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Swine influenza virus (SwIV) is considered a zoonosis and the fact that swine may act as an intermediate reservoir for avian influenza virus, potentially infectious for humans, highlights its relevance and the need to understand the interaction of different influenza viruses with the porcine immune system. Thus, in vitro porcine bone marrow-derived dendritic cell (poBMDCs) were infected with a circulating SwIV A/Swine/Spain/SF32071/2007(H3N2), 2009 human pandemic influenza virus A/Catalonia/63/2009(H1N1), low pathogenic avian influenza virus (LPAIV) A/Anas plathyrhynchos/Spain/1877/2009(aH7N2) or high pathogenic avian influenza virus (HPAIV) A/Chicken/Italy/5093/1999(aH7N1). Swine influenza virus H3N2 infection induced an increase of SLA-I and CD80/86 at 16 and 24h post infection (hpi), whereas the other viruses did not. All viruses induced gene expression of NF-κB, TGF-β, IFN-β and IL-10 at the mRNA level in swine poBMDCs to different extents and in a time-dependent manner. All viruses induced the secretion of IL-12 mostly at 24hpi whereas IL-18 was detected at all tested times. Only swH3N2 induced IFN-α in a time-dependent manner. Swine H3N2, aH7N2 and aH7N1 induced secretion of TNF-α also in a time-dependent manner. Inhibition of NF-κB resulted in a decrease of IFN-α and IL-12 secretion by swH3N2-infected poBMDC at 24hpi, suggesting a role of this transcription factor in the synthesis of these cytokines. Altogether, these data might help in understanding the relationship between influenza viruses and porcine dendritic cells in the innate immune response in swine controlled through soluble mediators and transcription factors., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Monocyte subsets have been shown to differ in the pattern of chemokine receptor expression and their migratory properties, both in human and mouse. Previously we have characterized in the swine several monocyte subpopulations, based on the expression of CD163, Tük4 and SLA-II, which share features with the populations described in human and mouse. Here, we have analysed the expression of different chemokine receptors in the CD163-Tük4+SLA-II- and CD163+Tük4-SLA-II+ populations of porcine monocytes. CD163+Tük4-SLA-II+ monocytes expressed higher CX3CR1 but lower CCR2 and CXCR4 mRNA levels than CD163-Tük4+SLA-II- monocytes. Moreover, porcine CCL2 binding on Tük4+SLA-II- but not on Tük4-SLA-II+ cells was detected by using a CCL2-green fluorescence protein (pCCL2-GFP) fusion protein. Finally, flow cytometric analyses of monocytes recovered after chemotaxis assays show a clear increase in the proportion of Tük4+SLA-II- cells in the fraction migrating toward CCL2, consistent with the polarized CCR2 expression in this monocyte population. The pattern of expression of these chemokine receptors reinforces the similarities of these porcine subsets with their human and mouse counterparts., (© The authors published by INRA/EDP Sciences, 2010.)

Abstract: Swine influenza virus (SwIV) causes sub-acute or acute respiratory infections on swine farms and pigs can act as “mixing vessels” for new influenza strains. Knowledge of the immune response of SwIV in its natural host, pigs, is very limited. Dendritic cells (DCs) mediate the induction of immunity to pathogens, but their interaction with SwIV has not been fully characterized. Thus, porcine bone marrow derived DCs (poBMDCs) were exposed to a circulating strain of H3N2 SwIV in vitro. Infection of poBMDCs resulted in structures resembling influenza virus inside poBMDCs in vesicles and also free in cytoplasm. Viral progeny was undetectable in supernatant but limited replication was detected in the first 8h after infection. However, viral particles from infected-poBMDCs were able to induce cytopathic effect in susceptible cells only when cell-to-cell interaction was favoured. The data generated in our studies reveal the particular interaction of H3N2 SwIV with conventional DCs. [Copyright &y& Elsevier]