The present invention relates to the field of veterinary vaccines, in particular to porcine vaccines against PCV2 and associated diseases. Specifically the invention relates to the finding that a mutation is required in PCV2b ORF2 protein, to prevent its nuclear accumulation upon expression in insect cells; the mutation introduces a Proline at amino acid position 131. This allows efficient expression in insect cells, easy harvesting, and generates large amounts of virus-like particles. The VLPs are highly effective in vaccines for porcines for reduction of infection by PCV2 or of associated signs of disease.