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J Immunol. 2018 Jul 15;201(2):533-547. doi: 10.4049/jimmunol.1800250. Epub 2018 Jun 1.

Porcine Circovirus Type 2 Suppresses IL-12p40 Induction via Capsid/gC1qR-Mediated MicroRNAs and Signalings.

Author information

1
College of Veterinary Medicine, Northwest A&F University, Yangling, China 712100.
2
Center for Retrovirus Research, The Ohio State University, Columbus, OH 43210.
3
Viruses and Emerging Pathogens Program, Infectious Diseases Institute, The Ohio State University, Columbus, OH 43210.
4
Department of Veterinary Biosciences, The Ohio State University, Columbus, OH 43210; and.
5
Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH 43210.
6
College of Veterinary Medicine, Northwest A&F University, Yangling, China 712100; dwtong@nwsuaf.edu.cn yonghuang@nwsuaf.edu.cn.

Abstract

Porcine circovirus (PCV) type 2 (PCV2), an immunosuppression pathogen, is often found to increase the risk of other pathogenic infections. Yet the relative immune mechanisms determining the susceptibility of PCV2-infected animals remain unclear. In this study, we confirmed that PCV2 infection suppressed IL-12p40 expression and host Th1 immune response, leading to a weakened pathogenic clearance upon porcine reproductive respiratory syndrome virus (PRRSV) or Haemophilus parasuis infection. PCV2 infection suppressed pathogens, LPS/IFN-γ, or LPS/R848-induced IL-12p40 expression in porcine alveolar macrophages. PCV2 capsid (Cap) was the major component to suppress IL-12p40 induction by LPS/IFN-γ, LPS/R848, PRRSV, or H. parasuis Either wild-type PCV2 or mutants PCV2-replicase 1 and PCV type 1-Cap2, which contained PCV2 Cap, significantly decreased IL-12p40 levels and increased the replication of PRRSV and H. parasuis in the lung tissues relative to mock or PCV type 1 infection. gC1qR, a Cap binding protein, was not involved in IL-12p40 induction but mediated the inhibitory effect of PCV2 Cap on IL-12p40 induction. PCV2 also activated PI3K/Akt1 and p38 MAPK signalings to inhibit IL-12p40 expression via inhibition of NF-κB p65 binding to il12B promoter and upregulation of miR-23a and miR-29b. Knockdown of Akt1 and p38 MAPK downregulated miR-23a and miR-29b and increased IL-12p40 expression. Inhibition of miR-23a and miR-29b attenuated the inhibitory effect of PCV2 on IL-12p40 induction, resulting in an increased IL-12p40 expression and Th1 cell population and reduced susceptibility to PRRSV or H. parasuis Taken together, these results demonstrate that PCV2 infection suppresses IL-12p40 expression to lower host Th1 immunity to increase the risk of other pathogenic infection via gC1qR-mediated PI3K/Akt1 and p38 MAPK signaling activation.

PMID:
29858268
PMCID:
PMC6039236
DOI:
10.4049/jimmunol.1800250
[Indexed for MEDLINE]
Free PMC Article

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