Innate Immune Evasion of Porcine Epidemic Diarrhea Virus Through miRNA-193a-5p/IL22/pBD1 Pathway in Intestinal...

Porcine epidemic diarrhea (PED) virus (PEDV) is a highly contagious intestinal infection that primarily affects suckling pigs. The interaction about the innate immune evasion of PEDV in intestinal epithelium and microRNA (miRNA) remains unclear. A strain of PEDV belonging to the G2a genotype, designated FJND 2022, was successfully isolated and confirmed. Then, the miRNA profile in exosomes-derived from intestinal porcine epithelial cell line (IPEC) infected with PEDV FJND 2022 for 48 h was evaluated. In exosomes from PEDV-infected IPECs, 34 miRNAs showed differential expression relative to blank cells. A total of 7762 target genes of those differentially expressed miRNAs were forecast, and the miR-193a-5P and its target mRNA interleukin (IL)22 and porcine β-defensin 1 (pBD1) attracted our interest. After infection with PEDV for 48 h, the mRNA levels and protein levels of IL22 and pBD1 were both notably downregulated, while the mRNA level of miR-193a-5P was significantly decreased. When IPECs were pretreated with the mimic of miR-193a-5P and then infected with PEDV, the mRNA levels of IL22 and pBD1 were significantly increased while the viral load of PEDV was significantly reduced. However, siRNA-mediated knockdown of IL22 abrogated the capacity of miR-193a-5p mimic pretreatment to restore pBD1 expression. Furthermore, the inhibitor of miR-193a-5P was pretreated with IPECs infected with PEDV, resulting in a notable downregulation of IL22 and pBD1 expression, and a significant upregulation of the virus load of PEDV. Finally, we also found that the expression levels of IL22, pBD1, and miR-193a-5P were notably reduced in the small intestinal epithelium of suckling piglets infected with PEDV for 48 h. Therefore, in this study we reveal that PEDV downregulates the miR-193a-5P expression in the intestinal epithelium to evade the antivirus of IL22/pBD1, which provides new insights into PEDV molecular pathogenesis and immune evasion mechanisms.