A substituted Norovirus capsid protein monomer, having only the P-domain and called an antigen-Norovirus P-domain monomer, includes a foreign antigen inserted into one or more of three surface loops present on each P-domain monomer by molecular cloning. The antigen-P-domain monomer can assemble spontaneously into an octahedral form, called an antigen-Norovirus P-particle, that is composed of 24 copies of the antigen-P-domain monomer. Each substituted P-domain monomer will contain one to three copies of the foreign antigen, for a total of 24-72 antigen copies on each antigen-P-particle. The antigen-P-particle is useful in methods for diagnosing, immunizing and treating individuals infected with a foreign virus, for example Rotavirus, and can serve as a carrier for presentation of foreign antigens for development of novel vaccines against many infectious and non-infectious diseases. The substituted Norovirus P-particles can be readily produced in E. coli and yeast, are highly stable and tolerate a wide range of physio-chemical conditions. A modified Norovirus P-domain monomer includes one or more restriction recognition sites inserted within one or more of the three loops of the P-domain monomers, to provide user-friendly cloning cassettes for conveniently inserting candidate foreign antigens into the surface loops. The P-particle-VP8 chimeras may also serve as a dual vaccine against both rotavirus and norovirus.
