FIG. 7.

(a) Purification of recombinant pET14b-E2 protein analyzed by SDS-PAGE. Lanes: 1, protein marker; 2, whole bacteria after induction; 3, soluble fraction after sonication; 4, insoluble fraction after sonication; 5, purified recombinant protein. (b) Characterization of polyclonal antibody against E2 by Western blotting. Lanes: 1, pET14b-E2 after induction; 2, pET14b-E2 without induction; 3, purified E2. (c) Reactivity of rabbit antibody against E2 by IFAT of CHSE cells infected with SAV-3 using a 1:400 dilution of the serum. (d) Virus yield reduction assay. TO cells in 24-well plates were stimulated with 10-fold serial dilutions of rIFN-α for 24 h and then infected with 1 MOI of SAV-3. Cell culture supernatants were collected when strong CPE were observed for the control infected cells. The virus titer of the supernatants at 10 days postinfection was determined by the TCID₅₀ method (n = 2) (means ± SEM). (e) Inhibition of E2 protein synthesis in interferon-treated TO cells. TO cells were treated with 0.47 μg/ml IFN-α for 24 h and subsequently infected with 1 MOI of SAV-3. At 2 days postinfection, cells were stained with anti-E2 antibody, and no cells were found to express virus protein. (f) TO cells without IFN treatment infected as described in the text and stained by IFAT for E2, showing distinct cytoplasmic staining in infected cells.