Abstract. Five Holstein heifers (approximately 8 months of age and weighing 225-275 kg) were inoculated subcutaneously with 1,000 TCID,,, of rinderpest virus, virulent Kabete 0 strain. They become clinically ill 2 to 5 days post-inoculation. with fever (40 C to 4 1.5 C), conjunctivitis, and diarrhea. All were euthanatized when moribund at 6 days postinoculation. The following tissues were collected in formalin, embedded in paraffin, and subsequently subjected to histopathologic and immunohistochernical examination: tongue, buccal rnucosa, soft palatc, esophagus, rumen. abomasum. duodenum. jejunum with and without Peyer's patch, ileum, cecum, proximal colonic lymphoid patch. spiral colon, eyelid. gall bladder, spleen, tonsil, trachea, lungs, and numerous lymph nodes. Inimunohistochemical examination was accomplished using a primary rabbit anti-rinderpest antibody, and either a peroxidasediaminobcnzidine or alkaline phosphatase-Vector Red detection substrate system. In the lymph nodes. spleen. and tonsil. depletion of lymphocytes from all areas was extensive, with antigen most prominent in persisting reticular cells throughout the tissues. In the intestine, necrotizing and ulcerative changes in the mucosa were extensive and widespread. Damage was most severe in areas overlying lymphoid patches. In both small and large intestine. antigen was distributed predominantly in epithelial cells, histiocytic cells in the lamina propria, and in remaining reticular cells o f lymphoid patches. In oral rnucosa, there were multiple ulcerations and numerous multinucleate syncytial cells, both containing and without antigen. Lungs and trachea had subtle yet consistent necrosis of epithelial cells, with antigen often distributed in a circumferential manner in epithelium of bronchioles.
