Adenovirus 5 and 35 vectors expressing Plasmodium falciparum circumsporozoite surface protein elicit potent antigen-specific cellular IFN-γ and antibody responses in mice

Falciparum malaria vaccine candidates have been developed using recombinant, replication-deficient serotype 5 and 35 adenoviruses (Ad5, Ad35) encoding the Plasmodium falciparum circumsporozoite surface protein (CSP) (Ad5.CS, Ad35.CS) (Crucell Holland BV, Leiden, The Netherlands). To evaluate the immunogenicity of these constructs, BALB/cJ mice were immunized twice with either Ad5.CS, Ad35.CS, empty Ad5-vector (eAd5), empty Ad35 vector (eAd35), or saline. Another group received the CSP-based RTS,S malaria vaccine formulated in the proprietary Adjuvant System AS01B (GlaxoSmithKline Biologicals, Rixensart, Belgium). Here we report that Ad5.CS, Ad35.CS, and RTS,S/AS01B, elicited both cellular and serologic CSP antigen-specific responses in mice. These adenoviral vectors induce strong malaria-specific immunity and warrant further evaluation.