title: A full-length cDNA infectious clone of North American type 1 porcine reproductive and respiratory syndrome virus: expression of green fluorescent protein in the Nsp2 region.
abstract: The recent emergence of a unique group of North American type 1 porcine reproductive and respiratory syndrome virus (PRRSV) in the United States presents new disease control problems for a swine industry that has already been impacted seriously by North American type 2 PRRSV. In this study, a full-length cDNA infectious clone was generated from a low-virulence North American type 1 PRRSV isolate, SD01-08. In vitro studies demonstrated that the cloned virus maintained growth properties similar to those of the parental virus. Virological, pathological, and immunological observations from animals challenged with cloned viruses were similar to those from animals challenged with the parental virus and a modified live virus vaccine. To further explore the potential use as a viral backbone for expressing foreign genes, the green fluorescent protein (GFP) was inserted into a unique deletion site located at amino acid positions 348 and 349 of the predicted Nsp2 region in the virus, and expression of the Nsp2-GFP fusion protein was visualized by fluorescent microscopy. The availability of this North American type 1 infectious clone provides an important research tool for further study of the basic viral biology and pathogenic mechanisms of this group of type 1 PRRSV in the United States.
authors.affiliation: Center for Infectious Disease Research and Vaccinology, Department of Veterinary Science, Box 2175, South Dakota State University, Brookings, SD 57007-1396, USA. ying.fang@sdstate.edu
authors.forename: Ying
authors.initials: Y
authors.lastname: Fang
authors.forename: Raymond R R
authors.initials: RR
authors.lastname: Rowland
authors.forename: Michael
authors.initials: M
authors.lastname: Roof
authors.forename: Joan K
authors.initials: JK
authors.lastname: Lunney
authors.forename: Jane
authors.initials: J
authors.lastname: Christopher-Hennings
authors.forename: Eric A
authors.initials: EA
authors.lastname: Nelson
mesh_terms: D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary / Q000032:analysis / Q000502:physiology*; D004279:DNA, Viral / Q000096:biosynthesis; D015967:Gene Expression Regulation, Viral; D049452:Green Fluorescent Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics* / Q000254:growth & development / Q000302:isolation & purification / Q000472:pathogenicity*; D013552:Swine; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics*; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics
chemical_list: D018076:DNA, Complementary; D004279:DNA, Viral; D017361:Viral Nonstructural Proteins; D014764:Viral Proteins; D049452:Green Fluorescent Proteins