Minimal interferon induction in dogs, using a modified polyriboinosinic-polyribocytidylic acid complex.

Adult Beagles failed to respond to high concentrations of interferon (IF) when they were injected with a nuclease-resistant complex poly I:C with poly-L-lysine and carboxymethylcellulose (PICLC), by the IV or intrathecal route. An IV dose of 1 mg of PICLC/kg of body weight was lethal to 1 of 3 adult dogs, but induced IF in only 2 dogs. Smaller doses were less toxic, but also were less effective. The injection of a high dose of a known IF inducer (3 X 10(8) egg LD50 of Newcastle disease virus) also failed to induce IF in Beagles. Interferon could not be induced in vitro when primary cultures of neonatal dog lung or kidney were treated with cultures of neonatal dog lung or kidney were treated with PICLC. When these primary cell cultures were compared with the cell line Madin-Darby canine kidney in an IF assay, no difference in sensitivity to IF-induced protection from infection with vesicular stomatitis virus could be shown. This indicated that the sensitivity of the Madin-Darby cell line was not the only factor in determining the lack of IF response in dogs and indicates that the dogs are poor responders to IF induction.