HNTCP‑expressing primary pig hepatocytes are a valuable tool for investigating hepatitis B virus infection and antiviral drugs

Abstract

Primary human hepatocytes (PHHs) are the ‘gold standard’ for investigating hepatitis B virus (HBV) infection and antiviral drugs. However, poor availability, variation between batches and ethical issues regarding PHHs limit their applications. The discovery of human sodium taurocholate co-transporting polypeptide (hNTCP) as a functional HBV receptor has enabled the development of a surrogate model to supplement the use of PHHs. In the present study, the evolutionary distance of seven species was assessed based on single-copy homologous genes. Based on the evolutionary distance and availability, PHHs and primary rabbit hepatocytes (PRHs) were isolated and infected with hNTCP-recombinant lentivirus, and susceptibility to HBV infection in the two cell types was tested and compared. In addition, HBV infection efficiency of hNTCP-expressing PPHs with pooled HBV-positive serum and purified particles was determined. The potential use of HBV-infected hNTCP-expressing PPHs for drug screening was assessed. The results demonstrated that pigs and rabbits are closer to humans in the divergence tree compared with mice and rats, indicating that pigs and rabbits were more likely to facilitate the HBV post-entry lifecycle. Following hNTCP complementation and HBV infection, PPHs and Huh7D human hepatocellular carcinoma cells, but not PRHs, exhibited increased hepatitis B surface antigen and hepatitis B e-antigen secretion, covalently closed circular DNA formation and infectious particle secretion. hNTCP-expressing PPHs were susceptible to infection with HBV particles purified from pooled HBV-positive sera, but were poisoned by raw HBV-positive sera. The use of HBV-infected hNTCP-expressing PPHs for viral entry inhibitor screening was revealed to be applicable and reproducible. In conclusion, hNTCP-expressing PPHs may be valuable tool for investigating HBV infection and antiviral drugs.