The expression and purification of recombinant CAV viral proteins. The three expression plasmids showed in Figure 1 were express in E. coli BL21 (DE3) and purified by GST affinity chromatography. The recombinant GST-tag proteins were separated by SDS-PAGE (a) and detected by Western-blotting (b) . Anti-GST tag monoclonal antibody was used to recognize the recombinant viral proteins. Lane M, pre-stained protein marker; lane BI, before IPTG induction; lane AI, after IPTG induction and cultivation for 4 hr; lane P, purified recombinant GST-tag protein. The red solid triangles pinpoint the various proteins.