Figure 2

Autophagy is induced by HBV expression and enhances HBV replication. HBV increases autophagy to favor its own replication. The exact steps impacted by autophagy are still unclear, but it seems that autophagy can either enhance HBV DNA replication or favor HBV envelopment. To date, different non-exclusive mechanisms for autophagy induction have been proposed. The regulatory protein HBx could directly activate autophagy through the induction of PI3KC3 activity or the up-regulation of beclin1 expression. Finally the small envelope protein (SHBs) has been shown to induce autophagy via the establishment of ER stress that triggers the unfolded protein response (UPR) and autophagy. Interestingly, a study has reported that induction of UPR triggers autophagy-dependent degradation of three HBV envelope proteins. This mechanism seems to be in contradiction with the previous finding. It will be interesting to determine if this autophagy-dependent mechanism regulates the overall production of viral particles following autophagy induction.