FIG 3.
The s2m is dispensable for SARS-CoV-2 in vivo. Intranasal inoculation of hamsters with CoV-2-s2m-WT and mutants, including CoV-2-s2mΔ2–42, which contains a deletion of the s2m; CoV-2-s2m2–5, which contains four mutations of the stem of the s2m; and CoV-2-s2m2–5,39–42, which contains complementary mutations predicted to restore the secondary structure of the s2m. Hamsters were sacrificed on days 3 and 6. (A) Mean hamster weight as percentage of starting weight is graphed, with error bars representing standard deviations. The weights of the hamsters infected with CoV-2-s2m-WT and mutant SARS-CoV-2 viruses were compared, and no difference was detected using a mixed-effect model with Geisser-Greenhouse correction [F[3,44] = 1.26, P = 0.30]. (B to D) There was no difference in lung infectious viral titer [Kruskal-Wallis H(3) = 0.62, P = 0.89] (B), lung viral RNA [Kruskal-Wallis H(3) = 2.0, P = 0.57] (C), and nasal wash viral RNA [Kruskal-Wallis H(3) = 2.2 P = 0.54] (D) from day 3 were identified comparing CoV-2-s2m-WT and s2m mutant viruses. (E to G) At 6 days postinoculation, there were also no differences in lung infectious viral titer [Kruskal-Wallis H(3) = 5.5, P = 0.14] (E), lung viral RNA [Kruskal-Wallis H(3) = 6.2, P = 0.10] (F), and nasal wash viral RNA [Kruskal-Wallis H(3) = 2.8, P = 0.42] (G) comparing CoV-2-s2m-WT to mutant s2m viruses. For all graphs in panels B to G, each dot is one animal. The dotted line represents the limit of detection of the respective assay.