PCV, Cytokines and Chemokines
The majority of studies investigating cytokine profiles in PCV2-infected pigs that have been published to date where done on pigs with naturally-acquired PMWS. Sipos et al. (2004) found an increase of IL-1α and IL-10 mRNA and down-regulation of IL-2 and IL-2Rα mRNA associated with PMWS by comparing 10 pigs with naturally acquired PMWS with 10 clinically healthy pigs. Pigs with naturally acquired PMWS pigs had an altered cytokine mRNA expression pattern with overexpression of IL-10 mRNA in thymus and IFN-γ mRNA in tonsil (Darwich et al., 2003b). Mononuclear cells from pigs with naturally acquired PMWS did not produce normal levels of IFN-γ, IL-1β, IL-2, IL-4 or IL-8 when they were challenged with a T-cell mitogen such as phytohemaglutinin or superantigens but they did produce some IFN-γ or IL-10 when challenged with recall PCV2 antigens (Darwich et al., 2003a). Sipos et al. (2005) compared 5 pigs affected by PDNS, 5 pigs with naturally acquired PMWS, and 5 healthy control pigs and found IL-1α, IL-6, and IFN-γ mRNA expressions elevated as well as an increased capacity of peripheral blood mononuclear cells to produce IL-2, IL-4, IL-6, IL-12, TNF-α, and IFN-γ in PDNS pigs compared to PMWS pigs. In PMWS pigs, IL-10 mRNA was significantly decreased compared to control pigs (Sipos et al., 2005).
Kim and Chae (2004) observed maximum expression of monocyte chemoattractant protein-1 (MCP-1) and macrophage inflammatory protein-1 (MIP-1) at 17 and 21 DPI in lymphoid tissues of experimentally PCV2-infected pigs by ISH and semiquantitive reverse transcriptase PCR. MCP-1 was correlated with PCV2 as determined by ISH done on serial sections of lymph nodes from PMWS-affected pigs, whereas IL-8 was not detected in the lesions (Kim and Chae, 2003c). Injection of granulocyte-macrophage colony stimulating factor (GM-CSF) encoding DNA had no significant effect on PCV2 replication in 5-week-old specific pathogen free (SPF) pigs injected with a tandem-cloned PCV2 DNA when compared to non-GM-CSF-injected pigs (Loizel et al., 2005). Further in vitro studies found that in the presence of intracytoplasmic PCV2, the function of natural interferon producing cells (conventional blood dendritic ells and plamacytoid dendritic cells) is disrupted which would impair the maturation of associated myeloid dendritic cells favoring the establishment of concurrent infections (Vincent et al., 2005).
Darwich L, Balasch M, Plana-Duran J, Segales J, Domingo M, Mateu E: Cytokine profiles of peripheral blood mononuclear cells from pigs with postweaning multisystemic wasting syndrome in response to mitogen, superantigen or recall viral antigens. J Gen Virol. 84:3453-3457, 2003a
Darwich L, Pie S, Rovira A, Segales J, Domingo M, Oswald IP, Mateu E: Cytokine mRNA expression profiles in lymphoid tissues of pigs naturally affected by postweaning multisystemic wasting syndrome. J Gen Virol. 84:2117-2125, 2003b
Kim J, Chae C: Expression of monocyte chemoattractant protein-1 but not interleukin-8 in granulomatous lesions in lymph nodes from pigs with naturally occurring postweaning multisystemic wasting syndrome. Vet Pathol. 40:181-186, 2003
Loizel C, Blanchard P, Grasland B, Dory D, Oger A, Nignol AC, Cariolet R, Jestin A: Effect of granulocyte-macrophage colony-stimulating factor on post-weaning multisystemic wasting syndrome in porcine circovirus type-2-transfected piglets. Int J Exp Pathol. 86:33-43, 2005
Sipos W, Duvigneau JC, Pietschmann P, Schilcher F, Hofbauer G, Hartl RT, Schmoll F: Porcine dermatitis and nephropathy syndrome (PDNS) is associated with a systemic cytokine expression profile indicative of proinflammation and a Th1 bias. Vet Immunol Immunopathol. 107:303-313, 2005
Sipos W, Duvigneau JC, Willheim M, Schilcher F, Hartl RT, Hofbauer G, Exel B, Pietschmann P, Schmoll F: Systemic cytokine profile in feeder pigs suffering from natural postweaning multisystemic wasting syndrome (PMWS) as determined by semiquantitative RT-PCR and flow cytometric intracellular cytokine detection. Vet Immunol Immunopathol. 99:63-71, 2004
Vincent IE, Carrasco CP, Guzylack-Piriou L, Herrmann B, McNeilly F, Allan GM, Summerfield A, McCullough KC: Subset-dependent modulation of dendritic cell activity by circovirus type 2. Immunology. 115:388-398, 2005