Viral antigen and B and T lymphocytes in lymphoid tissues of gnotobiotic piglets infected with hog cholera virus.

Four 4-day-old gnotobiotic piglets infected intranasally with the Kanagawa/74 strain of hog cholera virus (HCV) did not develop severe illness over a period of 3 weeks. Large amounts of HCV were isolated from the lymphoid tissues and serum at necropsy. After the acute phase, hyperplasia of histiocytes and plasmacytopoiesis were observed in two pigs (killed 14 and 21 days after inoculation). The number of CD4+ and CD8+ T lymphocytes increased significantly and their location was consistent with the site of HCV replication. The results suggest that a CD8+ T-lymphocyte reaction is associated with persistent HCV infection.