Skip to main content
. 2024 Feb 1;12(3):e03386-23. doi: 10.1128/spectrum.03386-23

Fig 4.

Fig 4

Histological images and lesion scores from mice infected with swine influenza viruses. BALB/c mice were inoculated with 1e5 PFU of the indicated viruses and euthanized, and the lungs were fixed for histological analysis at 2 and 4 DPI (n = 2 mice/virus/collection, repeated). Lungs were assigned histological lesion scores out of 22. (A–D) Images of lung sections from 4 DPI at 20× and 10× (inset) for A/swine/Missouri/A01444664/2013 (H1N2) (A), A/swine/North Carolina/152702/2015 (H1N2) (B), A/swine/North Carolina/154074/2015 (H1N1) (C), and A/swine/North Carolina/A01394568/2013 (H1N1) (D). (A) MO/664/swM: mild perivascular and peribronchiolar infiltrations of mostly lymphocytes and mild segmental necrosis of the bronchiolar epithelium are present, but there are no significant interstitial changes. Lesion score: 6 out of 22. (B) NC/702/pdmM: bronchioles are dilated and there are moderate peribronchiolar and mild perivascular infiltrations of mostly lymphocytes and diffuse necrosis of the bronchiolar epithelium. Focally extending from the central bronchiole, alveolar septa are thickened and there are small numbers of inflammatory cells in the alveoli. Lesion score: 10 out of 22. (C) NC/074/pdmM: bronchioles are slightly dilated with mild epithelial necrosis and sloughed epithelial cells and a few inflammatory cells in the lumen. There are mild to moderate peribronchiolar and perivascular infiltrations of mostly lymphocytes. Diffusely, the alveolar septa are mildly thickened, and the alveoli contain small numbers of inflammatory cells. Lesion score: 13 out of 22. (D) NC/568/pdmM: bronchioles are slightly dilated and lined by the attenuated epithelium. There are mild peribronchiolar and perivascular infiltrations of mostly lymphocytes. Diffusely, the alveolar septa are mildly thickened, and alveoli contain small numbers of inflammatory cells admixed with erythrocytes. Lesion score: 10 out of 22. (E and F) Histological lesion scores out of 22 for BALB/c mice inoculated with either the H1 or H3 swine influenza isolates. Statistical differences were calculated using two-way ANOVA between (E) MO/664/swM and the other viruses with Dunnett post hoc test or (F) MN/993/swM and NC/671/pdmM with Bonferroni post hoc test. *<0.05, **<0.005, ***<0.001.