Fig. 5. Virological characteristics of XBB.1.5 in vivo.
Syrian hamsters were intranasally inoculated with XBB.1, XBB.1.5, and Delta. Six hamsters of the same age were intranasally inoculated with saline (uninfected). Six hamsters per group were used to routinely measure the respective parameters (A). Four hamsters per group were euthanized at 2 and 5 d.p.i. and used for virological and pathological analysis (B–E). A Body weight, Penh, and Rpef values of infected hamsters (n = 6 per infection group). B Left Viral RNA loads in the oral swab (n = 6 per infection group). (Middle and right) Viral RNA loads in the lung hilum (middle) and lung periphery (right) of infected hamsters (n = 4 per infection group). C IHC of the viral N protein in the lungs of infected hamsters at 2 d.p.i. (left) and 5 d.p.i. (right). Representative figures (N-positive cells are shown in brown) and the percentage of N-positive cells in whole lung lobes (n = 4 per infection group) are shown. D H&E staining of the lungs of infected hamsters. Representative figures are shown in (D). Uninfected lung alveolar spaces are also shown. The raw data are shown in Supplementary Fig. 4B and Supplementary Fig. 4C. E Histopathological scoring of lung lesions (n = 4 per infection group). Representative pathological features are reported in our previous studies1,3,4,21–24. A–C, E Data are presented as the average ± SEM. (C) Each dot indicates the result of an individual hamster. A, B, E Statistically significant differences between XBB.1.5 and other variants across timepoints were determined by multiple regression. B, E The 0 d.p.i. data were excluded from the analyses. The FWERs calculated using the Holm method are indicated in the figures. C The statistically significant differences between XBB.1.5 and other variants were determined by a two-sided Mann–Whitney U test. C and D Each panel shows a representative result from an individual infected hamster. Scale bars, (C) 500 µm, (D) 200 µm.