was predicted to encode a ...19968883367
equine arteritis virus: a review of clinical features and management aspects.sero-epidemiological surveys have revealed that equine arteritis virus (eav) is prevalent in most european countries. the virus causes sporadic cases of respiratory disease and abortion in horses, the incidence of which has increased in recent years. mares and geldings eliminate virus after acute infection, but 30% to 60% of stallions become persistently infected. in these animals, eav is maintained within the reproductive tract and is shed continuously in the semen. persistent infection with ea ...19968903141
transmission of the south african asinine strain of equine arteritis virus (eav) among horses and between donkeys and horses.lateral and sexual transmission of eav among horses and lateral transmission between donkeys and horses were attempted by experimental infection with the south african asinine strain. clinical, immunological and virological responses were evaluated. all intramuscularly inoculated horses developed very mild clinical signs, were viraemic, shed virus from nasopharynx, and seroconverted. lateral infection was demonstrated in one in-contact mare. reinfection of two stallions by intranasal instillatio ...19968917855
comparison of nucleic and amino acid sequences and phylogenetic analysis of the gs protein of various equine arteritis virus isolates.the genetic variation in equine arteritis virus (eav) gs protein encoding gene was investigated. nucleic and deduced amino acid sequences from eight different eav isolates (one european, two american and five canadian isolates) were compared with those of the bucyrus reference strain. nucleotide and amino acid identities between these isolates and the bucyrus reference strain ranged from 92.3 to 96.4%, and 93.2 to 95.5%, respectively. however, phylogenetic tree analysis and estimation of genetic ...19968938984
genetic and amino acid analysis of the gl protein of canadian, american and european equine arteritis virus isolates.the genetic variation in equine arteritis virus (eav) gl protein encoding gene was investigated. nucleic and deduced amino acid sequences from 7 different eav isolates, including 4 eastern canadian field isolates, were compared with those of the bucyrus reference strain. nucleotide sequence identities between these isolates and the bucyrus reference strain ranged from 87.5% (vienna isolate) to 93.9% (11958 isolate). amino acid identities with the bucyrus reference strain varied from 90.2% (vienn ...19979008807
[equine arteritis virus: clinical symptoms and prevention].sero-epidemiological surveys have revealed that equine arteritis virus (eav) is prevalent in most european countries. the virus causes sporadic cases of respiratory disease and abortion in horses, the incidence of which has increased in recent years. mares and geldings eliminate virus after acute infection, but 30% to 60% of stallions become persistently infected. in these animals, eav is maintained within the reproductive tract and is shed continuously in the semen. persistent infection with ea ...19979012008
an infectious arterivirus cdna clone: identification of a replicase point mutation that abolishes discontinuous mrna transcription.equine arteritis virus (eav) is a positive-strand rna virus that uses a discontinuous transcription mechanism to generate a nested set of six subgenomic mrnas from which its structural genes are expressed. a stable bacterial plasmid (peav030) containing a full-length cdna copy of the 12.7-kb eav genome was constructed. after removal of a single point mutation in the replicase gene, rna transcripts generated in vitro from peav030 were shown to be infectious upon electroporation into bhk-21 cells. ...19979023370
a perspective on equine viral arteritis (infectious arteritis of horses). 19969025155
a survey for antibodies to equine arteritis virus in donkeys, mules and zebra using virus neutralisation (vn) and enzyme linked immunosorbent assay (elisa).a seroepidemiological survey of donkeys in south africa (n = 4300) indicated a wide distribution and increasing prevalence of antibodies to equine arteritis virus (eav). donkey sera inhibited equine arteritis virus infection in virus neutralisation (vn) tests and in elisa specifically bound to a recombinant antigen derived from the bucyrus isolate of eav. these results suggest that donkeys have been exposed to the same serotype of this virus as circulates among horses. a good correlation existed ...19979031862
reverse transcriptase activity in chicken embryo fibroblast culture supernatants is associated with particles containing endogenous avian retrovirus eav-0 rna.we have recently shown that live attenuated virus vaccines produced on chicken-derived cells contain low levels of particle-associated reverse transcriptase (rt). in both virus and corresponding control harvests produced on chicken embryo fibroblasts, these activities were present at significantly higher concentrations than in the vaccines. in order to identify the putative retrovirus sequence responsible for this activity, a novel method for the selective pcr amplification of particle-associate ...19979060660
is the south african asinine strain of equine arteritis virus a threat to local horses? 19969120846
neutralization determinants of laboratory strains and field isolates of equine arteritis virus: identification of four neutralization sites in the amino-terminal ectodomain of the g(l) envelope glycoprotein.the n-terminal hydrophilic ectodomain of the g(l) envelope glycoprotein of equine arteritis virus (eav) contains neutralization determinants of the virus. we developed a panel of 17 neutralizing murine monoclonal antibodies (mabs) to further characterize the neutralization determinants of eav. included were 6 mabs previously raised against a laboratory strain (eavucd) of the original bucyrus strain of eav, as well as 11 additional mabs that were raised against a neutralization-resistant variant ...19979185595
failure to establish chronic infection of the reproductive tract of the male horse with a south african asinine strain of equine arteritis virus (eav).eight sexually mature horse stallions were inoculated intranasally with a south african asinine strain of eav, a strain that was isolated from the semen of a donkey carrier. all horses developed fever, with maximum rectal temperatures of 38.9-39.9 degrees c recorded 3-6 d post challenge. six horses showed very mild clinical signs of equine viral arteritis and two were asymptomatic. the virus was recovered from the nasopharynxes of six horses 2-7 d after inoculation, and from buffy-coat samples o ...19979204499
molecular characterization of lelystad virus.lelystad virus (lv), the prototype of porcine reproductive respiratory syndrome virus, is a small enveloped virus, containing a positive strand rna genome of 15 kb. lv is tentatively classified in the family arteriviridae, which consists of lactate dehydrogenase-elevating virus (ldv), equine arteritis virus (eav) and simian hemorrhagic fever virus (shfv). these viruses have a similar genome organization and replication strategy as coronaviruses, but the size of the genome is much smaller (12-15 ...19979220614
detection of equine arteritis virus in the semen of carrier stallions by using a sensitive nested pcr assay.a nested pcr, developed for the detection of equine arteritis virus (eav) in semen, detected less than 2.5 pfu of eav per ml of naturally infected seminal plasma. based on results from testing 88 semen samples from 70 stallions, the sensitivity and specificity of the test were 100 and 97%, respectively.19979230412
equine viral arteritis in newborn foals: clinical, pathological, serological, microbiological and immunohistochemical observations.clinical, pathological, immunohistochemical, serological and microbiological findings are described for 2 geographically and temporally distinct equine arteritis virus (eav) epidemics in newborn foals. outbreak a occurred at a commercial standardbred breeding facility; outbreak b began in a group of research animals. clinical signs were severe and primarily referable to the respiratory tract. fever and leucopenia and/or thrombocytopenia were observed in foals surviving for more than 24 h. the mo ...19979234009
experimental exposure of pregnant mares to the asinine-94 strain of equine arteritis virus.clinical, virological and serological responses were evaluated in 10 pregnant mares after different challenge exposures to the asinine-94 strain of equine arteritis virus (eav). the outcome of maternal infection on the progeny was also investigated. mares were inoculated intranasally (n = 4), intramuscularly (n = 2), intravenously (n = 1), or contract-exposed (n = 3). all inoculated mares developed pyrexia, 5 showed mild clinical signs related to eav infection and 2 remained asymptomatic. viraem ...19979291073
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