Immunoperoxidase test for rabies: utility as a diagnostic test

Laboratory of Large Animal Pathology, University of Pennsylvania, New Bolton Center, Kennett Square 19348.

Although a fast and reliable fluorescent antibody (FA) test for rabies diagnosis is available, ideally the diagnostic procedure requires fresh or frozen brain tissues. In some instances (and particularly for retrospective studies), fresh or frozen tissues may not be available. In such cases, immunohistochemical tests may be utilized. Because such tests have been used only in a limited number of cases, their diagnostic reliability has not been thoroughly evaluated. This study documents the results of a streptavidin-biotin complex (ABC) immunoperoxidase test on formalin-fixed, paraffin-embedded brain tissues of domestic and wild animals that were positive on FA test for rabies prior to fixation. Thirty-nine of 40 rabies cases were positive with the ABC technique. Based on these preliminary results, the ABC technique appears reliable. However, more corroborative test results are needed before the ABC method can be used as a routine diagnostic procedure, especially with field samples and negative controls.