Fig. 2

Gross pathology and histopathological changes. a Lung of infected mink showed areas of extravasated blood and partial consolidation at 3 dpi. b No significant changes in the lung of control mink. Histopathology with hematoxylin-eosin staining in infected lung is shown in C–F (H&E, ×40). c On 3dpi, alveolar walls of minks in the infection group were markedly thickened and contained much of exudates resulting from inflammation. Substantial amounts of serous fluid had seeped out of veins, and infiltration of inflammatory cells into lung tissue was observed. d On 7 dpi, part of alveolar fusion and part of alveolar consolidated with exudates were observed. e On 11 dpi, the injury of the lung became to ease, but still have some exudes in the alveolar and some inflammatory cells infiltrated. f By 15 dpi, only a little of inflammatory cells infiltrated in alveolar