Fig. 4.

Lesions in rabbits caused by aerosolized RPXV. Parts (a)–(c) are from group 1 rabbits (PBS control) that expired due to rabbitpox. (a) Dorsal view of lungs with diffuse edema and multiple red consolidated foci of pneumonia (arrows). Scale units are mm; numbers on scale are cm. (b) Histologic section of lung showing a large bronchiole (B) with diffuse degeneration and necrosis of the lining epithelium, accompanied by hemorrhage, edema, and fibrin exudation into surrounding alveoli (arrows). Magnification 4×; bar = 20 μm. (c) Histologic section of a nasal passage showing diffuse congestion, edema, and subacute inflammation of the nasal mucosa overlying turbinate bones (B), with a large focus of epithelial degeneration and necrosis (area extending from one arrow to the other arrow). Magnification 10×; bar = 10 μm. (d) Histologic section of lung from a group 2 rabbit (Dryvax^® vaccinated) that had displayed clinical signs but survived. There is a large focus of granulomatous inflammation (between arrows); the necrotic and mineralized materials in the center of this lesion (asterisk) are probably remnants of a bronchiole. Magnification 4×; bar = 20 μm.