The replication of PEC in the porcine kidney cell line LLC-PK1 is dependent on the presence of BAs in the culture medium for at least two reasons: 1) BAs facilitate PEC escape from the endosome into cytoplasm for initiation of viral replication [8]; 2) BAs inhibit cellular innate immunity by downregulating phosphorylation of signal transducer and activator of transcription 1 (STAT1) upon PEC infection in LLC-PK1 [9]. The gene discussed is STAT1; the disease is infection.