Demonstration of infectious bovine rhinotracheitis virus antigen by immunoperoxidase method in tissues of aborted bovine fetuses preserved for 25 years in paraffin blocks.

Infectious bovine rhinotracheitis (IBR) virus antigen was demonstrated by the immunoperoxidase method in tissues of two aborted bovine fetuses, which had been stored for 25 years after fixing in formalin and embedding in paraffin. Necrotic foci were detected in the liver, kidney, adrenal gland, and thymus of the fetuses. Coincidenting with the distribution of the necrotic foci, IBR virus antigen was demonstrated by immunostaining. The present study proved the immunoperoxidase method in one of useful techniques to demonstrate IBR virus antigen in tissue sections from preserved paraffin blocks.