SVV infection weakly increased Grp78 and p-PERK expression and significantly enhanced p-eIF2α expression in PK-15 cells at 12 and 24 h in PK-15 cells compared to the control groups, while no differences in the expression of the above proteins between mock- and SVV-infected cells were observed at 36 and 48 h post-infection (hpi) (Fig. 1A). This evidence concerns the gene HSPA5 and infection.