Porcine epidemic diarrhea virus (PEDV), the causative agent of PED, belongs to the
genus Alphacoronavirus in the family Coronaviridae. Reactive oxygen species (ROS),
endoplasmic reticulum (ER) stress, and autophagy play crucial roles in regulating
a variety of cellular processes during viral infection. However, the precise role
of autophagy in PEDV-infected Vero cells remains largely elusive. To elucidate how
PEDV infection induces autophagy, this study ascertained whether ER stress was present
in PEDV-infected Vero cells. The results showed PEDV infection significantly increased
the expression of GRP78 and LC3Ⅱ. Treatment with the ER stress inhibitor 4-phenylbutyrate
(4-PBA) could significantly inhibit PEDV-induced autophagy. Antioxidants, such as
N-acetylcysteine (NAC), could significantly inhibit PEDV-induced ER stress and autophagy,
indicating that ROS act as an upstream regulator of ER stress-mediated autophagy.
Further research found that activation of ER stress triggered the unfolded protein
response (UPR) through PERK, IRE1, and ATF6 pathways during PEDV infection. However,
treatment with the PERK inhibitor GSK2606414, IRE1 inhibitor STF-083010 but not ATF6
inhibitor AEBSF reversed PEDV-induced autophagy. Taken together, the results of this
study showed that accumulated ROS played an essential role in regulating ER stress-mediated
autophagy during PEDV infection. We also found that PERK and IER1 pathways of UPR
signalling were involved in PEDV-induced autophagy. Furthermore, PEDV induced autophagy
to promote viral replication via PERK and IER1 pathways in Vero cells. These results
provide the mechanism of PEDV-induced ROS-dependent ER stress-mediated autophagy in
Vero cells through activating PERK and IRE1 pathways.