Porcine circovirus type 2 induces a strong cytopathic effect in the serum-free culture cell line CPK-NS

•CPK-NS cells passaged after inoculation with porcine circovirus type 2 (PCV2) showed cell detachment depending on the virus concentration.•The cell detachment was completely inhibited via neutralisation using antisera collected from PCV2-infected specific pathogen-free pigs.•The cell detachment was demonstrated to be cytopathic effect caused via infection of PCV2 which is normally non-cytopathogenic.•Application of CPK-NS cells would contribute towards the diagnosis and control of PCV2-mediated infectious diseases. When the adherent stable serum-free porcine kidney cell line CPK-NS were inoculated with porcine circovirus type 2 (PCV2) and passaged, viral titre concentration-dependent cell detachment was observed. The copy number of viral genes in supernatants of the infected CPK-NS cells decreased as cell detachment progressed. Furthermore, cell detachment was completely inhibited via neutralisation of the virus using antisera collected from PCV2-infected specific pathogen-free pigs. These results indicated that detachment of CPK-NS cells is a cytopathic effect (CPE) caused via infection with PCV2. Only a single round of cell passaging was required to observe clear a CPE when the inoculated viral titre was significantly high [≥104.5 median tissue culture infectious dose (TCID50)/mL]. Our study confirms that PCV2, which is normally non-cytopathogenic, is capable of inducing a distinct CPE in CPK-NS cells. Application of CPK-NS cells for detection of viruses may contribute towards the diagnosis and control of PCV2-mediated infectious diseases.