As shown in Fig. 5A to C, compared with the mock-infected cells, the endogenous pre-mRNA, circRNA, mRNA, and TNFAIP3 protein were synchronously upregulated in PDCoV-infected cells, and the ratio of mRNA to circTNFAIP3 was dramatically increased during the later stages of infection. The gene discussed is TNFAIP3; the disease is infection.