Fig. 6: USUV-associated microscopical lesions and cell tropism.
From: Experimental Usutu virus infection in Eurasian blackbirds (Turdus merula)
USUV-associated lesions (H&E) (a, c, e, g) and USUV tropism (b, d, f, h) in the main target organs of USUV Afr3-infected blackbirds. a, b Spleen of blackbird n.4: a small multifocal areas of necrosis in the spleen (arrows) and infiltration of plasma cells and mott cells (arrowheads). b USUV antigen in the cytoplasm of large mononucleated cells morphologically compatible with splenic macrophages (c, d) Liver of blackbird n.4: c diffuse vacuolization and pigment deposition in the cytoplasm of hepatocytes, multiple cells with pyknotic nuclei and hyper eosinophilic cytoplasm (single cell necrosis) (arrowheads). d USUV antigen in the cytoplasm of hepatocytes (arrowhead), endothelial lining of the sinusoids (arrow) and Kupffer’s cells (asterisks). e, f Brain, pallium of blackbird n.1: e multiple neurons undergoing acidophilic neuronal necrosis (arrowheads) and mild perivascular infiltration of mononucleated leukocytes (arrow). f USUV antigen in the cytoplasm of neurons (arrowheads). g, h Brain, cerebellum of blackbird n.1: g Multiple Purkinje cells in variable degree of degeneration from chromatolysis to acidophilic neuronal necrosis (arrowheads). h USUV antigen in the cytoplasm of Purkinje cells (arrowhead) and adjacent neurons of the molecular layer (arrow).
