Fig. 2.
Expression and purification of SARS-Cov N protein in E. coli. Full length of n gene (1–422 aa) (pET-fn) and partial n gene (1–120 aa) (pET-pn) were inserted into pET24a vector and transformed into BL21 (DE3) E. coli. After induction with IPTG, cells were harvested and lysed by 8 M urea and ultrasonic. Cell lysate was centrifuged. Recombinant proteins in supernatants were purified by DEAE-A50 absorption and gel extraction method [16]. A: expression of full length N protein in E. coli. Lane M: marker; lane 1: without IPTG induction; lane 2: with IPTG induction; lane 3: purified protein. B: expression of partial N protein in E. coli. Lane M: marker; lane 1: with IPTG induction; lane 2: without IPTG induction; lane 3: purified protein. C: Western blot assay. Cell lysates were resolved on SDS-PAGE gel and transferred to nitrocellulose membrane. The membrane was then incubated with 1:1000 serum of C3H/He mice which had received pcDN-fn vaccination and HRP labeled secondary antibody, sequentially. Positive bands were visualized by ECL reagent. Lane M: marker, lane 1: cell lysate of pET-pny lane 2: cell lysate of pET-fn; lane 3: BL21 (DE3) control cell lysate.