| sequence comparison of open reading frames 2 to 5 of low and high virulence united states isolates of porcine reproductive and respiratory syndrome virus. | the sequences of orfs 2 to 5 of five united states (us) porcine reproductive and respiratory syndrome virus (prrsv) isolates with differing virulence were determined. the nucleotide and deduced amino acid sequences of these isolates were compared with those of other known prrsv isolates. the amino acid sequence identity between seven us prrsv isolates was 91-99% in orf 2, 86-98% in orf 3, 92-99% in orf 4 and 88-97% in orf 5. the low virulence us isolate had highest sequence variation in orfs 2 t ... | 1995 | 8847527 |
| diagnosis of porcine reproductive and respiratory syndrome using infected alveolar macrophages collected from live pigs. | a highly sensitive method of detecting infection of live pigs with porcine reproductive and respiratory syndrome virus (prrsv) was developed by testing alveolar macrophages collected by pulmonary lavage. five pigs were exposed by oronasal inoculation or by contact to prrsv when they were 10 (1 pig) or 14 weeks (4 pigs) of age. diagnostic samples (alveolar macrophages and sera) were collected from each pig just before exposure to prrsv. during the next 9 weeks sera were collected at weekly interv ... | 1996 | 8861647 |
| in vivo detection of porcine reproductive and respiratory syndrome virus rna by in situ hybridization at different times postinfection. | we studied the distribution of porcine reproductive and respiratory syndrome virus (prrsv) rna in tissues by in situ hybridization at different times postinfection (p.i.). the probe used for in situ hybridization was prepared by reverse transcription of prrsv rna, followed by pcr amplification of the cdna. the sequence amplified corresponded to 433 bp from prrsv open reading frame 7, which is contained in the nucleocapsid protein gene and which is highly conserved in both european and american s ... | 1996 | 8862599 |
| porcine reproductive and respiratory syndrome virus (prrsv): monoclonal antibodies detect common epitopes on two viral proteins of european and u.s. isolates. | sixteen hybridoma cell lines secreting monoclonal antibodies (mabs) directed against two dutch isolates of the causative virus of porcine reproductive and respiratory syndrome (prrsv) were produced. the hybridoma cells resulted from fusions of sp2/0 myeloma cells with splenocytes of stu mice immunized with purified prrsv after induction of immunotolerance against host cell constituents. screening of supernatant fluids was performed by an indirect immunofluorescence assay on prrsv-infected porcin ... | 1996 | 8870188 |
| slow-reacting and complement-requiring neutralizing antibody in swine infected with porcine reproductive and respiratory syndrome (prrs) virus. | various conditions were evaluated and modified to enhance the sensitivity of the neutralization (nt) test for detecting antibody in swine infected with porcine reproductive and respiratory syndrome (prrs) virus. higher nt antibody titers were consistently obtained by the addition of 10% (v/v) complement, fresh guinea pig serum, to the virus diluent and by the incubation of serum-virus mixture at 4 degrees c for 24 hr. the appearance and persistence of antibodies detected by the modified nt test ... | 1996 | 8877973 |
| serological property and replication in cell cultures of porcine reproductive and respiratory syndrome viruses isolated in japan. | the serological property and replication in swine alveolar macrophages (sam) and marc-145 cell cultures of 35 porcine reproductive and respiratory syndrome (prrs) viruses isolated in sam were investigated. all the isolates were reacted almost equally with antisera against three japanese isolates including edrd-1 strain (american type) in immunoperoxidase monolayer assay (ipma), but weakly or did not react with antiserum against lelystad virus (european type) indicating that the japanese isolates ... | 1996 | 8877986 |
| chronological immunohistochemical detection and localization of porcine reproductive and respiratory syndrome virus in gnotobiotic pigs. | an immunogold-silver immunohistochemical technique was used to determine the chronological distribution and localization of porcine reproductive and respiratory syndrome virus (prrsv) in experimentally infected gnotobiotic pigs. thirty-two pigs were randomly allocated to infected (n = 24) or control (n = 8) groups. pigs in infected groups were inoculated at 3 days of age by nasal instillation of prrsv isolate atcc vr-2332 (total dose = 10(2.64) tcid50), and control pigs were exposed in the same ... | 1996 | 8885182 |
| nested pcr for detection and typing of porcine reproductive and respiratory syndrome (prrs) virus in pigs. | a nested polymerase chain reaction (pcr) was developed to detect porcine reproductive and respiratory syndrome (prrs) virus. a common primer set for european and north american type isolates of prrs virus was designed for reverse transcription pcr, and a specific primer set for each of the 2 type isolates was designed for nested pcr. the pcr that used a specific primer set detected the corresponding type of the virus at a level equivalent to 1 tcid50/100 microliters, but not the other type of is ... | 1996 | 8915992 |
| identification and characterization of a sixth structural protein of lelystad virus: the glycoprotein gp2 encoded by orf2 is incorporated in virus particles. | previously we have shown that lelystad virus (lv) contains five structural proteins, a nucleocapsid protein n, an integral membrane protein m, and three glycoproteins gp3, gp4, and gp5. in this study we identified a sixth structural protein of lelystad virus. the protein has an apparent molecular weight of 29 to 30 kda, was recognized by an orf2-specific antipeptide serum in western immunoblotting using sucrose gradient purified lv virions, and was shown to be n-glycosylated. it was therefore de ... | 1996 | 8918532 |
| typing of porcine reproductive and respiratory syndrome viruses by a multiplex pcr assay. | a rapid multiplex pcr assay was developed to distinguish between north american and european genotypes of porcine reproductive and respiratory syndrome (prrs) virus after a portion of the polymerase gene (open reading frame 1b) was sequenced for two north american prrs virus strains. dna products with unique sizes characteristic of each genotype were obtained. | 1997 | 8968921 |
| effects of a modified-live virus vaccine against porcine reproductive and respiratory syndrome in boars. | to determine whether vaccine virus is found in serum and semen of vaccinated boars, whether vaccination prevents subsequent shedding of wild-type virus after challenge exposure, and whether semen and blood variables are altered after vaccination or challenge exposure with wild-type virus, or both. | 1997 | 8989494 |
| differential reactivity of a monoclonal antibody directed to the membrane protein of porcine reproductive and respiratory syndrome virus. | a monoclonal antibody (2c12) against the 19 kda membrane (m) protein of a canadian isolate of porcine reproductive and respiratory syndrome (prrs) virus was produced. by indirect immunofluorescence (iif) cytoplasmic fluorescence was observed in infected cells, but the pattern of fluorescence was generally different and intensity was weaker than that observed using the nucleocapsid protein-directed monoclonal antibody sdow17. when tested by iif towards a total of 26 prrs virus isolates from canad ... | 1997 | 9008806 |
| detection of porcine reproductive and respiratory syndrome virus in paraffin-embedded tissues: comparison of immunohistochemistry and in situ hybridization. | a non-radioactive in situ hybridization (ish) method developed recently and an immunohistochemical method, the immunogold silver staining (igss), were compared for the detection of porcine reproductive and respiratory syndrome virus (prrsv) in formalin-fixed paraffin-embedded tissues. serial sections from 98 tissues, representing different organs from prrsv experimentally infected pigs, and serial sections from 46 lung tissues from field cases were tested by both methods. results obtained on tis ... | 1997 | 9015294 |
| comparative pathogenicity of nine us porcine reproductive and respiratory syndrome virus (prrsv) isolates in a five-week-old cesarean-derived, colostrum-deprived pig model. | one hundred forty-six 5-week- old cesarean-derived, colostrum-deprived (cdcd) pigs were inoculated intranasally with 1 of 9 us porcine reproductive and respiratory syndrome virus (prrsv) isolates. differences were found in severity of clinical respiratory disease, rectal temperatures (p < or = 0.001), gross lung lesions (p < or = 0.001), and microscopic lung lesions (p < or = 0.05). gross lung lesions were generally most severe 10 days postinoculation and were distributed primarily in the crania ... | 1996 | 9026065 |
| detection of porcine reproductive and respiratory syndrome virus in cell cultures and formalin-fixed tissues by in situ hybridization using a digoxigenin-labeled probe. | a nonradioactive in situ hybridization method is described for the detection of porcine reproductive and respiratory syndrome virus (prrsv) in cell cultures and in formalin-fixed paraffin-embedded tissue sections originating from experimentally infected pigs and from 1 field case. a 174 bp cdna probe targeting the viral rna encoding the nucleocapsid protein of a canadian prrsv isolate was generated by polymerase chain reaction. the cdna probe was labeled by random priming with digoxigenin-dutp u ... | 1996 | 9026078 |
| early serodiagnosis of porcine reproductive and respiratory syndrome virus infection of pigs by detection of slow-reacting and complement-requiring neutralizing antibody. | in order to evaluate and enhance the sensitivity of the neutralization (nt) test for detecting antibody in pigs infected with porcine reproductive and respiratory syndrome (prrs) virus, the effect of altered incubation conditions and complement use on neutralizing (nt) antibody titer were investigated. higher nt antibody titers were consistently obtained by addition of 20% guinea pig fresh serum to virus-serum mixtures in nt tests. furthermore, the complement-requiring nt antibody titer increase ... | 1997 | 9035074 |
| dual infections of feeder pigs with porcine reproductive and respiratory syndrome virus followed by porcine respiratory coronavirus or swine influenza virus: a clinical and virological study. | dual infections of pigs with porcine reproductive and respiratory syndrome virus (prrsv) followed by a second common respiratory virus, either porcine respiratory coronavirus (prcv) or swine influenza virus (siv), were studied. the aim was to determine if dual infections, as compared to single virus infections, result in enhanced clinical manifestations. it was also examined if prrsv replication affects replication of prcv or siv in the respiratory tract. groups of conventional 10 week old pigs ... | 1996 | 9054128 |
| induction of dual infections in newborn and three-week-old pigs by use of two plaque size variants of porcine reproductive and respiratory syndrome virus. | to determine whether pigs can be dually infected with different plaque variants of porcine reproductive and respiratory syndrome virus (prrsv). | 1997 | 9055970 |
| examination of virus shedding in semen from vaccinated and from previously infected boars after experimental challenge with porcine reproductive and respiratory syndrome virus. | danish artificial insemination (ai) centres house several boars antibody positive to porcine reproductive and respiratory syndrome virus as well as prrsv-naive boars which may become acutely infected. the risk of transmission of prrsv by semen may therefore constitute a serious problem to the danish pig industry. the use of a vaccination-program may be a way to avoid or reduce the problem. this study evaluates the use of two vaccines: one live, attenuated vaccine and one inactivated vaccine. a p ... | 1997 | 9057254 |
| evaluation of the effects of nursery depopulation on the persistence of porcine reproductive and respiratory syndrome virus and the productivity of 34 farms. | nursery depopulation has been described as an effective strategy for improving the performance of weaned pigs. in order to assess whether the strategy was effective under a wide range of conditions, a study was carried out on 34 farms in the usa. four groups with different depopulation protocols were designed on the basis of the location of the depopulated facility (on site vs off site) and the period for which the nursery remained empty (seven days vs 14 days). the changes in average daily live ... | 1997 | 9080641 |
| effect of heparin on infection of cells by porcine reproductive and respiratory syndrome virus. | to investigate whether heparin has any effect on the growth of porcine reproductive and respiratory syndrome virus (prrsv). | 1997 | 9140556 |
| temporal and morphologic characterization of the distribution of porcine reproductive and respiratory syndrome virus (prrsv) by in situ hybridization in pigs infected with isolates of prrsv that differ in virulence. | three groups of 5-week-old cesarian-derived, colostrum-deprived pigs were inoculated intranasally with either a high-virulence isolate (vr2385) or a low-virulence isolate (vr2431) of porcine reproductive and respiratory syndrome virus (prrsv) or with uninfected cell culture and media. formalin-fixed, paraffin-embedded tissues from pigs euthanatized at 10, 21, and 28 days post-inoculation were examined by in situ hybridization for prrsv nucleic acid using a digoxigenin-labeled antisense rna probe ... | 1997 | 9150544 |
| study on the suitability of sow colostrum for the serological diagnosis of porcine reproductive and respiratory syndrome (prrs). | serum and colostrum from 73 sows were collected. the serum samples were tested by immuno. peroxidase monolayer assay (ipma) and the corresponding colostrum samples with the indirect immuno fluorescent antibody (ifa) technique. all serum positive sows were colostrum positive and all colostrum negative were serum negative. eight sows only reacted positively in the colostral testing. compared to the serum standard test the specificity was 82.6% and the sensitivity 100%. the observed agreement betwe ... | 1997 | 9151534 |
| characterization of porcine reproductive and respiratory syndrome virus hemagglutinin. | porcine reproductive and respiratory syndrome virus hemagglutinin (hain) was readily adsorbed on mouse erythrocytes at 4, 22, or 37 degrees c, but not on goose erythrocytes. the adsorbed hain could not be eluted from the cells by resuspending in phosphate buffered saline, by incubating at 37 or 50 degrees c, or by incubating in the presence of neuraminidase. the hemagglutinating activity was not dependent on the ph and nacl molarity tested. the receptor of mouse erythrocytes for the hain was rel ... | 1997 | 9152937 |
| changes of lymphocyte subpopulations in pigs infected with porcine reproductive and respiratory syndrome (prrs) virus. | abnormal changes of t-cell subpopulation were observed in the peripheral blood lymphocytes of pigs infected with porcine reproductive and respiratory syndrome (prrs) virus. pigs with naturally occurring prrs revealed increases in cd2+ and cd8+ cells, and decreases in cd4+ cells and the ratios of cd4+/cd8+ cells. specific-pathogen-free pigs inoculated with prrs virus showed remarkable decreases in total lymphocytes, cd4+ and cd2+ cells on postinoculation day (pid) 3. the decline of cd4+ cells con ... | 1996 | 9157683 |
| evaluation of the effects of nursery depopulation of the profitability of 34 pig farms. | the financial impact of nursery depopulation was assessed on 34 pig farms by constructing a partial budget model to measure the profitability of the nursery production. the model measured margin over variable cost and used production data generated from a previous study; it assumed that fixed costs remained constant throughout the study and that feed cost, weaned pig cost and market price per nursery pig also remained fixed. the mean margin over variable cost per sow on the 34 farm after nursery ... | 1997 | 9172296 |
| an indirect elisa for the detection of antibodies against porcine reproductive and respiratory syndrome virus using recombinant nucleocapsid protein as antigen. | an indirect enzyme-linked immunosorbent assay termed rnprrs elisa using baculovirus-expressed and affinity-purified viral nucleocapsid protein (rnc) antigen was developed for detecting antibodies against porcine reproductive and respiratory syndrome virus (prrsv) in swine sera. sera (1395) originating from different european countries were used for the validation of this assay. the rnprrs elisa was capable of detecting antibodies in all sera known to contain anti-prrsv antibodies, resulting in 1 ... | 1997 | 9186940 |
| genetic variation and phylogenetic relationships of 22 porcine reproductive and respiratory syndrome virus (prrsv) field strains based on sequence analysis of open reading frame 5. | porcine reproductive and respiratory syndrome virus (prrsv) strains from 13 states in the united states, guatemala and canada were used to compare the envelope glycoprotein gene (orf 5) nucleotide and deduced amino acid sequences. the gene was the same size, 603 nt, for all the 22 field strains. these strains had 89-94% amino acid identity compared to reference strain vr 2332. a putative signal sequence and cleavage site between residues 31 and 32 was identified and three potential glycosylation ... | 1997 | 9191863 |
| antigenic variability of porcine reproductive and respiratory syndrome (prrs) virus isolates. influence of virus passage in pig. | in order to study the antigenic variability of porcine reproductive and respiratory syndrome virus (prrsv), 18 european and canadian field isolates were analysed with a panel of 15 monoclonal antibodies (mabs) raised against five different european and one canadian prrsv isolates. the antigenic pattern of these isolates was used to infer their phylogenetic relationships. isolates which had the same reactivity pattern were gathered together so that five antigenic profiles were analysed. the pairw ... | 1997 | 9208445 |
| baculovirus expression of proteins of porcine reproductive and respiratory syndrome virus strain olot/91. involvement of orf3 and orf5 proteins in protection. | porcine reproductive and respiratory syndrome virus (prrsv) is a new arterivirus that has spread rapidly all around the world in the last few years. the genomic region containing open reading frames (orfs) 2 to 7 of prrsv spanish isolate olot/91 was cloned and sequenced. the genomic sequence shared 95% identity with lelystad and tübingen isolates and between 61-64% with the orf7 region of the american isolates. orfs 2 to 7 were inserted into recombinant baculoviruses downstream of the polyhedrin ... | 1997 | 9208452 |
| cell-mediated immunity to porcine reproductive and respiratory syndrome virus in swine. | cell-mediated immunity has been demonstrated to be a necessary component of immunity against viral infection. methods to detect t-cell mediated immune responses to porcine reproductive and respiratory syndrome virus (prrsv) infection were established both in vitro as lymphocyte proliferation and in vivo as delayed-type hypersensitivity response (dth). optimal conditions for detection of lymphocyte proliferation were determined by testing different antigen concentrations and various stimulation p ... | 1997 | 9210282 |
| renal lesions associated with experimental porcine reproductive and respiratory syndrome virus (prrsv) infection. | | 1997 | 9211242 |
| general overview of prrsv: a perspective from the united states. | four years after the report of its discovery, porcine reproductive and respiratory syndrome virus (prrsv) continues to challenge swine producers, veterinary practitioners, and animal health researchers in the united states. the prevalence of infection is high--60% to 80% of herds is a reasonable estimate--but the clinical effects of infection vary widely among farms. in many herds, infection is unapparent and productivity seemingly unaffected. some infected herds report occasional respiratory di ... | 1997 | 9220613 |
| 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 ... | 1997 | 9220614 |
| comparative morphogenesis of three prrs virus strains. | the morphogenesis of a dutch prrs field strain virus (lelystad virus) was studied and compared to that of a u.s. field strain vr2332 and its attenuated vaccine strain jj1882. porcine lung alveolar macrophages (plam) and cl2621 cells were infected with high doses of virus (moi = 10). at 4, 6, 9, 12, 18, 24, and 48 h post infection (hpi) cells were fixed for electronmicroscopy or for detection of viral antigens by immunoperoxidase staining. from 6 hpi on, viral antigens were detected in the cytopl ... | 1997 | 9220615 |
| variation in open reading frames 3, 4 and 7 among porcine reproductive and respiratory syndrome virus isolates in the uk. | previous studies using monoclonal antibodies (mabs) have revealed antigenic variation among uk isolates of porcine reproductive and respiratory syndrome viruses (prrsv) and the use of in vitro translation products has shown that this variation lies in the protein encoded by open reading frame (orf) 3. this protein has been shown to be present in purified virion preparations, suggesting that it is a structural protein. the original objective was to investigate the degree of variation of orf3 amon ... | 1997 | 9220616 |
| pathogenesis and clinical aspects of a respiratory porcine reproductive and respiratory syndrome virus infection. | some pathogenetic and clinical aspects of the respiratory tract infection with porcine reproductive and respiratory syndrome virus (prrsv) are discussed. the acute and persistent stages of prrsv infection are treated separately. special attention is given to the author's work on experimental dual infections with prrsv and other enzootic porcine respiratory viruses. it was concluded that: (1) studies on the interactions of prrsv and its target cell, the pulmonary alveolar macrophage, are very sca ... | 1997 | 9220617 |
| porcine reproductive and respiratory syndrome virus: a persistent infection. | persistent infection with porcine reproductive and respiratory syndrome virus (prrsv) was shown in experimentally infected pigs by isolation of virus from oropharyngeal samples for up to 157 days after challenge. four 4 week old, conventional, prrsv antibody-negative pigs were intranasally inoculated with prrsv (atcc vr-2402). serum samples were collected every 2 to 3 days until day 42 post inoculation (pi), then approximately every 14 days until day 213 pi. fecal samples were collected at the t ... | 1997 | 9220618 |
| effect of porcine reproductive and respiratory syndrome virus on subsequent pasteurella multocida challenge in pigs. | this trial was conducted to evaluate the effect of porcine reproductive and respiratory syndrome virus (prrsv) on a subsequent challenge with pasteurella multocida in pigs. sixteen, 3-4 week-old piglets, from a prrsv and aujeszky disease virus (adv) free herd were used. animals were equally and randomly allocated in four groups which were treated according the following schedule: group i: negative controls; group ii: inoculation with only prrsv; group iii: inoculation with prrsv and p. multocida ... | 1997 | 9220619 |
| porcine reproductive and respiratory syndrome virus (prrsv) interaction with haemophilus parasuis. | the interaction of bacteria and virus has been well demonstrated in the pathogenesis of respiratory disease in swine. the interaction between porcine respiratory and reproductive syndrome virus (prrsv) and haemophilus parasuis has not been studied. we initiated studies to evaluate a possible effect of the prrsv on the pathogenesis of polyserositis caused by h. parasuis. a group of 30 three week old piglets were distributed in 4 groups. group i (10 pigs) was inoculated with prrsv and h. parasuis. ... | 1997 | 9220620 |
| dual infections of prrsv/influenza or prrsv/actinobacillus pleuropneumoniae in the respiratory tract. | to study the effect of a previous porcine respiratory and reproductive syndrome-infection (prrs) of the respiratory tract on influenza virus and actinobacillus pleuropneumoniae (app) infections, 3-week-old specific-pathogen-free (spf) piglets were intranasally infected with prrs virus. one week later, when the lung alveolar macrophages of prrsv infected pigs were lowest in number, a second infection was applied by intranasal aerosol of influenza virus h3n2 or by endobronchial instillation of a m ... | 1997 | 9220621 |
| immunity to prrsv: double-edged sword. | the immune system is a double-edged sword for porcine reproductive and respiratory syndrome virus (prrsv) infection. on one edge prrsv has a predilection for immune cells and the disease manifestations can be linked directly to changes in the immune system. prrsv appears to replicate extensively, if not exclusively, in cells of the immune lineage, notably macrophages; the direct replication of which may lead to immunosuppression, precipitate secondary infection and/or mediate disease. on the oth ... | 1997 | 9220622 |
| field isolates of porcine reproductive and respiratory syndrome virus (prrsv) vary in their susceptibility to antibody dependent enhancement (ade) of infection. | seventeen porcine reproductive and respiratory syndrome virus (prrsv) field isolates, including isolate isu-p, were evaluated for their susceptibility to antibody dependent enhancement (ade) of infection mediated by antibodies raised against prrsv isolate isu-p. progeny virus yields of isu-p and 4 of 16 field isolates in porcine alveolar macrophages (pam) were reduced following treatment with a concentration of antibody that neutralized isu-p (p < 0.01). in contrast, the yields of 12 of 17 field ... | 1997 | 9220623 |
| hematological and immunological parameters of 4 1/2-month old pigs infected with prrs virus. | 4 1/2-month old spf pigs were experimentally infected with prrs virus. blood samples were collected with regular intervals up to day 35 post inoculation (pi). serum was used for prrs virus isolation and antibody detection and stabilized blood for total leucocyte counts, differential counts and characterization of lymphocyte subpopulations by flow cytometry analysis using monoclonal antibodies specific for porcine cd2, cd4 and cd8. after an initial viremic period of 1-7 days duration for individu ... | 1997 | 9220624 |
| diagnosis of prrs. | this paper reviews various diagnostic methods for the detection of porcine reproductive and respiratory syndrome (prrs) virus or antibodies to prrs virus reported during the period from 1991 to 1995. in addition, experience from a european community concerted action and especially danish experiences concerning serological tests are presented. it is concluded that, in general, serological diagnosis with a high specificity and sensitivity is easy to perform on a herd level. however, no serological ... | 1997 | 9220625 |
| indirect fluorescent igm antibody response of pigs infected with porcine reproductive and respiratory syndrome syndrome virus. | igg and igm antibody responses were examined by an indirect fluorescent antibody method in pigs following inoculation with different porcine reproductive and respiratory syndrome virus (prrsv) isolates or a vaccine virus. viremia was also examined in the pigs. the igg antibody was first detected between 9 and 14 days post inoculation (pi) and maintained high titers for at least 7 weeks pi. no change in igg antibody titers was observed when the pigs were reinoculated with prrsv 35 days pi. igm an ... | 1997 | 9220626 |
| epidemiology of porcine reproductive and respiratory syndrome (prrs): an overview. | prrs disease was first recognised in the usa in 1987 and in europe in 1990 and since then the disease has spread widely throughout many pig-producing countries. after a severe epidemic phase, the infection has become endemic. the prevalence of infection is generally high in infected countries. however, in areas with a low density of pigs, infection may spread slowly and if infected animal movements are not significant, farm-to-farm spread can be controlled and prevalence of infection maintained ... | 1997 | 9220627 |
| clinical signs and economic losses caused by porcine reproductive and respiratory syndrome virus in a large breeding farm. | in july of 1994 an acute onset of maternal reproductive failure occurred in a 2,330 sow farrow-to-finish farm. clinical signs observed in the affected sows were typical for porcine reproductive and respiratory syndrome (prrs). during the first 6 weeks of the epizootic 1,117 sows farrowed; 216 (19.33%) farrowed before the 110th day of gestation. the majority of piglets born before term died within a few days of birth and the mortality rate for term piglets increased to a maximum of 75.56% during ... | 1997 | 9220628 |
| studies of porcine reproductive and respiratory syndrome (prrs) virus infection in avian species. | porcine reproductive and respiratory syndrome virus (prrsv) is a recently recognized virus of swine. as a newly emerging virus, much of the basic information regarding prrsv is in the process of discovery. we report three experiments with prrsv in birds, and a fourth experiment to evaluate the infectivity and transmissibility of avian-derived prrsv in swine. experiment 1 compared the susceptibility of muscovy ducks, mallard ducks, guinea fowl, and chickens to prrsv. birds were exposed to prrsv ( ... | 1997 | 9220630 |
| monitoring of porcine reproductive and respiratory syndrome virus infection in boars. | a major concern exists on transmission of porcine reproductive and respiratory syndrome virus (prrsv) via semen and effect of vaccination on prrsv shedding in semen. recent reports suggest that the virus can be transmitted by semen from boars infected experimentally or from natural sources. seminal shedding, viremia, and changes in semen quality in boars with or without vaccination were examined. nine boars were divided into three groups (three boars/group). group i boars were vaccinated with 2 ... | 1997 | 9220631 |
| results of a control programme for the porcine reproductive and respiratory syndrome in the french 'pays de la loire' region. | the porcine reproductive and respiratory syndrome (prrs) virus first entered the pays de la loire region in november 1992, with variable effects ranging from sub-clinical seroconversion to severe reproductive failure and piglet mortality, and significant reduction of daily weight gains in finishing pigs. an epidemiological survey was carried out in february 1993. since the infection prevalence was low (11 infected out of 2310 herds), the pig population was of medium density and the eradication p ... | 1997 | 9220633 |
| efficacy of an inactivated vaccine for prevention of reproductive failure induced by porcine reproductive and respiratory syndrome virus. | this report describes the results of experiments with an inactivated oily vaccine containing per dose about 10(5.5) median tissue culture infectious dose (tcid50) of the spanish strain of porcine reproductive and respiratory syndrome (prrs) virus grown in porcine alveolar macrophages (pams). in order to evaluate the efficacy of the vaccine, two experimental infection routes were tested in sows; subsequent intranasal (i.n.) and intravenous (i.v.) (out of a total of 93 piglets born to 7 sows, 16% ... | 1997 | 9220634 |
| posttranslational processing and identification of a neutralization domain of the gp4 protein encoded by orf4 of lelystad virus. | gp4 is a minor structural glycoprotein encoded by orf4 of lelystad virus (lv). when it was immunoprecipitated from cell lysates and extracellular virus of cl2621 cells infected with lv, it was shown to have an apparent molecular mass of approximately 28 and 31 kda, respectively. this difference in size occurred because its core n-glycans were modified to complex type n-glycans during the transport of the protein through the endoplasmic reticulum and golgi compartment. a panel of 15 neutralizing ... | 1997 | 9223499 |
| evaluation of a blocking elisa for screening of antibodies against porcine reproductive and respiratory syndrome (prrs) virus. | a blocking elisa was developed for the detection of antibodies against prrs virus with a view to satisfying the need for examination of blood samples on a large scale. the test was evaluated in comparison with an indirect elisa and the immunoperoxidase monolayer assay. the blocking elisa was sensitive and specific. it had a higher capacity and was cheaper to perform than the immunoperoxidase monolayer assay and the indirect elisa. it was comparable to the immunoperoxidase monolayer assay and bet ... | 1997 | 9228677 |
| virus quantification and identification of cellular targets in the lungs and lymphoid tissues of pigs at different time intervals after inoculation with porcine reproductive and respiratory syndrome virus (prrsv). | sixteen 6 week old conventional pigs were inoculated by aerosol with a european strain of porcine reproductive and respiratory syndrome virus (prrsv). virus replication was followed by virus titration and immunofluorescence in the lungs and in associated and distant lymphoid tissues at 3, 14, 21, 35, 42 and 82 days post-inoculation (dpi). prrsv replication was detected in alveolar macrophages, lungs, tonsils, spleen, retropharyngeal lymph nodes, bronchial lymph nodes and thoracic aortic lymph no ... | 1997 | 9228678 |
| seroprevalence of porcine reproductive and respiratory syndrome virus in dutch weaning pigs. | to determine whether under dutch field conditions prrsv infection occurs in weaning pigs before the finishing period, a cross-sectional study was performed on 32 breeding farms to estimate the seroprevalence of antibodies directed against prrsv in 4- to 5-week-old and 8- to 9-week-old pigs. farms were visited twice within 5 months, and during each sampling an average of 20 sera were randomly collected from a unit of 4- to 5-week-old and a unit of 8- to 9-week-old pigs. the sera (n = 2568) were t ... | 1997 | 9228679 |
| porcine reproductive and respiratory syndrome virus: routes of excretion. | this study was conducted to delineate potential sites of exit and duration of shedding of porcine reproductive and respiratory syndrome virus (prrsv). two experiments of 6 pigs each were conducted. pigs were farrowed in isolation, weaned at 7 days of age, and housed in individual hepa filtered isolation chambers. in each experiment, 3 pigs served as controls and 3 were inoculated intranasally with prrsv (atcc vr-2402) at 3 weeks of age. in a first experiment, on days 7, 14, 21, 28, 35, and 42 po ... | 1997 | 9231982 |
| comparative study of serological methods for the detection of antibodies to porcine reproductive and respiratory syndrome virus. | a comparison was made of serological diagnostic methods used for the detection of antibodies against porcine reproductive and respiratory syndrome (prrs) virus. in the "phase i" prrs test panel comparison, a panel of sera collected from 135 pigs of various ages, from north american herds with and without prrs histories, were sent to 4 different laboratories and tested by an indirect immunofluorescent assay (ifa), an immunoperoxidase monolayer assay (ipma) and an indirect enzyme-linked immunosorb ... | 1997 | 9242994 |
| macrophages and respiratory viruses. | this review highlights some of the interactions between alveolar macrophages and human/swine influenza a viruses, porcine reproductive and respiratory syndrome virus (prrsv), bovine parainfluenza type-3 (pi-3) virus, bovine respiratory syncytial virus (brsv) and bovine viral diarrhoea virus (bvdv). in influenza a infection, macrophage-cytokines are believed to mediate the typical constitutional effects and inflammation in the respiratory tract. the same cytokines possibly play a role in influenz ... | 1997 | 9247041 |
| immunohistochemical detection of porcine reproductive and respiratory syndrome virus antigen in neurovascular lesions. | | 1997 | 9249181 |
| airborne transmission of actinobacillus pleuropneumoniae and porcine reproductive and respiratory syndrome virus in nursery pigs. | to document airborne transmission of actinobacillus pleuropneumoniae and porcine reproductive and respiratory syndrome virus (prrsv) infection in nursery pigs. | 1997 | 9256964 |
| monoclonal antibodies to the orf5 product of porcine reproductive and respiratory syndrome virus define linear neutralizing determinants. | complementary dna encoding the orf5 gene of a quebec reference isolate (iaf-klop) of porcine reproductive and respiratory syndrome virus (prrsv) was cloned into the prokaryotic expression vectors pgex-4t and pet21a to produce orf5-glutathione s-transferase and orf5-polyhistidine fusion proteins. five hybridoma cell lines producing monoclonal antibodies (mabs) to the 25 kda viral envelope glycoprotein (gp5) were obtained from balb/c mice immunized with the affinity chromatography-purified gst-orf ... | 1997 | 9266981 |
| in vivo replication of porcine reproductive and respiratory syndrome virus in swine alveolar macrophages and change in the cell population in bronchoalveolar lavage fluid after infection. | replication of porcine reproductive and respiratory syndrome (prrs) virus in swine alveolar macrophages (am) and cell population in broncho-alveolar lavage fluid (balf) obtained from prrs virus-infected pigs were investigated. balf samples were periodically collected from 6 pigs infected with prrs virus and 3 non-inoculated control pigs by means of fiber-optic bronchoscope between post-inoculation day (pid) 0 and 56. the mean ratio of macrophages in balf collected from infected group was 92.7 +/ ... | 1997 | 9271447 |
| epitope mapping of the nucleocapsid protein of european and north american isolates of porcine reproductive and respiratory syndrome virus. | two major genotypes of porcine reproductive and respiratory syndrome virus (prrsv) have been described, which correspond to the european and north american isolates. prrsv nucleocapsid (n) protein has been identified as the most immunodominant viral protein. the n genes from two prrsv isolates, olot/91 (european) and québec 807/94 (north american), were cloned and expressed in: (i) baculovirus under the control of the polyhedrin promoter and (ii) escherichia coli using the pet3x system. the n pr ... | 1997 | 9292014 |
| a national serological survey to verify australia's freedom from porcine reproductive and respiratory syndrome. | to provide serological data to support australia's claim of freedom from porcine reproductive and respiratory syndrome. | 1997 | 9293344 |
| effect of heparin on a haemagglutinin of porcine reproductive and respiratory syndrome virus. | heparin inhibited haemagglutination by porcine reproductive and respiratory syndrome virus (prrsv) and by aujesky's disease virus, but failed to inhibit haemagglutination by parainfluenza virus type 3. the minimal inhibitory concentration of heparin required to inhibit 8 ha u of prrsv haemagglutinin ranged from 0.1 to 1 u ml-1. mouse erythrocytes failed to combine with the haemagglutination inhibitory factor of heparin. however, mouse erythrocytes treated with heparinase had greatly reduced aggl ... | 1997 | 9300545 |
| [porcine reproductive and respiratory syndrome: ten years of experience (1986-1996) with this undesirable viral infection]. | porcine reproductive and respiratory syndrome (prrs) is an infectious disease in swine that emerged 10 years ago. today, prrs is endemic in many if not all the pig-producing countries. the syndrome is due to a small enveloped rna virus which belongs to the new arteriviridae group. this group also includes the equine arterivirus and the simian hemorrhagic fever virus. the disease produces many clinical symptoms in pigs of any age but the two major features of the syndrome are respiratory and repr ... | 1997 | 9312328 |
| persistence of porcine reproductive and respiratory syndrome virus in intensive farrow-to-finish pig herds. | an epidemiological study of porcine reproductive and respiratory syndrome (prrs) within pig herds was conducted in 8 intensive farrow-to-finish pig farms. persistence of prrs virus (prrsv) in pig herds was demonstrated by regular postmortem examination on 2 farms for a period of 2 y. virus isolation and serum neutralization (sn) tests were performed on the sera collected from 9 groups of pigs (10 pigs/group) of various ages on 8 pig farms. except for 1 farm, isolation rates of prrsv reached the ... | 1997 | 9342454 |
| performance of elisa antigens prepared from 8 isolates of porcine reproductive and respiratory syndrome virus with homologous and heterologous antisera. | porcine reproductive and respiratory syndrome virus (prrsv) elisa antigens of high quality were produced using 8 different isolates of prrsv: the european lelystad virus (lv), the u.s. mn-1b, 89-46448, 93-44927, and 93-24025b, and the canadian lhva-93-3, pa-8 and gh-6 virus isolates. the performance of each of these 8 antigens and a commercial prrsv antibody test kit (idexx's herdchek) were measured against antisera raised in 5 groups of 6 piglets inoculated with either lv, mn-1b, 89-46448, 93-4 ... | 1997 | 9342455 |
| detection of nucleic acids of porcine reproductive and respiratory syndrome virus in the lungs of naturally infected piglets as determined by in-situ hybridization. | replication of porcine reproductive and respiratory syndrome virus (prrsv) was studied in formalin-fixed paraffin wax-embedded lung tissues from seven naturally infected piglets by in-situ hybridization with a non-radioactive digoxigenin-labelled probe. a 433 base pair cdna probe for the viral rna encoding the nucleocapsid proteins of a korean prrsv isolate was generated by the polymerase chain reaction. all seven piglets infected with prrsv showed a distinct, positive signal, scattered througho ... | 1997 | 9352440 |
| porcine reproductive and respiratory syndrome virus replicates in testicular germ cells, alters spermatogenesis, and induces germ cell death by apoptosis. | like other arteriviruses, porcine reproductive and respiratory syndrome virus (prrsv) is shed in semen, a feature that is critical for the venereal transmission of this group of viruses. in spite of its epidemiological importance, little is known of the association of prrsv or other arteriviruses with gonadal tissues. we experimentally infected a group of boars with prrsv 12068-96, a virulent field strain. by combined use of in situ hybridization and immunohistochemistry, we detected infection b ... | 1997 | 9371575 |
| seroprevalence of antibody to porcine reproductive and respiratory syndrome virus using enzyme-linked immunosorbent assay in selected herds in korea. | | 1997 | 9376439 |
| comparison of four rna extraction methods for the detection of porcine reproductive and respiratory syndrome virus by rt-pcr. | we compared four commercial rna isolation methods for the extraction of rna from porcine reproductive and respiratory syndrome virus (prrsv). the sensitivity of the methods was determined by extraction of rna from serial 10-fold dilutions of prrsv diluted in prrsv-negative porcine serum or in eagle's minimal essential medium (emem) followed by amplification of extracted nucleic acids by rt-pcr. the pcr products were detected in ethidium bromide-stained agarose gels. the qiaamp viral kit, which i ... | 1997 | 9385601 |
| the survival of salmonella anatum, pseudorabies virus and porcine reproductive and respiratory syndrome virus in swine slurry. | the survival of salmonella anatum, pseudorabies virus (prv), and porcine reproductive and respiratory syndrome virus (prrsv) in swine slurry was studied at different temperature (4 degrees c, 25 degrees c, and 37 degrees c) and ph (4.0, 7.0, and 10.0) conditions. the longest survival of s. anatum (56 days) was observed at 4 degrees c and ph 7.0. the pseudorabies and the prrs viruses also survived the longest at 4 degrees c and ph 7.0 but were inactivated within 8 and 14 days, respectively. | 1997 | 9385609 |
| differentiation of north american and european porcine reproductive and respiratory syndrome virus genotypes by in situ hybridization. | non-radioactive probes that can detect specifically north american and european isolates of porcine reproductive and respiratory syndrome virus (prrsv) in formalin-fixed paraffin-embedded tissues by in situ hybridization were developed. these probes allow the differentiation between north american and european genotypes of the prrs virus as well as the detection of both genotypes. two amplified cdna products generated by polymerase chain reaction (pcr), one from the cdna of the canadian prrsv lh ... | 1997 | 9389405 |
| development of a rt-pcr test coupled with a microplate colorimetric assay for the detection of a swine arterivirus (prrsv) in boar semen. | transmission of porcine reproductive and respiratory syndrome virus (prrsv) through boar semen has been demonstrated, stressing the need for a reliable semen prrsv detection test. a diagnostic assay was developed based on amplification of the prrsv rna by reverse transcription and polymerase chain reaction (rt-pcr) followed by detection of the amplification products by hybridization and colorimetric assay in microwell plates. a highly reproducible and efficient method of viral rna isolation from ... | 1997 | 9395141 |
| effect of attenuated erysipelothrix rhusiopathiae vaccine in pigs infected with porcine reproductive respiratory syndrome virus. | twenty 2nd specific pathogen-free pigs were divided into 4 groups: group a were infected with porcine reproductive and respiratory syndrome (prrs) virus at 6 weeks of age and treated with available swine erysipelas and swine fever combined vaccine (vaccinated) at 7 weeks of age; group b were vaccinated at 7 weeks of age and infected with prrs virus at 8 weeks of age; group c were vaccinated at 7 weeks of age: group d were neither vaccinated nor infected with prrs virus. all pigs were challenged ... | 1997 | 9409511 |
| isolation and identification of porcine reproductive and respiratory syndrome virus in cell cultures. | three strains of porcine reproductive and respiratory syndrome virus (prrsv) were isolated in porcine lung macrophage (plm) cultures from three swine herds. this has been the first successful isolation of prrsv in the czech republic and the strains received the designations capm v-501, capm v-502 and capm v-503, respectively. all the three isolates in plm were identified by immunofluorescence and immunoperoxidase tests and the strain capm v-502 also by electron microscopy using the ultrathin sec ... | 1997 | 9416008 |
| infectious transcripts from cloned genome-length cdna of porcine reproductive and respiratory syndrome virus. | the 5'-terminal end of the genomic rna of the lelystad virus isolate (lv) of porcine reproductive and respiratory syndrome virus was determined. to construct full-length cdna clones, the 5'-terminal sequence was ligated to cdna clones covering the complete genome of lv. when rna that was transcribed in vitro from these full-length cdna clones was transfected into bhk-21 cells, infectious lv was produced and secreted. the virus was rescued by passage to porcine alveolar lung macrophages or cl2621 ... | 1998 | 9420236 |
| clinical effects of porcine reproductive and respiratory syndrome virus on pigs during the early postnatal interval. | to determine the effect of congenital and early postnatal infection of pigs with porcine reproductive and respiratory syndrome virus (prrsv) on postnatal survival and growth. | 1998 | 9442243 |
| transplacental infection following exposure of gilts to porcine reproductive and respiratory syndrome virus at the onset of gestation. | twenty-five gilts without measurable porcine reproductive and respiratory syndrome (prrs) virus (prrsv) serum antibody titres were used for this experiment. all of them were randomly assigned to one of the treatment groups at the time of artificial insemination. twelve gilts were exposed to prrsv, of these, six were slaughtered on day 10 after exposure and constituted group a. the remaining six were slaughtered on day 20 after infection and constituted group c. thirteen gilts were used as contro ... | 1997 | 9444067 |
| serological studies on porcine pneumocystis carinii pneumonia: kinetics of the antibody titers in swine herds and the association of porcine reproductive and respiratory syndrome virus infection. | serological titers to pneumocystis carinii (pc) and porcine reproductive and respiratory syndrome virus (prrsv) were measured on a herd with epidemic pc pneumonia (case herd) and two comparison herds, by an indirect fluorescent-antibody technique. in the case herd, the geometric mean titer (gmt) for pc were 1:80 in pigs 1 week old, 1:10 in pigs 5 weeks old, and 1:80 to 1:190 in pigs over 6 weeks old. gmts for prrsv were > 1:145 in most of age groups over 7 weeks old. in comparison herds, pc and ... | 1997 | 9450249 |
| evaluation of the presence of porcine reproductive and respiratory syndrome virus in packaged pig meat using virus isolation and polymerase chain reaction (pcr) method. | an investigation was carried out to assess the potential presence of porcine reproductive and respiratory syndrome virus (prrsv) in packaged pig meat. samples of meat were collected at the processing plants and were sent to the laboratory for testing by virus isolation and reverse transcription-polymerase chain reaction (rt-pcr). samples collected at four plants were randomly selected from lots of packaged pig meat from different slaughtering days and were sent frozen to the laboratory. homogena ... | 1997 | 9451456 |
| homologous challenge of porcine reproductive and respiratory syndrome virus immunity in pregnant swine. | the clinical consequences of single or multiple exposure of pregnant gilts to porcine reproductive and respiratory syndrome virus (prrsv) at various stages of gestation were determined. thirty-three pregnant gilts were allotted to 6 experimental groups (5 to 7 gilts/group). gilts of groups 1 to 5 were exposed to strain nadc-8 of prrsv at the following times: group 1, gestation day (gd) 1; group 2, gds 1 and 90; group 3, gd 30; group 4, gds 30 and 90; group 5, gd 90. virus exposure was by either ... | 1997 | 9453123 |
| duration of homologous porcine reproductive and respiratory syndrome virus immunity in pregnant swine. | the duration of porcine reproductive and respiratory syndrome virus (prrsv) homologous immunity was tested in this study and found to last for at least 604 days post experimental exposure to field prrsv. eleven gilts (group a) received a primary exposure to field prrsv by either an oronasal (n = 6) or an intrauterine (n = 5) route. the gilts were naturally bred at selected times (143 to 514 days) after primary virus exposure. they were oronasally exposed a second time to the same strain of virus ... | 1997 | 9453124 |
| baculovirus expression and immunological detection of the major structural proteins of porcine reproductive and respiratory syndrome virus. | each of the three major structural proteins (envelope glycoprotein e, nonglycosylated membrane protein m, and nucleoprotein n) of an american strain of porcine reproductive and respiratory syndrome virus (prrsv) was expressed using a recombinant baculovirus expression system. insect cells infected with the respective recombinant baculovirus synthesized five distinct forms of glycoprotein e with a molecular mass (m(r)) of either 17, 20, 23, 25 or 26 k, and a single form of nonglycosylated protein ... | 1997 | 9460192 |
| effect of porcine reproductive and respiratory syndrome virus (prrsv) (isolate atcc vr-2385) infection on bactericidal activity of porcine pulmonary intravascular macrophages (pims): in vitro comparisons with pulmonary alveolar macrophages (pams). | porcine pulmonary intravascular macrophages (pims) were recovered by in situ pulmonary vascular perfusion with 0.025% collagenase in saline from six 8-week old, crossbred pigs. pulmonary alveolar macrophages (pams) were recovered by bronchoalveolar lavage from the same pigs for comparisons in each assay. the macrophages were exposed to prrsv (atcc vr-2385) in vitro for 24 h and infection was confirmed by an indirect immunofluorescence test or transmission electron microscopy. viral particles ten ... | 1997 | 9477481 |
| losses due to porcine reproductive and respiratory syndrome in a large swine farm. | the aim of the presented studies was to demonstrate losses and economical consequences of porcine reproductive and respiratory syndrome (prrs) outbreak in a large swine farm in poland. prior to the occurrence of prrs the piglets' mortality rate did not exceed 6%, losses among weaners and fatteners were lower than 3.5% and the percentage of sows that farrowed before term was 1.4%. during the first month after onset of the outbreak 25.6% of sows farrowed before 110 days of pregnancy, the percentag ... | 1997 | 9481519 |
| porcine reproductive and respiratory syndrome virus infection of gnotobiotic pigs: sites of virus replication and co-localization with mac-387 staining at 21 days post-infection. | the organ distribution of prrsv-infected cells in gnotobiotic piglets at 21 days after infection with prrsv isolate vr-2332 was examined by in situ hybridization. cells that expressed prrsv rna were identified in all tissues examined, including organs not usually characterized as sites of prrsv infection. prrsv-infected cells frequently appeared in clusters and were not always associated with microscopic lesions. the expression of prrsv rna co-localized with a macrophage monoclonal antibody, mac ... | 1997 | 9498609 |
| evidence of freedom from porcine reproductive and respiratory syndrome virus infection in switzerland. | | 1998 | 9507649 |
| [respiratory symptoms in meat pigs: is there a role for porcine respiratory corona virus (prcv) and porcine reproductive and respiratory syndrome virus (prrsv) in the etiology?]. | on a pig farm with about 2000 pigs, respiratory problems regularly developed in fattening pigs 3 to 4 weeks after the start of the fattening period. a postmortem examination was carried out on four pigs during the acute phase of their illness. the animals showed signs of viral pneumonia. in two animals porcine respiratory virus (prcv) was discovered and in the other two animals porcine reproductive and respiratory syndrome virus (prrsv). the possible role of these two viruses in the aetiology of ... | 1997 | 9534767 |
| cutaneous and systemic necrotizing vasculitis in swine. | a systemic vasculitis involving particularly the skin and kidneys has been recently described in swine under the name dermatitis/nephropathy syndrome. twelve pigs with gross cutaneous lesions typical of this condition were necropsied, and morphologic, immunohistochemical, microbiologic, and epidemiologic characteristics were studied. the pigs were divided into three groups comprising eight pigs with acute lesions, two with chronic lesions, and two with acute lesions kept for sequential skin biop ... | 1998 | 9539364 |
| porcine reproductive and respiratory syndrome. | in 1987, porcine reproductive and respiratory syndrome (prrs) was recognized in the usa as a new disease of swine causing late-term reproductive failure and severe pneumonia in neonatal pigs. the syndrome is caused by an rna virus referred to as prrs virus (prrsv), which is classified in the family arteriviridae. swine macrophages are the only indigenous cell type known to support prrsv replication. direct contact between infected and naive pigs is the predominant route of prrsv transmission. ex ... | 1998 | 9545131 |
| differentiation between porcine reproductive and respiratory syndrome virus isolates by restriction fragment length polymorphism of their orfs 6 and 7 genes. | three distinct antigenic profiles were identified by comparing the reactivities of 15 canadian field isolates, the attenuated u.s. vaccine (ingelvac mlv) strain and 2 european reference strains (lelystad and weybridge) of the porcine reproductive and respiratory syndrome virus (prrsv) by indirect immunofluorescence with a set of 4 monoclonal antibodies to the nucleocapsid (n) protein and 2 other to the matrix (m) protein. in the present study, 9 canadian isolates for which the sequences were det ... | 1998 | 9553709 |
| identification of a putative receptor for porcine reproductive and respiratory syndrome virus on porcine alveolar macrophages. | to identify the receptor which may determine the macrophage tropism of porcine reproductive and respiratory syndrome virus (prrsv), monoclonal antibodies (mabs) against porcine alveolar macrophages (pam) were produced. two mabs (41d3 and 41d5) which completely blocked prrsv infection of pam were further characterized. it was found that they reduce the attachment of prrsv to pam and immunoprecipitate a 210-kda membrane protein from pam. this protein was detected on the cell membranes of pam but n ... | 1998 | 9557752 |
| comparative sequence analysis of open reading frames 2 to 7 of the modified live vaccine virus and other north american isolates of the porcine reproductive and respiratory syndrome virus. | to elucidate changes associated with the attenuated virulence in a modified live porcine reproductive and respiratory syndrome (prrs) vaccine (boehringer ingelheim animal health, st. joseph, mo), derived from an american prototype atcc virus vr-2332, nucleotide sequence of 3' genome covering open reading frames (orfs) 2 to 7 coding regions from the vaccine virus was determined by rt-pcr with two overlapping fragments. comparisons showed 98 base changes (94 substitutions, 3 deletions, and 1 addit ... | 1998 | 9572560 |
| differentiation of a porcine reproductive and respiratory syndrome virus vaccine strain from north american field strains by restriction fragment length polymorphism analysis of orf 5. | the suitability of restriction fragment length polymorphism (rflp) analysis for differentiating a porcine reproductive and respiratory syndrome virus (prrsv) vaccine strain from other north american field strains was investigated. open reading frame 5 nucleotide sequence data of the vaccine virus, its parent strain vr-2332, and 22 other strains of prrsv included in this study indicated that 3 restriction enzyme gel patterns characterize the vaccine virus and the parent strain genotype. the combi ... | 1998 | 9576340 |
| ultrastructural study of porcine alveolar macrophages infected in vitro with porcine reproductive and respiratory syndrome (prrs) virus, with and without haemophilus parasuis. | two experiments were designed to study ultrastructural changes in porcine alveolar macrophages (pam) inoculated with porcine reproductive and respiratory syndrome (prrs) virus (experiment 1) and with prrs virus and haemophilus parasuis (experiment 2). in both experiments, the viral infectious dose represented a "multiplicity of infection" of 1. viral infection alone induced minimal ultrastructural changes at this dose, consisting only of an increase in lysosome numbers. mixed viral and bacterial ... | 1998 | 9595354 |
| immune response in pigs vaccinated with plasmid dna encoding orf5 of porcine reproductive and respiratory syndrome virus. | the orf5-encoded major envelope glycoprotein (gp5) of porcine reproductive and respiratory syndrome virus (prrsv) is one of the three major structural proteins of this virus. while some porcine convalescent sera and monoclonal antibodies directed against gp4 and gp5 have the capacity to neutralize the virus in vitro, the protein specificity of porcine neutralizing sera has not yet been established. dna immunization with a plasmid encoding gp5 of prrsv, under the control of a human cytomegaloviru ... | 1998 | 9603313 |
| porcine dermatitis and nephropathy syndrome in spain. | in august 1995, the first case of porcine dermatitis and nephropathy syndrome was diagnosed in the north-eastern part of spain; the pig showed characteristic dermal and renal lesions. between then and january 1996, nine further animals from five different herds were diagnosed; they showed signs of anorexia, depression and, sometimes, pyrexia. diarrhoea, glässer's disease, conjunctivitis and gastric ulcers also occurred on the farms where the diagnoses were made. the affected pigs died of renal f ... | 1998 | 9612914 |