A comparison of the avidin-biotin-peroxidase complex (ABC) and peroxidase-anti-peroxidase (PAP) immunocytochemical techniques for demonstrating Sendai virus infection in fixed tissue specimens.

Mice were infected with Sendai virus and killed 8 days later. Lungs were removed and perfused with ethanol, 10% neutral formalin, Bouin's, B-5, or Zenker's fixatives. Tissues were dehydrated, embedded in paraffin, sectioned and stained for the presence of Sendai virus using the avidin-biotin-peroxidase-complex (ABC) and peroxidase antiperoxidase (PAP) immunocytochemical techniques. Results of these techniques were compared. The ABC technique was more sensitive than the PAP. Sendai antigen was demonstrated by the ABC technique in lung tissue fixed with any fixative, whereas antigen could be demonstrated with consistency only in ethanol-fixed lung by the PAP technique. Trypsin treatment of lung prior to immunoperoxidase treatment failed to enhance staining with either technique and actually caused a decrease in staining in ethanol, B-5 and Zenker's-fixed specimens.