The role of the endoplasmic reticulum-associated degradation in establishment of persistent
Hepatitis B Virus infection
Hepatitis B virus (HBV) is a very important human pathogen that can have serious consequences on the health of infected patients. Chronic HBV infections are closely correlated with an increased risk of incidence of cirrhosis and hepatocellular carcinoma. The viral genome is represented by a molecule of DNA packaged within the nucleocapsid, which is surrounded by a lipid bilayer containing three envelope proteins. These proteins called L ("large"), M ("middle") and S ("small") are synthesized in the endoplasmic reticulum (ER) at a higher level so that the virus can secrete subviral particles and viral particles. Accumulation of misfolded or incomplete folded proteins in the ER may result in triggering cellular stress. Our previous results showed that EDEM proteins ("ER degradation-enhancing alpha-mannosidase-like") are expressed at high levels in cells with active HBV replication. HBV envelope proteins co-expression with EDEM1 protein results in their massive degradation, process that is reversible when EDEM1 is silenced (Lazar C. et al, 2012). Surprisingly, the removal of envelope proteins accumulated in the ER is done by autophagosomes/ lysosomes rather than by proteasome. And, most importantly, inhibition of expression of endogenous EDEM1 significantly increases the secretion of both enveloped virus and subviral particles.
In this context, the current project intends to continue these important findings and tries to elucidate the role of ERAD components in HBV life cycle and in the establishment of chronic infection both in vitro and in vivo.