Presence of the porcine circovirus type 2 (PCV2) Cap protein in the chitosan microparticles. (A) The kinetics of Cap protein release from chitosan microparticles were analysed by Dot blotting after heating to 90°C for 0, 5, 10, 15 and 30 min under acidic conditions. (B) Dot blot analysis was used to estimate the amount of Cap protein loaded into chitosan microparticles relative to purified PCV2 6 × his-cap protein (10 mg/ml). The immunoreactivity of the Cap protein-loaded microparticles was compared with that of PK15-derived PCV2 virions and yeast-derived PCV2 VLPs. (C) Electron micrographs showing yeast-derived PCV2 VLPs. The VLPs were viewed using by transmission electron microscopy (Zeiss EM 109) at 80 kV. Magnification, ×85,000.