Molecular cloning and sequencing of a gene encoding biologically active porcine alpha-interferon

Nine distinct genomic clones containing human alpha 1-interferon (IFN-alpha 1) related sequences were isolated from a porcine genomic library constructed in phage lambda. Restriction mapping and Southern blot analysis revealed that these clones contained a total of 10 potential porcine IFN-alpha genes or pseudogenes belonging to a multigene family of at least 12 members. One of these genes was subcloned in plasmid pUC8 and the recombinant plasmid obtained was shown to direct the synthesis of a low but detectable IFN-alpha activity in Escherichia coli JM103. The sequence of this porcine IFN-alpha gene (Po IFN-alpha 1) was determined. As expected, it contained no introns and encoded a 189-amino-acid-long preprotein with a putative signal peptide of 23 residues. The homology to human (Hu)IFN-alpha 1 was 78.5% at the nucleotide level and 64% at the amino acid level.