Abstract: An indirect enzyme-linked immunosorbent assay (ELISA) method was established to detect antibodies against porcine circovirus type 2 using the recombinant capsid protein (rCap) expressed by prokaryotic pQE30 vector as coating antigen. The various factors affected the experiments such as concentration and coating time of rCap, the serum dilution concentration, etc were optimized, and the storage period of the ELISA kit was also tested. The results demonstrated that optimal concentration of rCap for coating was 2.815 μg/mL, the optimal coating condition of rCap for ELISA was incubated at 37 ℃ for 2 hours, the dilution of serum sample was 1∶40, the work concentration of HRP-labeled rabbit anti-porcine IgG was 1∶500, the best blocking buffer was BAS with 1% concentration, and the critical value of positive and negative of ELISA was D450 nm=0.33. The specificity test showed that the established ELISA method was only displayed D450 nm＞0.33 for standard positive serum of PCV-2, but D450 nm＜0.33 for other serums of PCV-1, CSFV, JEV, PRV, PRRSV, etc which acting as the negative controls. Sixty-nine of 100 clinic suspicious PCV-2 infection samples was positive by using the established ELISA method. The storage period test of the ELISA kit showed that the kit could be stable for at least 12 months at 4 ℃. This study indicated that an indirect ELISA method for detection PCV-2 in serum was successfully established, and could be used for the rapid clinic diagnosis of PCV-2.

Key words: porcine circovirus type 2 (PCV-2); capsid protein; indirect ELISA; detection; application; kit