A Surfactin Lipopeptide Adjuvanted Hepatitis B Vaccines Elicit Enhanced Humoral and Cellular Immune Responses in Mice

WH1fungin (WF), a lipopeptide surfactin, has been verified as an immunoadjuvant previously. In this study, mice were intranasally or parenterally immunized with WF plus Hepatitis B surface antigen (HBsAg), then the immune responses were detected. The results showed 50 µg WF plus 20 μg HBsAg for intranasal and 10 μg WF plus 1 µg HBsAg for parenteral immunization was efficient inducing strong immune response against HBsAg in mice. A high titer and longterm anti-HBsAg IgG was observed for more than 19 weeks in intranasal or parenteral immunizations, much higher than that induced by CpG or Alum adjuvant. The anti-HBsAg IgA was also induced in intestine and lung, indicating that mucosal as well as systemic immune response was elicited for intranasal immunization. The IgG isotype in serum revealed WF induced a Th2-bias immune response with a higher titer of anti-HBsAg IgG1 than IgG2a in mice. Moreover, WF also induced more Th1 cells producing interferon (IFN)-γ and stronger cytotoxic T lymphocytes response than controls for intramuscular administration. These data further confirmed that WF induced Th1- as well as Th2- type immune response toward HBsAg. Taken together, WF-adjuvanted HBsAg elicits more effective immune response than that adjuvanted by Alum or CpG, suggesting its potential for development of more efficient HBV vaccines in the future.