Microscopic lesions and viral antigen localization in the spleen of a 5 week old rabbit (Oryctolagus cuniculus) (rabbit 306) inoculated with Lagovirus europaeus G1.2 (BlMt-1). Asterisks denote the white pulp. A Uninfected control (rabbit 130). 200× magnification. B Terminal stage of acute infection. There is lymphoid depletion and tingible body macrophages (arrows) in the white pulp and macrophage hyperplasia in the adjacent red pulp. 200× magnification. C Red pulp of the uninfected control (rabbit 130). 400× magnification. D Red pulp of rabbit 306. Note the indistinct, hyaline stroma and presence of small, dark pyknotic cells (arrowheads). 400× magnification. E Rabbit 306. Active phagocytosis by macrophages in the red pulp (arrows) and numerous pyknotic cells (arrowheads). The macrophage indicated at the bottom of the image has phagocytized a pyknotic cell. 400× magnification. F Immunohistochemical visualization of viral capsid antigen (brown staining) in the cytoplasm of viable macrophages (arrows) in the terminal stage of acute infection. Note that no staining is associated with pyknotic cells. 400× magnification.