The Experts below are selected from a list of 228 Experts worldwide ranked by ideXlab platform
Charles M Rice - One of the best experts on this subject based on the ideXlab platform.
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isolation and characterization of noncytopathic pestivirus mutants reveals a role for nonstructural protein ns4b in viral Cytopathogenicity
Journal of Virology, 2001Co-Authors: Lin Qu, Laura K. Mcmullan, Charles M RiceAbstract:Isolates of bovine viral diarrhea virus (BVDV), the prototype pestivirus, are divided into cytopathic (cp) and noncytopathic (ncp) biotypes according to their effect on cultured cells. The cp viruses also differ from ncp viruses by the production of viral nonstructural protein NS3. However, the mechanism by which cp viruses induce cytopathic effect in cell culture remains unknown. Here we used a genetic approach to isolate ncp variants that arose from a cp virus at low frequency. A bicistronic BVDV (cp strain NADL) was created that expressed puromycin acetyltransferase as a dominant selectable marker. This bicistronic virus exhibited slightly slower growth kinetics and smaller plaques than NADL but remained cp. A number of independent ncp variants were isolated by puromycin selection. Remarkably, these ncp variants produced NS3 and viral RNA at levels comparable to those of the cp parent. Sequence analyses uncovered no change in NS3, but for all ncp variants a Y2441C substitution at residue 15 of NS4B was found. Introduction of the Y2441C substitution into the NADL or bicistronic cp viruses reconstituted the ncp phenotype. Y2441 is highly conserved among pestiviruses and is located in a region of NS4B predicted to be on the cytosolic side of the endoplasmic reticulum membrane. Other engineered substitutions for Y2441 also affected viral Cytopathogenicity and viability, with Y2441V being cp, Y2441A being ncp, and Y2441D rendering the virus unable to replicate. The ncp substitutions for Y2441 resulted in slightly increased levels of NS2-3 relative to NS3. We also showed that NS3, NS4B, and NS5A could be chemically cross-linked in NADL-infected cells, indicating that they are associated as components of a multiprotein complex. Although the mechanism remains to be elucidated, these results demonstrate that mutations in NS4B can attenuate BVDV Cytopathogenicity despite NS3 production.
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infectious bovine viral diarrhea virus strain nadl rna from stable cdna clones a cellular insert determines ns3 production and viral Cytopathogenicity
Journal of Virology, 1998Co-Authors: Ernesto Mendez, Nicolas Ruggli, Marc S Collett, Charles M RiceAbstract:Bovine viral diarrhea virus (BVDV), strain NADL, was originally isolated from an animal with fatal mucosal disease. This isolate is cytopathic in cell culture and produces two forms of NS3-containing proteins: uncleaved NS2-3 and mature NS3. For BVDV NADL, the production of NS3, a characteristic of cytopathic BVDV strains, is believed to be a consequence of an in-frame insertion of a 270-nucleotide cellular mRNA sequence (called cIns) in the NS2 coding region. In this study, we constructed a stable full-length cDNA copy of BVDV NADL in a low-copy-number plasmid vector. As assayed by transfection of MDBK cells, uncapped RNAs transcribed from this template were highly infectious (>10(5) PFU/microg). The recovered virus was similar in plaque morphology, growth properties, polyprotein processing, and Cytopathogenicity to the BVDV NADL parent. Deletion of cIns abolished processing at the NS2/NS3 site and produced a virus that was no longer cytopathic for MDBK cells. This deletion did not affect the efficiency of infectious virus production or viral protein production, but it reduced the level of virus-specific RNA synthesis and accumulation. Thus, cIns not only modulates NS3 production but also upregulates RNA replication relative to an isogenic noncytopathic derivative lacking the insert. These results raise the possibility of a linkage between enhanced BVDV NADL RNA replication and virus-induced Cytopathogenicity.
Gregor Meyers - One of the best experts on this subject based on the ideXlab platform.
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a cellular j domain protein modulates polyprotein processing and Cytopathogenicity of a pestivirus
Journal of Virology, 2001Co-Authors: G Rinck, Gregor Meyers, H.-j. Thiel, C Birghan, T Harada, Norbert TautzAbstract:Pestiviruses are positive-strand RNA viruses closely related to human hepatitis C virus. Gene expression of these viruses occurs via translation of a polyprotein, which is further processed by cellular and viral proteases. Here we report the formation of a stable complex between an as-yet-undescribed cellular J-domain protein, a member of the DnaJ-chaperone family, and pestiviral nonstructural protein NS2. Accordingly, we termed the cellular protein Jiv, for J-domain protein interacting with viral protein. Jiv has the potential to induce in trans one specific processing step in the viral polyprotein, namely, cleavage of NS2-3. Efficient generation of its cleavage product NS3 has previously been shown to be obligatory for the Cytopathogenicity of the pestiviruses. Regulated expression of Jiv in cells infected with noncytopathogenic bovine viral diarrhea virus disclosed a direct correlation between the intracellular level of Jiv, the extent of NS2-3 cleavage, and pestiviral Cytopathogenicity.
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The genetic basis for Cytopathogenicity of pestiviruses.
Veterinary Microbiology, 2000Co-Authors: Beate M Kümmerer, Paul Becher, Heinzjurgen Thiel, Norbert Tautz, Gregor MeyersAbstract:Two biotypes of pestiviruses, cytopathogenic (cp) and noncp viruses, can be distinguished by their effects on tissue culture cells. Identification of cp bovine viral diarrhea virus (BVDV) has been frequently reported since antigenically closely related noncp and cp BVDV can be isolated from cattle with fatal mucosal disease (MD) and are called a virus pair. In contrast to the BVDV system, only few cp border disease virus (BDV) and cp classical swine fever virus (CSFV) strains have been described. Serological analyses and sequence comparison studies showed that cp pestiviruses arise from noncp viruses by mutation. Elaborate studies during the last 10 years revealed that in most cases RNA recombination is responsible for the generation of the cp viruses. Recent results showed a second way for the development of a cp pestivirus which is based on the introduction of a set of point mutations within the NS2 gene.
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correlation between point mutations in ns2 and the viability and Cytopathogenicity of bovine viral diarrhea virus strain oregon analyzed with an infectious cdna clone
Journal of Virology, 2000Co-Authors: Beate M Kümmerer, Gregor MeyersAbstract:Cytopathogenicity of Bovine viral diarrhea virus (BVDV) is correlated with expression of the nonstructural protein NS3, which can be generated by processing of a fusion protein termed NS2-3. For the cytopathogenic (cp) BVDV strain Oregon, NS2-3 processing is based on a set of point mutations within NS2. To analyze the correlation between NS2-3 cleavage and Cytopathogenicity, a full-length cDNA clone composed of cDNA from BVDV Oregon and the utmost 5'- and 3'-terminal sequences of a published infectious BVDV clone was established. After transfection of RNA transcribed from this cDNA clone, infectious virus with similar growth characteristics to wild-type BVDV Oregon could be recovered that also exhibited a cytopathic effect. Based on this cDNA construct and published cp and noncp infectious clones, chimeric full-length cDNA clones were constructed. Analysis of the recovered viruses demonstrated that the presence of the NS2 gene of BVDV Oregon in a chimeric construct is sufficient for NS2-3 processing and a cp phenotype. Since previous studies had revealed that the amino acid serine at position 1555 of BVDV Oregon plays an important role in efficient NS2-3 cleavage, mutants of BVDV Oregon with different amino acids at this position were constructed. Some of these mutants showed NS2-3 cleavage efficiencies in the range of the wild-type sequence and allowed the recovery of viruses that behaved similarly to wild-type virus with regard to growth characteristics and Cytopathogenicity. In contrast, other mutants with considerably reduced NS2-3 cleavage efficiencies propagated much more slowly and reverted to viruses expressing polyproteins with sequences allowing efficient NS2-3 cleavage. These viruses apparently induced cytopathic effects only after reversion.
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Classical swine fever virus: recovery of infectious viruses from cDNA constructs and generation of recombinant cytopathogenic defective interfering particles.
Journal of virology, 1996Co-Authors: Gregor Meyers, Heinzjurgen Thiel, Till RümenapfAbstract:The 5'- and 3'-terminal sequences of the genomic RNA from classical swine fever virus (CSFV) were determined, and the resulting information was used for construction of full-length CSFV cDNA clones. After transfection of in vitro-transcribed RNA derived from a cDNA construct, infectious CSFV was recovered from porcine cells. To confirm the de novo generation of infectious CSFV from cloned DNA, a genetically tagged CSFV was constructed. In comparison with parental CSFV, the recombinant viruses were retarded in growth by about 1 order of magnitude. Introduction of a deletion by exchange of part of the full-length construct for corresponding cDNA fragments derived from the genomes of cytopathogenic CSFV defective interfering particles (DIs) (G. Meyers and H.-J. Thiel, J. Virol. 69:3683-3689. 1995) resulted in recovery of cytopathogenic DIs in the DI genomes is responsible for their Cytopathogenicity. The established system will allow novel approaches to analysis of pestiviral molecular biology and in particular to elucidation of the molecular basis of attenuation and Cytopathogenicity of these viruses.
Norbert Tautz - One of the best experts on this subject based on the ideXlab platform.
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a cellular j domain protein modulates polyprotein processing and Cytopathogenicity of a pestivirus
Journal of Virology, 2001Co-Authors: G Rinck, Gregor Meyers, H.-j. Thiel, C Birghan, T Harada, Norbert TautzAbstract:Pestiviruses are positive-strand RNA viruses closely related to human hepatitis C virus. Gene expression of these viruses occurs via translation of a polyprotein, which is further processed by cellular and viral proteases. Here we report the formation of a stable complex between an as-yet-undescribed cellular J-domain protein, a member of the DnaJ-chaperone family, and pestiviral nonstructural protein NS2. Accordingly, we termed the cellular protein Jiv, for J-domain protein interacting with viral protein. Jiv has the potential to induce in trans one specific processing step in the viral polyprotein, namely, cleavage of NS2-3. Efficient generation of its cleavage product NS3 has previously been shown to be obligatory for the Cytopathogenicity of the pestiviruses. Regulated expression of Jiv in cells infected with noncytopathogenic bovine viral diarrhea virus disclosed a direct correlation between the intracellular level of Jiv, the extent of NS2-3 cleavage, and pestiviral Cytopathogenicity.
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The genetic basis for Cytopathogenicity of pestiviruses.
Veterinary Microbiology, 2000Co-Authors: Beate M Kümmerer, Paul Becher, Heinzjurgen Thiel, Norbert Tautz, Gregor MeyersAbstract:Two biotypes of pestiviruses, cytopathogenic (cp) and noncp viruses, can be distinguished by their effects on tissue culture cells. Identification of cp bovine viral diarrhea virus (BVDV) has been frequently reported since antigenically closely related noncp and cp BVDV can be isolated from cattle with fatal mucosal disease (MD) and are called a virus pair. In contrast to the BVDV system, only few cp border disease virus (BDV) and cp classical swine fever virus (CSFV) strains have been described. Serological analyses and sequence comparison studies showed that cp pestiviruses arise from noncp viruses by mutation. Elaborate studies during the last 10 years revealed that in most cases RNA recombination is responsible for the generation of the cp viruses. Recent results showed a second way for the development of a cp pestivirus which is based on the introduction of a set of point mutations within the NS2 gene.
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Establishment and Characterization of Cytopathogenic and Noncytopathogenic Pestivirus Replicons
Journal of virology, 1999Co-Authors: Norbert Tautz, G Rinck, T Harada, A. Kaiser, Sven-erik Behrens, Heinzjurgen ThielAbstract:Defective interfering particles (DIs) of bovine viral diarrhea virus (BVDV) have been identified and shown to be cytopathogenic (cp) in the presence of noncytopathogenic (noncp) helper virus. Moreover, a subgenomic (sg) RNA corresponding in its genome structure to one of those BVDV DIs (DI9) was replication competent in the absence of helper virus. We report here that an sg BVDV replicon which encodes from the viral proteins only the first three amino acids of the autoprotease N(pro) in addition to nonstructural (NS) proteins NS3 to NS5B replicates autonomously and also induces lysis of its host cells. This demonstrates that the presence of a helper virus is not required for the lysis of the host cell. On the basis of two infectious BVDV cDNA clones, namely, BVDV CP7 (cp) and CP7ins- (noncp), bicistronic replicons expressing proteins NS2-3 to NS5B were established. These replicons express, in addition to the viral proteins, the reporter gene encoding beta-glucuronidase; the release of this enzyme from transfected culture cells was used to monitor cell lysis. Applying these tools, we were able to show that the replicon derived from CP7ins- does not induce cell lysis. Accordingly, neither N(pro) nor any of the structural proteins are necessary to maintain the noncp phenotype. Furthermore, these sg RNAs represent the first pair of cp and noncp replicons which mimic complete BVDV CP7 and CP7ins- with respect to Cytopathogenicity. These replicons will facilitate future studies aimed at the determination of the molecular basis for the Cytopathogenicity of BVDV.
Paul Becher - One of the best experts on this subject based on the ideXlab platform.
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a single point mutation in nonstructural protein ns2 of bovine viral diarrhea virus results in temperature sensitive attenuation of viral Cytopathogenicity
Journal of Virology, 2009Co-Authors: Alexander Pankraz, Simone Preis, Heinzjurgen Thiel, Andreas Gallei, Paul BecherAbstract:For Bovine viral diarrhea virus (BVDV), the type species of the genus Pestivirus in the family Flaviviridae, cytopathogenic (cp) and noncytopathogenic (ncp) viruses are distinguished according to their effect on cultured cells. It has been established that Cytopathogenicity of BVDV correlates with efficient production of viral nonstructural protein NS3 and with enhanced viral RNA synthesis. Here, we describe generation and characterization of a temperature-sensitive (ts) mutant of cp BVDV strain CP7, termed TS2.7. Infection of bovine cells with TS2.7 and the parent CP7 at 33°C resulted in efficient viral replication and a cytopathic effect. In contrast, the ability of TS2.7 to cause Cytopathogenicity at 39.5°C was drastically reduced despite production of high titers of infectious virus. Further experiments, including nucleotide sequencing of the TS2.7 genome and reverse genetics, showed that a Y1338H substitution at residue 193 of NS2 resulted in the temperature-dependent attenuation of Cytopathogenicity despite high levels of infectious virus production. Interestingly, TS2.7 and the reconstructed mutant CP7-Y1338H produced NS3 in addition to NS2-3 throughout infection. Compared to the parent CP7, NS2-3 processing was slightly decreased at both temperatures. Quantification of viral RNAs that were accumulated at 10 h postinfection demonstrated that attenuation of the Cytopathogenicity of the ts mutants at 39.5°C correlated with reduced amounts of viral RNA, while the efficiency of viral RNA synthesis at 33°C was not affected. Taken together, the results of this study show that a mutation in BVDV NS2 attenuates viral RNA replication and suppresses viral Cytopathogenicity at high temperature without altering NS3 expression and infectious virus production in a temperature-dependent manner.
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The genetic basis for Cytopathogenicity of pestiviruses.
Veterinary Microbiology, 2000Co-Authors: Beate M Kümmerer, Paul Becher, Heinzjurgen Thiel, Norbert Tautz, Gregor MeyersAbstract:Two biotypes of pestiviruses, cytopathogenic (cp) and noncp viruses, can be distinguished by their effects on tissue culture cells. Identification of cp bovine viral diarrhea virus (BVDV) has been frequently reported since antigenically closely related noncp and cp BVDV can be isolated from cattle with fatal mucosal disease (MD) and are called a virus pair. In contrast to the BVDV system, only few cp border disease virus (BDV) and cp classical swine fever virus (CSFV) strains have been described. Serological analyses and sequence comparison studies showed that cp pestiviruses arise from noncp viruses by mutation. Elaborate studies during the last 10 years revealed that in most cases RNA recombination is responsible for the generation of the cp viruses. Recent results showed a second way for the development of a cp pestivirus which is based on the introduction of a set of point mutations within the NS2 gene.
Heinzjurgen Thiel - One of the best experts on this subject based on the ideXlab platform.
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a single point mutation in nonstructural protein ns2 of bovine viral diarrhea virus results in temperature sensitive attenuation of viral Cytopathogenicity
Journal of Virology, 2009Co-Authors: Alexander Pankraz, Simone Preis, Heinzjurgen Thiel, Andreas Gallei, Paul BecherAbstract:For Bovine viral diarrhea virus (BVDV), the type species of the genus Pestivirus in the family Flaviviridae, cytopathogenic (cp) and noncytopathogenic (ncp) viruses are distinguished according to their effect on cultured cells. It has been established that Cytopathogenicity of BVDV correlates with efficient production of viral nonstructural protein NS3 and with enhanced viral RNA synthesis. Here, we describe generation and characterization of a temperature-sensitive (ts) mutant of cp BVDV strain CP7, termed TS2.7. Infection of bovine cells with TS2.7 and the parent CP7 at 33°C resulted in efficient viral replication and a cytopathic effect. In contrast, the ability of TS2.7 to cause Cytopathogenicity at 39.5°C was drastically reduced despite production of high titers of infectious virus. Further experiments, including nucleotide sequencing of the TS2.7 genome and reverse genetics, showed that a Y1338H substitution at residue 193 of NS2 resulted in the temperature-dependent attenuation of Cytopathogenicity despite high levels of infectious virus production. Interestingly, TS2.7 and the reconstructed mutant CP7-Y1338H produced NS3 in addition to NS2-3 throughout infection. Compared to the parent CP7, NS2-3 processing was slightly decreased at both temperatures. Quantification of viral RNAs that were accumulated at 10 h postinfection demonstrated that attenuation of the Cytopathogenicity of the ts mutants at 39.5°C correlated with reduced amounts of viral RNA, while the efficiency of viral RNA synthesis at 33°C was not affected. Taken together, the results of this study show that a mutation in BVDV NS2 attenuates viral RNA replication and suppresses viral Cytopathogenicity at high temperature without altering NS3 expression and infectious virus production in a temperature-dependent manner.
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The genetic basis for Cytopathogenicity of pestiviruses.
Veterinary Microbiology, 2000Co-Authors: Beate M Kümmerer, Paul Becher, Heinzjurgen Thiel, Norbert Tautz, Gregor MeyersAbstract:Two biotypes of pestiviruses, cytopathogenic (cp) and noncp viruses, can be distinguished by their effects on tissue culture cells. Identification of cp bovine viral diarrhea virus (BVDV) has been frequently reported since antigenically closely related noncp and cp BVDV can be isolated from cattle with fatal mucosal disease (MD) and are called a virus pair. In contrast to the BVDV system, only few cp border disease virus (BDV) and cp classical swine fever virus (CSFV) strains have been described. Serological analyses and sequence comparison studies showed that cp pestiviruses arise from noncp viruses by mutation. Elaborate studies during the last 10 years revealed that in most cases RNA recombination is responsible for the generation of the cp viruses. Recent results showed a second way for the development of a cp pestivirus which is based on the introduction of a set of point mutations within the NS2 gene.
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Establishment and Characterization of Cytopathogenic and Noncytopathogenic Pestivirus Replicons
Journal of virology, 1999Co-Authors: Norbert Tautz, G Rinck, T Harada, A. Kaiser, Sven-erik Behrens, Heinzjurgen ThielAbstract:Defective interfering particles (DIs) of bovine viral diarrhea virus (BVDV) have been identified and shown to be cytopathogenic (cp) in the presence of noncytopathogenic (noncp) helper virus. Moreover, a subgenomic (sg) RNA corresponding in its genome structure to one of those BVDV DIs (DI9) was replication competent in the absence of helper virus. We report here that an sg BVDV replicon which encodes from the viral proteins only the first three amino acids of the autoprotease N(pro) in addition to nonstructural (NS) proteins NS3 to NS5B replicates autonomously and also induces lysis of its host cells. This demonstrates that the presence of a helper virus is not required for the lysis of the host cell. On the basis of two infectious BVDV cDNA clones, namely, BVDV CP7 (cp) and CP7ins- (noncp), bicistronic replicons expressing proteins NS2-3 to NS5B were established. These replicons express, in addition to the viral proteins, the reporter gene encoding beta-glucuronidase; the release of this enzyme from transfected culture cells was used to monitor cell lysis. Applying these tools, we were able to show that the replicon derived from CP7ins- does not induce cell lysis. Accordingly, neither N(pro) nor any of the structural proteins are necessary to maintain the noncp phenotype. Furthermore, these sg RNAs represent the first pair of cp and noncp replicons which mimic complete BVDV CP7 and CP7ins- with respect to Cytopathogenicity. These replicons will facilitate future studies aimed at the determination of the molecular basis for the Cytopathogenicity of BVDV.
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Classical swine fever virus: recovery of infectious viruses from cDNA constructs and generation of recombinant cytopathogenic defective interfering particles.
Journal of virology, 1996Co-Authors: Gregor Meyers, Heinzjurgen Thiel, Till RümenapfAbstract:The 5'- and 3'-terminal sequences of the genomic RNA from classical swine fever virus (CSFV) were determined, and the resulting information was used for construction of full-length CSFV cDNA clones. After transfection of in vitro-transcribed RNA derived from a cDNA construct, infectious CSFV was recovered from porcine cells. To confirm the de novo generation of infectious CSFV from cloned DNA, a genetically tagged CSFV was constructed. In comparison with parental CSFV, the recombinant viruses were retarded in growth by about 1 order of magnitude. Introduction of a deletion by exchange of part of the full-length construct for corresponding cDNA fragments derived from the genomes of cytopathogenic CSFV defective interfering particles (DIs) (G. Meyers and H.-J. Thiel, J. Virol. 69:3683-3689. 1995) resulted in recovery of cytopathogenic DIs in the DI genomes is responsible for their Cytopathogenicity. The established system will allow novel approaches to analysis of pestiviral molecular biology and in particular to elucidation of the molecular basis of attenuation and Cytopathogenicity of these viruses.
