title: Identification of amino acid residues important for anti-IFN activity of porcine reproductive and respiratory syndrome virus non-structural protein 1.
abstract: The non-structural protein 1 (nsp1) of porcine reproductive and respiratory syndrome virus is partly responsible for inhibition of type I interferon (IFN) response by the infected host. By performing alanine-scanning mutagenesis, we have identified amino acid residues in nsp1α and nsp1β (the proteolytic products of nsp1) that when substituted with alanine(s) exhibited significant relief of IFN-suppression. A mutant virus (16-5A, in which residues 16-20 of nsp1β were substituted with alanines) encoding mutant nsp1β recovered from infectious cDNA clone was shown to be attenuated for growth in vitro and induced significantly higher amount of type I IFN transcripts in infected macrophages. In infected pigs, the 16-5A virus exhibited reduced growth at early times after infection but quickly regained wild type growth properties as a result of substitutions within the mutated sequences. The results indicate a strong selection pressure towards maintaining the IFN-inhibitory property of the virus for successful propagation in pigs.
authors.affiliation: School of Veterinary Medicine and Biomedical Sciences and the Nebraska Center for Virology, University of Nebraska-Lincoln, Lincoln, NE 68583-0900, USA.
authors.forename: Lalit K
authors.initials: LK
authors.lastname: Beura
authors.forename: Sakthivel
authors.initials: S
authors.lastname: Subramaniam
authors.forename: Hiep L X
authors.initials: HL
authors.lastname: Vu
authors.forename: Byungjoon
authors.initials: B
authors.lastname: Kwon
authors.forename: Asit K
authors.initials: AK
authors.lastname: Pattnaik
authors.forename: Fernando A
authors.initials: FA
authors.lastname: Osorio
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D057809:HEK293 Cells; D054884:Host-Pathogen Interactions / Q000276:immunology; D006801:Humans; D007113:Immunity, Innate; D007370:Interferon Type I / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000235:genetics; D008264:Macrophages / Q000276:immunology / Q000821:virology; D016297:Mutagenesis, Site-Directed; D019318:Porcine Reproductive and Respiratory Syndrome / Q000276:immunology / Q000821:virology; D019316:Porcine respiratory and reproductive syndrome virus / Q000737:chemistry* / Q000235:genetics / Q000276:immunology* / Q000472:pathogenicity; D013552:Swine; D017361:Viral Nonstructural Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*
chemical_list: D017931:DNA Primers; D007370:Interferon Type I; D017361:Viral Nonstructural Proteins