Expression of bioactive porcine interferon-alpha in Lactobacillus casei

In this study, we constructed an expression cassette containing the inducible lac promoter and the secretion signal from an S-layer protein of Lactobacillus brevis for the expression of porcine interferon-alpha (IFN-alpha) in Lactobacillus casei (Lb. casei). Reverse-transcriptase PCR verified the presence of porcine IFN-alpha mRNA in the recombinant Lb. casei. The porcine IFN-alpha protein expressed in the recombinant Lb. casei was identified by both Western blot analysis and ELISA. We used various pH values and induction times to optimize the yield of IFN-alpha, and found that induction with 0.8 % lactose for 16 h under anaerobic conditions produced the highest concentrations of IFN-alpha. Furthermore, the activity of porcine IFN-alpha in the cultural supernatant was evaluated on ST cells infected with pseudorabies virus. The results revealed that porcine IFN-alpha inhibited virus replication in vitro. The findings of our study indicate that recombinant Lb. casei producing porcine IFN-alpha has great potential for use as a novel oral antiviral agent in animal healthcare.