Pegylated interferon(IFN) α-2a(Peg-IFN-α) not only inhibit viral replication, but also play an important role in immune regulation, while entecavir(ETV) drugs only inhibit viral replication. In hepatitis B infection, Plasmacytoid Dendritic Cells（pDCs） are the main effector cells in early antiviral innate immune response. This study was aimed at investigating the changes of pDCs frequency and function, and the expression of costimulatory molecules CD86(Cluster of Differentiation antigen 86) during Peg-IFN-αand entecavir(ETV) therapy.Meanwhile, investigators want to verify whether Peg-IFN-α suppressed the virus and the reduction of virus led to the recovery of pDCs function, or Peg-IFN-α enhanced pDCs function which gave rise to the decline of the virus.