摘要AIM: To investigate the antiviral effect of beta-L enantiomer of 2', 3'-didehydro-2', 3'-dideoxyadenosine (β-L-D4A) on 2.2.15 cells transfected with the hepatitis B virus (HBV) genome. METHODS: Larnivudine (3TC) as a positive control. Then, HBV DNA in treated 2.2.15 cells and the Hepatitis B surface antigen (HBsAg) in the culture supernatants were detected to determine the inhibitory effect of β-L D4A.At the same time, 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (NTT) was used to detect the survival ratio of 2.2.15 cells. RESULTS: β-L-D4A has a dose-dependent inhibitory effect on HBV DNA replication; this effect was apparent when the concentration was above 1 rnol/L. When β-L D4A was at the highest concentration, 100 mol/L, the HBsAg inhibition ratio was above 50%. The Therapeutic index (TI) of β-L-D4A was above 2.1.CONCLUSION:β-L-D4A has a dose-dependent inhibitory effect on the replication of HBV DNA and the secretion of HBsAg at low toxicity.