Fig. 1: Clinical follow-up, viral replication in Syrian hamsters and seroneutralization tests.

a Experimental timeline. Groups of 12 hamsters were intranasally infected with 2 × 10³ TCID₅₀ of Alpha variant or G614 strain for comparative assessment, or with a mix (1:1) of both viral strains for competition experiment (10³ TCID₅₀ of each). b Comparative clinical follow-up. Weights are expressed as normalized weights (i.e. % of initial weight). ***, ** and * symbols indicate that normalized weights for the Alpha variant group are significantly higher than those of the G614 group with a p-value ranging between 0.0001–0.001, 0.001–0.01, and 0.01–0.05, respectively (two-way ANOVA test with Tukey’s post-hoc analysis) (n = 12). c–e Comparative assessment of viral RNA yields in lungs (c), nasal washes (d), and guts (e), measured using a RT-qPCR assay. ** and * symbols indicate that viral RNA yields for the Alpha variant group are significantly lower than those of the G614 group with a p-value ranging between 0.001–0.01 and 0.01–0.05, respectively (n = 12; Mann–Whitney and unpaired t tests). f and g Comparative assessment of infectious titers in lungs (f) and nasal washes (g), measured using a TCID₅₀ assay. h and i Competition experiments. Two specific RT-qPCR assays were used to measure the quantity of each virus in lungs (h) and nasal washes (i). Results are expressed as [G614/Alpha variant] ratios. *** and * symbols indicate that ratios at 4 dpi are higher than those at 2 dpi or in inocula with a p-value ranging between 0.0001–0.001 and 0.01–0.05, respectively (n = 12; Mann–Whitney tests). j and k Seroneutralization tests performed with sera from animals sacrificed at 7 dpi. 90% (j) and 99% (k). Yield Reduction Neutralization Titers (90–99YRNT) were determined against four strains of SAR-CoV-2: G614 strain, Alpha variant, Beta variant, and Delta variant. Results from statistical analysis are presented in Supplementary Tables 4–8 (n = 4). b–k Data represent mean ± SD.