Fig. 1

Fine tune interactions between the host and hepatitis B virus (HBV) during the chronic natural course of infection. CTL = cytotoxic T lymphocyte; HLA = human leukocyte antigen; IL = interleukin; IFN = interferon; NK = natural killer cell; PD-1 = program death – 1; PD-L1 = program death ligand-1; TLR = toll like receptor