Cloning and Biologic Activities of a Bovine Interferon-α Isolated from the Epithelium of a Rotavirus-Infected Calf

Abstract

A cDNA encoding a distinct bovine (Bo) interferon (IFN) α, designated BoIFN-αE, was generated from gut epithelial cells isolated from a rotavirus-infected calf. The BoIFN-αE cDNA sequence shared a greater than 90% identity with the other BoIFN-α subtypes. The cDNA encoding BoIFN-αE has been expressed in insect cells using the baculovirus Autographa californica nuclear polyhedrosis virus (AcMNPV) as a vector. Insect cells infected with recombinant virus secreted a protein with a relative molecular mass of 19,500 into the culture medium not observed in cells infected with wild-type AcMNPV. Supernatants harvested from cultures of insect cells infected with the recombinant AcMNPV encoding IFN-αE inhibited the replication of Semliki Forest virus in a bovine cell line and typically showed 10⁶ dilution units/ml of antiviral activity. However, differences were observed between the activities of recombinant BoIFN-αE and BoIFN-α₁ 1 on the proliferation of WC1⁺ γ/δ T cells. Purified ( > 99%) WC1⁺ γ/δ T cells failed to proliferate to IFN-α₁ 1 or concanavalin A and IFN-αE acted as a weak proliferative signal to these cells, demonstrating a functional difference between two closely related BoIFN-α subtypes.