Figure 3

Histopathology and immunohistochemistry analyses of liver from BALB and C.MBT-Rvfs2 mice on day 3 p.i. Three distinct histological profiles were found in 10 BALB and 8 C.MBT-Rvfs2 infected mice. Profile 1: (A) Randomly distributed, multifocal inflammatory lesions (arrowheads) with (B,C) small well-delimited foci of necrotic/apoptotic hepatocytes associated with neutrophil infiltration (C, black arrows). (D,E) Small clusters of RVFV N protein-positive hepatocytes recognized by immunohistochemistry. Profile 2: (F) Multifocal inflammatory lesions randomly distributed in the liver (arrowheads) with (G,H) more extensive and severe foci of necrotic/apoptotic hepatocytes than in Profile 1 (H, black circles: apoptotic bodies). (I,J) Slightly larger clusters of N-positive hepatocytes observed after immunohistochemistry. Profile 3: (K–M) Massive necrosis/apoptosis of hepatocytes (M black circle: apoptotic body; black star: intranuclear viral inclusion), (N,O) with a strong and diffuse immunohistochemistry staining for RVFV N protein in the parenchyma. None of these lesions were observed in the liver of uninfected BALB and C.MBT-Rvfs2 mice. A, B, C, F, G, H, K, L, M: Hematoxylin and eosin staining; D, E, I, J, N, O: Immunohistochemistry for RVFV N protein.