Fig. 4.

Antiviral activity of recombinant PoIFN-β on PK15 cells. PK15 cells were treated with 10-fold serially diluted PoIFN-β_CHO (Start from 1.1 × 10⁶ IU/ml) for 24 h, and then challenged with 10³ TCID₅₀ TGEV (A–C) and PRV (F–H), when CPE formed in the virus control wells (D and I) reached 90–100%, the effect of antiviral activity was evaluated under a microscope, and the culture medium in each well were collected to titer TGEV or PRV on PK15 cells in 96-well plates (K). 110 IU/ml of PoIFN-β_CHO (A, K) completely protected PK15 cells against the infection of TGEV, but 11 IU/ml (B, K) and 1.1 IU/ml (C, K) did not. While 1100 IU/ml of PoIFN-β_CHO (F, K) completely protected against the infection of PRV, but 110 IU/ml (G, K) and 11 IU/ml (H, K) did not. The well free from interferon but addition virus was set as virus control (VC) (D, I and K), the wells free from interferon and virus were set as blank control (BC) (E, J and K).