Fig. 4.

The pathological changes in tree shrews after infection with swine and avian influenza viruses. A. Representative gross appearance of lungs from tree shrews inoculated with SW2783, ZZ346 influenza viruses and PBS. B. The organ coefficient of different organs from tree shrews (n = 4 per group) infected with influenza viruses. Data are show as means ± SD. Asterisks indicate significant differences, *P<0.05. C. Histopathology of tree shrew respiratory tract tissues infected with SW2783 and ZZ346 influenza viruses. Tree shrews (n = 4 per group) were infected with 10⁵ TCID₅₀ /mL of swine SW2783 and avian ZZ346 influenza virus, respectively. Representative pathological images (HE staining) of nasal turbinate, trachea, and lung tissues were harvested on 3 and 5 dpi. Black arrows indicate infiltration of inflammatory cells, cell necrosis, sloughed epithelial cells and alveolar septal congestion. Bar, 50 μm.