title: Antibody titres and boosting after natural malaria infection in BK-SE36 vaccine responders during a follow-up study in Uganda.
abstract: The malaria vaccine BK-SE36 is a recombinant protein (SE36) based on the Honduras 1 serine repeat antigen-5 of Plasmodium falciparum, adsorbed to aluminium hydroxide gel. The phase Ib trial in Uganda demonstrated the safety and immunogenicity of BK-SE36. Ancillary analysis in the follow-up study of 6-20 year-old volunteers suggest significant differences in time to first episodes of clinical malaria in vaccinees compared to placebo/control group. Here, we aimed to get further insights into the association of anti-SE36 antibody titres and natural P. falciparum infection. Children who received BK-SE36 and whose antibody titres against SE36 increased by ≥1.92-fold after vaccination were categorised as responders. Most responders did not have or only had a single episode of natural P. falciparum infection. Notably, responders who did not experience infection had relatively high anti-SE36 antibody titres post-second vaccination compared to those who were infected. The anti-SE36 antibody titres of the responders who experienced malaria were boosted after infection and they had lower risk of reinfection. These findings show that anti-SE36 antibody titres induced by BK-SE36 vaccination offered protection against malaria. The vaccine is now being evaluated in a phase Ib trial in children less than 5 years old.
authors.affiliation: Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871 Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Yagi
authors.affiliation: Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871 Japan.
authors.forename: Nirianne M Q
authors.initials: NM
authors.lastname: Palacpac
authors.affiliation: Department of Public Health, Faculty of Medicine, Osaka City University, Osaka 545-8585, Japan.|Sumida Hospital, Medical Co. Living Together Association (LTA) Clinical Pharmacology Center, Tokyo 130-0021 Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ito
authors.affiliation: Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871 Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Oishi
authors.affiliation: Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871 Japan.
authors.forename: Sawako
authors.initials: S
authors.lastname: Itagaki
authors.affiliation: Med Biotech Laboratories, Plot 4-6 Bell Close, Port Bell Road Luzira, Kampala, Uganda.
authors.forename: Betty
authors.initials: B
authors.lastname: Balikagala
authors.affiliation: Med Biotech Laboratories, Plot 4-6 Bell Close, Port Bell Road Luzira, Kampala, Uganda.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Ntege
authors.affiliation: Med Biotech Laboratories, Plot 4-6 Bell Close, Port Bell Road Luzira, Kampala, Uganda.|Department of Disease Control and Environmental Health, School of Public Health, College of Health Sciences, Makerere University, P.O. Box 7072, Kampala, Uganda.
authors.forename: Adoke
authors.initials: A
authors.lastname: Yeka
authors.affiliation: Med Biotech Laboratories, Plot 4-6 Bell Close, Port Bell Road Luzira, Kampala, Uganda.
authors.forename: Bernard N
authors.initials: BN
authors.lastname: Kanoi
authors.affiliation: Med Biotech Laboratories, Plot 4-6 Bell Close, Port Bell Road Luzira, Kampala, Uganda.
authors.forename: Osbert
authors.initials: O
authors.lastname: Katuro
authors.affiliation: The Research Foundation for Microbial Diseases of Osaka University, 2-9-41 Yahata-cho, Kanonji, Kagawa 768-0061 Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Shirai
authors.affiliation: Department of Public Health, Faculty of Medicine, Osaka City University, Osaka 545-8585, Japan.
authors.forename: Wakaba
authors.initials: W
authors.lastname: Fukushima
authors.affiliation: Department of Public Health, Faculty of Medicine, Osaka City University, Osaka 545-8585, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Hirota
authors.affiliation: Med Biotech Laboratories, Plot 4-6 Bell Close, Port Bell Road Luzira, Kampala, Uganda.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Egwang
authors.affiliation: Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamadaoka, Suita, Osaka 565-0871 Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Horii
mesh_terms: D000293:Adolescent; D000328:Adult; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology; D000953:Antigens, Protozoan / Q000008:administration & dosage* / Q000276:immunology; D002648:Child; D005260:Female; D006801:Humans; D007117:Immunization, Secondary; D017780:Malaria Vaccines / Q000008:administration & dosage* / Q000276:immunology; D016778:Malaria, Falciparum / Q000097:blood / Q000276:immunology / Q000517:prevention & control; D008297:Male; D014454:Uganda
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D017780:Malaria Vaccines