Plasma cell changes in the gland of Harder following infectious bursal disease virus infection of the chicken.

Tissue changes in the gland of Harder (GH) were studied following infection of day-old chicks with infectious bursal disease virus (IBDV). Broiler chicks that lacked maternal antibody to IBDV were inoculated with IBDV at 1 day of age and were maintained segregated from uninoculated controls. Plasma cell (PC) content of the GH was lowered among infected chickens from 1 to 7 weeks postinoculation. Since the GH in uninoculated control birds was not densely populated with PCs until 3 weeks of age, the PC depletion found in young chickens infected with IBDV became more clear with age. After the chickens were 3 weeks old, fewer (P less than .01) plasma cells were observed in the GH of IBDV-infected chicks than in uninoculated controls. Lymphoid follicles and heterophil populations in the GH did not appear to be affected by IBDV infection, nor could necrotic or degenerative changes be found in the acini or excretory ducts. The observation of fewer PCs suggests that a major lymphoid tissue of the upper respiratory tract is comprised by IBDV infection of day-old chicks.U