ATF4 and infection: The gene expression analysis showed a significant induction of the ER stress markers DDIT3/CHOP, ATF3, ATF4, CEBPB and the autophagy marker MAP1LC3B, both at 6 h and 24 h post-infection; HSPA5 was significantly induced only after 24 h, while CHAC1 did not show any significant variation (Fig 4A).