| properties of border disease virus as studied in a sheep cell line. | a fetal lamb muscle cell line has been isolated in which two strains of border disease virus replicate well and induce a clear-cut cytopathic effect, thus providing a sensitive and practical assay system for both the virus and neutralizing antibodies. this system enabled us to study some characteristics of border disease virus in comparison with two other agents responsible for hog cholera and bovine viral diarrhea. our results indicate that the last virus and the border disease agent are indist ... | 1979 | 94539 |
| the distribution of antibodies to border disease virus among sheep in england and wales. | within a sample of the sheep population of england and wales, 10.8 per cent of 3506 individuals had immunodiffusion test antibody to bovine viral diarrhoea mucosal disease virus antigen. there were marked differences between various geographical regions in the proportion of sheep with antibody, and border disease may be more common in some areas than disease records indicate. | 1978 | 214835 |
| border disease: persistant infection with the virus. | two genetically related sheep that produced border disease-affected lambs from successive pregnancies were identified. these sheep, and some of their progeny, were found to be persistently infected with a virus antigenically related to bovine virus diarrhoea/mucosal disease virus. only one of the sheep developed detectable serum antibody to the virus, and this animal only produced it 12 months after being detected as infected. the epidemiological significance of sheep persistently infected with ... | 1979 | 225856 |
| border disease: a sequential study of surviving lambs and an assessment of its effect on profitability. | pregnant dorset horn gimmers inoculated with a non-cytopathic strain of the border disease virus produced "hairy shaker" lambs that were individually affected to a varying degree. surviving lambs were observed for a period of up to 20 weeks when neurological signs were seen to gradually disappear. during this time live virus was isolated from a wide variety of sites in nearly all of the infected lambs. the infected animals grew at a significantly slower rate compared with the controls, particula ... | 1979 | 473556 |
| protection of piglets born from ruminant pestivirus experimentally infected sows, and their contacts, to the challenge with hog cholera virus. | two groups, a and b, of two specific pathogen-free pregnant sows were experimentally infected between the 25th and 29th days post-breeding with two strains of ruminant pestivirus: nadl cytopathic bovine viral diarrhoea virus for group a and aveyron non-cytopathic border disease virus french strain for group b. two other pregnant sows (group c) were kept uninoculated as control. when 7 weeks old, 8 piglets of group c were put in contact with 4 piglets of group a (group d), and 8 other piglets of ... | 1992 | 1324630 |
| the production and survival of lambs persistently infected with border disease virus. | from 1985 to 1989 lambs persistently infected with border disease virus (bdv) were produced for comparative immunological studies by infecting 57 susceptible pregnant ewes between 50 and 60 days' gestation with moredun or oban strains of bdv. ewes were infected either by injection with virus grown in cell culture or by housing with lambs excreting bdv. there was no significant difference in the outcomes of these different methods of infection. there was a significant difference in the number of ... | 1992 | 1325333 |
| pestivirus is a common contaminant in maedi-visna and caprine arthritis-encephalitis virus stocks. | eight different laboratory stocks of maedi-visna or caprine arthritis-encephalitis virus were examined for the presence of pestiviruses by a fixed-cell immunoperoxidase assay with polyclonal and monoclonal antibodies. all of the viral stocks examined were found to contain noncytopathic pestivirus contaminants. the panel of monoclonal antibodies could not type the isolates as being more related to bovine virus diarrhea virus or border disease virus. however, the results did indicate that all isol ... | 1992 | 1335836 |
| toxoplasmosis and border disease in 54 swedish sheep flocks. seroprevalence and incidence during one gestation period. | serum samples from 704 animals from 54 swedish sheep flocks were analysed by elisa twice during 1 breeding season for antibodies to toxoplasma gondii and border disease virus (bdv). an elisa, originally developed for the detection of antibodies to bovine viral diarrhoea virus (bvdv) in cattle, was assessed on sheep sera and the results were compared with those obtained in a virus neutralization test. the correlation between the 2 assays proved good. before breeding, 132 (19%) sheep in 42 flocks ... | 1992 | 1503001 |
| cell phenotypes in the efferent lymph of sheep persistently infected with border disease virus. | the prefemoral efferent lymphatics of sheep persistently infected (pi) with border disease virus (bdv) were cannulated in order to study the effects of the virus on cells of the immune system. efferent lymphocytes recovered from pi sheep were phenotyped using a panel of monoclonal antibodies (moab) specific for ovine cell-surface markers and compared to lymphocytes recovered from normal, healthy controls. pi sheep had an increased percentage of cells expressing the t cell-associated molecules cd ... | 1992 | 1544225 |
| detection of cattle infected with bovine viral diarrhea virus using nucleic acid hybridization. | a ribonucleic acid (rna) hybridization assay to identify cattle infected by bovine viral diarrhea virus (bvdv) is described. the rna probe was derived from the coding region at the 3' end of the genome of the nadl strain of bvdv. total rna from infected cell cultures or peripheral blood leukocytes from suspect animals was extracted and applied to nylon membranes with a slot blot apparatus. peripheral blood leukocytes were tested concurrently for bvdv by virus isolation. the results of hybridizat ... | 1991 | 1645592 |
| a monoclonal antibody capture elisa to detect antibody to border disease virus in sheep serum. | an enzyme-linked immunosorbent assay (elisa) has been developed to detect antibody to border disease virus (bdv) in sheep serum. a monoclonal antibody bound to 96-well microplates was used to capture antigen from detergent-solubilised bdv-infected cells. single dilutions of test sera were then added to wells containing bound bdv antigen and control wells containing uninfected cell lysates. specific antibody to bdv was detected by an anti-ovine igg antiserum conjugated with horseradish peroxidase ... | 1991 | 1659026 |
| cytopathic and non-cytopathic biotypes of border disease virus induce polypeptides of different molecular weight with common antigenic determinants. | ten monoclonal antibodies have been raised against lysates of cells infected with cytopathic border disease virus (bdv). these antibodies all recognize non-cytopathic bdv and react with a number of different strains of bovine viral diarrhoea virus (bvdv). studies with radiolabelled cell lysates show that all the antibodies precipitate two polypeptides of apparent mr 80,000 and 130,000 from cells infected with cytopathic virus and a single polypeptide of apparent mr 120,000 from cells infected wi ... | 1990 | 1693167 |
| alterations in lymphocyte subpopulations in peripheral blood of sheep persistently infected with border disease virus. | fourteen sheep persistently infected with border disease virus were investigated to examine the effects of persistent viraemia on lymphocyte subpopulations in peripheral blood and their responses to the mitogen phytohaemagglutinin (pha) in vitro. persistently infected sheep had significantly more cd8+ (cytotoxic-suppressor) t-lymphocytes than uninfected sheep of the same age (p less than 0.001). the total number of cd4+ (helper) t-lymphocytes were not significantly different but there were more ... | 1990 | 1693799 |
| immunocytochemical localization of border disease virus in the spinal cord of fetal and newborn lambs. | the peroxidase-antiperoxidase technique was used to determine the cellular localization of border disease (bd) virus in cryostat sections of fetal and newborn lamb spinal cord following experimental infection by maternal inoculation in early gestation. viraemic fetuses and lambs with hypomyelinogenesis showed bd viral antigen in neurons, glia, ependymal cells, vascular endothelial cells and fibrocytes within the dura mater. double immunolabelling demonstrated co-expression of bd viral antigen an ... | 1990 | 1710789 |
| genetic comparison of ovine and bovine pestiviruses. | viral rna oligonucleotide fingerprinting was used to compare genetic relationship among pestiviruses originating from ovine or bovine host species. ovine pestiviruses, including reference border disease virus and 2 border disease isolates originating from natural pestivirus infections of sheep, appeared to have a more distant genetic relationship among themselves than with certain bovine pestiviruses. a closer genetic relatedness was evident between border disease virus and 3 noncytopathic bovin ... | 1990 | 1964772 |
| pestivirus infections in ruminants other than cattle. | pestiviruses infect a wide range of domestic, captive and free-living ruminants. among domestic livestock, border disease virus is a well recognised cause of an important congenital disease of sheep in virtually all sheep-rearing countries of the world. the clinical signs, pathogenesis, diagnosis, epidemiology and control of this disease are described in detail. one natural outbreak of border disease in domestic goats has been described and there is serological and virological evidence that pest ... | 1990 | 1966719 |
| bovine virus diarrhoea virus: speculation and observations on current concepts. | this final chapter highlights the advances and some of the unanswered questions concerning bovine virus diarrhoea virus (bvdv) presented in this review by specialists from around the world. persistently viraemic cattle play an essential role in the dissemination of bvdv but it is suggested that acute infections with the virus are also important. the role of latency is considered but, as yet, there is no evidence that it plays a part in pathogenesis. it is well established that bvdv, border disea ... | 1990 | 1966724 |
| an elisa for detecting pestivirus antigen in the blood of sheep persistently infected with border disease virus. | a monoclonal antibody capture enzyme-linked immunosorbent assay (elisa) has been developed to detect a pestivirus-specific antigen in leucocytes of sheep persistently infected with border disease virus. a blind trial was conducted to compare the specificity of the elisa with conventional tissue culture virus isolation on blood samples from 58 sheep, aged 3 to 48 months. there was total agreement between the two tests; 27 sheep were shown to be bdv-infected. the elisa od values of the positive sa ... | 1990 | 2157728 |
| intracellular virus-induced polypeptides of pestivirus border disease virus. | intracellular virus specific polypeptides of pestivirus, border disease virus (bdv) in bovine turbinate cells were analysed by radio-immunoprecipitation with specific antisera. eleven viral polypeptides with molecular weights of 220, 165, 118, 84, 66, 58, 55, 53, 45, 37 and 31 kda, respectively, were detected in infected cells. of these, the 165, 118, 84, 66, 58, 55, 53, 45 and 31 kda proteins were found to be glycosylated. comparative studies indicated that the polypeptides induced by bdv share ... | 1990 | 2161595 |
| a blocking elisa to differentiate hog cholera virus antibodies in pig sera from those due to other pestiviruses. | the blocking elisa technique was extended to comparative serology by using 3 different pestivirus strains: hog cholera virus (hcv) alfort strain propagated in pk15 cell line, border disease virus (bdv) aveyron strain in pk15 and bvd nadl** strain in fetal calf kidney (fck) primary cells. rabbit antisera to the alfort hcv strain and aveyron bdv strain were raised for use in the test. a bovine hyperimmune serum to bvd virus was also used for detecting antibodies specific to bvd virus. the elisa wa ... | 1990 | 2163232 |
| antigenic comparisons of hog cholera virus isolates from europe, america and asia using monoclonal antibodies. | nineteen monoclonal antibodies (mabs) with specificity for hog cholera virus (hcv) were prepared. they were used in an immune binding (peroxidase linked) assay to determine the reaction patterns of hcv isolates from europe, brazil, usa, japan and malaysia, as well as laboratory reference strains of the virus. a further panel of 17 mabs raised against bovine virus diarrhoea virus (bvdv) was included in the study, together with 5 mabs raised against a non-hcv pestivirus of porcine origin. all the ... | 1990 | 2178905 |
| border disease. virus-induced decrease in thyroid hormone levels with associated hypomyelination. | border disease (bd) was induced in lambs by inoculation of their dams at 50 days gestation with border disease virus (bdv) isolate #31. at birth, the clinically affected lambs had diffuse spinal cord hypomyelination, confirmed by immunocytochemical staining for myelin-associated glycoprotein and myelin basic protein. in the bd lambs, large numbers of thyroid follicular epithelial cells and scattered pituitary cells contained bdv antigen by immunofluorescence staining. double labeling techniques ... | 1987 | 2441139 |
| comparative analysis of monoclonal antibodies against pestiviruses: report of an international workshop. | thirty-three pestivirus strains were grown in cell culture and characterized by immunostaining with 19 monoclonal antibodies (mabs) raised against hog cholera virus (hcv), with 42 mabs against bovine viral diarrhoea virus (bvdv) and with 13 mabs against border disease virus (bdv). seven mabs reacted with all pestivirus strains tested, eight mabs detected only the seven hcv strains, three detected only the 16 bvdv strains. no mab was found that was specific for bdv. bvdv and bdv strains were broa ... | 1989 | 2549680 |
| characterization of porcine and some ruminant pestiviruses by cross-neutralization. | serologic relationships between 11 pestivirus strains that originated from pigs and five that originated from cattle or sheep were studied by cross-neutralization. experiments were performed with pig and sheep sera raised against the strains. the results were analysed by a computerized taxonomic procedure. the 16 viruses were classified into four distinct serologic groups. all hog cholera virus (hcv) strains were classified in one group; the other three groups consisted of strains that can infec ... | 1989 | 2552645 |
| modulation of the cellular immune responses to t-cell-dependent and t cell-independent antigens in lambs with induced bovine viral diarrhea virus infection. | functional interaction between lymphoid cells and lymphotropic viruses is particularly evident for bovine viral diarrhea virus (bvdv) in cattle and its closely related virus, the border disease virus (bvdv) in sheep. the most important aspect of acute or chronic phases of bvdv or bdv infection was the host's increased susceptibility to secondary bacterial or viral infection. to study the ability of bvdv to alter the development of the cellular immune responses to concomitant inoculation with t c ... | 1989 | 2552879 |
| antigenic differentiation of pestivirus strains with monoclonal antibodies against hog cholera virus. | thirty-one bovine viral diarrhoea virus (bvdv) or border disease virus (bdv) strains and 94 hog cholera virus (hcv) strains were grown in cell culture, and characterized by immunostaining with 13 monoclonal antibodies (mabs) and one polyclonal serum (pab) against hcv. all 125 strains were recognized by the pab. none of the bvdv or bdv strains were detected by the 13 mabs. seven mabs detected all 94 hcv strains. six other mabs detected heterogeneity among and within hcv strains. the mabs are usef ... | 1989 | 2560281 |
| serologic examination of aborted ovine and bovine fetal fluids for the diagnosis of border disease, bluetongue, bovine viral diarrhea, and leptospiral infections. | fetal serum from most of 994 bovine and 553 ovine aborted fetuses was tested serologically for antibodies to border disease (bd), bovine viral diarrhea (bvd), and bluetongue (bt) viruses, and to leptospira sp., and the results were compared with the results of isolation procedures, fluorescent antibody tests (fat), and histologic examinations of the same fetuses. antibodies to bt virus were not found in any of the 994 bovine and 553 ovine fetuses. antibody titers to bvd virus were present in 39 ... | 1989 | 2562192 |
| lymphocyte subpopulations in the blood of sheep persistently infected with border disease virus. | the surface phenotypes of peripheral blood lymphocytes in groups of lambs and adult sheep persistently infected with border disease virus (p-i bd) were compared with those of healthy controls. the proportion and number of lymphocytes bearing surface immunoglobulin (sig+) and expressing class ii mhc antigen (b cells) were significantly increased. a significant increase in cd1+ lymphocytes was also evident. conversely, the proportion of t lymphocytes in p-i bd lambs was reduced. a marked reduction ... | 1989 | 2787717 |
| the ultrastructure of cell cultures infected with border disease and bovine virus diarrhoea viruses. | the morphology of border disease virus and bovine virus diarrhoea virus in infected bovine embryonic testis cells was examined by electron microscopy. particles which appeared to be mature virions of both viruses were similar, being roughly circular and approximately 46 nm in diameter with a 20 to 25 nm core. virus replication took place totally within the cytoplasm in association with structures formed from modified endoplasmic reticulum. | 1987 | 2821174 |
| bovine viral diarrhoea virus infections in piglets born to sows vaccinated against swine fever with contaminated vaccine. | on eight farms a congenital pestivirus infection in piglets was detected which could be traced to vaccination of the dams against swine fever (sf). viruses isolated from the piglets were not recognised by monoclonal antibodies (mcas) against swine fever virus (sfv) and were shown to be bovine viral diarrhoea virus (bvdv) or border disease virus. the expected 'chinese' strain of sfv could not be demonstrated in the batch of vaccine that had been used on these farms. instead, a contaminating pesti ... | 1988 | 2848299 |
| some antigenic and cultural properties of border disease and bovine viral diarrhoea viruses. | in vitro comparison of the replication cycles of three strains of border disease virus and one strain of bovine viral diarrhoea virus showed similar growth curve patterns and a tendency of cell-free virus to exceed cell-associated virus. each virus was antigenically distinguishable from the others in cross-neutralisation tests. | 1986 | 3012858 |
| experimentally induced ovine border disease: extensive hypomyelination with minimal viral antigen in neonatal spinal cord. | border disease (bd) was experimentally induced in 9 lambs by inoculation of their dams with the bd-31 strain of border disease virus (bdv) at 50 days of gestation. these ewes developed serum-neutralizing antibody titers to bdv. the diagnosis of bd in their lambs was confirmed by hairy birthcoats, intrauterine growth retardation, tremors, and hypomyelination. three clinically healthy age-matched control lambs, whose dams had been given an inoculum containing only bdv-free cell culture supernatant ... | 1987 | 3032028 |
| enzyme-linked immunosorbent assay for the detection of antibodies to bovine virus diarrhea virus in sera from border disease virus-infected sheep. | an enzyme-linked immunosorbent assay (elisa) was established for the rapid detection of specific antibodies against the causative agent of border disease in ovine sera. polyethylene-glycol concentrated, equilibrium density gradient purified bovine virus diarrhea virus was used as test antigen. the optimal amount of antigen was 0.5 microgram/well, and the optimal concentration of conjugate was at 1/4,000 dilution. a total of 20 ovine serum samples, which had been collected from animals with or wi ... | 1987 | 3038292 |
| disease outbreak investigation. three case studies. | three case studies of the investigation of outbreaks of disease or deviations from target performance are presented. the first is a study of a mastitis problem in a dairy herd, made evident by increased somatic cell counts. the pattern of the production problem is carefully analyzed and conclusions are reached that indicate an infection with environmental contaminant organisms, thus permitting control measures to be introduced. the second case study is an investigation of an outbreak of neonatal ... | 1988 | 3259458 |
| border disease without nervous signs or fleece changes. | a natural infection with border disease virus occurred in a flock on low ground in argyll in the spring of 1984. the outbreak was unusual in that the typical clinical signs of border disease, ie, tremor and, or, fleece changes were not present; manifestations of disease were restricted to abortion and the birth of small weak lambs. the disease was shown to have been introduced to the flock by four healthy ewes persistently infected with border disease virus among a group of 39 purchased in octob ... | 1987 | 3576934 |
| tropism of border disease virus for oligodendrocytes in ovine fetal brain cell cultures. | primary dissociated ovine brain cell cultures prepared from 50- or 140-day-old fetuses were inoculated with border disease virus (bdv). the cells present in the cultures were identified, using immunofluorescence procedures and sera against various cns cell-specific markers. these markers were glial fibrillary acidic protein, myelin basic protein, myelin-associated glycoprotein, neuron-specific enolase, neurofilament protein, and fibronectin. double-labeling immunofluorescence techniques for visu ... | 1987 | 3592384 |
| multiple neural cell types are infected in vitro by border disease virus. | border disease (bd) of sheep results from a congenitally acquired nonarbotogavirus infection which causes a highly selective central nervous system (cns) pathological lesion consisting of diffuse decreased myelination without inflammation or neuronal destruction. thus, a selective disruption of oligodendroglial function appears to occur. in order to investigate the in vitro cell tropism of bd virus, primary cultures derived from fetal and adult ovine cns and peripheral nervous system were inocul ... | 1987 | 3655836 |
| serologic survey of viral antibodies in the peruvian alpaca (lama pacos). | sera from more than 100 alpacas (lama pacos) from the peruvian southern sierra were examined for antibodies to 8 viruses known to infect other domestic animals. on the basis of these serologic findings and previously published serologic or clinical data, it is now known that the alpaca can be infected with the following viruses: parainfluenza-3, bovine respiratory syncytial virus, bovine herpesvirus-1, bluetongue virus, border disease virus, influenza a virus, rotavirus, rabies virus, vesicular ... | 1987 | 3826854 |
| viral persistence and abnormalities of the central nervous system after congenital infection of sheep with border disease virus. | lambs congenitally infected with border disease (bd) virus and sheep exposed to bd virus as adults were studied for one year to determine the pathogenesis of congenital exposure compared with adult exposure to the virus. persistent bd virus was isolated in tissue culture and detected by immunofluorescence of the peripheral white blood cells, urine, and cerebrospinal fluid of lambs with congenital bd up to one year of age. these animals had no detectable serum neutralizing antibody response to th ... | 1985 | 3881541 |
| the effects of challenge with homologous and heterologous strains of border disease virus on ewes with previous experience of the disease. | | 1980 | 6248575 |
| persistence in tissues of border disease virus antigen demonstrable by immunofluorescence. | | 1980 | 6265994 |
| border disease: virus persistence, antibody response and transmission studies. | three groups of five and one group of four oestrus-synchronised sheep were inoculated with border disease (bd) virus at 52 +/- 2 days after their first service. transmission of virus to offspring as demonstrated by virus isolation, detection of viral antigen and, or antibody response occurred in 12 of 19 sheep and probably in four others which aborted or produced stillborn lambs. both apparently normal and clinically affected animals excreted virus in saliva, urine and faeces, and excretion and ... | 1981 | 6265995 |
| border disease virus isolation from postpartum ewes. | the prevalence of border disease virus in a flock of targhee sheep in southern idaho was determined by serologic and virologic techniques. of 249 ewes, 73 (29%) were seropositive to the antigenically related togavirus, bovine seropositive to the antigenically related togavirus, bovine viral diarrhea virus (bvdv). concurrent testing of sera from 337 neonatal lambs indicated that 172 (51%) were seropositive for bvdv. it was observed that a high percentage (35%) of the bvdv-seropositive lambs were ... | 1982 | 6283955 |
| border disease virus infection of the newborn lamb. | | 1983 | 6301617 |
| the pathology of a spontaneous and experimental mucosal disease-like syndrome in sheep recovered from clinical border disease. | the pathological changes which accompanied a severe clinical syndrome characterized by intractable diarrhoea and/or respiratory distress in sheep recovered from clinical border disease consisted of inflammatory lymphoproliferative lesions in several organs, notably the cns and intestinal tract. the syndrome has been reproduced experimentally by "super-infection" with homologous border disease virus. the differential diagnosis is discussed and attention drawn to the similarity between the enteric ... | 1983 | 6309922 |
| congenital infections with nonarbo togaviruses. | the present review deals with the similarities and differences of selected aspects of prenatal pestivirus infections of domestic animals and congenital rubella of man. hog cholera virus, bovine virus diarrhoea virus and border disease virus are antigenically closely related, but unrelated to rubella virus. the nonarbo togaviruses are capable of producing congenital infections resulting in a wide spectrum of abnormalities. the infected foetus can die in utero, in the neonatal period, or it may be ... | 1983 | 6314636 |
| border disease virus isolation from postpartum ewes. | | 1982 | 7103215 |
| [purchase of sheep and the bvd-risk connected with it]. | | 1995 | 7482480 |
| rapid characterization of new pestivirus strains by direct sequencing of pcr-amplified cdna from the 5' noncoding region. | reverse transcription coupled with the polymerase chain reaction (rt-pcr) was used for the rapid laboratory diagnosis of pestivirus infections. a direct dna sequencing method was developed for the analysis of the amplified cdna from the 5' noncoding region of the viral genome. 70 pestivirus strains were compared in this study. sequence analysis allowed the characterization of each isolate as either classical swine fever virus (csfv), bovine viral diarrhea virus, or border disease virus, respecti ... | 1994 | 7529990 |
| effects of congenital infection of sheep with border disease virus on myelin proteins. | border disease (bd) of sheep is caused by a virus in the genus pestivirus that results in decreased myelination throughout the cns when acquired congenitally. pregnant ewes were inoculated with bd virus at 50 days of gestation, and myelin proteins were quantified in several regions of the cns during prenatal and postnatal development of infected lambs for comparison with age-matched controls. newborn field-infected lambs were also examined. myelin basic protein (mbp), proteolipid protein (plp), ... | 1993 | 7693867 |
| a double monoclonal antibody elisa for detecting pestivirus antigen in the blood of viraemic cattle and sheep. | a panel of monoclonal antibodies (mabs) has been produced to the p125/p80 non-structural polypeptide of border disease virus (bdv) and bovine virus diarrhoea virus (bvdv). this polypeptide appears to be highly conserved among bdv and bvdv isolates and consequently the mabs directed against it have a broad cross-reactivity with pestivirus isolates. the epitope specificities of these mabs were determined by competitive binding and four of the mabs with mutually exclusive epitope specificities were ... | 1995 | 7716885 |
| a proposed division of the pestivirus genus using monoclonal antibodies, supported by cross-neutralisation assays and genetic sequencing. | sixty-six pestiviruses from ruminant and porcine hosts were analysed with a panel of 76 monoclonal antibodies raised against 9 different viruses. reactivity was used to construct epitope similarity maps for all of the viruses. four principal virus subgroups were demonstrated. one subgroup equated to classical swine fever virus (csfv) and included most porcine pestiviruses but none from ruminants. a second subgroup contained mainly viruses of bovine origin, including reference bovine viral diarrh ... | 1995 | 7735309 |
| further characterization of border disease virus isolates: evidence for the presence of more than three species within the genus pestivirus. | the molecular analysis of three ovine pestivirus strains revealed the existence of two distinct groups of sheep-derived pestiviruses, namely "true" border disease virus strains (bdv) and bovine viral diarrhea virus (bvdv)-like strains. as an extension of these studies rt-pcr and nucleotide sequencing of the autoprotease (npro) and nucleocapsid protein (c) encoding regions of additional serologically defined ovine pestivirus strains were performed. a comparison of npro and c revealed that three o ... | 1995 | 7747470 |
| congenital infection of pigs with ruminant-type pestiviruses. | congenital infections of pigs were induced with two ruminant-type pestiviruses isolated from pigs. one of the viruses was bovine viral diarrhoea virus-like and the other border disease virus-like. both produced symptoms similar to those observed with low virulence strains of classical swine fever virus. a striking effect of persistent virus infection in post-natal life was stunting in viraemic animals. it was also shown that a congenitally infected pig shed virus for 2.5 years and in sufficient ... | 1994 | 7806701 |
| distribution of border disease virus antigen in lymphocyte subpopulations in the peripheral blood of experimentally infected lambs. | ten lambs were experimentally infected with border disease virus and the distribution of viral antigen in lymphocyte subpopulations studied by flow cytometry. the virus was isolated in culture from the peripheral blood mononuclear cells (mnc) of all experimentally infected lambs for a mean period of 9.8 +/- 1.03 days. the peak virus titre of 3.26 log10 tcid50 per 10(6) mnc was attained day 9 post-inoculation (pi). viral antigen was present in peripheral blood lymphocytes of experimentally infect ... | 1994 | 7856073 |
| cytotoxic t cell responses in lambs experimentally infected with border disease virus. | mononuclear cells cytotoxic to a noncytopathic strain of border disease virus (bdv) but not to uninfected cells were detected in the peripheral blood of experimentally infected lambs, 10 days after experimental infection, reaching peak levels of cytotoxicity 15 days post-inoculation. the specificity of the cytotoxic activity to bdv-infected cells was tested by including autologous targets infected with another virus (bovine respiratory syncytial virus, brsv) and normal uninfected autologous targ ... | 1994 | 7941304 |
| border disease virus antigens in lymphocyte subpopulations in the peripheral blood of persistently infected sheep. | biotinylated virus-specific antibodies were used to detect border disease virus antigen by flow cytometry in the mononuclear cells of the peripheral blood of 15 sheep persistently infected with border disease virus. the viral antigen was present in 12.86 +/- 4.65% (mean +/- sd) of mononuclear cells (mnc). the percentage of mnc that contained viral antigen was higher in lambs than in adult sheep, with mean rates of 22.68 +/- 5.02% and 11.65 +/- 4.39%, respectively. depletion methods were used to ... | 1994 | 7975185 |
| border disease virus: delineation by monoclonal antibodies. | many ovine pestiviruses from britain and a number of atypical porcine isolates are largely unrecognised by monoclonal antibodies (mabs) specific for reference strains of classical swine fever virus and bovine viral diarrhoea virus (bvdv). additional mabs have therefore been produced using some of these "unreactive" pestiviruses. two of the viruses used were atypical porcine isolates (strains 87/6 and vosges), whilst another had been isolated from a sheep (59386). thirty-three mabs were selected, ... | 1994 | 7979965 |
| nucleotide sequence analysis of the structural gene coding region of the pestivirus border disease virus. | border disease virus (bdv) of sheep, an important ovine pathogen, is serologically related to the two other well characterized members of the pestivirus genus of the flaviviridae family, namely bovine viral diarrhea virus (bvdv) and hog cholera virus (hocv). to determine its genetic relationship to bvdv and hocv, the genome of bdv strain, bd-78 encompassing the 5' untranslated region (utr) and structural gene coding region was molecularly cloned and the nucleotide sequence determined. the sequen ... | 1994 | 7985409 |
| [bovine virus diarrhea/mucosal disease: a review]. | infections with the bovine viral diarrhea/mucosal disease virus (bvdv) are widespread and cause a variety of diseases including reproductive disorders, abortion and malformation, pneumoenteritis, thrombocytopenia and mucosal disease. together with the closely related border disease virus of sheep (bdv) and european swine fever virus (csfv), also referred to as hog cholera virus, bvdv is now classified in the genus pestivirus of the flaviviridae family. the bvdv exists in two biotypes, noncytopat ... | 1994 | 8036482 |
| persistent pestivirus infection in sheep in apulia (southern italy). | a study in a flock of 100 sheep was carried out to detect animals persistently infected with border disease virus (bdv). from buffy coats of animals without neutralizing antipestivirus antibodies, 6 non cytopathic pestiviruses were isolated in cell cultures. using 3 monoclonal antibodies, the 6 viruses were initially characterized as bdv strains. | 1994 | 8065275 |
| prevalence of border disease virus infection in a small group of canadian sheep. | | 1994 | 8069842 |
| [clinical aspects and diagnosis of border disease]. | the term border disease (bd) refers to a clinical condition of newborn lambs that results from congenital infection by a pestivirus (family: flaviviridae), occurring during the first one-half of gestation. the most prominent clinical features are tonic-clonic tremors and hairy fleece ("hairy shaker" symptomatology). moreover early transplacental infection often causes fetal death, abortion or stillbirth and teratogenic disorders. in germany there are only few reports on clinical cases of bd, how ... | 1994 | 8165658 |
| replication of border disease virus in ovine lymphocytes and monocytes in vitro. | adherent and non-adherent mononuclear cells obtained from the peripheral blood of normal sheep supported the in vitro replication of a non-cytopathic and a cytopathic strain of border disease virus (bdv) with no apparent cytopathic effects. there was a significant rise in virus titres in adherent mononuclear cells (monocyte) and non-adherent (lymphocyte) cultures infected with both non-cytopathic and cytopathic strains of bdv 24 hours after inoculation. peak virus titres of 5.36 log10 tcid50 ml- ... | 1994 | 8191010 |
| effects of experimental infection with border disease virus on lymphocyte subpopulations in the peripheral blood of lambs. | experimental infection with border disease virus was characterised by significant changes in the total numbers of leucocytes and neutrophils, and in the proportions and numbers of the different lymphocyte subpopulations. three days after experimental infection there was significant leucopenia due to lymphocytopenia and neutropenia (p < 0.001). the lymphocytopenia and neutropenia lasted for up to seven days after inoculation. the lymphocytopenia was due to a reduction in the number of both t cell ... | 1994 | 8191011 |
| lymphocyte responses to viral antigens and phytohaemagglutinin in persistently viraemic sheep and lambs experimentally infected with border disease virus. | lymphocytes obtained from lambs 5 to 21 days after experimental infection with border disease virus (bdv) showed significant blastogenic responses to live or inactivated bdv. live virus stimulated significantly higher lymphocyte transformation (lt) responses than inactivated virus. lymphocytes obtained from uninfected control and persistently infected lambs had no significant response to live or inactivated antigen. lymphocyte responses to phytohaemagglutinin were significantly higher in control ... | 1994 | 8203131 |
| border disease virus transmitted to sheep and cattle by a persistently infected ewe: epidemiology and control. | in a swedish sheep flock comprising 202 ewes and 13 rams, a pair of twin lambs born in the spring of 1990 demonstrated signs of border disease (bd) and were persistently infected (pi) with border disease virus (bdv). investigation showed that bdv had been introduced in the preceding tupping period 5-6 months earlier by a bought-in ewe which, on the basis of immunoperoxidase- and polymerase chain reaction techniques, was shown to be pi with bdv. only 7 of the ewes, all of which had been in close ... | 1994 | 8209823 |
| the nucleotide sequence of the 5'-untranslated region of bovine viral diarrhoea virus: its use as a probe in rapid detection of bovine viral diarrhoea viruses and border disease viruses. | a 289 bp cdna fragment from the 5'-untranslated region (utr) of 16 bovine viral diarrhoea virus (bvdv) isolates was amplified by reverse transcription and polymerase chain reaction, and sequenced by dideoxy dna sequencing. the sequence showed greater than 90% homology between the isolates and bvdv nadl in this region, and greater than 97% homology within a 72 base sub-region (nt 314-386). the 289 bp fragment was then used as a probe for rapid detection of bvdv and border disease virus (bdv) from ... | 1993 | 8264668 |
| arachidonic acid immunoregulation in lambs persistently infected with border disease virus. | to evaluate arachidonic acid-related immunoregulatory mechanisms during long-term persistent pestivirus infection, we measured plasma contents of leukotriene c4 (ltc4), prostaglandin d2 (pgd2) and their plasma fatty acid (fa) precursor, arachidonic acid (aa), in six lambs with congenital border disease (bd). significantly elevated average plasma ltc4 during the first half year of life was associated with increased pdg2 when compared to uninfected control lambs. significantly elevated total plasm ... | 1993 | 8281741 |
| molecular characterization of border disease virus, a pestivirus from sheep. | three serologically different pestivirus strains isolated from sheep were selected for molecular analysis. cdna and deduced amino acid sequences of the genomic regions encoding glycoproteins e1 and e2 were obtained from the three strains. a comparison with amino acid sequences of bovine viral diarrhea virus (bvdv) and classical swine fever virus (csfv) revealed that one of the three ovine pestivirus strains can be grouped together with bvdv. the other two strains, however, were clearly different ... | 1994 | 8291236 |
| presumptive diagnostic differentiation of hog cholera virus from bovine viral diarrhea and border disease viruses by using a cdna nested-amplification approach. | hog cholera virus (hcv), bovine viral diarrhea virus (bvdv), and border disease virus (bdv) are closely related pestiviruses. bvdv and bdv are found worldwide but seldom cause disease in swine. in contrast, hcv has been successfully eradicated from swine in several nations but poses a potentially devastating threat to them because of its great virulence. rapid differential diagnosis of hcv from bvdv and bdv infections in swine is vital for detection of the possible reintroduction of hcv into nat ... | 1993 | 8384625 |
| detection of hog cholera virus and differentiation from other pestiviruses by polymerase chain reaction. | reverse transcription coupled with the polymerase chain reaction (rt-pcr) was used for the detection and differentiation of pestiviruses. for this purpose, one primer pair was selected from a highly conserved region of the genome of pestiviruses. using these primers (pest 1-pest 2), dna fragments of between 72 and 74 bp could be amplified from all pestivirus isolates tested. in order to differentiate hog cholera virus (hcv) from bovine viral diarrhea virus (bvdv) and border disease virus (bdv), ... | 1993 | 8388887 |
| nucleotide sequence of the bovine viral diarrhoea virus osloss strain: comparison with related viruses and identification of specific dna probes in the 5' untranslated region. | the nucleotide sequence of the cytopathic osloss isolate of bovine viral diarrhoea virus (bvdv) was deduced from overlapping cdna clones and from pcr products. the osloss genome is an rna molecule of positive polarity containing 12,480 nucleotides and having the capacity to code for a polyprotein of 3975 amino acids. the presence of the previously described internal stop codon in this viral sequence was disproved after direct sequencing of the appropriate pcr-amplified fragment. except for the p ... | 1993 | 8393084 |
| an immunohistochemical study of the distribution of border disease virus in persistently infected sheep. | three seronegative sheep persistently infected with border disease virus and six seropositive, non-viraemic sheep were examined for the cellular distribution of the agent. these animals originated from a closed flock which had been kept in an isolation facility for 5 years. they were killed and immediately necropsied. there were no gross abnormalities other than reduced body weight of the persistently infected sheep. two samples of each major organ were collected. the first sample was fixed by i ... | 1995 | 8543676 |
| characterization of the camel skin cell line dubca. | a skin fibroblast cell culture was established from a 2-month-old dromedary foetus. the cells were transformed by infection with sv40 and cloned in soft agar. the established cell line is now designated dubca cells (dubai camel) and has been in permanent culture for 95 passages. the cell culture was examined morphologically, chromosome preparations made and dna fingerprinting performed by hybridization with the oligonucleotide probe (gtg)5. sv40 large t antigen was detected by western blotting. ... | 1995 | 8556315 |
| a nested polymerase chain reaction assay to differentiate pestiviruses. | viruses that comprise the pestivirus genus cause significant losses to the livestock industry. based on sequence analysis, currently 4 distinct genotypes are identified of which 3 infect cattle and sheep. distinguishing between bovine and ovine isolates by serological tests has often been difficult because of a high degree of cross reactivity. in this study, a nested polymerase chain reaction (pcr) assay was developed to identify and distinguish between bovine viral diarrhea virus (bvdv) type i, ... | 1995 | 8578861 |
| border disease in sheep. | the current knowledge on border disease in sheep is reviewed. this is a congenital and teratogenic disorder induced by pestivirus. the history, etiology, epidemiology, clinical aspects, and pathologic lesions at postnatal and intrauterine infections (as well as in congenitally affected animals), pathogenesis, immunity, diagnosis, and control and prevention of the syndrome are discussed. | 1995 | 8581864 |
| bovine virus diarrhea and mucosal disease in free-ranging and captive deer (cervidae) in germany. | from 1990 until 1992, 355 blood samples of roe deer (capreolus capreolus) (n = 123), red deer (cervus elaphus) (n = 60), fallow deer (dama dama) (n = 87) and other cervid species (n = 85) from three different habitats (n = 180) and 11 wildlife parks or zoos (n = 175) in germany were tested for prevalence of pestivirus antibodies. seventeen samples were seropositive for bovine viral diarrhea virus (bvdv); only one animal had antibodies for border disease virus. microneutralization test titers ran ... | 1995 | 8583646 |
| ruminant pestiviruses. | the ruminant pestiviruses, bovine virus diarrhoea virus (bvdv) and border disease virus (bdv) are highly successful and important pathogens which infect ruminant species worldwide. although the serological relationships among ruminant pestiviruses require further clarification, there is growing evidence for two antigenic groups, one of which predominates in cattle and one in sheep. the success of pestiviruses stems from the ability of the non-cytopathic (ncp) biotype of the virus to cross the pl ... | 1995 | 8605577 |
| cytopathogenicity of border disease virus is correlated with integration of cellular sequences into the viral genome. | two border disease virus (bdv) pairs each consisting of cytopathogenic (cp) and non-cp viruses have been analyzed at the molecular level. within the ns2-3 (p125) encoding region of both cp viruses, insertions of cellular sequences were identified which were absent in the corresponding non-cp isolates. a comparative sequence analysis revealed that within each pair the cp and non-cp viruses are almost identical. this strongly suggests that the cp bdv isolates developed from the non-cp viruses by r ... | 1996 | 8627775 |
| swine and ruminant pestiviruses require the same cellular factor to enter bovine cells. | pestiviruses initiate infection of susceptible cells by receptor-mediated endocytosis. cellular plasma membrane or endosomal molecules involved in translocation of these viruses into the cytosol have not been unequivocally identified. we reported previously that a mutant cell line derived from madin-darby bovine kidney (mdbk) cells, termed crib-1, was resistant to infection with bovine viral diarrhoea virus. crib-1 cells were also resistant to infection with classical swine fever virus and borde ... | 1996 | 8683219 |
| six antigenic groups within the genus pestivirus as identified by cross neutralization assays. | antigenic differences between pestivirus isolates of ruminant and porcine origin were characterized by neutralization assays. first, six different clusters of pestiviruses were identified by clustering cross-neutralization results of 13 pestivirus strains tested against 23 sera. cluster i consisted of four strains of bovine viral diarrhoea virus (bvdv) of bovine origin and two bvdv isolates of porcine origin. cluster ii consisted of one sheep isolate and two porcine bdv isolates. cluster iii con ... | 1995 | 8748547 |
| demonstration and genotyping of pestivirus rna from mammalian cell lines. | we examined 20 cell lines of various animal origins for the presence of pestivirus contamination by the reverse transcription-polymerase chain reaction (rt-pcr), and found 15 (75%) cell lines were positive. the rt-pcr products of the 5' untranslated region (utr) of pestivirus genome were sequenced and subjected to genotyping. stem-loop structures at three variable regions in the 5' utr render genotyping of the contaminated pestiviruses. bovine cell lines tested were all contaminated with genotyp ... | 1995 | 8789057 |
| genetic identification of pestivirus strain frijters as a border disease virus from pigs. | a pig pestivirus isolate, the frijters strain, was characterized by using reverse transcription-pcr (rt-pcr), followed by rflp and direct sequencing of the amplicons. restriction endonuclease enzyme avai and bg/i digestion of 5' nc genomic region pcr products suggested that frijters strain belongs to the border disease viruses (bdv). this finding was confirmed by nucleotide sequencing of the amplified part of the 5-nc genomic region, which revealed 94% and 95% nucleotide similarity between the f ... | 1996 | 8795011 |
| fine mapping of a c-terminal linear epitope highly conserved among the major envelope glycoprotein e2 (gp51 to gp54) of different pestiviruses. | envelope glycoprotein e2 (gp51 to gp54) is the major neutralizing antigen of pestiviruses, which include classical swine fever virus (csfv), bovine viral diarrhoea virus (bvdv), and border disease virus (bvd). previous studies carried out using a panel of monoclonal antibodies raised against csfv strain brescia have revealed the existence of four antigenic domains, a to d, of the e2 protein, all of which are located at the n-terminal half of the molecule. here we report the detailed mapping, usi ... | 1996 | 8806512 |
| antigenically different pestivirus strains induce congenital infection in sheep: a model for bovine virus diarrhea virus vaccine efficacy studies. | to study the efficacy and safety of bovine virus diarrhea virus (bvdv) vaccines there is need for a valid challenge model. we investigated whether sheep can be used in such a challenge model. we intranasally inoculated six groups (a-f) of seronegative sheep at day 49 of gestation with either of five antigenically different bvdv strains and one border disease virus strain. a seventh group (g) was housed for 10 days with a persistently infected calf and an eighth group (h) served as control. from ... | 1996 | 8810006 |
| phylogenetic analysis of pestivirus based on the 5'-untranslated region. | a phylogenetic tree of pestiviruses constructed by analyzing their 5'-untranslated region (utr) indicated that the genetic relatedness between border disease virus and hog cholera virus is much closer than that between genotypes of various bovine diarrhoea viruses. this suggests that these viruses are host variants within a single species, which can be distinguished by comparison of secondary structures at three variable loci in the 5'-utr. | 1996 | 8886099 |
| natural transmission of orf virus from clinically normal ewes to orf-naive sheep. | the apparent natural transmission of orf virus from clinically normal ewes to susceptible sheep was observed during a border disease vaccine experiment. the 14 susceptible sheep were persistently infected with border disease virus and had been reared indoors in isolation from other sheep since birth. their ages ranged from two to four years and they were housed in two groups; group 1 consisted of four sheep persistently infected with the moredun strain of border disease virus and group 2 consist ... | 1996 | 8903019 |
| comparative studies of border disease and closely related virus infections in experimental pigs and sheep. | a pestivirus originally isolated from weaner pigs was shown to be capable of infecting weaners experimentally, but without inducing significant signs of disease. when inoculated into pregnant sows and ewes in early gestation, both the porcine virus and an antigenically similar ovine border disease isolate could induce congenital infections in both species. | 1995 | 8920113 |
| expression and characterization of part of hog cholera virus non-structural proteins. | in a preceding paper, the molecular cloning and partial nucleotide sequence of the alfort strain of hog cholera virus (hcv) was described. to study the genetic organization of the 3'-end of the hcv genome, which encodes some of the non-structural proteins, a cdna fragment (s2.20) of 849 nucleotides was subcloned into the bacterial expression vector pgex-3x and expressed in escherichia coli as a s2.20-glutathione-s-transferase fusion protein (s2.20-gst). this protein was used to produce hcv-speci ... | 1996 | 8928577 |
| detection and identification of ruminant and porcine pestiviruses by nested amplification of 5' untranslated cdna regions. | based on published gene sequences of bovine viral diarrhoea virus (bvdv) type i and classical swine fever virus (csfv), genus- and species-specific primers were designed to detect and identify pestivirus cdna sequences in a nested polymerase chain reaction (pcr). the pcr primers were validated using cdna synthesized from 146 pestivirus isolates, comprising representatives of all four so far described genotypes (bvdv type i, bvdv type ii, csfv and border disease virus), as well as others of uncer ... | 1997 | 9029529 |
| genetic characterization of ruminant pestiviruses: sequence analysis of viral genotypes isolated from sheep. | historically, the genus pestivirus was believed to contain three species of viruses; bovine viral diarrhea virus (bvdv), border disease virus (bdv) and classical swine fever virus (csfv). however, based on limited sequence analysis of a small number of pestiviral isolates from domestic livestock, evidence has recently emerged indicating that at least four distinct genotypes exist. in an attempt to gain a better understanding of the degree of viral variation among ruminant pestiviruses, the entir ... | 1997 | 9037733 |
| differentiation of classical swine fever virus from ruminant pestiviruses by reverse transcription and polymerase chain reaction (rt-pcr). | a reverse transcriptase-polymerase chain reaction (rt-pcr) assay was designed to allow the differentiation of pestiviruses by the expected size of the amplified fragments. one oligonucleotide primer, conserved amongst pestiviruses, and two others specific for either classical swine fever virus (csfv) or bovine viral diarrhea virus (bvdv), were designed from the 5' non-coding region of the genome. csfv infected cultures (10 strains) amplified a fragment of an expected size of 200 bp; bvdv culture ... | 1996 | 9054133 |
| molecular characterization of ovine pestiviruses. | forty-two ovine pestivirus isolates, collected over a period of 18 years, were compared by phylogenetic analysis. the viruses were mostly field isolates from britain; two others originated from sweden and two from new zealand. rt-pcr products were obtained from two genomic regions, one within the 5'-noncoding (5'-nc) region, and the other encompassing parts of the p20 (npro) and c coding regions. direct sequencing of the 5'-nc pcr products, followed by computer-assisted phylogenetic analysis, di ... | 1997 | 9129644 |
| phylogenetic analysis of pestiviruses from domestic and wild ruminants. | infections with pestiviruses occur in cattle, sheep, pigs and also in numerous other ungulate species. in the present study, pestiviruses from goat, buffalo, deer and giraffe were analysed at the molecular level; unusual strains from cattle and pigs were also included. a phylogenetic analysis of the respective pestiviruses was undertaken on the basis of a fragment from the 5' noncoding region as well as the gene encoding autoprotease npro. statistical analyses of the respective phylogenetic tree ... | 1997 | 9191930 |
| detection of border disease virus in sheep efferent lymphocytes by immunocytochemical and in situ hybridisation techniques. | the prefemoral efferent lymphatics of four sheep persistently infected with a non cytopathic (ncp) isolate of border disease virus (bdv) were cannulated. recovered lymphocytes were examined for the presence of virus by an immunocytochemical technique employing a pool of monoclonal antibodies which recognise the 120k non-structural polypeptide of ncp bdv. the results revealed that 9.5% of the lymphocytes carried virus antigen. lymphocytes from two of the sheep were studied by in situ hybridisatio ... | 1991 | 9210939 |
| polymerase chain reaction amplification of segments of pestivirus genomes. | reverse transcription followed by polymerase chain reaction (pcr) amplification of a region of the viral genome at the 3' end of the glycoprotein(s) gene was employed with the aim of determining its applicability as a diagnostic tool for pestiviruses. candidate primers were designed, from homologous segments detected by comparison between the sequences of strains nadl, osloss and alfort. a segment of 634 base pairs on the glycoprotein gene was targeted for amplification. segments of five pestivi ... | 1991 | 9210946 |
| progeny of sheep persistently infected with border disease virus. | most lambs affected with border disease die early in life but those which survive gradually loose their body tremors and their fleece abnormalities become less clear. seven female lambs persistently infected with border disease virus were reared to maturity and bred from when they were 2 to 3 years old. two failed to conceive but five gave birth to 6 live lambs with clinical signs of border disease characterized by hairy and pigmented fleece with or without body tremors. the epidemiological sign ... | 1991 | 9210952 |
| [bovine diarrhea virus: an update]. | bovine viral diarrhea virus (bvdv) is a pathogen of cattle, member of the family flaviviridae, genus pestivirus, which also includes classical swine fever virus (csfv, or hog cholera virus), and border disease virus of sheep (bdv). it causes important economical losses associated mainly with reproductive failure. pestiviruses are small enveloped viruses, with a diameter of about 40 nm. the nucleocapsid is probably icosahedral . the genome consists of a single stranded positive rna, encoding appr ... | 1997 | 9229725 |
| secondary structure of the 5'-noncoding region of border disease virus genome rnas. | the computer predicted secondary structures from the 5'-nc genome region of four border disease virus (bdv) strains collected from sheep in england and scotland over a period 1976-1986 were prepared. the fold program from gcg sequence analysis software package was used for the analysis of a 243 bp rna fragment. two typical shapes of secondary structures were observed which contained multiple imperfect stem-loop motifs. the shape of those structures exactly fit with the grouping of bdv strains to ... | 1997 | 9238865 |