Oral MucoRice expressing double-mutant cholera toxin A and B subunits induces toxin-specific neutralising immunity

Rice-expressed cholera toxin B (CTB) subunit is a cold-chain-free oral vaccine that effectively induces enterotoxin-neutralising immunity. We created another rice-based vaccine, MucoRice, expressing nontoxic double-mutant cholera toxin (dmCT) with CTA and CTB subunits. Western-blot analysis suggested that MucoRice-dmCT had the shape of a multicomponent vaccine. Oral administration of MucoRice-dmCT induced CTB- but not CTA-specific serum IgG and mucosal IgA antibodies, generating protective immunity against cholera toxin without inducing rice-protein-specific antibody responses. The potency of MucoRice-dmCT was equal to that of MucoRice-CTB vaccine. MucoRice has the potential to be used as a safe multicomponent vaccine expression system.