Research Article: A Pre-Clinical Safety Evaluation of SBP (HBsAg-Binding Protein) Adjuvant for Hepatitis B Vaccine

Date Published: January 19, 2017

Publisher: Public Library of Science

Author(s): Jingbo Wang, Caixia Su, Rui Liu, Baoxiu Liu, Inam Ullah Khan, Jun Xie, Naishuo Zhu, Isabelle A Chemin.


Although adjuvants are a common component of many vaccines, there are few adjuvants licensed for use in humans due to concerns about their toxic effects. There is a need to develop new and safe adjuvants, because some existing vaccines have low immunogenicity among certain patient groups. In this study, SBP, a hepatitis B surface antigen binding protein that was discovered through screening a human liver cDNA expression library, was introduced into hepatitis B vaccine. A good laboratory practice, non-clinical safety evaluation was performed to identify the side effects of both SBP and SBP-adjuvanted hepatitis B vaccine. The results indicate that SBP could enhance the HBsAg-specific immune response, thus increasing the protection provided by the hepatitis B vaccine. The safety data obtained here warrant further investigation of SBP as a vaccine adjuvant.

Partial Text

The infectious disease hepatitis B, which is caused by the hepatitis B virus (HBV), has troubled people worldwide for many years. The current prophylactic HBV vaccines, which are based on recombinant hepatitis B surface antigen (HBsAg), have successfully decreased rates of HBV infection and transmission. However, there are more than 2 billion people who have been infected with HBV and are therefore at high risk for liver failure, cirrhosis, or cancer [1]. Specific groups of patients respond poorly or not at all to conventional HBV vaccines. Because of the poor immunogenicity of HBsAg, new methods are needed to improve the ability of the HBV vaccine to trigger protective immunity [2, 3]. Third-generation HBV vaccines that combine small S antigen with PreS1 and PreS2 antigens have been shown to induce a stronger immune response in non- and low responders than current HBV vaccines [4]. Conventionally used adjuvants, such as aluminum salts, allow for persistent release of the antigen, delaying clearance and resulting in more exposure to the immune system [5]. Adjuvants can elicit effective innate and adaptive immune responses through increasing the ability of antigens to activate signaling pathways.

Although the existing HBV vaccine provides many people with significant protection against infection [13], a more effective vaccine is required for poor-response groups [14, 15]. In a previous study, we found an HBsAg-binding protein that could promote the immune process both in vitro and in vivo. Its adjuvanticity in connection with several antigens (HBsAg, rabies [16], and rotavirus [17]) has been evaluated in mice and the results indicate that it has the potential to be a new adjuvant for use in human vaccines.




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