Nasal Vaccines Against Hepatitis B: An Update

After several decades of immunization against hepatitis B virus, the question still remains whether a new vaccine could avoid the limitations of the current vaccine similar to those associated with its injectable form or ineffectiveness on chronic hepatitis B disease. A hypothesis to overcome first limitation is the development of an intranasal vaccine, self-administered, able to achieve not only systemic immunity, but also sIgA on the vaginal mucosa which would be a great advantage to prevent the sexually transmitted disease cases. Injectable hepatitis B vaccines that are already available in the market led to achieving protection mainly through a strong antibody-mediated response. For chronic hepatitis, a strong cellular immune response would also be required. The aim of this review is to give an overview of the work done in recent years, with the objective of developing a vaccine that can be administered by intranasal route. A discussion of the leading studies is presented, focusing not only on potential antigens, but also on promising adjuvants for the hepatitis B antigen. The results of the immune response generated with different formulations are summarized in tables. It is important to note that almost all studies claimed the induction of specific mucosal immune response (sIgA) and a balanced cellular and humoral Th1/Th2 or a Th1-type immune response. The further evaluation of these formulations, using a laboratory animal model of viral hepatitis B, would allow scientific community to conclude about the utility of these new adjuvants, particularly on a combined immunotherapy strategy for chronic hepatitis B.