Our results show that PCV2 infection significantly increased (P < 0.01) the expression of the ERS related genes GRP78 and GADD153/CHOP at the mRNA and protein level in mice, which was similar to reports that hepatitis B and C virus-induced hepatitis induced apoptosis, autophagy, and the unfolded protein response41. Here, DDIT3 is linked to hepatitis A virus infection.