Patent ID: 8017127

Claim:
In a method for the preparation of recombinant chimeric immunogenic particles that are comprised of a plurality of monomers containing influenza A virus M2e polypeptide fused to hepatitis B virus core (HBc) protein, wherein a host organism is transformed with nucleic acid that encodes said monomers, said transformed host expresses said monomers and said monomers are present in said host as said recombinant chimeric immunogenic particles, the improvement that comprises recovering said recombinant chimeric immunogenic particles (i) after heating a buffer solution of said particles at a temperature of about 50° to about 70° C. for a time period of about 1.5 to about 3 hours, or (ii) after heating a buffer solution of said particles and an effective amount of a protease inhibitor at a temperature of about 50° to about 70° C. for a time period of about 1.5 to about 3 hours.