Expression of CDV F1 Protein in E.coli and Preliminary Use of the Expressed Protein in ELISA

A prokaryotic expression plasmid, named pET28-F1, was constructed by the CDV F1 gene and cloned into pET-28a(+). The CDV F1 protein could be expressed by pET28-F1 in BL21(DE3)lysS at high level, up to 23.52% of the total protein of the induced bacteria. Indirect ELISA for detection of the serum antibodies against CDV was developed. The recombinant CDVF1 protein was used as antigen. Each well of an ELISA plate was coated with 1μg refined CDVF1 protein. Before being added the serum samples were pre-incubated with supernatant of the normal abstracts of E.coli for 15-30 min at room temperature. The supernatant of E.coli could eliminate the non-specific antibodies in the serum samples, but not necessary for highly purified F1 protein. The results showed the assay was characterized by its specificity, simplicity and economical cost.