Vaxfectin (registered trademark) Enhances Both Antibody and In Vitro T Cell Responses to Each Component of a 5-gene Plasmodium falciparum Plasmid DNA Vaccine Mixture Administered at Low Doses

We previously reported the capacity of the cationic lipid-based formulation, Vaxfectin (registered trademark) to enhance the immunogenicity and protective efficacy of a low dose plasmid DNA vaccine against Plasmodium yoelii malaria in mice. Here, we have extended this finding to human Plasmodium falciparum genes, evaluating the immune enhancing effect of Vaxfectin (registered trademark) formulation on a mixture designated CSLAM of five plasmid DNA vaccines encoding antigens from the sporozoite (PfCSP, PfSSP2/TRAP), intrahepatic (PfLSA1), and erythrocytic (PfAMA1, PfMSP1) life cycle stages of P. falciparum administered at 2, 10 or 50 microgram doses. Vaxfectin (registered trademark) formulation enhanced both antibody and cellular immune responses ro each component of the multi-antigen vaccine mixture, as assessed by ELISA, IFAT, and IFN-gamma ELlspot, respectively. There was no apparent antigenic competition, as indicated by comparison of responses induced in mice immunized with PfCSP vs. CSLAM. These data showing that Vaxfectin (registered trademark) can enhance the immunogenicty of plasmid DNA vaccines administered at low doses per body weight, and in combinations, has important clinical implications for the development of a vaccine against malaria, as well as against other public health threats. Published in Vaccine, v28 p3055-3065, 2010. Sponsored in part by USAMRMC.