Prokaryotic expression and establishment of an indirect ELISA assay for the VP2 gene of porcine parvovirus.

The completed NS1 gene was amplified from PPV DNA by PCR method.Then the products were cloned into pET32c vector and the sequence was determined.The recombinant plasmid pET32c-NS1 was transformed into BL21 competent cells and expressed in very high level as inclusion body when induced with IPTG.Western blot analysis proved the renaturation protein with good immunoreactivity against PPV antibody.The indirect ELISA method for the detection of PPV specific antibody in procine serum was established with the optional working circumstances for the ELISA assay(antigen concentration : 3.1 μg/mL;optimal serum dilution :1∶100) using chessboard titration.The positive criterion of this ELISA method was ODtesting serum≥0.4 and ODtesting serum/ODstandard positive value≥2.1.