The aim of this study was to investigate the function of CD8+ T lymphocytes in HBV infection, including the expression of activation molecules (CD69) and apoptosis-inducing molecules (CD178) in the pathogenesis of chronic HBV infection (IT and HBeAg-positive CHB), and their role in hepatitis B (CHB and AHB). The gene discussed is CD8A; the disease is hepatitis B virus infection.