Induction of humoral and cellular immune response to HBV vaccine can be up-regulated by STING ligand.

A persistent hepatitis B virus (HBV) infection is characterized by a lack of or a weak immune response to HBV. Efficient induction of the HBV-specific immune response leads to the clearance of HBV. Stimulator of interferon (IFN) genes (STING) is a cytoplasmic sensor of intracellular DNA from microbes and host cells. In the present study, we examined the efficacy of cyclic guanosine monophosphate-adenosine monophosphate (cGAMP) that is a ligand of the STING pathway as an HBV vaccine adjuvant. Wild-type (WT) mice and HBV-transgenic (HBV-Tg) mice were immunized with hepatitis B surface antigen (HBsAg) and cGAMP. The vaccination with HBsAg and cGAMP significantly enhanced the humoral and cellular immune response to HBsAg in WT and HBV-Tg mice. Cytokine production related to Th1 and Th2 responses and the activation of antigen-presenting cells in lymphoid tissues were induced by cGAMP. Vaccination using cGAMP may overcome tolerance in patients with chronic HBV infection.