Induction of Anti-Hepatitis B Virus Immune Responses Through DNA Immunization

Cellular and humoral immune responses to different hepatitis B virus (HBV) antigens are believed to play an essential role in the elimination of virus by the host. It is well established that the humoral immune response to HBV envelope antigens leads to protection against infection. By contrast, the activity of a broad-based cellular immune response to different HBV antigens has been shown to be one of the most important factors contributing to virus elimination from infected hepatocytes and may play an important role in the pathogenesis of the severity of hepatitis and the subsequent development of chronic liver disease (1 ). More than 300 million people worldwide have persistent HBV infection and cytotoxic T-lymphocyte (CTL) activity against HBV structural proteins is not detectable in peripheral blood lymphocytes derived from these individuals. It is known that some chronic HBV-infected individuals spontaneously clear HBV DNA from serum each year, and this phenomenon is often accompanied by increased CD4⁺ T-helper cell responses and acute exacerbation of the liver disease as manifested by increased alanine aminotransferase levels.