title: TLR9 adjuvants enhance immunogenicity and protective efficacy of the SE36/AHG malaria vaccine in nonhuman primate models.
abstract: The SE36 antigen, derived from serine repeat antigen 5 (SERA5) of Plasmodium falciparum, is a promising blood stage malaria vaccine candidate. Ongoing clinical trials suggest the efficacy of the SE36 vaccine could be increased by the incorporation of more effective adjuvants into the vaccine formulation. 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. Administration of a crude extract of P. falciparum parasite resulted in the induction of more SE36-specific IgG antibodies in monkeys vaccinated with a combination of SE36/AHG and adjuvant, as opposed to vaccination 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 with the combined SE36/AHG and K3 ODN formulation effectively suppressed parasitemia and symptoms of malaria following challenge infections. Furthermore, no serious adverse events were observed. Our results show that the novel vaccine formulation of K3 ODN with SE36/AHG demonstrates safety, potent immunogenicity and efficacy in nonhuman primates, and this vaccine formulation may form the basis of a more effective malaria vaccine.
authors.affiliation: Department of Molecular Protozoology; Research Institute for Microbial Diseases; Osaka University at Suita; Osaka, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tougan
authors.forename: Taiki
authors.initials: T
authors.lastname: Aoshi
authors.forename: Cevayir
authors.initials: C
authors.lastname: Coban
authors.forename: Yuko
authors.initials: Y
authors.lastname: Katakai
authors.forename: Chieko
authors.initials: C
authors.lastname: Kai
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Yasutomi
authors.forename: Ken J
authors.initials: KJ
authors.lastname: Ishii
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Horii
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage / Q000009:adverse effects*; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D004195:Disease Models, Animal; D006420:Hemeproteins / Q000008:administration & dosage / Q000009:adverse effects*; D007074:Immunoglobulin G / Q000097:blood; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008252:Macaca fascicularis; D017780:Malaria Vaccines / Q000008:administration & dosage / Q000009:adverse effects* / Q000276:immunology*; D016778:Malaria, Falciparum / Q000276:immunology / Q000517:prevention & control*; D009838:Oligodeoxyribonucleotides / Q000008:administration & dosage / Q000009:adverse effects*; D018512:Parasitemia / Q000517:prevention & control; D012453:Saimiri; D051217:Toll-Like Receptor 9 / Q000819:agonists*
chemical_list: D000276:Adjuvants, Immunologic; D000913:Antibodies, Protozoan; C408982:CPG-oligonucleotide; D006420:Hemeproteins; D007074:Immunoglobulin G; D017780:Malaria Vaccines; D009838:Oligodeoxyribonucleotides; D051217:Toll-Like Receptor 9; C020753:hemozoin
keywords: CpG ODN; Plasmodium falciparum; SE36; TLR9 ligand adjuvant; malaria vaccine; nonhuman primate model; synthetic hemozoin