ERN1 and infection: Furthermore, the successive transfection of p3×Flag-IRE1α and p3×Flag-XBP1 constructs into PK-15 cells, subsequently followed by infection with CSFV (MOI = 1), elucidated that the overexpression of these ER stress-associated proteins not only substantially enhanced viral replication but also resulted in a pronounced upregulation of SCD1 protein expression (Fig. 6G and H).