A novel adjuvant G3 induces both Th1 and Th2 related immune responses in mice after immunization with a trivalent inactivated split-virion influenza vaccine

A preferred adjuvant should promote both Th1 and Th2 responses. However, most adjuvants in common use are biased towards a Th2-driven response. Therefore, the ability of a novel saponin-based adjuvant G3 to inducing balanced Thl and Th2 responses in BALB/c mice immunized with a split trivalent seasonal influenza vaccine was evaluated in comparison to that of the adjuvant Al(OH) 3 . Clear differences in the IgG profiles induced by G3, Al(OH)(3) or non-adjuvanted vaccine were recorded. Both adjuvants enhanced high and similar levels of the Th2 associated IgG1 subtype compared to mice given vaccine alone. Only G3 enhanced the IgG2a subclass reflecting a Th1 response, whereas Al(OH)(3) even abrogated the IgG2a production. Accordingly, G3 enhanced the production of IL-2 and IFN-gamma and also of IL-2/IFN-gamma double secreting cells, emphasizing the strong Th1 driving effect of G3. Only Al(OH)(3) increased splenocyte production of IL-17. Taken together, the results indicate a strong propensity for G3 to induce both Th1 and Th2 driven immune responses. (C) 2018 The Authors. Published by Elsevier Ltd.