Fig. 3

Effects of different doses of ATRA and H9N2 virus on the gross pathology of lungs of mice. f–h and n–p are the lungs of dead mice, and the rest are the lungs of mice at 19 days after inoculation. n = 3–5. a Blank group, mice receiving sterile PBS inoculation and cottonseed oil injection at 0–9 days after inoculation; b–h ATRA1-ATRA7 group, mice receiving sterile PBS inoculation and ATRA injection (1, 5, 10, 20, 40, 60, and 80 mg/kg, respectively) at 0–9 days after inoculation; i H9N2 group, mice receiving H9N2 virus (10⁵ TCID₅₀) inoculation and cottonseed oil injection at 0–9 days after inoculation; j–p ATRA1 + H9N2-ATRA7 + H9N2 group, mice receiving H9N2 virus (10⁵ TCID₅₀) inoculation and ATRA injection (1, 5, 10, 20, 40, 60, and 80 mg/kg, respectively) at 0–9 days after inoculation. ATRA, all-trans retinoic acid; TCID₅₀, median tissue culture infective dose