title: A virulent strain of porcine reproductive and respiratory syndrome virus does not up-regulate interleukin-10 levels in vitro or in vivo.
abstract: Porcine reproductive and respiratory syndrome virus (PRRSV) causes reproductive failure and respiratory illness in infected pigs. It has been postulated that the ability of PRRSV to induce the anti-inflammatory cytokine interleukin-10 (IL-10) in macrophages of infected pigs would be important for PRRSV immunopathogenesis, although this property would be variable and might be dependent on the strain. Several strains were reported to induce IL-10 in infected macrophages while others would not. In this study, we analyzed the IL-10 expression during in vitro and in vivo infections by a well-characterized virulent strain of PRRSV, vFL12, which is derived from an infectious clone. Our results showed that the vFL12 strain did not up-regulate IL-10 at mRNA or protein levels in either infected macrophages or dendritic cells in vitro. Furthermore, immunofluorescence staining for IL-10 on tonsil sections of PRRSV-infected pigs did not produce any evidence of IL-10 induction in PRRSV-infected cells or in bystander cells of the lymphoid tissues. Hence, based on these results obtained with a well-characterized highly pathogenic PRRSV strain it may be concluded that the induction of IL-10 release is not a part of the PRRSV virulence mechanisms.
authors.affiliation: School of Veterinary Medicine & Biomedical Sciences, University of Nebraska-Lincoln, Lincoln, NE 68583, USA. fosorio@unl.edu
authors.forename: Sakthivel
authors.initials: S
authors.lastname: Subramaniam
authors.forename: Jung-Hyang
authors.initials: JH
authors.lastname: Sur
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: D000818:Animals; D002478:Cells, Cultured; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D005786:Gene Expression Regulation; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism*; D008214:Lymphocytes / Q000378:metabolism; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D019318:Porcine Reproductive and Respiratory Syndrome / Q000378:metabolism* / Q000821:virology; D019316:Porcine respiratory and reproductive syndrome virus / Q000502:physiology*; D013552:Swine; D015854:Up-Regulation
chemical_list: D016207:Cytokines; D016753:Interleukin-10