The present invention relates to the preparation of the recombinant antigen of the viral capsid of Porcine circovirus 2 (PCV-2) and modifications thereof, upon expression in a prokaryotic system, purification in the monomer form, recovery of virus-like particles (VLPs) and their use in vaccine formulations, diagnostic kits and a system for quantifying in vaccine lots of the PCV-2 antigen by means of a capture ELISA assay. The antigens and vaccine formulations can be used in animals immunization in programs for combatting PCV-2-associated diseases in conventional swine breeding systems, and represent alternatives to the commercially available vaccines. The ELISA kit can be used for testing the quality of commercial and/or experimental vaccines against PCV-2.
