FIGURE 2.

Histopathological observations of tissues of the IFNAR^-/- mice infected with SFTSV. The spleen, lymph nodes, bone marrow, and livers of SFTSV-infected and uninfected mice were used for histopathologic observations. Losses of the structure with massive apoptosis were observed in hematoxylin and eosin-stained tissues (A); Magnified images of pyknosis and karyorrhexis observed in the necrotic lesions are indicated at the top right corner of the infected spleen and lymph node. The increased myeloid/erythroid ratio in the bone marrow of infected mice was observed (B); A magnified image of moderate necrosis collocating with edema and fibrin is shown at the top right corner. Colocalization of B220-positive cells with necrotic lesions in the spleen and lymph node (C) as well as IbaI-positive cells with enlarged cytoplasm in the liver (D) were visualized by immunohistochemistry.