Transfection of a rat hepatoma cell line with a construct expressing humanliver annexin V confers susceptibility to hepatitis B virus infection

Previously, we have found that human liver annexin V (hA-V; in earlier repo rts referred as Endonexin II) is a specific hepatitis B surface antigen (HB sAg) binding protein. In this study, we demonstrate that transfection of ra t hepatoma FTO 2B cells, a cell line that is not infectable by hepatitis B virus (HBV) and does not express hA-V, with a construct containing the hA-V gene, resulted in hA-V expressing cells susceptible to HBV infection. Afte r in vitro infection, transfected FTO cells (assigned as FTO 9.1 cells) exp ressing hA-V in cultures were shown to contain HBV-precore/core, X mRNAs, a nd covalently closed circular (ccc) DNA as detected by polymerase chain rea ction (PCR). The presence of HBV ccc and replicative intermediate DNA was a lso demonstrated by Southern blot hybridization assay. HBV DNA secreted in the culture medium was also evident as determined by quantitative branched DNA (bDNA) assay. HBsAg and hepatitis B core antigen (HBcAg) could also be detected by an immunocytochemical method in 10% to 15% of the cells at day 3 and day 5 after infection. Infectivity of in vitro-propagated HBV was dem onstrated by infection of the naive FTO 9.1 cells with the culture supernat ant from HBV-carrier cultures. In contrast to primary cultures of human hep atocytes and FTO 9.1 cells, primary rat and mouse hepatocytes, as well as r at hepatoma cell lines that do not express hA-V, are not susceptible to HBV infection. These findings suggest that hA-V plays a key role in the initia l step of HBV infection and that the species-specific susceptibility to HBV infection and replication in hepatocytes is associated with the expression of hA-V.