Enhanced humoral and cell-mediated immune responses after immunization with trivalent influenza vaccine adjuvanted with cationic liposomes

The recent pandemic caused by new influenza A (H1N1) has emphasized the need for improved influenza vaccines with enhanced immune responses that ideally include longlived humoral and CMI responses and mediate a broad protection. This study demonstrates that administration of trivalent influenza vaccine (TIV) with the cationic liposome adjuvant system CAF01 enhances the humoral immune response as measured by hemagglutinin inhibition titers and influenza-specific serum antibody titers, and promote a strong Th1 response with augmented levels of IL-1β, IL-2, IL-12, IFN-γ and TNF-α. Furthermore, high levels of IL-17 are detected in agreement with CAF01's ability to promote TH17 responses. Importantly, the Th1/Th17 cytokine profile is still maintained 20 weeks after the last vaccination. The CAF01 adjuvanted influenza vaccine reduces weight loss and temperature decrease and results in complete survival of mice challenged with the drifted H1N1 influenza strain A/PR/8/34. Overall, the results suggest that CAF01 is a potent adjuvant system for future, improved influenza vaccines.