In order to obtain a recombinant fusion protein of porcine β-defensin-2 and interferon αwith broad-spectrum antibacterial and antiviral activities at the same time,the genes encoding both proteins were fused in series and inserted into the pPICZαA vector.This construct was then elec-trotransferred into Pichia pastoris KM71H cells to construct an engineered strain.Following methanol-induced expression,the recombinant protein was concentrated and isolated.The cytotox-icity of the protein was assessed using the MTT assay and a porcine red blood cell hemolysis test.Subsequently,the in vitro antibacterial and antiviral activities of the recombinant fusion protein were evaluated.The results showed that the engineered strain pPICZαA-PBD2-IFNα-KM71H of Pichia pastoris was successfully obtained,and the fusion protein PBD2-IFN-α was obtained by concentrating and purifying the fermentation broth after fermentation induction and expression.Its concentration was 1.116 g/L and molecular weight was 25 kDa.When the concentration of fusion protein was lower than 4-4 g/L,it had no obvious toxicity to PK-15 cells and porcine red blood cells.The diameter of the inhibition zone produced by the fusion protein on the mixed plate of Escherichia coli and Staphylococcus aureus was(15.0±0.9)mm,which had obvious antibacterial activity.The antiviral activity of the fusion protein against VSV in PK-15 cells was 8.89 × 105 U/mL measured by Reed-Muench method.This study laid a theoretical foundation for further develo-ping the recombinant fusion protein as an antibacterial and antiviral product.

In order to obtain a recombinant fusion protein of porcine β-defensin-2 and interferon αwith broad-spectrum antibacterial and antiviral activities at the same time,the genes encoding both proteins were fused in series and inserted into the pPICZαA vector.This construct was then elec-trotransferred into Pichia pastoris KM71H cells to construct an engineered strain.Following methanol-induced expression,the recombinant protein was concentrated and isolated.The cytotox-icity of the protein was assessed using the MTT assay and a porcine red blood cell hemolysis test.Subsequently,the in vitro antibacterial and antiviral activities of the recombinant fusion protein were evaluated.The results showed that the engineered strain pPICZαA-PBD2-IFNα-KM71H of Pichia pastoris was successfully obtained,and the fusion protein PBD2-IFN-α was obtained by concentrating and purifying the fermentation broth after fermentation induction and expression.Its concentration was 1.116 g/L and molecular weight was 25 kDa.When the concentration of fusion protein was lower than 4-4 g/L,it had no obvious toxicity to PK-15 cells and porcine red blood cells.The diameter of the inhibition zone produced by the fusion protein on the mixed plate of Escherichia coli and Staphylococcus aureus was(15.0±0.9)mm,which had obvious antibacterial activity.The antiviral activity of the fusion protein against VSV in PK-15 cells was 8.89 × 105 U/mL measured by Reed-Muench method.This study laid a theoretical foundation for further develo-ping the recombinant fusion protein as an antibacterial and antiviral product.