Figure 6

Histological changes in spleens of mice infected with 'scid-adapted' MARV. Scid mice were challenged IP with 1000 pfu of 'scid-adapted' MARV-Ci67 and tissue samples were collected on days 0, 2, 4, 6, and 8 after challenge (n = 4–5/group). (A-G) Tissues from the MARV-infected mice were stained with hematoxylin and eosin and representative pictures from day 0 (A-B), 4 (C-D), and 6 (E-G) are shown. (A-B) Control scid mouse sampled at day 0 (i.e. uninfected) contain abnormal spleen morphology due to lack of B and T lymphocytes. (C-F) Spleens from the MARV-infected scid mice at days 4 and 6 display increasingly more visual loss of cells in both the red and white pulp. (G) At late stages of the disease, the spleen contains notable necrosis/apoptosis of lymphocytes often with tingible body macrophages and large lymphoblasts in the white pulp. (H) Immunoperoxidase stain of a spleen from a scid mouse at 6 days postinfection showing presence of Marburg viral antigen (brown). Magnifications were 4× for panels A, C, and E, 20× for panels B, D, and F, and 40× for panels G-H.