[Cell proteins that potentially interact with HBV polymerase were identified by co-immunoprecipitation-based LC-MS/MS...

Hepatitis B virus (HBV) is a major cause of chronic liver disease, and frequently results in hepatitis, cirrhosis, and ultimately hepatocellular carcinoma. HBV polymerase (Pol) is an essential viral protein that is important for HBV replication and might be involved in the development of hepatocellular carcinoma. Protein-protein interactions appears to be crucial for its role. The aim of this study was to screen and identify the proteins that interact with Pol using a co-immunoprecipitation-based LC-MS/MS identification technique. The HBV Pol gene was amplified by polymerase chain reaction (PCR) and cloned into pCDNA3.1(+). The recombinant plasmid pCDNA3. 1(+)-Pol-flag was transfected into HeLa cells. Liquid chromatography and tandem mass spectrometry (LC-MS/MS) identified 45 proteins that co-immunoprecipitated with flag-tagged HBV Pol. Eleven of these have previously been reported as proteins that interact with HBV Pol. A proof-of-concept-based Ingenuity Pathway Analysis (IPA, www.ingenuity.com) was used to characterize the functions and pathways of these 45 identified proteins and HBV Pol. Among these proteins, four proteins may play a role in three major molecular cellular networks, and are therefore worthy of further investigation.