Assessing hepatitis B virus infectivity in blood components following pathogen reduction using a human hepatocyte model.

Background: Pathogen reduction technologies (PRTs) have the potential to reduce the risk of emerging transfusion transmissible infections. Evaluating PRT activity against hepatitis B virus (HBV) presents some unique challenges due to the lack of robust model systems. Surrogate viruses (e.g., duck HBV) can be used, but may differ from the human pathogen in ways that influence susceptibility to a given PRT.

Methods: Whole blood (WB) collected from volunteers was spiked with human plasma from deferred HBV-positive donors. Spiked WB was then treated with the nucleic acid crosslinking compound S-303 or left untreated. Additional physical and chemical treatments were also assessed. Plasma prepared from the spiked WB was used to inoculate human hepatocyte cultures isolated from chimeric mice with humanized livers. Culture medium was monitored over time for hepatitis B surface antigen (HBsAg) and viral DNA. Cell lysates were analyzed for evidence of covalently closed circular (ccc) DNA.

Results: The culture system faithfully measured infectious HBV in blood components. S-303 treatment of HBV-spiked WB prevented infection of hepatocyte cultures, as monitored by HBsAg expression, at concentrations as low as 0.125 mM of S-303 or with incubation times as short as 1 h. Additionally, S-303 treatment prevented the accumulation of T5 exonuclease-resistant HBV DNA in inoculated hepatocytes, suggesting that S-303 prevents establishment of HBV cccDNA.

Conclusion: This model mimics transfusion transmission by using donor-derived HBV and mouse-passaged human hepatocytes, allowing evaluation of the efficacy of different PRTs against authentic human HBV isolates. We found S-303 to be a potent inactivator of HBV.