Production of recombinant ovine interferon tau using a Bombyx mori nuclear polyhedrosis baculovirus expression system.

ABSTRACT Ovine interferon tau (oIFN-τ) is an embryonic protein of critical importance in the establishment of pregnancy in the sheep. We have produced recombinant (r) oIFN-τ using a baculovirus expression system and demonstrated the biological activity of the protein produced. Bombyx mori larvae were infected with B. mori nuclear polyhedrosis virus (BmNPV), modified by inserting a cDNA coding for oIFN-τ downstream of the strong polyhedron promoter. Following infection, antiviral activity of the haemolymph rose to a maximum of 3.6 × 108 u/mL (equivalent to 3 mg roIFN-τ/mL) by day 5, when haemolymph was collected and stored frozen. Control haemolymph, collected from uninfected insects at an equivalent time, contained no antiviral activity. The roIFN-τ was partially purified by gel filtration column chromatography and the presence of roIFN-τ confirmed by western blotting. The biological activity of the partially purified roIFN-τ was tested in ewes. Treatment with roIFN-τ caused a significant delay in luteoly...