Fig. 4: Growth kinetics of Omicron subvariants in hACE2 hamsters.

Naïve transgenic hACE2 Syrian hamsters (n = 4 males and n = 4 females for BQ.1.1 and XBB; n = 4 females for BA.2.75) were infected with 10⁵ PFU (30 μL total volume) of virus. a Body weights of virus-infected hACE2 hamsters were monitored daily for 5 days. Data were analyzed by using a two-way analysis of variance (ANOVA) and Dunnett’s multiple comparisons test with the comparison to the BA.2.75-infected animals. P values: * <0.05, ** <0.01; ns - not significant. † - lethality in the indicated number of hamsters out of a total of four infected hamsters. b A separate group of infected animals was euthanized at 4 dpi for virus titration (n = 4 males and n = 4 females for BQ.1.1 and XBB; n = 4 females for BA.2.75). Virus titers in the lung, nasal turbinate, and brain tissues were determined by performing a standard plaque assay with Vero E6-TMPRSS2-T2A-ACE2 cells. Vertical bars show the mean ± s.e.m. Points indicate data from individual animals. The lower limit of detection is indicated by the horizontal dashed line. Data were analyzed by using a one-way ANOVA with Tukey’s multiple comparisons test. P values of <0.05 were considered statistically significant and are the only values shown.