In vitro interferon production by bovine tissues: induction with infectious bovine rhinotracheitis virus

The interferon-inducing ability of infectious bovine rhinotracheitis (IBR) virus was determined in tissue cultures of bovine origin inoculated with untreated and ultraviolet (UV) irradiated IBR viruses. Interferon was assayed by the plaque-reduction method in bovine fetal kidney (BFK) cell cultures, using vesicular stomatitis virus as challenge virus. Highest interferon concentrations were produced by cultures of bovine fetal (BF) spleen cells and aveolar macrophage cultures derived from adult cattle. Moderate interferon concentrations were produced by peripheral blood leukocyte (PBL) suspension cultures from adult cattle with serum-neutralizing antibodies against IBR virus. Cultures of PBL from 1 cow without detectable serum-neutralizing antibodies against IBR virus did not produce detectable interferon in response to IBR virus. Cultures of PBL from cattle with or without detectable serum-neutralizing antibodies against IBR virus produced interferon when stimulated with phytohemagglutinin (PHA). Low levles of viral inhibitors were detected infrequently in monolayer cultures of BFK and BF nasal mucosa inoculated with UV-irradiated IBR virus and in BF tracheal organ cultures inoculated with untreated IBR virus. Interferon was not detected in fluids collected from IBR virus-exposed monolayer cultures of primary and secondary BF lung, secondary BF tracheal mucosa, secondary BF liver, secondary BF adrenal, and PBL in the 4th and 7th passages. The antiviral inhibitors from BF spleen, bovine alveolar macrophage, and PBL cultures induced with IBR virus, as well as inhibitors from PBL cultures induced with PHA, had the usual properties of interferon.