Autophagy: a novel guardian of HCV against innate immune response.

Autophagy is an evolutionarily conserved process that catabolizes intracellular components and maintains cellular homeostasis. Autophagy involves the sequestration of cytoplasmic content within a double-membraned autophagosome, and the fusion of the autophagosome with a lysosome to form an autolysosome for subsequent degradation (Fig. 1A). Autophagy plays a pivotal role in various aspects of cellular responses to stresses, such as nutrient deprivation, damaged organelles, aggregated proteins, exposure to endoplasmic reticulum (ER) stress and pathogen infections. Virus infection often leads to ER stress and induction of the unfolded protein response (UPR). Recent studies reveal that virus-induced UPR may activate autophagy to support the virus life cycle. However, the exact roles of the UPR and autophagy in host cell-virus interactions are still enigmatic.