Development of a nasal vaccine for chronic hepatitis B infection that uses the ability of hepatitis B core antigen to stimulate a strong Th1 response against hepatitis B surface antigen.

There are estimated to be 350 million chronic carriers of hepatitis B infection worldwide. Patients with chronic hepatitis B are at risk of liver cirrhosis with associated mortality because of hepatocellular carcinoma and other complications. An important goal, therefore, is the development of an effective therapeutic vaccine against chronic hepatitis B virus (HBV). A major barrier to the development of such a vaccine is the impaired immune response to HBV antigens observed in the T cells of affected patients. One strategy to overcome these barriers is to activate mucosal T cells through the use of nasal vaccination because this may overcome the systemic immune downregulation that results from HBV infection. In addition, it may be beneficial to present additional HBV epitopes beyond those contained in the traditional hepatitis B surface antigen (HbsAg) vaccine, for example, by using the hepatitis B core antigen (HBcAg). This is advantageous because HBcAg has a unique ability to act as a potent Th1 adjuvant to HbsAg, while also serving as an immunogenic target. In this study we describe the effect of coadministration of HBsAg and HBcAg as part of a strategy to develop a more potent and effective HBV therapeutic vaccine.