title: Correlation between point mutations in NS2 and the viability and cytopathogenicity of Bovine viral diarrhea virus strain Oregon analyzed with an infectious cDNA clone.
abstract: 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.
authors.affiliation: Federal Research Centre for Virus Diseases of Animals, D-72076 Tübingen, Germany.
authors.forename: B M
authors.initials: BM
authors.lastname: Kümmerer
authors.forename: G
authors.initials: G
authors.lastname: Meyers
mesh_terms: D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002460:Cell Line; D003001:Cloning, Molecular; D003588:Cytopathogenic Effect, Viral / Q000235:genetics*; D017931:DNA Primers; D018076:DNA, Complementary; D001908:Diarrhea Viruses, Bovine Viral / Q000235:genetics* / Q000472:pathogenicity; D016297:Mutagenesis, Site-Directed; D017354:Point Mutation; D017361:Viral Nonstructural Proteins / Q000235:genetics*
chemical_list: D017931:DNA Primers; D018076:DNA, Complementary; D017361:Viral Nonstructural Proteins