title: Genomic analysis and pathogenic characteristics of Type 2 porcine reproductive and respiratory syndrome virus nsp2 deletion strains isolated in Korea.
abstract: Porcine reproductive and respiratory syndrome virus (PRRSV) is a globally ubiquitous swine virus that exhibits genetic and pathogenic heterogeneity among isolates. The present study was conducted to determine the complete genome sequence and pathogenicity of two Korean type 2 PRRSV nonstructural protein 2 (nsp2) deletion mutants, CA-2 and KNU-12-KJ4. The full-length genomes of CA-2 and KNU-12-KJ4 were determined to be 15,018 and 15,019 nucleotides in length, excluding the poly(A) tail, respectively, which were 393- or 392-nucleotide shorter than that of the type 2 NA prototype strain VR-2332 due to the presence of notable large deletions within the nsp2 gene. The genomes of CA-2 and KNU-12-KJ4 consisted of a 189- or 190-nucleotide 5' untranslated region (UTR), a 14,677-nucleotide protein-coding region, and a 151-nucleotide 3' UTR. Whole genome evaluation revealed that the nucleotide sequences of CA-2 and KNU-12-KJ4 are most similar to each other (10.7% sequence divergence), and then to the Korean strain CA-1 (11.3% sequence divergence) and the US strain MN184C (13.1% sequence divergence), respectively. To evaluate the in vitro immunity of nsp2 deletion variants, we sought to explore alteration of inflammatory cytokine and chemokine expression in PAM-pCD163 cells infected with each virus strain using quantitative real-time RT-PCR. Cytokine genes including IL-8, IL-10, and TNF-α, and chemokines such as MCP-1 and RANTES were found to be significantly elevated in nsp2 deletion virus-infected PAM cells. In contrast, expression of interferons (IFN-β, γ, and λ) and antiviral genes including ISG-15, -54, and -56 were unchanged or down-regulated in PAM cells infected with the nsp2 deletion mutants. Animal studies to assess the pathogenicity of nsp2 deletion PRRSVs demonstrated that both CA-2 and KNU-12-KJ4 strains notably produce weight loss in infected pigs. Furthermore, the nsp2 deletion mutants replicated well in pigs with significantly increased and prolonged viremia kinetics. Taken together, our results indicate that, among the three isolates, the outcome of in vitro and in vivo infection by CA-2 and KNU-12-KJ4 is comparable, suggesting that the large nsp2 deletion may be one of the viral genetic determinants contributing to PRRSV pathogenicity.
authors.affiliation: Choongang Vaccine Laboratory, Daejeon 304-348, Republic of Korea.
authors.forename: Hwan-Won
authors.initials: HW
authors.lastname: Choi
authors.affiliation: Choongang Vaccine Laboratory, Daejeon 304-348, Republic of Korea.
authors.forename: Eeuri
authors.initials: E
authors.lastname: Nam
authors.affiliation: School of Life Sciences, KNU Creative BioResearch Group (BK21 plus program), Kyungpook National University, Daegu 702-701, Republic of Korea.
authors.forename: Yoo Jin
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: Choongang Vaccine Laboratory, Daejeon 304-348, Republic of Korea.
authors.forename: Yun-Hee
authors.initials: YH
authors.lastname: Noh
authors.affiliation: Choongang Vaccine Laboratory, Daejeon 304-348, Republic of Korea.
authors.forename: Seung-Chul
authors.initials: SC
authors.lastname: Lee
authors.affiliation: Choongang Vaccine Laboratory, Daejeon 304-348, Republic of Korea.
authors.forename: In-Joong
authors.initials: IJ
authors.lastname: Yoon
authors.affiliation: College of Veterinary Medicine, Chungnam National University, Daejeon 305-764, Republic of Korea.
authors.forename: Hyun-Soo
authors.initials: HS
authors.lastname: Kim
authors.affiliation: College of Veterinary Medicine, Chungbuk National University, Cheongju 361-763, Republic of Korea.
authors.forename: Shien-Young
authors.initials: SY
authors.lastname: Kang
authors.affiliation: College of Medicine and Medical Research Institute, Chungbuk National University, Cheongju 361-763, Republic of Korea.
authors.forename: Young-Ki
authors.initials: YK
authors.lastname: Choi
authors.affiliation: School of Life Sciences, KNU Creative BioResearch Group (BK21 plus program), Kyungpook National University, Daegu 702-701, Republic of Korea. Electronic address: changhee@knu.ac.kr.
authors.forename: Changhee
authors.initials: C
authors.lastname: Lee
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D002460:Cell Line; D016207:Cytokines / Q000235:genetics; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D016679:Genome, Viral / Q000235:genetics*; D008969:Molecular Sequence Data; D019318:Porcine Reproductive and Respiratory Syndrome / Q000473:pathology / Q000821:virology; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics / Q000472:pathogenicity; D011897:Random Allocation; D056910:Republic of Korea; D017384:Sequence Deletion; D012689:Sequence Homology, Nucleic Acid; D013552:Swine; D017361:Viral Nonstructural Proteins / Q000235:genetics*; D014766:Viremia / Q000473:pathology / Q000662:veterinary*
chemical_list: D000914:Antibodies, Viral; D016207:Cytokines; D017361:Viral Nonstructural Proteins
keywords: Genome sequence; Immune response; PRRSV; Pathogenicity; nsp2 deletion