Current progress in the development of therapeutic vaccines for chronic hepatitis B virus infection.

Chronic hepatitis B is still a major public health issue despite the successful prophylactic vaccination attempts. Chronicity of hepatitis B virus (HBV) is mainly due to its ability to debilitate host's immune system. Therefore, major measures have been taken to stop this process and help patients with chronic hepatitis B infection recover from their illness. While satisfactory results have been achieved using preventive HBV vaccines, a reliable and effective therapeutic treatment is still in need of extensive studies. Current treatments for chronic hepatitis B include direct antiviral agents and nucleoside/nucleotide analogs, which are not always effective and are also costly. In addition, due to the fact that chronic HBV is responsible for debilitation of the immune system, studies have focused on developing therapeutic vaccines to help host's immune system recover and limit the infection. Several approaches including but not restricted to recombinant peptide-based, DNA-based, viral vector-based, and cell-based approaches are currently in use to develop therapeutic vaccines against the chronic form of HBV infection. In the current review, the authors will first discuss the role of the immune system in chronic hepatitis B infection and will then focus on latest advancements in therapeutic vaccination of HBV especially the clinical trials that have been carried out so far.