Enteric lesions induced by different pseudorabies (Aujeszky's disease) virus strains inoculated into closed intestinal loops of pigs

National Institute of Animal Health, Tsukuba, Ibaraki, Japan.

Three different strains of pseudorabies (Aujeszky's disease) virus were inoculated into ligated closed loops in the jejunum and ileum of five specific-pathogen-free pigs. Infected areas were compared with respect to distribution of histologic lesions and pseudorabies virus antigen. Two wild-type strains of pseudorabies virus produced enteric lesions consisting of necrosis of the subepithelial macrophages in the basilar crypt epithelium, necrosis of the lymphoid follicles in the Peyer's patches, degeneration of the epithelial cells in the crypt and villi, degeneration of the neuronal cells in the myenteric plexuses, and formation of intranuclear inclusion bodies on postinoculation days 2-4. Pseudorabies virus antigen was initially detected in subepithelial macrophages of the dome of Peyer's patches on postinoculation day 2 and subsequently extended to superficial epithelium and deeper into the lymphoid follicles and myenteric plexuses on postinoculation days 3-4. Many pseudorabies virus particles were also detected in the center of their necrotic foci. However, 1 mutant strain (ara-T-resistant) of pseudorabies virus did not produce enteric lesions. The results suggest that the primary target of infection by wild-type strains of pseudorabies virus might be the macrophages distributed in the subepithelial area of the dome Peyer's patches.