Reduced antigen presentation capability and modified inflammatory/immunosuppressive cytokine expression of induced monocyte-derived dendritic cells from peripheral blood of piglets infected with porcine circovirus type 2

Abstract

The efficiency of immune responses and host defense against pathogens largely depends on the function of dendritic cells (DCs). Porcine circovirus type 2 (PCV2) infection causes viremia and extensive modulation of immune activities in the blood. The objective of the present study was to investigate the effects of PCV2 infection in vivo on the immunological function of DCs induced from peripheral blood monocytes (MoDCs). At different points after infection with PCV2, peripheral blood monocytes from PCV2-infected pigs were used to induce differentiation of DCs in vitro. Flow cytometry and quantitative real-time reverse transcription PCR were conducted to detect mRNA expression of surface markers related to antigen presentation and inflammatory/immunosuppressive cytokines of the induced MoDCs. The ability of induced MoDCs to stimulate T cells was measured using an MTS assay. In the early phase of infection at 3 days post-inoculation (DPI), IL-10, IL-8 and MIP-1β in MoDCs were upregulated significantly. By the peak of virus proliferation at 7 DPI, antigen presentation molecules SLA-DR (MHC II) and CD80/86 together with cytokines IL-12 and IL-10 had decreased, accompanied by a rapid reduction of IL-8 and MIP-1β. The T cell stimulation index of induced MoDCs in PCV2 groups after different infection times declined to some extent, with a significant difference at 7 DPI. PCV2 infection in vivo functionally reduced the antigen presentation capability of induced MoDCs from peripheral blood and modified expression of inflammatory/immunosuppressive cytokines that may be related to PCV2-induced immunosuppression.

Genetic Characterization of Porcine Circovirus 3 Strains Circulating in Sardinian Pigs and Wild Boars

“…In our study, co-infection of two swine viruses (PCV2 and PPV) was assessed and the results showed a large frequency of both the viruses in domestic and free ranging pigs as well as in wild boars. Although further studies are needed to better characterize the PCV3 impact on the pig immune system, we can hypothesize that, by analogy with PCV2 whose immunosuppressive activity has already been demonstrated [37,38], PCV3 infection might compromise the swine immune system to a certain extent, thus facilitating concomitant infection with other common viruses. Indeed, conversely to what we observed, other authors found that even if co-circulation of PCV2 and PCV3 is a common occurrence in pig farms, co-infections of individual pigs seems to be rare [39].…”

Importance of the Major Histocompatibility Complex (Swine Leukocyte Antigen) in Swine Health and Biomedical Research

“…SLA-typed pigs are used in vaccine design, disease models, and allogeneic and xenogeneic transplantation. of piglets infected with porcine circovirus type 2 (91). Based on GWAS analyses, Walker et al (92) verified that host genotype explained 64% of the phenotypic variation for overall PCV2 viral load, with two major quantitative trait loci (QTL), one identified on SSC7 near the SLA complex class II locus and, importantly, a missense mutation in the SYNGR2 on SSC12.…”

Porcine Dendritic Cells and Viruses: An Update

“…In vivo, PCV2 antigen has been found in macrophages, DC, and follicular dendritic cells [97,98,99]. A recent study focused on moDC generated from blood monocytes of PCV-2 infected pigs [100]. It was observed that PCV2 infection in vivo impaired DC functions: at the peak of virus proliferation (7 days post-infection), moDC generated from infected pigs presented reduced MHC II and CD80/86 expressions, lower levels of IL-10, IL-12, IL-8, MIP-1β, and reduced ability to stimulate T cells.…”

“…It was observed that PCV2 infection in vivo impaired DC functions: at the peak of virus proliferation (7 days post-infection), moDC generated from infected pigs presented reduced MHC II and CD80/86 expressions, lower levels of IL-10, IL-12, IL-8, MIP-1β, and reduced ability to stimulate T cells. This DC dysfunction could be at least, in part, responsible for PCV2-induced immunosuppression [100]. Interactions of PCV2 with different DC subsets are summarized in Figure 5.…”