Expression of hepatitis B virus x protein in hepatocytes suppresses CD8 T cell activity

Background: CD8(+) T cells contribute to the clearance of Hepatitis B virus (HBV) infection and an insufficient CD8(+) T cell response may be one of the major factors leading to chronic HBV infection. Since the HBx antigen of HBV can up-regulate cellular expression of several immunomodulatory molecules, we hypothesized that HBx expression in hepatocytes might affect CD8(+) T cell activity.

Methods: We analyzed the activation and apoptosis of CD8(+) T cells co-cultured with primary hepatocytes rendered capable of expressing HBx by recombinant baculovirus infection.

Results: Expression of HBx in hepatocytes induced low production of interferon-γ and apoptosis of CD8(+) T cells, with no effect on CD8 T cell proliferation. However, transcriptional levels of H-2K, ICAM-1 and PD-1 ligand did not correlate with HBx expression in hepatocytes.

Conclusion: Our results suggest that HBx may inhibit CD8(+) T cell response by regulation of interferon-γ production and apoptosis.