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nucleotide sequence comparison of the 3' regions of avian retroviruses ny203 and ntre-2.we have been characterizing molecular clones of two subgroup e avian retroviruses (ntre-2 and ny203rav-60) that produce different proliferative diseases after inoculation into susceptable k28 chickens. both viruses arose by recombination between exogenous and endogenous viral genomes. to further characterize regions of these viruses that are important for the production of disease, we have determined the nucleotide sequence of a 1.2-kb ecori fragment extending from the carboxyl end of gp85 throu ...19863008429
multiple enhancer domains in the 3' terminus of the prague strain of rous sarcoma virus.the 3' terminal region of the prague strain of rous sarcoma virus (prrsv) contains at least three distinct domains that comprise two functional enhancer elements. two of these domains (designated b and c) are found in the u3 region of the 3' long terminal repeat (ltr) while the third (designated a) is located in the sequences immediately preceding the ltr termed xsr sequences. combinations of adjacent domains [e.g., (a + b or b + c)] are capable of activating the expression of the sv40 early pro ...19846089114
sequence comparison in the crossover region of an oncogenic avian retrovirus recombinant and its nononcogenic parent: genetic regions that control growth rate and oncogenic potential.ntre 7 is an avian retrovirus recombinant of the endogenous nononcogenic rous-associated virus-0 (rav-0) and the oncogenic, exogenous, transformation-defective (td) prague strain of rous sarcoma virus b (td-prrsv-b). oligonucleotide mapping had shown that the recombinant virus is indistinguishable from its rav-0 parent except for the 3'-end sequences, which were derived from td-prrsv-b. however, the virus exhibits properties which are typical of an exogenous virus: it grows to high titers in tis ...19826298596
pathogenesis of porcine reproductive and respiratory syndrome virus infection in gnotobiotic pigs.the pathogenesis of porcine reproductive and respiratory syndrome virus (prrsv) was determined in gnotobiotic pigs by studying the sequential development of microscopic lesions and sites of virus distribution and replication. thirty-two pigs (three pigs/infected group and one pig/control group) were inoculated by nasal instillation of either prrsv isolate atcc vr-2332 (total dose 10(2.6) tcid50) or uninfected cell culture supernatant. infected and control pigs were euthanized at 12 hours, and 1, ...19957483210
differentiation of u.s. and european isolates of porcine reproductive and respiratory syndrome virus by monoclonal antibodies.monoclonal antibodies (mabs) to two u.s. isolates of porcine reproductive and respiratory syndrome (prrs) virus were prepared. two mabs specifically recognized a conserved epitope on the putative 15-kda nucleocapsid protein of u.s. and european isolates of prrs virus. four other mabs recognized epitopes on the 15-kda protein of u.s. but not european isolates of prrs virus. collectively, this indicates that prrs viruses contain both conserved and divergent epitopes on the 15-kda viral protein.19937508455
porcine reproductive and respiratory syndrome: neb-1 prrsv infection did not potentiate bacterial pathogens.a 2-phase study was conducted to evaluate the ability of the neb-1 strain of porcine reproductive and respiratory syndrome virus (prrsv) to potentiate common bacterial pathogens of swine. in phase i, 25 of 50 4-5-week-old specific-pathogen-free (spf) pigs were exposed to neb-1 prrsv (day 0). seven days after virus inoculation, 8 groups received 1 of 4 bacterial pathogens: haemophilus parasuis, streptococcus suis, salmonella cholerasuis, and pasteurella multocida. the ability of neb-1 prrsv to pr ...19957578444
sequence analysis of open reading frames (orfs) 2 to 4 of a u.s. isolate of porcine reproductive and respiratory syndrome virus.the sequence of orfs 2 to 4 of a u.s. isolate of porcine reproductive and respiratory syndrome virus (prrsv), atcc vr2385, was determined by analysis of a cdna lambda library. the cdna clones containing prrsv specific sequences were selected using a vr2385 orf 4 specific pcr probe and sequenced. the orfs 2, 3 and 4 overlapped each other and encoded polypeptides with predicted m(r) of 29.5 kda (orf 2), 28.7 kda (orf 3) and 19.5 kda (orf 4), respectively. no overlap was found between orfs 4 and 5, ...19957646363
molecular analysis of the orfs 3 to 7 of porcine reproductive and respiratory syndrome virus, québec reference strain.the cdna sequence of the 3'-terminal genomic region of the québec iaf-exp91 strain of porcine reproductive and respiratory syndrome virus (prrsv) was determined and compared to those of other reference strains from europe (lelystad virus) and us (atcc vr2385, mn-1b). the sequence (2834 nucleotides) which encompassed orfs 3 to 7 revealed extensive genomic variations between the québec strain and lelystad virus (lv), resulting from high number of base substitutions, additions and deletions. the or ...19957661693
detection of porcine reproductive and respiratory syndrome virus in boar semen by pcr.porcine reproductive and respiratory syndrome virus (prrsv) causes a devastating disease in swine. the presence and transmission of prrsv by boar semen has been demonstrated by using a swine bioassay. in this assay, 4- to 8-week-old pigs were inoculated intraperitoneally with semen from prrsv-infected boars. seroconversion of these piglets indicated the presence of prrsv in semen. seroconversion in gilts has also been demonstrated following artificial insemination with semen from prrsv-infected ...19957665637
antigenic differences between european and american isolates of porcine reproductive and respiratory syndrome virus (prrsv) are encoded by the carboxyterminal portion of viral open reading frame 3.antigenic differences between european and american isolates of porcine reproductive and respiratory syndrome virus (prrsv) were revealed by serologic analysis of a recombinant protein derived from prrsv open reading frame 3 (orf 3). the hydrophilic carboxyterminal 199 amino acids encoded by the orf 3 of a european (lelystad) isolate of prrsv were expressed as a recombinant fusion protein (bp03-p) in a baculovirus gene expression system. sera from gnotobiotic swine exposed to prototypic referenc ...19957667907
comparative study of a blocking enzyme-linked immunosorbent assay and the immunoperoxidase monolayer assay for the detection of antibodies to the porcine reproductive and respiratory syndrome virus in pigs.a blocking enzyme-linked immunosorbent assay (elisa) for detecting antibodies to the porcine reproductive and respiratory syndrome virus (prrsv) in pig sera was developed and compared with the immunoperoxidase monolayer assay (ipma), the most widely used serological diagnostic test in europe. the blocking elisa was specific and more sensitive than the ipma when applied to field sera and to sera which were collected early after an experimental infection with prrsv. problems with high background a ...19957730433
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
immunohistochemical identification of porcine reproductive and respiratory syndrome virus (prrsv) antigen in the heart and lymphoid system of three-week-old colostrum-deprived pigs.porcine reproductive and respiratory syndrome virus (prrsv) antigens were detected by a streptavidin-biotin complex technique in tissues of 3-week-old colostrum-deprived pigs that had been inoculated intranasally with prrsv and had developed moderate respiratory disease. moderate, multifocal, tan-colored consolidation of the lungs and severe enlargement of the lymph nodes were noted at necropsy. severe interstitial pneumonia characterized by type 2 pneumocyte proliferation, septal infiltration w ...19957771065
production, characterization and reactivity of monoclonal antibodies to porcine reproductive and respiratory syndrome virus.this report describes the preparation of six monoclonal antibodies (mabs) raised against a british isolate of porcine reproductive and respiratory syndrome virus (prrsv), their characterization in terms of protein specificity and their reactivity with different prrs viruses from europe and the usa. radioimmunoprecipitation and western blotting studies of mab reactivity with proteins from cell lysates of infected cells and purified virus revealed that four of the six mabs (wbe1 and wbe4-6) precip ...19957782765
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
serological studies in austrian fattening pigs with respiratory disorders.serum samples of 253 fattening pigs out of 44 different herds with respiratory signs were examined for antibodies to aujeszky's disease virus by elisa, swine influenza virus (hi test), porcine respiratory coronavirus (elisa) and porcine reproductive and respiratory syndrome virus (ipma). one single case of aujeszky's disease was detected at slaughter. on the other hand 24.5% of the animals proved to be positive for swine influenza, although no vaccine is licensed in austria, and 63.6% reacted po ...19947810433
detection of porcine reproductive and respiratory syndrome virus and efficient differentiation between canadian and european strains by reverse transcription and pcr amplification.two sets of oligonucleotide primers (1008ps-1009pr and 1010pls-1011plr) were designed according to the sequence of the nucleocapsid protein (n) gene of quebec reference strain iaf-exp91 of porcine reproductive and respiratory syndrome virus (prrsv). the primers were used in reverse transcription and pcr (rt-pcr) experiments for detection of viral genomic rna either from infected porcine alveolar macrophages (pam) or tissues from experimentally infected specific-pathogen-free pigs. considering th ...19947814546
recurrent reproductive failure associated with porcine reproductive and respiratory syndrome in a swine herd.an investigation of a case of recurrent reproductive failure in a swine herd was conducted. the subject farm (a) and a neighboring farm (b) had experienced an acute outbreak of porcine reproductive and respiratory syndrome in 1990. during 1992, farm a experienced recurrent episodes of conception failure, stillbirths, preweaning mortality, and sow mortality. similar clinical findings were not evident on farm b. evaluation of production records indicated that the problem was occurring in first-par ...19947852155
serum immune responses to the proteins of porcine reproductive and respiratory syndrome (prrs) virus.the antibody responses of pigs to porcine reproductive and respiratory syndrome virus (isolate vr-2332) were evaluated by indirect immunofluorescence, virus neutralization, and immunoblotting. all pigs in each group were positive by indirect immunofluorescence 14-21 days postexposure (dpe), and antibodies to specific viral proteins (15, 19 or 26 kd) were initially demonstrated by immunoblotting at 7-21 days dpe. neutralizing antibodies were detected in only 2 pigs that were inoculated intranasal ...19947858019
pulmonary lesions in fetuses exposed in utero to porcine reproductive and respiratory syndrome virus. 19947858028
isolation and serological characterization of porcine reproductive and respiratory syndrome (prrs) viruses from pigs with reproductive and respiratory disorders in japan.three porcine reproductive and respiratory syndrome viruses (prrsvs) were successfully isolated from stillborn piglets and fattening pigs derived from different herds affected either with an epizootic reproductive failure or a severe chronic respiratory distress in japan. the isolates were reacted with antisera against both european (lelystad virus) and american (strain 46448) prrsvs in indirect immunofluorescence (iif). however, cross immunoperoxidase monolayer assay revealed the close serologi ...19947865590
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
persistence of porcine reproductive and respiratory syndrome virus infection in a swine operation.a herd of quebec seedstock pigs experienced in early 1992 a typical outbreak of porcine reproductive and respiratory syndrome (prrs) associated with lesions of interstitial, proliferative and necrotizing pneumonia in weaned piglets. the nature of the infection was confirmed by serology using indirect immunofluorescence (iif) and virus isolation in primary cultures of porcine alveolar macrophages (pam). farm production recovered after eight weeks of losses. in order to evaluate the persistence of ...19947889462
immune response and persistence of the porcine reproductive and respiratory syndrome virus in infected pigs and farm units.the kinetics of the serum antibody response to porcine reproductive and respiratory syndrome (prrs) virus and the persistence of the virus after infection were determined in experimentally and naturally infected pigs. in an experimental study, four specific pathogen free (spf) sows were infected with a french strain of prrs virus at 90 days of gestation, and their piglets (the test piglets) were monitored for 29 weeks from birth. in one litter, antibodies against prrs virus were absent before th ...19947941249
a modified serum neutralization test for the detection of antibody to porcine reproductive and respiratory syndrome virus in swine sera.various conditions were evaluated and modified to improve the sensitivity of the serum neutralization (sn) test for detecting antibody in pigs infected with porcine reproductive and respiratory syndrome virus (prrsv). higher sn titers were consistently obtained by the addition of 20% fresh swine serum to the virus diluent and by the use of a permissive cell clone (marc-145) derived from the ma-104 cell line. test sera used to assess the sn test were obtained from 2 groups of 3-week-old pigs infe ...19947948196
cloning, expression, and sequence analysis of the orf4 gene of the porcine reproductive and respiratory syndrome virus mn-1b.porcine reproductive and respiratory syndrome virus (prrsv) mn-1b strain open reading frame 4 (orf4) has been cloned, sequenced, and expressed in escherichia coli. the homologies of nucleotide and amino acid sequences between mn-1b (us isolate) and lv (european isolate) are 69% and 64%, respectively. the data also showed that orf4 of mn-1b is 36 bases shorter than that of lv. western blot analysis of expressed recombinant orf4 protein reacted with 65% (26/40) of prrsv-infected pig sera tested. t ...19947948197
lymph node lesions in neonatal pigs congenitally exposed to porcine reproductive and respiratory syndrome virus. 19947948210
immunohistochemical detection of swine influenza virus and porcine reproductive and respiratory syndrome virus in porcine proliferative and necrotizing pneumonia cases from québec. 19947954227
porcine reproductive and respiratory syndrome virus identification in proliferative and necrotizing pneumonia cases from ontario. 19947954232
prevention of the spread of porcine reproductive and respiratory syndrome virus in endemically infected pig herds by nursery depopulation.an attempt was made to prevent the spread of the virus of porcine reproductive and respiratory syndrome (prrs) on three minnesota pig farms that had been experiencing chronic nursing pig problems, including poor growth rates and increased mortality of post weaning pigs. the prrs virus and different bacterial pathogens were isolated from all three farms during the initial investigation, and all the farms had a high prevalence of prrs virus-seronegative breeding animals. all the pigs tested within ...19947985341
temporal characterization of transplacental infection of porcine fetuses with porcine reproductive and respiratory syndrome virus.pregnant gilts were exposed to porcine reproductive and respiratory syndrome virus (prrsv) by iv inoculation at or about gestation day 30 (3 gilts), 50 (3 gilts), 70 (3 gilts), or 90 (5 gilts) to investigate the likelihood of transplacental infection with prrsv at various stages of gestation. at or about 3, 6, and 9 weeks after exposure, gilts were either euthanatized while still pregnant or allowed to farrow. gilts and pigs were observed for clinical signs of infection, and gilts, pigs, and fet ...19947998696
non-transmission of porcine reproductive and respiratory syndrome virus by seropositive pigs from an infected herd. 19948009789
mice and rats (laboratory and feral) are not a reservoir for prrs virus.porcine reproductive and respiratory syndrome (prrs) is caused by an unclassified arterivirus. the syndrome was first reported in the usa in 1987 as epizootics of reproductive failure in sows and respiratory disease in nursery, growing, and fattening pigs. an enzootic form of the disease has now emerged, characterized by interstitial pneumonia and an increased incidence of secondary infections. because the disease has now become enzootic on many farms, rodents were investigated as a possible res ...19948011773
experimental porcine reproductive and respiratory syndrome virus infection in one-, four-, and 10-week-old pigs.one-, 4-, and 10-week-old pigs were exposed to porcine reproductive and respiratory syndrome virus (prrsv) to determine the effect of age on clinical signs, hematologic alterations, the onset and duration of viremia, routes of virus shedding, antibody production, and microscopic lesions produced by prrsv isolate atcc vr-2332. the response to prrsv infection was similar among age groups. fever, usually prolonged, and a marked dyspnea with cutaneous erythema when restrained for sample collection w ...19948011777
molecular cloning and nucleotide sequencing of the 3'-terminal genomic rna of the porcine reproductive and respiratory syndrome virus.the genomic rna of a porcine reproductive and respiratory syndrome virus (prrsv) isolate from the u.s.a., vr 2385 (atcc), was copied into cdna after priming with oligo(dt) and cloned into phage lambda. the cdna clones representing the 3'-terminal genomic rna of the virus were isolated and sequenced. the genome is a positive-stranded, polyadenylated rna with an estimated size of 15 kb. analysis of the resulting sequence identified three complete open reading frames (orfs) with the potential to en ...19948021610
interaction of porcine reproductive and respiratory syndrome virus with swine monocytes. 19948036775
development of a streptavidin-biotin immunoperoxidase procedure for the detection of porcine reproductive and respiratory syndrome virus antigen in porcine lung. 19948068760
detection of porcine reproductive respiratory syndrome virus by the polymerase chain reaction.a polymerase chain reaction (pcr) is described for the detection of the porcine reproductive respiratory syndrome virus (prrsv). using the pcr we were able to detect about 30 infectious units of prrsv resolved in tissue culture medium or sperm. for the detection of prrsv in sperm the pcr is 10-times more sensitive than culturing in alveolar macrophages. for the detection of prrsv, pcr provides a good alternative to cell culture methods.19948071416
characterization of infection with endemic porcine reproductive and respiratory syndrome virus in a swine herd.infection of 8-week-old pigs with endemic porcine reproductive and respiratory syndrome (prrs) virus was detected on a farm that had an epidemic of prrs in 1989. during the 2.5 years since the original epidemic, reproductive performance of the breeding herd had been within acceptable limits, but mortality had periodically exceeded one-fourth of the pigs in the nursery (195 died of 761 weaned, 25.6%). investigators attempted to determine the age and humoral immune status of pigs infected with end ...19948077141
excretion of porcine reproductive and respiratory syndrome virus in semen after experimentally induced infection in boars.four boars intranasally inoculated with porcine reproductive and respiratory syndrome (prrs) virus were monitored for 56 days after exposure for changes in semen characteristics and for the presence of virus in the semen. clinically, 2 of 4 boars had mild respiratory signs of 1 day's duration after infection. changes in appetite, behavior, or libido were not detected. all boars seroconverted on the indirect fluorescent antibody and serum virus neutralization tests by day 14 after inoculation. vi ...19948077142
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
serological studies on the potential synergism of porcine reproductive and respiratory syndrome virus and influenza-, corona- and paramyxoviruses in the induction of respiratory symptoms in swine.sera from 265 finishing pigs belonging to 70 herds, in which severe respiratory disorders were observed, were examined for antibody prevalence to porcine reproductive and respiratory syndrome virus (prrsv), influenza virus subtypes h3n2 and h1n1, porcine respiratory corona virus (prcv) and a recently described porcine paramyxovirus (ppmv). by immunoperoxidase-monolayer assay 69.1% of these sera were positive for prrsv. hemagglutination inhibiting activity was found in 55.1% of the sera for influ ...19938128802
[prevalence of antibodies against the viruses of european swine fever, aujeszky's disease and "porcine reproductive and respiratory syndrome" in wild boars in the federal states sachsen-anhalt and brandenburg].during the hunting season from 1991/1992 blood samples were collected from wild boar shot in the federal states of sachsen-anhalt (482 samples) and brandenburg (177 samples) which corresponds to 2.1 and 0.4% of the total hunting bag. all sera were screened in a complex trapping blocking (ctb) elisa for antibodies against hog cholera virus (hcv) and in an indirect elisa for antibodies against aujeszky's disease virus (adv). additionally the sera were tested for neutralizing antibodies against hcv ...19948131731
interaction between streptococcus suis serotype 2 and porcine reproductive and respiratory syndrome virus in specific pathogen-free piglets.secondary specific pathogen-free (sspf) piglets were inoculated intranasally with streptococcus suis serotype 2 alone, porcine reproductive and respiratory syndrome virus (prrsv) alone, or with prrsv followed by s suis. uninfected piglets were used as controls. pigs inoculated with prrsv (atcc vr-2332) followed by challenge with a virulent strain (87555) of s suis serotype 2 developed clinical signs, suppurative meningitis and large numbers of s suis in their tissues, including the brain and men ...19948135015
porcine reproductive and respiratory syndrome virus: morphological, biochemical and serological characteristics of quebec isolates associated with acute and chronic outbreaks of porcine reproductive and respiratory syndrome.cytolytic and noncytolytic strains of the porcine reproductive and respiratory syndrome virus (prrsv) were isolated in primary cultures of porcine alveolar macrophages (pam) from lung homogenates of stillborn fetuses or blood samples of dyspneic piglets collected from quebec pig farms having experienced acute or chronic outbreaks of prrs. serological identification of the virus was confirmed by indirect immunofluorescence and indirect protein a-gold immunoelectron microscopy using reference anti ...19948143254
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
enhanced replication of porcine reproductive and respiratory syndrome (prrs) virus in a homogeneous subpopulation of ma-104 cell line.two different cell populations, high- (marc-145) and low-permissive cell clones (l-1) to porcine reproductive and respiratory syndrome (prrs) virus, were derived from ma-104 cell line (parent cell: p) by cell cloning. maximum virus yields in marc-145, p, and l-1 cell clones were 10(8.5), 10(3.5), and 10(2.5) tissue culture infective dose 50 (tcid50)/0.1 ml, respectively. the marc-145 cell clone supported replication of all 11 different porcine reproductive and respiratory syndrome virus isolates ...19938257302
pathogenesis of porcine reproductive and respiratory syndrome virus infection in mid-gestation sows and fetuses.two experiments were undertaken to evaluate whether porcine reproductive and respiratory syndrome (prrs) virus was able to cross the placenta and infect midgestation fetuses following intranasal inoculation of sows and whether prrs virus directly infected fetuses following in utero inoculation. in experiment 1, eight sows between 45 and 50 days of gestation were intranasally inoculated with prrs virus (atcc vr-2332), and four control sows were inoculated with uninfected cell culture lysate. viru ...19938269364
immunohistochemical detection of porcine reproductive and respiratory syndrome virus using colloidal gold.two cytopathic agents were isolated on porcine alveolar macrophages following inoculation with homogenates of lung tissues from pigs showing respiratory problems. these isolates were identified as porcine reproductive and respiratory syndrome (prrs) virus isolates by indirect immunofluorescence using a prrs virus (prrsv) specific monoclonal antibody (mab) and were designated as lhva-92-1 and lhva-92-2. immunogold electron microscopy using a porcine prrs positive serum pool and protein a-gold res ...19938269370
endemic porcine reproductive and respiratory syndrome virus infection of nursery pigs in two swine herds without current reproductive failure. 19938373860
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
seroprevalence of indirect fluorescent antibody to porcine reproductive and respiratory syndrome virus in selected swine herds. 19938507706
pathogenesis of in utero infection in porcine fetuses with porcine reproductive and respiratory syndrome virus.porcine fetuses were exposed in utero to porcine reproductive and respiratory syndrome virus (prrsv) at stages of gestation ranging from 34 to 85 days and examined 17 to 31 days later to determine the effect of gestational age on fetal susceptibility. for each of the 8 litters tested during the study, all of the fetuses of 1 horn of the uterus were exposed to virus by intraamniotic injection; those of the other horn were exposed similarly to a sham inoculum that consisted of sterile cell culture ...19958521351
antigenic comparison of canadian and us isolates of porcine reproductive and respiratory syndrome virus using monoclonal antibodies to the nucleocapsid protein.fifteen canadian field isolates of porcine reproductive and respiratory syndrome (prrs) virus from quebec and ontario were compared with 5 us prrs virus (prrsv) isolates and with the european lelystad isolate using monoclonal antibodies (mabs) sdow17, ep147, and vo17 directed to the 15-kda nucleocapsid protein of prrsv. all canadian and us isolates tested by indirect immunofluorescence were recognized by the 3 mabs, and individual titers of mabs towards canadian and us prrsv isolates were simila ...19958521358
pattern of infection with the porcine reproductive and respiratory syndrome virus on swine farms in belgium.on four closed breeding-fattening farms, 17 sows and their litters were examined for porcine reproductive and respiratory syndrome virus (prrsv) antibodies in the blocking enzyme-linked immunosorbent assay (elisa). on each farm, the pigs were born within the same week and remained together for 12 weeks. the pigs were followed serologically to determine the antibody profile with the purpose of establishing the infection pattern of prrsv. a total of 13 sows had antibodies and a positive correlatio ...19958546019
stability of porcine reproductive and respiratory syndrome virus in the presence of fomites commonly found on farms.to determine the survival of porcine reproductive and respiratory syndrome virus (prrsv) on nonliving substances (fomites) at 25 to 27 c.19968575971
persistence of porcine reproductive and respiratory syndrome virus in serum and semen of adult boars.four seronegative adult boars were intranasally inoculated with porcine reproductive and respiratory syndrome virus (prrsv) isolate vr-2332. serum and semen were collected 2-3 times weekly for over 100 days postinoculation (dpi). serum samples were assayed for prrsv by virus isolation (vi) and a polymerase chain reaction (pcr) and screened for antibodies to prrsv using the indirect fluorescent antibody (ifa) and virus neutralization (vn) tests. semen was assayed for prrsv rna by pcr. virus and v ...19958580165
comparison of immunogold silver staining (igss) with two immunoperoxidase staining systems for the detection of porcine reproductive and respiratory syndrome virus (prrsv) antigens in formalin-fixed tissues. 19958580180
evaluation of an indirect fluorescent igm antibody test for the detection of pigs with recent infection of porcine reproductive and respiratory syndrome virus. 19958580181
[diagnosis of contagious diseases in animals using pcr].the pcr is used for diagnostic purposes as it allows to detect infections agents within a much shorter time than by cultural isolation. in addition, it can detect non-infectious viruses and bacteria in clinical samples. these advantages are important factors in the diagnosis of highly contagious animal diseases (mainly caused by viruses) since a rapid laboratory diagnosis will allow to take immediate disease control actions. pcr is routinely used at the institute of african and classical swine f ...19958584867
[significance of prrs virus infections for respiratory tract infections in swine--a literature review].the paper summarises present knowledge concerning the possible role of a virus which has in the meantime been classified as belonging to the arteriviridae and which causes prrs (porcine reproductive and respiratory syndrome), in the pathogenesis of respiratory diseases four years after first isolation of the virus. although the fact that prrsv-infection produces an immunity which protects swine from repeated bouts of prrsv is common knowledge by now, reinfection with the virus might be possible. ...19958591744
comparison of the pathogenicity of two us porcine reproductive and respiratory syndrome virus isolates with that of the lelystad virus.the lelystad virus or one of two us isolates (vr2385, vr2431) of porcine reproductive and respiratory syndrome virus were given intranasally to 25 4-week-old cesarian-derived colostrum-deprived pigs. pigs from these groups were necropsied at 1, 2, 3, 5, 7, 10, 15, 21, or 28 days postinoculation. the lelystad virus and vr2431 induced mild transient pyrexia, dyspnea, and tachypnea. vr2385 induced labored and rapid abdominal respiration, pyrexia, lethargy, anorexia, and patchy dermal cyanosis. all ...19958592800
open reading frame 5 of porcine reproductive and respiratory syndrome virus as a cause of virus-induced apoptosis.the gene product of open reading frame 5 (p25) of porcine reproductive and respiratory syndrome (prrs) virus has been expressed by coinfection of culture cells with vaccinia virus expressing the t7 rna polymerase and a recombinant vaccinia virus encoding the open reading frame 5 gene under the t7 promoter and the encephalomyocarditis virus internal ribosome entry site. in spite of the reported efficiency of the expression system, very poor accumulation of p25 protein was observed and a strong cy ...19968627762
improved performance of a large pig complex after sequential nursery depopulation.an attempt was made to compare the productivity and financial benefits of nursery depopulation on five large pig farms which were all part of one complex. each farm had been experiencing poor post weaning performance for 12 months, and had previously been infected with porcine reproductive and respiratory syndrome virus (prrsv). a plan to depopulate each nursery sequentially was established, and the pigs were moved to fattening facilities on one of the farms (farm 3) where space was available. o ...19968629320
evaluation of the persistence of porcine reproductive and respiratory syndrome virus in pig carcases.the presence of porcine reproductive and respiratory syndrome (prrs) virus in pig meat was assessed in samples collected from experimentally infected pigs and from the carcases of pigs from infected herds at an abattoir. in the experimental study, pigs approximately six months old were inoculated with two isolates of prrs virus and tissue samples were collected seven and 14 days after inoculation. at seven days, prrs virus was recovered from lungs, tonsils, lymph nodes and muscle tissues, and vi ...19958644434
kinetics of humoral immune response to the major structural proteins of the porcine reproductive and respiratory syndrome virus.the kinetics of appearance of antibodies directed to the major structural proteins n, m and e of porcine reproductive and respiratory syndrome virus (prrsv) was followed in pigs naturally- and experimentally-exposed to the virus. specific igm antibody titers were first detected by indirect immunofluorescence (iif) at the end of the first week of prrsv infection, peaked by day 14 to 21 post-inoculation (p.i.), then rapidly decreased to undetectable levels by day 35 to 42 p.i. on the other hand, s ...19968645111
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
pathogenesis of plaque variants of porcine reproductive and respiratory syndrome virus in pregnant sows.to determine whether porcine reproductive and respiratory syndrome virus plaque variants vary in their pathogenicity in causing late-term reproductive failure.19968669762
a nested set of six or seven subgenomic mrnas is formed in cells infected with different isolates of porcine reproductive and respiratory syndrome virus.the subgenomic mrnas (sg mrna) of porcine reproductive and respiratory syndrome virus (prrsv) were characterized. the number of sg mrnas, which form a 3'-coterminal nested set in prrsv-infected cells, varied from six to seven among prrsv isolates with differing virulence. the additional species of sg mrna in some isolates of prrsv was designated as sg mrna 3-1. the leader-mrna junction sequences of sg mrnas 3, 3-1 and 4 were found to contain a similar six nucleotide sequence motif, u(g)ua(g/c)ac ...19968683215
genetic variation in porcine reproductive and respiratory syndrome virus isolates in the midwestern united states.the nucleotide sequence of a 3266 bp region encompassing open reading frames (orfs) 2 through 7 of the porcine reproductive and respiratory syndrome virus (prrsv) was determined for 10 isolates recovered from the midwestern united states. pairwise comparisons showed that genetic distances between isolates ranged from 2.5% to 7.9% (mean 5.8% +/- 0.2%) whereas the lelystad strain from europe was, on average, 34.8% divergent from us clones. thus, us and european prrsv isolates represent genetically ...19968683216
effect of post-coital intrauterine inoculation of porcine reproductive and respiratory syndrome virus on conception in gilts.the effect of porcine reproductive and respiratory syndrome virus (prrsv) on early gestation was investigated by exposing susceptible gilts to the virus shortly after they had been bred naturally. sixteen gilts were exposed intrauterinely to prrsv and 23 gilts received a sham inoculum. one day after exposure, and on or about seven, 14, and 30 days after exposure, the gilts were bled and the serum was tested for prrsv and homologous antibody. the pregnancy status of each gilt was determined on da ...19968686138
comparison among strains of porcine reproductive and respiratory syndrome virus for their ability to cause reproductive failure.to compare the virulence of selected strains of porcine reproductive and respiratory syndrome virus (prrsv) relative to reproductive performance of pregnant gilts.19968725809
antibody-dependent enhancement (ade) of porcine reproductive and respiratory syndrome virus (prrsv) infection in pigs.infection of porcine alveolar macrophages by the porcine reproductive and respiratory syndrome virus (prrsv) was significantly enhanced in vitro by antibody raised against the prrsv isolate isu-p (p < 0.01). increased yields and infection rates were highly correlated (r = 0.95) and the ratio of yield to infection rate was greater than 1.4, suggesting that more than one mechanism was responsible for enhanced infection. antibody-dependent enhancement (ade) of infection was also demonstrated in viv ...19968733920
comparison of a commercial elisa and an immunoperoxidase monolayer assay to detect antibodies directed against porcine respiratory and reproductive syndrome virus.a commercially available enzyme-linked immunosorbent assay (elisa) for the detection of antibodies against porcine respiratory and reproductive syndrome virus (prrsv) was compared to an immunoperoxidase monolayer assay (ipma). serum samples used were collected from pigs experimentally infected with either the american or european antigenic type of prrsv, and also from piglets born to sows that had been experimentally infected with the european antigenic type of prrsv. in addition, three sets of ...19968734646
porcine reproductive and respiratory syndrome virus does not exacerbate mycoplasma hyopneumoniae infection in young pigs.the purpose of this study was to determine if porcine reproductive and respiratory syndrome (prrs) virus infection altered the severity of acute mycoplasma hyopneumoniae (mh) infection in young pigs. twenty five, 3-week-old male pigs were randomly assigned by litter and weight to one of 3 groups. groups 1 (prrs only, n = 5) and 2 (prrs + mh, n = 10) were inoculated intranasally with prrs virus (in-5 isolate, 10(5) tcid50) and viremia in all pigs was confirmed by virus isolation from serum 3 days ...19968734647
antigenic variability among north american and european strains of porcine reproductive and respiratory syndrome virus as defined by monoclonal antibodies to the matrix protein.two hybridoma cell lines producing monoclonal antibodies (mabs) to the 19-kda matrix (m) protein of porcine reproductive and respiratory syndrome virus (prrsv) were obtained from balb/c mice that were immunized with a reference quebec tissue culture-adapted strain (strain iaf-klop). the polypeptide specificities of the mabs were determined by immunoblotting and immunoprecipitation tests with concentrated and purified preparations of the virus and by determining their reactivities with the escher ...19968735103
characteristics of major structural protein coding gene and leader-body sequence in subgenomic mrna of porcine reproductive and respiratory syndrome virus isolated in japan.nucleotide sequence, 1713nt in length, of porcine reproductive and respiratory syndrome virus (prrsv) isolated in japan was determined. the sequence encompassed 3 overlapping open reading frames (orfs), orf5 to orf7. these orfs encodes major structural proteins of prrsv. the deduced amino acid sequence of each orf showed higher than 87.5% identity with an american isolate, and lower (54.6 to 80.5%) identity with an european isolate. this result supported a previous report about antigenic charact ...19968741275
isolation of porcine respiratory coronavirus from pigs affected with porcine reproductive and respiratory syndrome.four cytopathogenic viruses were isolated in cpk cells derived from porcine kidneys from tonsils and lungs of 3 of 15 pigs affected with porcine reproductive and respiratory syndrome virus. physicochemically and morphologically, the isolates were similar to a coronavirus. the isolates were not distinguished from transmissible gastroenteritis virus (tgev) by a neutralization test using polyclonal antibodies, but differentiated from tgev by monoclonal antibodies capable of discriminating between t ...19968741277
alveolar macrophages as a diagnostic sample for detecting natural infection of pigs with porcine reproductive and respiratory syndrome virus. 19968744747
porcine reproductive and respiratory syndrome virus: seminal transmission. 19968761977
detection of porcine reproductive and respiratory syndrome virus and mycoplasma hyorhinis antigens in pulmonary lesions of pigs suffering from respiratory distress.eleven field cases of a disease characterized by severe dyspnoea or abdominal breathing were examined post mortem. the affected pigs had antibody against porcine reproductive and respiratory syndrome virus (prrsv). the predominant lung lesions were severe proliferative and interstitial pneumonia, and slight suppurative bronchopneumonia. the lesions were closely associated with the sites at which prrsv and mycoplasma hyorhinis antigens were detected. four of five pigs inoculated with prrsv develo ...19968762589
structural polypeptides of the american (vr-2332) strain of porcine reproductive and respiratory syndrome virus.the structural polypeptides of the isolate vr-2332 of porcine reproductive and respiratory syndrome virus were analyzed in sucrose gradient-purified virions. the virus had an average density of 1.15 g/cm3 and contained, by sds-page, three major polypeptides with apparent molecular weights of 15, 19 and 26-30 kda, which were designated as nucleocapsid (n), matrix (m) and envelope (e), respectively. the predominant structural protein was n. n-glycosidase f digestion only affected e whereas o-glyco ...19968774694
exposure of gilts in early gestation to porcine reproductive and respiratory syndrome virus.twenty-five gilts without measurable serum antibody titres to porcine reproductive and respiratory syndrome virus (prrsv) were identified and 16 were inoculated with prrsv at seven, 14 or 21 days of gestation and killed 20 to 22 days later to determine the effect of the virus on their embryos. the remaining nine gilts were not exposed to prrsv, but were killed at the same stages of gestation. the gilts were observed for clinical signs of infection and the gilts and their embryos were tested for ...19968782359
an elisa for porcine reproductive and respiratory syndrome: production of antigen of high quality.a reliable method was developed to produce a viral antigen preparation from porcine reproductive and respiratory syndrome virus (prrsv) infected marc-145 cells by solubilizing the virus with triton x-100. this method eliminated problems previously encountered with high background reactions associated with prrsv antigen or cell control antigen. with this new antigen, an indirect enzyme-linked immunosorbent assay (elisa) was adapted to detect swine serum anti-body against prrsv. in the elisa, non- ...19968785725
antibody production and blastogenic response in pigs experimentally infected with porcine reproductive and respiratory syndrome virus.seven five-week piglets were infected intranasally with 10(5) tcid50 of porcine reproductive and respiratory syndrome (prrs) virus strain iaf.exp91. all virus-exposed pigs developed fever, labored abdominal breathing, conjunctivitis, and lymph node enlargement within the first 96 h postexposure (pe), which continued to d 10 to 14 pe. two pigs that were necropsied at d 7 and 10 pe had diffuse interstitial pneumonitis, cardiopathy and lymphadenopathy. all 5 remaining pigs produced serum igm and ig ...19968785726
comparison of the antigen distribution of two us porcine reproductive and respiratory syndrome virus isolates with that of the lelystad virus.one hundred 4-week-old cesarean-derived colostrum-deprived pigs were inoculated with one of two different us porcine reproductive and respiratory syndrome virus (prrsv) isolates (vr2385, vr2431) or the european lelystad virus to detect and compare the location and amount of virus antigen. interstitial pneumonia, myocarditis, lymphadenopathy, and encephalitis were consistently seen in all three groups; however, disease and lesions were more severe in the vr2385 group. immunohistochemical evaluati ...19968801709
porcine reproductive and respiratory syndrome virus enters cells through a low ph-dependent endocytic pathway.the entry pathway of porcine reproductive and respiratory syndrome virus (prrsv) into marc-145 cells was investigated using a variety of drugs that interfere with the ph of intracellular vesicles by different mechanisms. virus entry was assessed by measuring viral rna replication or production of infectious virus. chloroquine, ammonium chloride and bafilomycin a1 inhibited rna replication or production of infectious virus in a dose-dependent manner. these drugs inhibited virus replication when a ...19968806181
phylogenetic relationships of european strains of porcine reproductive and respiratory syndrome virus (prrsv) inferred from dna sequences of putative orf-5 and orf-7 genes.the complete orf-5 gene and a fragment of the orf-7 gene from 14 different european porcine reproductive and respiratory syndrome virus (prrsv) isolates were amplified by reverse transcriptase polymerase chain reaction (rt-pcr), and their nucleotide sequences were determined. the orf-7 gene displayed nucleotide and amino acid identities of 94.1-99.6% and 95.3-100% among isolates from different countries. the orf-5 gene showed higher nucleotide (87.1-99.2% identity) and amino acid (-88% identity) ...19968806183
hemagglutination with porcine reproductive and respiratory syndrome virus.porcine reproductive and respiratory syndrome (prrs) virus grown on marc-145 cell cultures was tested for hemagglutination (ha) with erythrocytes from a variety of species at 4 degrees c, room temperature and 37 degrees c. ha was observed at all temperatures with mouse erythrocytes but not with cattle, sheep, goat, horse, swine, guinea pig, mongolian gerbil, goose and chicken erythrocytes. the ha activity was enhanced by treatment of virus materials with tween 80 followed by treatment with ether ...19968811620
histopathological findings in pigs of various ages suffering from spontaneous infection with the porcine reproductive and respiratory syndrome virus (prrsv).a retrospective study was carried out to investigate the morphology of 29 routinely necropsied german landrace pigs of various ages, namely five fetuses, eight neonates, five suckling piglets and 11 weaners, being either serologically prrsv-positive or born or aborted from prrsv positive sows. virus antigen was immunohistochemically demonstrated in 12 out of 27 (44%) lungs tested. the distinguishing histopathological features of prrsv-induced spontaneous disease are interstitial pneumonia accomp ...19968818300
fetal microscopic lesions in porcine reproductive and respiratory syndrome virus-induced abortion.microscopic lesions in four cases of abortion caused by porcine reproductive and respiratory syndrome virus (prrsv) were characterized by arteritis, myocarditis, and encephalitis. fetal prrsv infection was confirmed by virus isolation or immunohistochemistry and serology. although fetal microscopic lesions in prrsv abortions are rarely reported, diagnosticians should consider prrsv when these lesions occur.19968826015
isolation and experimental oral transmission in pigs of a porcine reproductive and respiratory syndrome virus isolate.a virus inducing a cytopathic effect on porcine alveolar macrophages was isolated from the lungs of a pig with respiratory problems and lesions of proliferative and necrotizing pneumonia. the isolate was found to react with porcine reproductive and respiratory syndrome virus (prrsv) monoclonal antibodies by indirect immunofluorescence and was designated lhva-93-3. the virus could also be propagated on the marc-145 cell line. the lhva-93-3 macrophage-passaged isolate was inoculated orally or intr ...19958830470
structural gene analysis of a quebec reference strain or porcine reproductive and respiratory syndrome virus (prrsv).the 3' end genomic region of a québec prrsv reference strain (iaf-exp91), propagated in porcine alveolar macrophages (pam), was sequenced and compared to the prototype european strain, the lelystad virus (lv). the sequence, which represents the 3'-terminal 2834 nucleotides, encompassed 5 orfs corresponding to orfs 3 to 7 of lv. extensive genomic variations resulting from an important rate of nucleotide additions, substitutions, and deletions were demonstrated between the two viruses. indeed, the ...19958830492
identification and characterization of the porcine reproductive and respiratory virus orfs 7, 5 and 4 products.porcine reproductive and respiratory syndrome virus (prrsv) causes abortions and respiratory diseases in pigs. the prrsv genome is a positive-sense polyadenylated rna molecule of about 15 kb. along with the genes for structural proteins (envelope, matrix and nucleocapsid proteins) prrsv genome contains a number of orfs potentially encoding nonstructural proteins (ns). to investigate the nature of the prrsv orfs 7, 5 and 4 products, we have cloned the envelope (orf5) nucleocapsid (orf7) and ns4 ( ...19958830500
structural proteins of porcine reproductive and respiratory syndrome virus (prrsv). 19958830501
ultrastructural characteristics and morphogenesis of porcine reproductive and respiratory syndrome virus propagated in the highly permissive marc-145 cell clone.a québec reference strain of prrsv (iaf-klop) was successfully propagated in marc-145 cells, a highly permissive cell clone to prrsv derived from the ma-104 cell line. purified extracellular virions appeared as pleomorphic but mostly spherical enveloped particles, 50-72 nm in diameter, with an isometric core about 25-30 nm. by indirect immunofluorescence, detection of viral antigens within the cytoplasm was possible as soon as 6 h.p.i. nucleocapsids, budding at smooth endoplasmic reticulum (er), ...19958830552
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
gross and microscopic lesions in porcine fetuses infected with porcine reproductive and respiratory syndrome virus.diagnosis of porcine reproductive and respiratory syndrome virus (prrsv)-induced reproductive failure in swine is difficult because of the rapid inactivation of virus in fetuses that have died prior to abortion or farrowing. in this report, we describe gross and microscopic lesions of diagnostic value found in fetuses transplacentally infected with prrsv during late gestation. seven sows free of prrsv-specific antibody and 1 sow (#8) that had been previously infected with prrsv were oronasally e ...19968844568
characterization of a high-virulence us isolate of porcine reproductive and respiratory syndrome virus in a continuous cell line, atcc crl11171. 19968844584
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