Knockdown expression of IL-10Rα gene inhibits PRRSV replication and elevates immune responses in PBMCs of Tibetan pig in vitro

Increase of interleukin-10 (IL-10) induced by Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) infection has been intensely studied to inhibit the anti-viral responses of host pigs. Blockade of expression of IL-10 receptor (IL-10R) by RNA interference (RNAi) may relieve the immunosuppression caused by excessive IL-10 in PRRSV infection. The recombinant short hairpin expressing plasmid targeted to pig IL-10R alpha was transfected into peripheral blood mononuclear cells of Tibetan pig (Tp-PBMCs) prior to PRRSV inoculation, then the replication of PRRSV and immune responses in Tp-PBMCs were evaluated. The recombinant interfering plasmid greatly decreased PRRSV yield. The transcriptional level of IL-10R alpha was obviously inhibited by recombinant interfering plasmid; the expression of IL-10 was also down-regulated, while that of TGF-beta 1 was not affected. Furthermore, the recombinant plasmid notably up-regulated the mRNA levels of TLR3, TLR7, IFN-alpha, IFN-gamma, IL-2, IL-4, IL-12p40 and MyD88, while that of IL-8 was apparently decreased; In addition, cell viability of Tp-PBMCs was clearly enhanced by the interfering recombinant plasmid. Our results suggest that knockdown the expression of pig IL-10R alpha can evidently inhibit the PRRSV infection and enhance the anti-viral immune responses of pig immune cells, which may be a promising way for preventing virus infection and developing new effective immune-regulator to strengthen the host immunity against PRRS.