In vitro protective effect of bacteria-derived bovine alpha interferon I1 against selected bovine viruses.

We used bacteria-derived bovine alpha-interferon I1 (Bo IFN-alpha I1) to study its antiviral effect in a bovine turbinate cell line on bovine diarrhea virus, infectious bovine rhinotracheitis virus, parainfluenza 3 virus, and pseudorabies virus. We based our study upon replicate tests for each strain by using a block titration system with various concentrations of Bo IFN-alpha I1 against various concentrations of virus. The data were compiled in two-axis tables (replicate X concentration) and were statistically analyzed by the Spearman-Karber method. An increase in the concentration of Bo IFN-alpha I1 enhanced its protective effect against every test virus strain. Bo IFN-alpha I1 had a marked in vitro effect on the bovine diarrhea viral strains. It demonstrated less protection against the pseudorabies and parainfluenza 3 viruses. Its effectiveness against the two infectious bovine rhinotracheitis viral strains was lesser and of a low order.