Autophagy by hepatitis B virus and for hepatitis B virus.

Autophagy is a catabolic process by which cells remove unwanted proteins and damaged organelles. It is important for maintaining cellular homeostasis and can also be used by cells to remove intracellular microbial pathogens. As such, some viruses such as herpes simplex virus-1 (HSV-1) have evolved mechanisms to suppress autophagy for their survival. In contrast, other viruses such as poliovirus, hepatitis C virus (HCV) and dengue viruses have instead evolved mechanisms to use this pathway to enhance their replication. Recently, we demonstrated that hepatitis B virus (HBV), a DNA virus that infects hepatocytes, could enhance and use autophagy for its DNA replication. This enhancement of autophagy is mediated by its X protein, which binds to and activates phosphatidylinositol-3-kinase class 3 (PI3KC3), an enzyme important for the initiation of autophagy. The persistent activation of autophagy in hepatocytes by HBV during chronic infection may play an important role in HBV pathogenesis.