Vet. Res. (2008) 39:07
DOI: 10.1051/vetres:2007045

Classical swine fever virus induces activation of plasmacytoid and conventional dendritic cells in tonsil, blood, and spleen of infected pigs

Agnès Jamin^{1, 2}, Stéphane Gorin¹, Roland Cariolet³, Marie-Frédérique Le Potier¹ and Gaëlle Kuntz-Simon<sup>1

1</sup>  French Agency for Food Safety (AFSSA), Poultry and Swine Research Laboratory, Swine Virology Immunology Unit, BP 53, 22440 Ploufragan, France
²  Present address: Institut National de la Recherche Agronomique (INRA), UMR Systèmes d'Élevage, Nutrition Animale et Humaine, 35590 Saint-Gilles, France
³  French Agency for Food Safety (AFSSA), Poultry and Swine Research Laboratory, Section of Healthy Pig Production and Experimentation, BP 53, 22440 Ploufragan, France

(Received 5 April 2007; accepted 21 August 2007 ; published online 21 November 2007)

Abstract - Classical swine fever virus (CSFV) compromises the host immune system, causing indirect leucopoenia and disruption of in vitro T cell stimulation capacity. In order to explore the potential role of dendritic cells (DC) in such phenomena, the activation of conventional DC (cDC) and plasmacytoid DC (pDC) in blood and secondary lymphoid organs of infected pigs was investigated in the early time course post-inoculation (pi), together with viral components dissemination and cytokine production in serum. Whereas CD11R1⁺CD172a⁺ cDC frequencies were markedly reduced in blood and spleen, analysis of CD4⁺CD172a⁺ pDC numbers revealed a rapid turn-over of this DC subset in tissues pi. Both subsets matured and were activated after infection, as demonstrated by down-regulation of CD1a, up-regulation of the co-stimulation molecule CD80/86 and expression of cytokines. cDC essentially expressed tumor necrosis factor alpha (TNF-) and interleukin (IL)-10, whereas pDC produced alpha interferon (IFN-) and IL-12. IFN- and TNF- productions revealed an enhancement of innate anti-viral immune responses. Detection of antigen activated B lymphocytes in tonsil T-cell areas at 72 h pi, subsequently to the transient translocation of the viral E2 protein within germinal centres at 48 h pi, indicates the initiation of humoral response. This response was also evidenced by an important IL-10 production in serum one week pi. IL-12 expression in organs, as well as transient detection of IL-18 and IFN- in serum, reflected the initiation of cellular immune responses. However, the uncommonly high levels of TNF- and IFN- produced by DC and measured in serum early post-infection, together with IL-10 expression in spleen, could play a role in the disruption of immune system cells, either inducing apoptosis or impairing DC functionalities themselves.

Key words: antigen presenting cells / secondary lymphoid organs / interferon / E2 antigen / pestivirus

Corresponding author: g.kuntz.simon@afssa.fr

© INRA, EDP Sciences 2007