Constant antigenic drift (point mutations in the hemagglutinin) and occasional antigenic shift (exchange of the RNA segment encoding hemagglutinin) result in rapid changes of the antigenic make-up of circulating influenza viruses. As a consequence current vaccines which rely predominantly on the induction of antibody responses against the viral hemagglutinin rapidly loose effectiveness. In order to develop vaccines that offer broader protection against drift and shift variants we study vaccines which contain viral proteins other than hemagglutinin alone, like whole inactivated virus vaccines or virosomes with encapsulated or membrane-incorporated conserved viral proteins.
With these vaccines we aim at the induction of influenza-specific cytotoxic T lymphocytes in addition to induction of antibody responses. Moreover, we combine the selected vaccines with suitable adjuvants which can help in further broadening the immune response. This work is performed in the context of the EU-funded consortium UNISEC.