Fig. 4.

Detection of PFN producing CD8⁺ T cells in spleen. (A) Chickens were inoculated with IBDV and spleen tissues were collected at 3, 5 and 7 PID. Spleen sections from virus free chickens (a, b and c) and IBDV-infected chickens (d, e, and f) were examined (40×) for the presence of PFN by immunohistochemistry using anti-human PFN mAb. Development of brown color shown by arrow indicates positive staining for PFN. (B) Double staining for CD8⁺ cells, positive for PFN; blue staining shown by arrow represents CD8⁺ positive T cells and brown staining represented black arrow head shows PFN positive cells and white arrow head shows double positive cells respectively.