Cytosolic retinoic acid-inducible gene I(RIG-I) is an important innate immune RNA sensor and can induce antiviral cytokines, e.g., interferon-β(IFN-β). Innate immune response to hepatitis B virus(HBV) plays a pivotal role in viral clearance and persistence. However, knowledge of the role that RIG-I plays in HBV infection is limited. The woodchuck is a valuable model for studying HBV infection. To characterize the molecular basis of woodchuck RIG-I(w RIG-I), we analyzed the complete coding sequences(CDSs) of w RIG-I, containing 2778 base pairs that encode 925 amino acids. The deduced w RIG-I protein was 106.847 k D with a theoretical isoelectric point(p I) of 6.07, and contained three important functional structures [caspase activation and recruitment domains(CARDs), DEx D/H-box helicases, and a repressor domain(RD)]. In woodchuck fibroblastoma cell line(WH12/6), w RIG-I-targeted small interfering RNA(si RNA) down-regulated RIG-I and its downstrean effector–IFN-β transcripts under RIG-I' ligand, 5'-ppp double stranded RNA(ds RNA) stimulation. We also measured m RNA levels of w RIG-I in different tissues from healthy woodchucks and in the livers from woodchuck hepatitis virus(WHV)-infected woodchucks. The basal expression levels of w RIG-I were abundant in the kidney and liver. Importantly, w RIG-I was significantly up-regulated in acutely infected woodchuck livers, suggesting that RIG-I might be involved in WHV infection. These results may characterize RIG-I in the woodchuck model, providing a strong basis for further study on RIG-I-mediated innate immunity in HBV infection.
Chronic hepatitis B virus(CHB) is currently treated with either interferon-based or nucleot(s)idebased antiviral therapies.However,treatment with pegylated interferon alpha results in a durable antiviral response in only about 30%patients and is associated with side effects.Most patients receiving nucleot(s)ide analogue treatment do not establish long-term,durable control of Infection and have rebounding viremia after cessation of therapy.Thus,novel therapy strategies are necessary to achieve the induction of potent and durable antiviral immune responses of the patients which can maintain long-term control of viral replication.Therapeutic vaccination of HBV carriers is a promising strategy for the control of hepatitis B.Here the authors review new therapeutic vaccination strategies to treat chronic hepatitis B which may be introduced for patient treatment in the future.
