A preparation of an inactivated or freeze-dried yeast cell or cell-surface-containing portion thereof expressing a porcine viral epitope, wherein the epitope is expressed on the surface of the yeast cell. The yeast is typically is non-viable. The yeast is typically from the genus Saccharomyces, and is preferably Saccharomyces cerevisiae, but may be from the genus Pichia, for example Pichia pastoris, or may be from the genus Kluyveramyces, for example K. lactis. The viral epitope may be from a Coronavirus, optionally from PEDV, TGEV, porcine hemagglutinating encephalomyelitis virus or PRCV； a porcine to Rotavirus； or a virus of the Circoviridae family, optionally from PCV2. The viral epitope expressed by the yeast is preferably PCV2 ORF2 (Cap protein).
