Molecular Cloning of a Gene Encoding Porcine Interferon-β

Abstract

A gene encoding the porcine inferieron-β (poIFN-β) was cloned from a genomic library. The sequence of a potential intronless coding region as well as 1,265 bp of the 5′- and 277 bp of the 3′-flanking regions is presented. The gene is predicted to encode a mature protein of 165 amino acids and a signal peptide of 21 amino acids. This probable poIFN-β shows high homology (63%) with human (hu) IFN-β at the amino acid level, but less with porcine (po) IFN-α₁ (32%). It contains three cysteines and three potential N-glycosylation sites. A region of the 5′ flank (−116 to −159) of the gene is homologous to the IFN gene regulatory element (IRE) of the huIFN-β gene which mediates virus inducibility. Southern blot analysis indicates that the poIFN-β gene is present as a single copy in the porcine genome. Its expression in porcine peripheral blood leukocytes stimulated in vitro by pseudorabies virus (PRV) was demonstrated at the RNA level both by Northern blot analysis and by in situ hybridization. The latter approach in addition detected only about one IFN-β mRNA-containing cell per 2,000 PRV-stimulated porcine leukocytes, a frequency in the same range as that for leukocytes containing IFN-α mRNA.