Fig. 1: The screening of the SARS-CoV-2 Alpha variant spike substitutions in hamsters by competition assay.
From: The N501Y spike substitution enhances SARS-CoV-2 infection and transmission
a, Design of the hamster competition fitness studies. The mutant viruses were mixed 1:1 (PFU ratio) with WT virus and inoculated into donor hamsters intranasally at a total titre of 105 PFU per hamster. The donor hamsters were co-housed with recipient hamsters 1 day after infection. After 8 h of contact, the donors were removed. All hamsters were subjected to nasal washes daily until 4 days after infection and organs were collected 4 days after inoculation or contact. b–g, Competition of different Alpha mutants with WT virus. b, d, f, Final:inoculum PFU ratio of WT virus expressing 8 individual spike mutations or the Alpha spike protein that includes all 8 mutations: nasal washes (b), tracheae (d) and lungs (f) in donor hamsters 4 days after inoculation. c, e, g, Final:donor inoculum ratios of WT virus expressing 8 individual spike mutations or the Alpha spike protein: nasal washes (c), tracheae (e) and lungs (g) in recipient hamsters 4 days after contact. In b–g, red dots represent individual hamsters (n = 5). In catseye plots, the horizontal line shows the mean and the shaded region represents s.e.m. Numbers along the top indicate the relative fitness estimates. P values were calculated for the group (strain) coefficient for each linear regression model.
