Antiviral and antiluteolytic activity of recombinant bovine IFN-omega1 obtained from Pichia pastoris.

The gene coding for bovine interferon-omega1 (BoIFN-omega1) was recently cloned and expressed at high levels in the yeast Pichia pastoris. The recombinant BoIFN-omega1 protein shows antiviral activity in different cell lines and has an antiluteolytic effect in cyclic ewes. In this article, we describe a method for purification of BoIFN-omega1 expressed in the methylotrophic yeast P. pastoris and characterization of its activity in vivo. The recombinant protein secreted to the culture medium had low activity because of self-aggregation. BoIFN-omega1 was solubilized using urea and desalting and finally purified by ion exchange chromatography on Q-Sepharose Fast Flow. The yield of purified product was approximately 300 mg/L of fermentation culture, with a specific antiviral activity of 10(8) IU/mg. Its purity was at least 80%. The biologic characterization of purified BoIFN-omega1 was determined by induction of an antiviral state on ewes challenged with 100 lethal doses (LD) of Aujeszky virus and by the extension of the corpus luteum life span and interestrous interval in cyclic cows. Ewes treated with 2 x 106 IU/kg BoIFN-omega1 were protected from Aujeszky virus infection. In cows receiving an intrauterine infusion of 1 mg BoIFN-omega1, equally distributed between the two uterine horns, twice daily from day 14 to day 22 of the experimental estrous cycle, the lifespan of the corpus luteum (25 vs. 19 days) and the interestrous intervals (26 vs. 21 days) were extended when compared with a control group (p < 0.05). We show that recombinant BoIFN-omega1 purified from P. pastoris has high antiviral activity and is an effective antiluteolytic agent in cattle.