Swine interferon. I. Induction in porcine cell cultures with viral and synthetic inducers.

The production of interferon by porcine kidney (PK(15)) cell culture in response to viral and synthetic inducers was studied. The inducers used included a synthetic double-stranded polyribonucleotide, polyriboinosinic-polyribocytidylic acid (Poly I:C), swine influenza virus and three strains of pseudorabies virus. Following exposure to these inducers cell culture fluids were examined for interferon by the plaque-reduction method. The Poly I:C and the swine influenza virus induced production of interferon by PK(15) cell cultures, whereas, all three strains of pseudorabies virus at the two concentrations tested failed to induce production of interferon in vitro. The antiviral substance produced in PK(15) cells was identified as an interferon because it was pH stable, non-dialyzable, sensitive to trypsin, non-sedimentable, relatively heat stable, host-species specific and it possessed broad-spectrum antiviral activity. The latter was demonstrated by inhibition of vesicular stomatitis, vaccinia and pseudorabies viruses. Differences in interferon activity against the different viruses were observed.