Fig. 5

Photomicrographs illustrating hematoxylin and eosin staining (HE, first and third rows of panels) and immunohistochemistry (IHC, second and fourth rows of panels) on sections of eyelid (panels a-d) and spleen (e-f) at day 5 pi. Tissues were harvested from 4-week-old White Leghorn chickens infected with rZJ1-IL2 (first column of panels), and rZJ1-GFP (second column of panels). Alkaline phosphatase method and hematoxylin counterstain. In the eyelid, histopathological changes consist of severe edema (asterisks), which markedly expands the submucosa, accumulation of pleomorphic cellular infiltrate (macrophages, heterophils, lymphocytes), exudation of fibrin, and multifocal areas of coagulative necrosis. This severe conjunctivitis is similar in intensity in both rZJ1-Il2 (panel a) and rZJ1-GFP (panel b) groups. Presence of lesion in the eyelid is associated with positive immunohistochemical labeling, which is intense and diffuse in rZJ1-GFP-infected birds (panel d), while in rZJ1-IL2-infected birds is less intense and multifocal (panel c). In the spleen, rZJ1-IL2-infected birds display mild to moderate lymphoid depletion and accumulation of prominent macrophage in the ellipsoid areas, which appear confluent (dashed lines, panel e). These changes are associated with minimal NDV immunohistochemical labeling, which is not present at day 5 pi (panel g). Birds infected with rZJ1-GFP show severe lesions in the spleen, consisting of lymphoid depletion, prominent macrophages, exudation of fibrin and accumulation of necrotic debris (arrows, panel f). These lesions are associated with intense and diffuse immunohistochemical labeling for NDV (panel h)