PROS1 and infection: Following infection of sodium taurocholate co-transporting polypeptide (NTCP)-expressing HepG2 cells with HBV and vesicular stomatitis virus G protein (VSV.G)-pseudotyped HIV, we found that productive HIV infection led to a twofold upregulation of HBV surface (HBs) mRNA and a marked increase in intracellular production and cellular retention of HBs antigen (HBsAg).