title: RNAi suppression of rice endogenous storage proteins enhances the production of rice-based Botulinum neutrotoxin type A vaccine.
abstract: Mucosal vaccines based on rice (MucoRice) offer a highly practical and cost-effective strategy for vaccinating large populations against mucosal infections. However, the limitation of low expression and yield of vaccine antigens with high molecular weight remains to be overcome. Here, we introduced RNAi technology to advance the MucoRice system by co-introducing antisense sequences specific for genes encoding endogenous rice storage proteins to minimize storage protein production and allow more space for the accumulation of vaccine antigen in rice seed. When we used RNAi suppression of a combination of major rice endogenous storage proteins, 13 kDa prolamin and glutelin A in a T-DNA vector, we could highly express a vaccine comprising the 45 kDa C-terminal half of the heavy chain of botulinum type A neurotoxin (BoHc), at an average of 100 μg per seed (MucoRice-BoHc). The MucoRice-Hc was water soluble, and was expressed in the cytoplasm but not in protein body I or II of rice seeds. Thus, our adaptation of the RNAi system improved the yield of a vaccine antigen with a high molecular weight. When the mucosal immunogenicity of the purified MucoRice-BoHc was examined, the vaccine induced protective immunity against a challenge with botulinum type A neurotoxin in mice. These findings demonstrate the efficiency and utility of the advanced MucoRice system as an innovative vaccine production system for generating highly immunogenic mucosal vaccines of high-molecular-weight antigens.
authors.affiliation: Division of Mucosal Immunology, Department of Microbiology and Immunology, The Institute of Medical Science, The University of Tokyo, Tokyo, 108-8639, Japan. yukiy@ims.u-tokyo.ac.jp
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Yuki
authors.forename: Mio
authors.initials: M
authors.lastname: Mejima
authors.forename: Shiho
authors.initials: S
authors.lastname: Kurokawa
authors.forename: Tomoko
authors.initials: T
authors.lastname: Hiroiwa
authors.forename: Il Gyu
authors.initials: IG
authors.lastname: Kong
authors.forename: Masaharu
authors.initials: M
authors.lastname: Kuroda
authors.forename: Yoko
authors.initials: Y
authors.lastname: Takahashi
authors.forename: Tomonori
authors.initials: T
authors.lastname: Nochi
authors.forename: Daisuke
authors.initials: D
authors.lastname: Tokuhara
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kohda
authors.forename: Shunji
authors.initials: S
authors.lastname: Kozaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kiyono
mesh_terms: D000818:Animals; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000096:biosynthesis* / Q000276:immunology; D019274:Botulinum Toxins, Type A / Q000096:biosynthesis*; D001906:Botulism / Q000517:prevention & control; D004195:Disease Models, Animal; D020868:Gene Silencing; D005983:Glutens / Q000037:antagonists & inhibitors; D051379:Mice; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D055315:Prolamins / Q000037:antagonists & inhibitors; D016372:RNA, Antisense / Q000235:genetics / Q000378:metabolism; D055314:Seed Storage Proteins / Q000037:antagonists & inhibitors*
chemical_list: D001428:Bacterial Vaccines; D055315:Prolamins; D016372:RNA, Antisense; D055314:Seed Storage Proteins; D005983:Glutens; D019274:Botulinum Toxins, Type A