ObjectiveTo investigate thrombosis in mouse lung tissue after infection with influenza A virus, and compare the differences between mouse strains with different immune status. MethodsInfluenza H1N1(A/California/7/2009) and H3N2(A/Brisbane/10/07) were used in this infectivity study. Forty BALB/c mice, 50 NOD-Scid mice, 33 Scid mice, 33 BALB/C-nu mice, 33 NOD/LTJ mice and 10 icosl-KO mice were anesthetized by ether inhalation and inoculated intranasally with 0.05 mL suspension of infectious virus H1N1 or H3N2. The pathogenic changes were observed and the virus copy numbers in the lung tissue were detected by real-time PCR. ResultsVarying degrees of interstitial pneumonia were observed in the lung tissue of mice infected with H1N1 and H3N2 viruses. There was thrombosis within the lung tissue in 13 mice of H1N1 group and 6 mice of H3N2 group. The main components of the thrombus were cellulose and platelets. ConclusionsOur results support that thrombosis may occur in the lungs of all studied mouse strains after infection with influenza A (H1N1) and (H3N2) viruses. 