2013 Volume 133 Issue 11 Pages 1153-1157
The SE36 antigen, derived from serine repeat antigen 5 (SERA5) of Plasmodium falciparum, is a promising blood stage malaria vaccine candidate. Previous clinical trials indicated the protective efficacy of BK-SE36 malaria vaccine that is constituted of SE36 recombinant protein and aluminum hydroxide gel. In this study, we assessed the safety, immunogenicity and protective efficacy of SE36/AHG formulated with TLR9 ligand adjuvants K3 CpG oligodeoxyribonucleotides (CpG ODNs) (K3 ODN), D3 ODN or synthetic hemozoin, in two non-human primate models. SE36/AHG with or without each adjuvant was administrated to cynomolgus monkeys. A combination of TLR9 ligand adjuvant with SE36/AHG induced higher humoral and cellular immune response compared with SE36/AHG alone. The most effective TLR9 ligand, K3 ODN, was chosen for further vaccine trials in squirrel monkeys, in combination with SE36/AHG. All monkeys immunized SE36/AHG with K3 ODN effectively suppressed parasitemia and symptoms of malaria following challenge infection. Furthermore, no serious adverse events were observed. Our results show that the novel vaccine formulation of K3 ODN with SE36/AHG is safety, potent immunogenicity and efficacy in nonhuman primates. We are conducting the first in human clinical trials with this formulation.