Properties of natural porcine interferons.

Natural porcine interferons (PoIFNs) were obtained from: adherent peripheral blood leukocytes induced with Newcastle disease virus (NDV) (IFN-alpha), kidney fibroblasts induced with poly(I:C) (IFN-beta) and whole blood leukocytes induced with phytohemagglutinin (IFN-gamma). PoIFN-alpha was active in porcine, bovine, human, and murine cells. It was sensitive to anti-human IFN-alpha antiserum. Analyzed by SDS-polyacrylamide gel electrophoresis and by gel filtration, the molecular weight of the main fraction of PoIFN-alpha was between 25,200 and 28,700. PoIFN-beta and a small fraction of PoIFN-alpha were bound to concanavalin A which suggests that they are glycoproteins. PoIFN-beta and PoIFN-gamma were active only in porcine and bovine, and porcine cells, respectively. Physicochemical properties of porcine IFNs resembled those of human IFNs. PoIFN-alpha or PoIFN-beta and PoIFN-gamma acted synergistically in the antiviral assays. Thus, the porcine IFN system appears to be similar to the system in the human and in murine species, being serologically related to the former.