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pilot scale thermal treatment of pig slurry for the inactivation of animal virus pathogens.this paper describes a pilot scale treatment plant that has been designed and built for the thermal inactivation in pig slurry of two viruses that infect pigs--african swine fever virus (asfv) and swine vesicular disease virus (svdv). the plant treats pig slurry continuously at a rate of up to 100 litres/hour and functions by heating the slurry, maintaining at least 99.99% of the slurry at the required temperature for a minimum period of 5 minutes, and then recovering the heat to raise the tempe ...199910565423
the rna-dependent rna polymerases of different members of the family flaviviridae exhibit similar properties in vitro.the virus-encoded rna-dependent rna polymerase (rdrp), which is required for replication of the positive-strand rna genome, is a key enzyme of members of the virus family flaviviridae. by using heterologously expressed proteins, we demonstrate that the 77 kda ns5b protein of two pestiviruses, bovine viral diarrhoea virus and classical swine fever virus, and the 100 kda ns5 protein of the west nile flavivirus possess rdrp activity in vitro. as originally shown for the rdrp of hepatitis c virus, r ...199910573150
an african swine fever virus orf with similarity to c-type lectins is non-essential for growth in swine macrophages in vitro and for virus virulence in domestic swine.an african swine fever virus (asfv) orf, 8cr, with similarity to the c-type lectin family of adhesion proteins has been described in the pathogenic isolate malawi lil-20/1. the similarity of 8cr to cellular and poxvirus genes associated with cell adhesion, cell recognition and virus infectivity suggested that 8cr may be of significance to asfv-host cell interactions. sequence analysis of the 8cr orf from additional pathogenic asfv isolates demonstrated conservation among isolates from both pig a ...199910573162
the effectiveness of routine serological surveillance: case study of the 1997 epidemic of classical swine fever in the netherlands.the authors describe the value of routine serological surveillance in detecting the introduction of classical swine fever virus into a disease-free population. the first investigation concerned the question of whether the epidemic of classical swine fever (csf), which occurred from 1997 to 1998 in the netherlands, could have been detected using the existing monitoring system for notifiable diseases. the investigation used data from the csf epidemic of 1997/1998 and from the existing monitoring s ...199910588006
classical swine fever: the european experience and a guide for infected areas.classical swine fever (csf) (hog cholera) virus infection is still of world-wide concern, either because of the direct effects of the disease on swine breeding in areas where the virus is epizootic or enzootic, or as a threat in areas where the virus has been eradicated. the authors provide an overview of the characteristics of the disease. special emphasis is placed on the chronic form of disease, particularly in the late stages of eradication programmes. in the early 1980s, the european union ...199910588007
in vitro inhibition of the replication of haemorrhagic septicaemia virus (vhsv) and african swine fever virus (asfv) by extracts from marine microalgae.we have screened for in vitro inhibition of viral replication with extracts from the following marine microalgae: porphyridium cruentum, phaeodactylum tricornutum, tetraselmis suecica, chlorella autotrophica, dunaliella tertiolecta, dunaliella bardawil, isochrysis galbana, isochrysis galbana var tiso, ellipsoidon sp. and tetraselmis tetrathele. we have used as viral models two enveloped viruses of significant economic importance, the viral hemorrhagic septicemia virus (vhsv) of salmonid fish and ...199910588334
laboratory decision-making during the classical swine fever epidemic of 1997-1998 in the netherlands.the national reference laboratory for classical swine fever (csf) virus in the netherlands examined more than two million samples for csf virus or serum antibody during the csf epizootic of 1997-1998. the immense amount of samples and the prevalence of border disease (bd) virus and bovine viral diarrhoea (bvd) virus infections in dutch pig herds necessitated the diagnostic efforts of the laboratory to be focused on generating csf specific test results throughout the eradication campaign. detecti ...199910619155
transmission of classical swine fever virus within herds during the 1997-1998 epidemic in the netherlands.in this paper, we describe the transmission of classical swine fever virus (csf virus) within herds during the 1997-1998 epidemic in the netherlands. in seven herds where the infection started among individually housed breeding stock, all breeding pigs had been tested for antibodies to csf virus shortly before depopulation. based upon these data, the transmission of csf virus between pigs was described as exponential growth in time with a parameter r, that was estimated at 0.108 (95% confidence ...199910619156
quantification of the transmission of classical swine fever virus between herds during the 1997-1998 epidemic in the netherlands.in this study, we describe a method to quantify the transmission of classical swine fever virus (csfv) between herds from data collected during the 1997-1998 epidemic in the netherlands. from the contacts between infected herds and the serological findings shortly before depopulation, we estimated the week of virus introduction and the length of the period over which the herd emitted virus for each csfv-infected herd. from these data, we estimated the infection-rate parameter beta (the average n ...199910619157
the 1997-1998 classical swine fever epidemic in the netherlands--a survival analysis.the aim of this analysis was to characterise the temporal pattern of infection during the 1997/98 classical swine fever (csf) epidemic in the netherlands and hence identify and quantify risk factors for infection in different enterprise types and areas. survival analysis and cox proportional hazards regression were used to describe the epidemic. substantial differences in temporal survival patterns (herd breakdown rate) were found between areas where different control policies operated. factors ...199910619158
spatial and stochastic simulation to evaluate the impact of events and control measures on the 1997-1998 classical swine fever epidemic in the netherlands. ii. comparison of control strategies.using the spatial, temporal and stochastic simulation model intercsf, several alternative pre-emptive slaughter strategies that could have been applied in the dutch classical swine fever (csf) epidemic of 1997-1998 were evaluated. furthermore, effects of changes in some disease-spread and disease-control parameters were studied. intercsf simulates the spread of csf between farms through local spread and contacts (animals, transport and persons). disease spread is affected by control measures imp ...199910619161
observations on the quasispecies composition of three animal pathogenic rna viruses.the quasispecies nature of three animal pathogenic rna viruses of field origin was examined by testing variants of classical swine fever virus (csfv) originating from geographically different areas, feline coronavirus (fcov) detected from the same animal by successive sampling, and rabbit haemorrhagic disease virus (rhdv) originating from successive outbreaks in the same geographic area. clinical samples were investigated using reverse transcriptase polymerase chain reaction (rt-pcr) and ensuing ...199910641337
infections with flaviviridae.the family of the flaviviridae contains 3 genera: (i) the hepaciviruses, to which belongs hepatitis c virus (hcv), (ii) the flaviviruses and (iii) the pestiviruses. over 140 million people, more than four times the number of hiv-positive individuals, are chronically infected with the hcv. hepatitis g virus (hgv) has not yet been assigned to a genus. the impact of this recently discovered virus is yet to be established. infections with flaviviruses such as yellow fever virus (yfv), dengue fever v ...199910655776
phylogenetic comparison and molecular epidemiology of classical swine fever virus.the genetic diversity of classical swine fever virus (csfv) was studied by rt-pcr amplification and sequencing of a 409 bp fragment of the ns5b polymerase region. a total of 106 viruses isolated from 20 countries over a period of 52 years (1945-1997) were included in the phylogenetic study. the results showed that the viruses could be divided into two main groups. group 1 consisted of asian and south american isolates from the 1980s, as well as of old european and american isolates. group 2 cons ...199910595410
classical swine fever virus in plasma and peripheral blood mononuclear cells of acutely infected swine.the distribution of classical swine fever virus (csfv) in plasma, monocytes, t and b lymphocytes in peripheral blood was monitored during experimentally induced acute classical swine fever infection in piglets. six piglets were infected with 10(3.8) tcid50 of virus and blood samples taken up to 18 days post-inoculation (p.i.). infectious virus was detected in monocytes, t and b lymphocytes to similar titres in five of the six infected piglets. infectious virus was detected earlier in plasma than ...199910605368
[the morphological structure of classical swine fever virus and some characteristics of its multiplication].some characteristics of the multiplication of classical swine fever virus(csfv) thiverval strain were studied by means of the immunofluorescence technique. under optimum culture conditions, the concentration of csfv in the culture liquid multiplicated by mpk cells is ten times higher than by pk-15 cells. the half-life period of csfv at 37 degrees c is 3 hour. the location of csfv's replication in host cells is detected by the monoclonal antibodies of the structural protein e2 and the non-structu ...199912555533
[molecular clone and sequence analysis of cdna fragments of hog cholera virus strain c].the 5' nonencoding region, p23 and p14 encoding region and e1 gene of hog cholera virus (hcv) strain c were amplified from total rna extracted from hcv strain c infected rabbit spleen by reverse transcription and nested or half--nested pcr. the pcr products were cloned into pgem-t vector. nucleotide sequencing was performed using an abi prism sequencing device; based on the incorporation of fluoresect labelled dideoxynuclotide teminators. the obtained sequences on 5' noncoding region and part of ...199912555563
african swine fever virus infection in the argasid host, ornithodoros porcinus porcinus.the pathogenesis of african swine fever virus (asfv) infection in ornithodoros porcinus porcinus was examined in nymphal ticks infected with the asfv isolate chiredzi/83/1. at times postinfection (p.i.) ranging from 6 h to 290 days, ticks or dissected tick tissues were titrated for virus and examined ultrastructurally for evidence of virus replication. the asfv infection rate in ticks was 100% in these experiments, and virus infection was not associated with a significant increase in tick mortal ...19989499019
lymphocyte apoptosis during classical swine fever: implication of activation-induced cell death.infection of pigs with classical swine fever virus (csfv), a member of the flaviviridae family, causes a severe leukopenia, particularly notable with the lymphocytes. the goal of this study was to analyze mechanisms behind this csfv-induced lymphopenia. to this end, the kinetics of leukocyte depletion, the appearance of apoptotic cells, and virus infection of leukocytes after infection of pigs with the virulent csfv strain brescia were analyzed. depletion of b and t lymphocytes was noted as earl ...19989499036
a retention signal necessary and sufficient for endoplasmic reticulum localization maps to the transmembrane domain of hepatitis c virus glycoprotein e2.the hepatitis c virus (hcv) genome encodes two envelope glycoproteins (e1 and e2). these glycoproteins interact to formin a noncovalent heterodimeric complex which is retained in the endoplasmic reticulum (er). to identify whether e1 and/or e2 contains an er-targeting signal potentially involved in er retention of the e1-e2 complex, these proteins were expressed alone and their intracellular localization was studied. due to misfolding of e1 in the absence of e2, no conclusion on the localization ...19989499075
african swine fever virus is wrapped by the endoplasmic reticulum.african swine fever (asf) virus is a large dna virus that shares the striking icosahedral symmetry of iridoviruses and the genomic organization of poxviruses. both groups of viruses have a complex envelope structure. in this study, the mechanism of formation of the inner envelope of asf virus was investigated. examination of thin cryosections by electron microscopy showed two internal membranes in mature intracellular virions and all structural intermediates. these membranes were in continuity w ...19989499098
thrombocytopenia associated with apoptotic megakaryocytes in a viral haemorrhagic syndrome induced by a moderately virulent strain of african swine fever virus.a viral haemorrhagic syndrome was induced in 14 pigs by inoculation with an african swine fever (asf) virus strain of moderate virulence, to determine changes in megakaryocyte (mk) numbers and morphology and thus to assess the role of these cells in the thrombocytopenia characteristic of subacute asf. the strain tested induced changes in the proportion of different types of mk (typical nucleated mks, apoptotic mks and immature mks); it also caused subcellular lesions over the first 7 days post-i ...19989500234
a new assay for classical swine fever virus based on cytopathogenicity in porcine kidney cell line fs-l3.a new assay termed the dome disappearance method for classical swine fever virus (csfv) using fs-l3 cells with serum-free culture medium was developed. the csfv live vaccine gpe- strain grows well and shows a slight cytopathic effect (cpe) in fs-l3 cells. this cpe results in the disappearance of the unique fluid-filled multicellular domes on a single monolayer of fs-l3 cells. by using this phenomenon, dome disappearance, as a marker of infection, it was possible to determine the titers of csfv a ...19989506817
deletion of a cd2-like gene, 8-dr, from african swine fever virus affects viral infection in domestic swine.an african swine fever virus (asfv) gene with similarity to the t-lymphocyte surface antigen cd2 has been found in the pathogenic african isolate malawi lil-20/1 (open reading frame [orf] 8-dr) and a cell culture-adapted european virus, ba71v (orf ep402r) and has been shown to be responsible for the hemadsorption phenomenon observed for asfv-infected cells. the structural and functional similarities of the asfv gene product to cd2, a cellular protein involved in cell-cell adhesion and t-cell-med ...19989525608
a novel method for pestivirus genotyping based on palindromic nucleotide substitutions in the 5'-untranslated region.a simple and practical method was developed for pestivirus genotyping based on analysis of the secondary structures in the 5'-untranslated region (utr). three stable stem-loop structures, v1, v2 and v3, predicted by computer in the 5'-utr, included strictly conserved consensus base-pairings which are shared by all the genotypes of pestivirus or are characteristic to each genotype of pestivirus. on the basis of the palindromic nucleotide substitution at the secondary structural level, six genotyp ...19989562417
evolution of viral dna-dependent dna polymerases.dna viruses as their host cells require a dna-dependent dna polymerase (pol) to faithfully replicate their genomic information. large eukaryotic dna viruses as well as bacterial viruses encode a specific pol equipped with a proofreading 3'-5'-exonuclease, and other replication proteins. all known viral pol belong to family a and family b pol. common to all viral pol is the conservation of the 3'-5'-exonuclease domain manifested by the three sequence motifs exo i, exo ii, and exo iii. the polymer ...19989562890
is the major capsid protein of iridoviruses a suitable target for the study of viral evolution?iridoviruses are large cytoplasmic dna viruses that are specific for different insect or vertebrate hosts. the major structural component of the non-enveloped icosahedral virus particles is the major capsid protein (mcp) which appears to be highly conserved among members of the family iridoviridae, phycodnaviridae, and african swine fever virus. the amino acid sequences of the known mcps were used in comparative analyses to elucidate the phylogenic relationships between different cytoplasmic dna ...19989562891
an experimental infection with classical swine fever virus in weaner pigs. i. transmission of the virus, course of the disease, and antibody response.the spread of classical swine fever (csf) virus (strain lorraine), originally isolated in the first csf infected herd of the 1993-1994 belgian epizootic, was examined in an isolation unit with three adjacent pens and 15 weaner pigs per pen. virus was introduced through experimental inoculation of one weaner pig in the middle pen (pen 2). the experimentally inoculated pig became viraemic 4 days post-inoculation (dpi) and the pen mates at 12 (n = 9) and 14 dpi (n = 5). the first viraemia in pens 1 ...19989563158
an experimental infection with a classical swine fever virus in weaner pigs. ii. the use of serological data to estimate the day of virus introduction in natural outbreaks.in a companion paper a logistic regression model of seroprevalence over time was developed on the basis of data obtained during an experimental infection of weaner pigs with classical swine fever (csf) virus. the model was applied to seroprevalence data from three outbreaks of the 1993-1994 epizootic to test whether the model could predict correctly the day of virus introduction into the herd. it was concluded that the logistic regression model has potential as a tool to estimate in retrospect t ...19989563159
the african swine fever virus proteins p54 and p30 are involved in two distinct steps of virus attachment and both contribute to the antibody-mediated protective immune response.the nature of the initial interactions of african swine fever (asf) virus with target cells is only partially known, and to date only the asf virus protein p12 has been identified as a viral attachment protein. more recently, antibodies to viral proteins p54 and p30 have been shown to neutralize the virus, inhibiting virus binding and internalization, respectively. therefore, we investigated the role of these proteins in the receptor-mediated asf virus endocytosis in swine macrophages, the natur ...19989568043
specific interaction of eukaryotic translation initiation factor 3 with the 5' nontranslated regions of hepatitis c virus and classical swine fever virus rnas.translation of hepatitis c virus (hcv) and classical swine fever virus (csfv) rnas is initiated by cap-independent attachment (internal entry) of ribosomes to the approximately 350-nucleotide internal ribosomal entry segment (ires) at the 5' end of both rnas. eukaryotic initiation factor 3 (eif3) binds specifically to hcv and csfv iress and plays an essential role in the initiation process on them. here we report the results of chemical and enzymatic footprinting analyses of binary eif3-ires com ...19989573242
complete genomic sequence of border disease virus, a pestivirus from sheep.the genus pestivirus of the family flaviviridae comprises three established species, namely, bovine viral diarrhea virus (bvdv), classical swine fever virus (csfv), and border disease virus from sheep (bdv). in this study, we report the first complete nucleotide sequence of bdv, that of strain x818. the genome is 12,333 nucleotides long and contains one long open reading frame encoding 3, 895 amino acids. the 5' noncoding region (ncr) of bdv x818 consists of 372 nucleotides and is thus similar i ...19989573288
the major structural protein of african swine fever virus, p73, is packaged into large structures, indicative of viral capsid or matrix precursors, on the endoplasmic reticulum.african swine fever virus (asfv) is a large enveloped dna virus that shares the striking icosahedral symmetry of iridoviruses. to understand the mechanism of assembly of asfv, we have been studying the biosynthesis and subcellular distribution of p73, the major structural protein of asfv. sucrose density sedimentation of lysates prepared from infected cells showed that newly synthesized p73 was incorporated into a complex with a size of 150 to 250 kda. p73 synthesized by in vitro translation mig ...19989573294
a recombinant classical swine fever virus stably expresses a marker gene.the gene coding for bacterial chloramphenicol acetyltransferase (cat) was inserted in frame into the viral npro gene of the full-length cdna clone pa187-1 of the classical swine fever virus (csfv) strain alfort/187. rna transcribed in vitro from the resulting plasmid was transfected into sk-6 porcine kidney cells. infectious progeny virus va187-cat recovered from transfected cells had growth characteristics indistinguishable from those of parental virus va187-1. in cells infected with va187-cat ...19989573312
inducible gene expression from african swine fever virus recombinants: analysis of the major capsid protein p72.a method to study the function of individual african swine fever virus (asfv) gene products utilizing the escherichia coli lac repressor-operator system has been developed. recombinant viruses containing both the laci gene encoding the lac repressor and a strong virus late promoter modified by the insertion of one or two copies of the lac operator sequence at various positions were constructed. the ability of each modified promoter to regulate expression of the firefly luciferase gene was assaye ...19989580160
expression of the glycoprotein e2 of the classical swine fever virus in escherichia coli.the glycoprotein e2 sequences of classical swine fever virus (strain p97) were cloned, sequenced and expressed in e. coli. result from sds-polyacrylamide gel electrophoresis analysis of expressed proteins revealed the presence of a prominently stained band corresponding to a molecular mass of 61 kda, which is in agreement with the predicted size from the dna sequence. the recombinant e2 protein contained an aminoterminal tag of six histidines that could be used for purification by the nickel che ...19989592734
expression of african swine fever virus envelope protein j13l inhibits vaccinia virus morphogenesis.the african swine fever virus (asfv) strain malawi lil20/1 open reading frame (orf) j13l was expressed in vaccinia virus (vv) from a strong synthetic late promoter as either a complete orf (vsj1) or lacking codons 1-31 (vsj2). each recombinant vv produced a small plaque which rapidly reverted to a normal size upon passage. the yield of infectious virus from a single cycle infection with vsj1 or vsj2 was reduced 50- to 100-fold compared to wild-type (wt) and a revertant virus (vsj5) in which the ...19989603332
characterization of african swine fever virion proteins j5r and j13l: immuno-localization in virus particles and assembly sites.the j5r open reading frame (orf) of the malawi lil 20/1 african swine fever virus (asfv) isolate encodes a 111 amino acid protein with a putative transmembrane domain at the n terminus. antisera raised against the predicted c-terminal peptide were used to identify the j5r protein by western blotting in cells infected with asfv or with recombinant vaccinia virus expressing the j5r orf. this showed that the j5r protein migrates with an apparent molecular mass of 23-25 kda, depending on the virus i ...19989603333
a conserved african swine fever virus right variable region gene, l11l, is non-essential for growth in vitro and virulence in domestic swine.the right variable region of the african swine fever virus (asfv) genome is known to contain genes with functions involving virus virulence and host range in swine. a novel open reading frame, orf l11l, which was absent in the non-pathogenic, cell culture-adapted european isolate ba71v, was identified in the pathogenic african isolate malawi lil-20/1. the location of l11l in the right variable region, together with its absence in ba71v, suggested that l11l may have a function in virus virulence ...19989603334
cloning, expression and sequence analysis of the classical swine fever virus nucleocapsid protein.the dna complementary to the 5'-terminal 1929 nucleotides of classical swine fever virus (csfv; alias hog cholera virus, hcv) lpc vaccine strain rna was cloned and sequenced. the sequence encompasses a 5'-noncoding region (ncr) of 264 nucleotides and an open reading frame (orf) of 1665 nucleotides. the cloned sequence contains genes of four viral proteins, p23, nucleocapsid (core) protein, e0 and part of e1 proteins. alignment of the 5'-terminal 1929 nucleotides of lpc strain with other strains ...19989608668
the recombinant nucleocapsid protein of classical swine fever virus can act as a transcriptional regulator.the cdna of the nucleocapsid (core) protein of classical swine fever virus (csfv) was generated by reverse transcription-polymerase chain reaction (rt-pcr) and cloned into a eukaryotic expression vector. the effect of the recombinant core protein on the transcriptional regulation of cellular as well as viral promoters was studied. using transient transfection assay, our results demonstrated that the core protein can activate the promoter of human heat shock protein 70 gene, and suppressed the sv ...19989617770
differentiation of types 1a, 1b and 2 bovine viral diarrhoea virus (bvdv) by pcr.there are two genotypes among bovine viral diarrhoea viruses (bvdv), bvdv1 and bvdv2. within the bvdv1 genotype there are two distinct subgenotypes, bvd1a and bvd1b. serology and monoclonal antibody binding are used to differentiate bvdv from classical swine fever virus (csfv) and border disease virus (bdv), the other members of the pestivirus genus. these techniques are less useful in the differentiation and segregation of viruses within the bvdv species. in this study, differential polymerase ...19989633045
african swine fever: a disease characterized by apoptosis.the cell tropism, organ distribution and resultant pathology of african swine fever were compared in domestic pigs infected with lethal (malawi) and sublethal (malta) isolates of african swine fever virus (asfv). after infections with both isolates, asfv was predominantly localized in cells of the mononuclear phagocytic system and was not observed in endothelial cells in lymphoid tissue. more severe tissue destruction and cell depletion, associated with high levels of infected macrophages, were ...19989634085
the pathogenesis of african swine fever in the resistant bushpig.bushpigs and warthogs are natural reservoir hosts of african swine fever virus (asfv) in the wild, showing no clinical signs of disease when infected with the same highly virulent isolates of asfv that induce rapid, haemorrhagic death in domestic pigs. in contrast to domestic pigs, infection of bushpigs with malawi isolate results in low levels of virus replication and lymphocyte apoptosis within the spleen, and a relatively low spread of virus to other lymphoid tissues. however, at 10 days post ...19989634086
inactivation of the rnase activity of glycoprotein e(rns) of classical swine fever virus results in a cytopathogenic virus.envelope glycoprotein e(rns) of classical swine fever virus (csfv) has been shown to contain rnase activity and is involved in virus infection. two short regions of amino acids in the sequence of e(rns) are responsible for rnase activity. in both regions, histidine residues appear to be essential for catalysis. they were replaced by lysine residues to inactivate the rnase activity. the mutated sequence of e(rns) was inserted into the p10 locus of a baculovirus vector and expressed in insect cell ...19989420210
a prokaryotic-like mode of cytoplasmic eukaryotic ribosome binding to the initiation codon during internal translation initiation of hepatitis c and classical swine fever virus rnas.initiation of translation of hepatitis c virus and classical swine fever virus mrnas results from internal ribosomal entry. we reconstituted internal ribosomal entry in vitro from purified translation components and monitored assembly of 48s ribosomal preinitiation complexes by toe-printing. ribosomal subunits (40s) formed stable binary complexes on both mrnas. the complex structure of these rnas determined the correct positioning of the initiation codon in the ribosomal "p" site in binary compl ...19989420332
a nonessential african swine fever virus gene uk is a significant virulence determinant in domestic swine.sequence analysis of the right variable genomic region of the pathogenic african swine fever virus (asfv) isolate e70 revealed a novel gene, uk, that is immediately upstream from the previously described asfv virulence-associated gene nl-s (l. zsak, z. lu, g. f. kutish, j. g. neilan, and d. l. rock, j. virol. 70:8865-8871, 1996). uk, transcriptionally oriented toward the right end of the genome, predicts a protein of 96 amino acids with a molecular mass of 10.7 kda. searches of genetic databases ...19989444996
infection with classical swine fever virus: effects on phenotype and immune responsiveness of porcine t lymphocytes.t lymphocytes obtained from pigs infected with a lethal dose of classical swine fever virus were analysed for phenotypic changes in the composition of t-cell subpopulations and for alterations in their immune responsiveness in vitro during the course of disease. viral antigen detected in all subpopulations and the selective depletion of cd4- cd8- gamma/delta t cells showed that peripheral blood t lymphocytes were affected in the terminal stage (14-19 days post-infection) of classical swine fever ...19989460919
characterization of a bovine viral diarrhea virus isolated from roe deer in germany.the 5' untranslated region (5' utr) of cytopathogenic pestiviruses isolated from two seronegative roe deer (capreolus capreolus) in northern germany was partially sequenced and compared with those of 28 other pestiviruses. due to the occurrence within a narrow location and the complete identity of the sequenced fragments from both roe deer isolates (sh9 and sh11) they seem to belong to the same bovine virus diarrhea virus (bvdv) strain called sh9/11. this strain is highly homologous (up to 93% i ...19989476225
inhibition of nuclear factor kappab activation by a virus-encoded ikappab-like protein.certain viruses have evolved mechanisms to counteract innate immunity, a host response in which nuclear factor kappab (nf-kappab) transcription factors play a central role. african swine fever virus encodes a protein of 28.2 kda containing ankyrin repeats similar to those of cellular ikappab proteins, which are inhibitors of nf-kappab. transfection of the african swine fever virus ikappab gene inhibited tumor necrosis factor- or phorbol ester-induced activation of kappab- but not ap-1-driven rep ...19989479002
modulation of t cell and monocyte function in the spleen following infection of pigs with african swine fever virus.infection of pigs with many strains of african swine fever virus (asfv) has been shown to cause a loss or marked decrease in the ability of splenocytes to respond to mitogens. these observations have been extended by cell fractionation and reconstitution experiments to show that the mitogen stimulated proliferative capacity of both the cd4+ and cd8+ t cells is affected. similarly, monocytes which are directly infectable by virus, are functionally defective as antigen presenting cells when added ...19989646434
entry of african swine fever virus into vero cells and uncoating.african swine fever virus (asfv) enters vero cells by adsorptive endocytosis [valdeira, m.l., geraldes, a., 1985. morphological study on the entry of african swine fever virus into cells, biol cell. 55, 35-40]. electron microscopy of a lysosomotropic drug-controlled penetration indicated that this step takes place in the endosomes, after fusion between the viral envelope and the limiting membrane of the endosome. inhibition studies with colcemid, cytochalasin b, sodium azide, dinitrophenol, lyso ...19989646445
development and evaluation of a novel antigen capture assay for the detection of classical swine fever virus antigens.an antigen-capture enzyme immunoassay (eia) was developed to detect classical swine fever virus (csfv) antigen directly from 10% w/v tissue suspension. the assay, based on the sandwich principle, uses a biotinylated monoclonal antibody bound to streptavidin-coated microplates as the capture system and a swine anti-csfv antibody and rabbit anti-swine hrpo-conjugate as the detector system. the antigen-capture eia was compared with conventional virus isolation and polymerase chain reaction (pcr) fo ...19989646447
molecular characterization of the 3' noncoding region of classical swine fever virus vaccine strains.the genomes of classical swine fever virus (csfv) vaccine strains are poorly characterized, and the mechanisms for their attenuation remain unknown. the aim of the present study was to characterize the 3' noncoding region (3' ncr) of a number of attenuated vaccine strains of csfv in order to examine changes in the viral genome after attenuation. the results showed that the 3' ncr:s of porcivac, rovac, russian lk and original chinese vaccine strain contain insertions very similar to that present ...19989654685
low density blood granulocytic cells induced during classical swine fever are targets for virus infection.classical swine fever virus infection of pigs causes a severe leukopenia and immunosuppression. in the present study, the kinetics of virus infection, and identification of target cells for the virus in peripheral blood were analysed. virus infection was often not detectable before 5-7 days p.i. a minority of animals yielded detectable infected cells at 3 days p.i., but < 5% pbmc. it was not until 10 days p.i. that this figure increased-to 35-70% pbmc depending on the animal. detailed analysis o ...19989656461
membrane-anchored incorporation of a foreign protein in recombinant influenza virions.the rna polymerase i system for in vivo synthesis of recombinant influenza vrna molecules was used for the expression of a chimeric protein, consisting of the 341-amino-acid ectodomain of the glycoprotein e2 of classical swine fever virus and the 37-amino-acid c-terminal membrane anchor of the influenza virus hemagglutinin (ha). during infection with an influenza a helper virus the amplified pseudo-viral rna was packaged into progeny virions together with influenza vrna segments. the foreign fus ...19989656996
african swine fever virus infection of the bushpig (potamochoerus porcus) and its significance in the epidemiology of the disease.warthog (phacochoerus aethiopicus), giant forest hog (hylochoerus meinertzhageni) and bushpig (potamochoerus porcus) are known to be susceptible to infection with african swine fever (asf) virus. little however, is known about the ecology of the disease in the bushpig. this study has shown that the bushpig remains viraemic for between 35 and 91 days following infection during which time it is able to infect the tick vector o. moubata. these ticks were able to transmit the disease to pigs. the vi ...19989659687
[the situation of classical swine fever in wild boars in the european community and selected aspects of disease transmission].the situation of classical swine fever (csf) in europe is described on the basis of the literature. in the european community, csf is present among wild boars in germany (federal states mecklenburg-western pomerania, brandenburg and lower saxony), in france (northern vosges) and in italy (regio emìlìa romagna in 1997 and sardinia--enzootically infected). infected wild boars are important as a source of infection for domestic pigs in germany. selected aspects of the transmission of csf virus from ...19989674308
a viral mechanism for inhibition of the cellular phosphatase calcineurin.the transcription factor nfat (nuclear factor of activated t cells) controls the expression of many immunomodulatory proteins. african swine fever virus inhibits proinflammatory cytokine expression in infected macrophages, and a viral protein a238l was found to display the activity of the immunosuppressive drug cyclosporin a by inhibiting nfat-regulated gene transcription in vivo. this it does by binding the catalytic subunit of calcineurin and inhibiting calcineurin phosphatase activity.19989677199
full-length gbv-c/hgv genomes from nine japanese isolates: characterization by comparative analyses.the genomes of nine gbv-c/hgv isolates from japanese chronic hepatitis patients were fully sequenced and characterized. they shared 85% nucleotide sequence homology with previously characterized isolates from the us and west africa. homology studies and phylogenetic analyses showed that the japanese isolates formed a third group distinct from the established groups 1 and 2. the genetic distances between the three groups of gbv-c/hgv were very similar to the distances between the two classical sw ...19989687865
border disease of sheep and goats.border disease (bd) is a congenital virus disease of sheep and goats first reported in 1959 from the border region of england and wales. bd virus (bdv) is a pestivirus in the genus flaviviridae and is closely related to classical swine fever virus and bovine virus diarrhoea virus (bvdv). nearly all isolates of bdv are non-cytopathogenic (ncp) in cell culture. there are no defined serotypes but pestiviruses isolated from sheep exhibit considerable antigenic diversity and three distinct antigenic ...19989689745
ultrastructural pathology of the bone marrow in pigs inoculated with a moderately virulent strain (dr'78) of african swine fever virus.interpretation of changes in bone marrow during infectious processes is quite complex. this paper reports bone marrow lesions observed in pigs inoculated with a moderately virulent asf virus strain and studies their relationship to the pathogenesis of the disease. in this work, we have carried out the structural and ultrastructural study of the bone marrow of 14 large white x landrace pigs that were inoculated by the intramuscular route with 10(5) 50% hemodsorbing doses (had50) of the dominican ...19989690128
macrophage culture: influence of species-specific incubation temperature.cultured mammalian cells are traditionally maintained at 37 degrees c, despite the fact that core body temperatures differ considerably among mammals. considering the body temperature of the adult pig, comparison was made of porcine macrophage cultures maintained at 37 degrees c and 39.2 degrees c. examination of the cells showed that granularity was higher in macrophages maintained at 39.2 degrees c, although no differences in cell size were observed. the density of mhc class i and ii expressio ...19989692868
a novel approach to the detection of classical swine fever virus by rt-pcr with a fluorogenic probe (taqman).detection of classical swine fever virus (csfv) and its discrimination from other pestiviruses can be achieved by virus isolation (vi) in cell cultures, antigen detection, or molecular analysis. to simplify the latter, a 5'-nuclease assay (taqman) was developed for the rapid and specific detection of csfv with the minimum of downstream pcr processing. a pair of 5'-non-coding region, panpestivirus-specific pcr primers were assessed in a one-step reverse transcription-pcr with each of 36 diverse p ...19989694320
detection of african swine fever virus in infected pig tissues by immunocytochemistry and in sity hybridisation.the techniques for determining cellular sites of establishment and persistence of african swine fever virus (asfv) were established in susceptible domestic pigs and the resistant african reservoir hosts, the warthog and bushpig. detection, both in vitro and in vivo, was achieved by in situ hybridisation and immunocytochemistry, focusing principally on specific probes for vp73, a major capsid protein. hybridisation of radio-labelled probes for dna and rna was relatively insensitive and time consu ...19989694328
migration of mitochondria to viral assembly sites in african swine fever virus-infected cells.an examination by electron microscopy of the viral assembly sites in vero cells infected with african swine fever virus showed the presence of large clusters of mitochondria located in their proximity. these clusters surround viral factories that contain assembling particles but not factories where only precursor membranes are seen. immunofluorescence microscopy revealed that these accumulations of mitochondria are originated by a massive migration of the organelle to the virus assembly sites. v ...19989696857
classical swine fever virus leader proteinase npro is not required for viral replication in cell culture.the sequence encoding the viral leader proteinase npro was replaced by the murine ubiquitin gene in a full-length cdna clone of the classical swine fever virus (csfv) strain alfort/187. the recombinant virus va187-ubi showed growth characteristics similar to those of the parent va187-1 virus. at two occasions cells infected with va187-ubi exhibited a cytopathic effect and were found to contain a subgenomic viral rna. this rna lacked the same viral genes as the subgenomic rna which has been found ...19989696875
[procoagulant activity in swine leukocytes, infected with the swine classical plague virus].an increased level of the procoagulant activity (pca) has been observed in porcine leukocytes in vitro infected with virulent or vaccine strains of hog cholera virus in comparison with intact cells. pca was similarly induced in infected leukocytes from swine immune to hog cholera virus. increased pca levels were detected in culture medium with leukocytes from intact and immune animals infected in vitro with both virulent and vaccine strains of hog cholera virus in comparison with the pca levels ...19989702815
critical factors affecting the diagnostic reliability of enzyme-linked immunosorbent assay formats.this paper aims to evaluate different formats of the enzyme-linked immunosorbent assays (elisas) for detection of virus-specific antibodies and focuses on factors that may influence the diagnostic reliability of such tests. newly developed and well-established elisas for detection of infections of bovine herpesvirus 1 (bhv1), bovine respiratory syncytial virus (brsv), classical swine fever virus (csfv), pseudorabies virus (prv) and bovine viral diarrhoea virus (bvdv) are used as examples. differ ...19989713894
cholesterol affects african swine fever virus infection.african swine fever virus (asfv) enters cells by receptor mediated endocytosis and requires a fusion event between the viral envelope and the limiting membrane of the endosome at low ph. in order to investigate the role of cholesterol in the early stages of asfv infection, we have studied the effect of the removal of cell and viral membrane cholesterol by cholesterol oxidase treatment of cells and virions, as well as the effect of some inhibitors of cholesterol synthesis on the infectious pathwa ...19989714715
isolation and characterization of cytopathogenic classical swine fever virus (csfv).two new classical swine fever virus (csfv) isolates obtained from naturally infected swine were found to exhibit a cytopathogenic (cp) phenotype. according to their reactivity with monoclonal antibodies (mabs) the isolates cpbw1 and cpmvp1 were classified as antigenic types "lothringen'92" and "flandern'90", respectively. in northern blot analyses and pcr assays csfv rna of subgenomic length was detected in infected cells indicating the presence of defective interfering particles. nucleotide seq ...19989722875
serological and immunohistochemical study of african swine fever in wild boar in spain.a serological and immunohistochemical study of african swine fever was carried out in wild boar killed in seven municipalities in the north of the province of córdoba during two hunting seasons (1991-92 and 1992-93), when the area was affected by the disease. fourteen of 147 wild boar analysed by elisa and immunoblotting had antibodies to african swine fever virus. the immunohistochemical study revealed that four cases (two seropositive and two seronegative) showed immunoreactivity to the anti-v ...19989725185
intracellular virus dna distribution and the acquisition of the nucleoprotein core during african swine fever virus particle assembly: ultrastructural in situ hybridisation and dnase-gold labelling.african swine fever virus (asfv) is a large complex icosahedral double-stranded dna virus that replicates in the cytoplasm of susceptible cells. assembly of new virus particles occurs within the perinuclear viroplasm bodies known as virus factories. two types of virus particle are routinely observed: "fulls," which are particles with an electron-dense dna-containing nucleoid, and "empties," which consist of the virus protein and membrane icosahedral shell but are without the incorporation of the ...19989740789
pathogenesis of mucosal disease, a deadly disease of cattle caused by a pestivirus.two biotypes of pestiviruses, cytopathogenic (cp) and non-cytopathogenic (noncp) viruses, are distinguished by their effects on tissue culture cells. in contrast to the bovine viral diarrhoea virus (bvdv) system, only a few cp border disease virus (bdv) and cp classical swine fever virus (csfv) strains have been described. antigenically closely related noncp and cp bvdv can be isolated from cattle with fatal mucosal disease (md) and are called a virus pair. the generation of cp bvdv in an animal ...19989741637
maternal recognition of foetal infection with bovine virus diarrhoea virus (bvdv)--the bovine pestivirus.pestiviruses are the veterinary viruses with genome homology to human hepatitis c virus (hcv). this group includes classical swine fever virus (csfv), border disease virus of sheep (bdv) and bovine virus diarrhoea virus (bvdv). there are some similarities in the pathology of all three virus infections; in utero transmission to the foetus can cause early embryonic losses, severe congenital abnormalities and, particularly with bvdv, lifelong persistent infections. in situ hybridisation studies hav ...19989741639
immunohistochemical and ultrastructural evidence of hog cholera virus infection of megakaryocytes in bone marrow and spleen.twelve pigs were inoculated with a highly virulent strain of hog cholera virus (hcv) to study viral infection of megakaryocytes in the bone marrow and spleen. immunohistochemical and ultrastructural examination revealed hcv infection in a small proportion (2.5-9.0%) of these cells from the 2nd to the 9th day after inoculation, at which time the experiment was terminated. megakaryocyte infection accounts for the presence of viral antigens in platelets. the latter may represent a passive vehicle f ...19989749356
[classical swine fever in 1993 in switzerland: molecular-epidemiologic characterization of the virus isolate].rt-pcr followed by direct nucleotide sequencing of the amplified cdna was carried out to analyse most of the 5' nontranslated region (5'ntr) of classical swine fever virus (csfv) isolates from the five 1993 disease outbreaks in switzerland. sequence data were compared to other csfv strains, and dendrograms were constructed in order to determine the phylogenetic relationship of the swiss virus strains. dendrograms formed by the analysis of different parts of the 5'ntr were compared. it was shown ...19989757784
comparative detection of classical swine fever virus in striated muscle from experimentally infected pigs by reverse transcription polymerase chain reaction, cell culture isolation and immunohistochemistry.classical swine fever (csf) is a highly contagious viral disease, which can be transmitted by csfv-contaminated swill. in 1993, four csf outbreaks in switzerland were caused presumably by feeding pigs with improperly heated swill. the aim of the investigations was to find a suitable method for csfv detection in striated muscle samples of infected pigs in order to allow routine testing of meat for virus contamination. the sensitivity of virus detection in striated muscle was compared with the det ...19989763128
african swine fever virus is enveloped by a two-membraned collapsed cisterna derived from the endoplasmic reticulum.during the cytoplasmic maturation of african swine fever virus (asfv) within the viral factories, the dna-containing core becomes wrapped by two shells, an inner lipid envelope and an outer icosahedral capsid. we have previously shown that the inner envelope is derived from precursor membrane-like structures on which the capsid layer is progressively assembled. in the present work, we analyzed the origin of these viral membranes and the mechanism of envelopment of asfv. electron microscopy studi ...19989765444
application of genetic methods to study the relationship between classical swine fever outbreaks.eleven viruses isolated between 1993 and 1997 from outbreaks of classical swine fever in the neighbouring countries of slovakia, the czech republic and austria were compared after partial sequencing of the ns5b and e2 genes. viruses collected from south-central and west slovakia were indistinguishable during a period of four years, even when associated with outbreaks of variable severity. outbreaks that occurred in the czech republic in 1996 involved two types of virus, one of which was related ...19989769081
an rt-pcr assay for the specific detection of classical swine fever virus in clinical samples.a simple reverse transcriptase-polymerase chain reaction (rt-pcr) assay has been developed for the specific amplification of dna after reverse transcription of rna from the classical swine fever virus (csfv). a pair of oligonucleotides was selected from an area of high homology in the genome of csfv strains, but which differed from the corresponding sequences in the genome of bovine viral diarrhea virus (bvdv) strains. using these primers (csfv1-csfv2), a csfv specific dna band of 174 bp was amp ...19989779556
african swine fever virus nl gene is not required for virus virulence.previously, we described a highly conserved nonessential african swine fever virus (asfv) right variable region gene, nl. deletion of nl from the european pathogenic isolate e70 resulted in almost complete attenuation of the virus in domestic swine. to study gene function further, nl gene deletion mutants were constructed from two pathogenic african asfv isolates, malawi lil-20/1 (mal) and pretoriuskop/96/4 (pr4). unexpectedly, both mal (mal-deltanl) and pr4 (pr4deltanl) null mutants remained hi ...19989780062
classical swine fever virus: discrimination between vaccine strains and european field viruses by restriction endonuclease cleavage of pcr amplicons. 19989787502
[methods of laboratory diagnosis of hog cholera].the review emphasizes the significance of laboratory methods for the diagnosis of hog cholera virus. in addition to virus isolation and immunofluorescent method, enzyme immunoassay (eia) of virus-specific antigen and antibodies are recommended. commercial eia kits for laboratory diagnosis of hog cholera virus and test-systems whose development is in progress now are characterized.19989791879
functionality and cell anchorage dependence of the african swine fever virus gene a179l, a viral bcl-2 homolog, in insect cells.the african swine fever virus gene a179l has been shown to be a functional member of the ced9/bcl-2 family of apoptosis inhibitors in mammalian cell lines. in this work we have expressed the a179l gene product (p21) under the control of the baculovirus polyhedrin promoter using a baculovirus system. expression of the a179l gene neither altered the baculovirus replication phenotype nor delayed the shutoff of cellular protein synthesis, but it extended the survival of the infected insect cells to ...19989811766
the african swine fever virus thymidine kinase gene is required for efficient replication in swine macrophages and for virulence in swine.african swine fever virus (asfv) replicates in the cytoplasm of infected cells and contains genes encoding a number of enzymes needed for dna synthesis, including a thymidine kinase (tk) gene. recombinant tk gene deletion viruses were produced by using two highly pathogenic isolates of asfv through homologous recombination with an asfv p72 promoter-beta-glucuronidase indicator cassette (p72gus) flanked by asfv sequences targeting the tk region. attempts to isolate double-crossover tk gene deleti ...19989811782
establishment of a serum-free culture cell line, cpk-ns, which is useful for assays of classical swine fever virus.a stable porcine kidney cell line, cpk-ns, was established and maintained in serum-free culture. a cytopathic effect (cpe) was observed clearly in cpk-ns cells infected with some classical swine fever virus (csfv) strains which did not show the exaltation of newcastle disease virus (end) phenomenon. chromosome condensation and dna fragmentation, a marker for apoptosis, were detected in cells infected with end phenomenon-negative csfv strains. by using the cpe induced by infection with an end phe ...19989820575
identification of a 25-aminoacid sequence from the major african swine fever virus structural protein vp72 recognised by porcine cytotoxic t lymphocytes using a lipoprotein based expression system.identification of african swine fever virus (asfv) proteins recognised by cytotoxic t lymphocytes (ctl) from swine surviving asfv/nh/p68 infection was assessed using expression vectors based on the pseudomonas aeruginosa outer membrane lipoprotein i gene (opri). viral antigens expressed as fusion lipoproteins were shown to be taken efficiently by porcine blood-derived macrophages incubated with outer membrane protein preparations from transformed e. coli. to assess recognition by ctl the fusion ...19989820580
in vivo effect on pig chromosomes of high dosage vaccine against classic swine fever.hog cholera virus (hcv) can induce chromosome abnormalities in diseased pigs as well as in those vaccinated with attenuated virus vaccine against classic swine fever. an experiment was made using animals from potency and safety control tests of commercial vaccines in argentina. the different types of chromosomal alterations observed were chromatid and chromosome breaks, chromatid exchanges, polyploid, multiple aberrations cells, and chromosome pulverization. in this study the occurrence of chrom ...19989838191
comparison of a reverse transcription-polymerase chain reaction assay and virus isolation for the detection of classical swine fever virus.the authors evaluated the ability of a reverse transcription-polymerase chain reaction (rt-pcr) assay to detect classical swine fever virus (csfv) in comparison with virus isolation and detection by an indirect immunoperoxidase assay (vi-ipa). to determine the specificity of the assay, samples from 60 spleens, 45 tonsils, ten submandibular lymph nodes, eight mesenteric lymph nodes and four kidneys, collected from pigs of various ages which had been slaughtered in abattoirs in canada (a populatio ...19989850538
application of a computer program for genetic typing of classical swine fever virus isolates from germany.the commercial software program hla sequityper (amersham pharmacia biotech), designed originally for human leukocyte antigen typing, was adapted for rapid typing of classical swine fever (csf) virus isolates. the program compares new sequence data with those stored in a database file and calculates the most probable assignment. for generating the csf virus sequence database, 150 bp of the 5' nontranslated genomic region (5'-ntr) from 88 german classical swine fever virus isolates from outbreaks ...19989870589
porcine cells persistently infected with classical swine fever virus protected from pestivirus-induced cytopathic effect.cytopathogenicity of classical swine fever virus (csfv) depends on the presence of defective particles containing a subgenomic (sg) rna with a defined deletion. in a previous report we described the spontaneous generation of this sg rna and therefore of cytopathogenic (cp) csfv in porcine kidney cell cultures persistently infected with csfv. frequently, some cells survived the cpe and could be further propagated. they remained positive for viral antigen and continued to shed complete virus and i ...19989880012
characterization of immobilization methods for african swine fever virus protein and antibodies with a piezoelectric immunosensor.a direct piezoelectric flow injection analysis immunoassay for the detection of african swine fever virus and antibodies is presented. the peptide-specific monoclonal antibody 18bg3 and the virus protein 73 were used for detection with a quartz crystal microbalance. accumulation of the analyte on the surface of this mass-sensitive biosensor resulted in a shift of the resonant frequency. highly selective receptor layers were applied on the sensing electrode of the quartz crystal for detection of ...19989883562
prostaglandin a1 inhibits replication of classical swine fever virus.prostaglandins (pgs) have been shown to inhibit the replication of several dna and rna viruses. here we report the effect of prostaglandin (pga1) on the multiplication of a positive strand rna virus, classical swine fever virus (csfv) in pk15 cells. pga1 was found to inhibit the multiplication of csfv. at a concentration of 5 micrograms/ml, which was nontoxic to the cells, pga1 inhibitis virus production in 99%. in pga1 treated cells the size and number of characteristic classical swine fever fo ...19989921308
molecular cloning and nucleotide sequence of 3'-terminal region of classical swine fever virus lpc vaccine strain.a cdna of the 3'-terminus of classical swine fever virus (lpc vaccine strain) was cloned and sequenced. the 3431 nucleotides and deduced amino acid sequences were compared with those of other pestiviruses, and the similarity of nucleotide sequences and deduced amino acid sequences were found to be 84-95% and 95-98%, respectively. similar to other isolates of classical swine fever virus, the sequenced region included the non-structural gene p58 (ns5a) and part of p76 (ns5b) gene. the p76 gene of ...19989926397
sequence and organization of the left multigene family 110 region of the vero-adapted l60v strain of african swine fever virus.sequencing of the left variable region of the l60v vero cell-adapted strain of african swine fever virus (asfv) showed the presence of three genes belonging to multigene family 110 (mgf110) and of a fourth unrelated gene. this gene was separated from the mgf110 genes by a region rich in direct repeats. the first mgf110 gene, v1l, with 104 codons, was only moderately related to the other two, w1l and w2l, with 124 and 80 codons, respectively. these two genes were closely related, w2l being a trun ...19979482593
genetic heterogeneity of classical swine fever virus in central europe.the aim of this work was to genetically characterize central european isolates of classical swine fever virus (csfv) and to evaluate the applicability of molecular analysis in the epizootiology of csfv infections. thirty four viruses, derived from central european pigs or wild boar, were examined. all of these viruses were detected by each of three sets of oligonucleotide primers which had been designed for the specific rt-pcr amplification of different genomic regions. comparative sequence anal ...19979495535
generation of cytopathogenic subgenomic rna of classical swine fever virus in persistently infected porcine cell lines.two biological clones (a.1 and b.2) of the classical swine fever virus strain alfort/187 and the recombinant virus va187-1, derived from a cdna clone of alfort/187, were used to establish persistently infected cultures of the swine kidney cell lines sk-6 and pk-41. it was found that 100% of the cells in the passaged cultures were positive for viral antigen throughout the course of the experiment. additionally, supernatants collected upon passaging of the cells continuously contained high titers ...19979498611
the evolution of virus-induced apoptosis.viruses from several different families are able to exploit their host's cell death programmes so as to maximize viral fitness. consideration of the evolution of such strategies has lead to the suggestion that the virus should inhibit apoptosis, in order to prolong the life of the cell and thereby maximize the number of progeny virions. the host, on the other hand, should stimulate apoptosis thereby inhibiting viral growth and blocking viral spread. for example, the function of the latent membra ...19979447732
an improved elisa for the detection of serum antibodies directed against classical swine fever virus.the complex-trapping-blocking (ctb) elisa for detection of antibodies against classical swine fever virus (csfv) using two monoclonal antibodies (mabs) directed against envelope glycoprotein e2, has been improved using recombinant csfv e2-antigen. the newly developed ceditest elisa for csfv-ab is a modification of the ctb-elisa as described by wensvoort et al. (1988) and bloemraad et al. (1993). the old ctb-elisa format comprised of a two-step, single-dilution test which had to be performed by h ...19979460193
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