Enhanced mucosal immunogenicity of prion protein following fusion with B subunit of Escherichia coli heat-labile enterotoxin

Mucosal vaccine against prion protein (PrP), a major component of prions, is urgently awaited since the oral transmission of prions from cattle to humans is highly suspected. In the present study, we produced recombinant bovine and mouse PrPs fused with or without the B subunit of Escherichia coli heat-labile enterotoxin (LTB) and intranasally immunized mice with these fused proteins. Fusion with LTB markedly enhanced the mucosal immunogenicity of bovine PrP, producing a marked increase in specific IgG and IgA titer in serum. Mouse PrP also showed slightly increased immunogenicity following fusion with LTB. These results demonstrate that LTB-fused PrPs might be potential candidates for protective mucosal prion vaccines.