Fig. 4. Tracheal lesions are mild to moderate regardless of the SARS-CoV-2 strain infection in hamsters.

A Representative images showing tracheal lesions in hamsters infected with VOCs Gamma, Delta, Omicron or 614 G strain. Trachea histopathological changes were characterized by neutrophilic/heterophilic exocytosis (arrows) and sub-epithelial infiltration of macrophages and neutrophils/heterophils (asterisks). The insets show a higher magnification of the ciliated epithelium. Intact cilia are indicated by arrowheads. In all groups, most cells show ciliary loss. Hematoxylin and eosin stain. Scale bars = 50 µm and 10 µm (inset). B Semi-quantitative analysis of tracheal histopathology revealed no statistically significant differences in the recorded scores among the groups. Data are shown as box and whisker plots. The bounds of the box plot indicate the 25th and 75th percentiles, the bar indicates medians, and the whiskers indicate minima and maxima. Data were tested by two-tailed Mann–Whitney-U tests followed by Benjamini–Hochberg correction. A p-value of ≤0.05 was chosen as the cut-off for statistical significance. N = 5 animals/group for VOCs Gamma and Delta and 6 animals/group for VOC Omicron and 614 G. For quantifications, one entire cross- and one entire longitudinal section were evaluated per animal. Source data are provided as a Source Data file.