[62] Cloning, Expression, and Purification of Rat IFN-α1

This chapter describes the introduction of a structural gene for a rat alpha interferon subtype (rat IFN-α) into Escherichia coli to obtain an efficient expression system for the production of large quantities of rat interferon. This provide a more economic way of production than does the system employing a rat continuous cell line and also make it possible to study the properties of a single gene product. DNA complementary to rat interferon messenger RNA (mRNA) isolated from Ratec cells induced by Sendai virus is cloned and amplified in E. coli. A purified complementary DNA (cDNA) fragment identified by hybridization with the mouse α2 gene is then used as a probe for the isolation of the chromosomal genes from a rat gene library. The procedure for the production and purification of this type of interferon is described. Attempts to increase production with other host/vector systems are described and some characteristics of rat IFN-αl are discussed. The finding that rat IFN-αl reacts with antibodies against human IFN-α2 indicates that certain interferon subtypes of rat and human origin has strong antigenic similarities.