Fig. 2: Syrian hamster model—study design, viral shedding, viral load, infectious titers, and viral antigen.

a Hamsters were intranasally infected with SARS-CoV-2. MK-4482 was administered pre-infection at 12 and 2 h before infection, or post-infection starting 12 h post-infection. Treatment was continued in both groups every 12 h for 3 consecutive days. Animals were euthanized on day 4 and lungs were harvested. T = treatment (red: pre-infection and black: post-infection treatments); I = infection; S = swab samples and N = necropsy. b Oral swab samples (N = 6 per group) were collected on days 2 and 4 post-infection and viral shedding determined by RT-PCR (p Value Vehicle vs Pre-treatment = >0.9999, p Value Vehicle vs Post-treatment = >0.9999, One-way ANOVA, Kruskal–Wallis test). c Oral swab samples (N = 6 per group) were titered for infectious virus (TCID₅₀) on Vero E6 cells⁴³ (p Value Vehicle vs Pre-treatment = 0.5701, p Value Vehicle vs Post-treatment = >0.9999, One-way ANOVA, Kruskal–Wallis test). d Lung viral loads (N = 6 per group) were determined by using RT-PCR (p Value Vehicle vs Pre-treatment = 0.0189, p Value Vehicle vs Post-treatment = 0.1032, One-way ANOVA, Kruskal–Wallis test). e Lung samples (N = 6 per group) were homogenized and titered for infectious virus (TCID₅₀)⁴³ on Vero E6 cells. Two independent lung samples were measured from each animal (N = 12 per group) (p Value Vehicle vs Pre-treatment = 0.0091, p Value Vehicle vs Post-treatment = 0.0102, One-way ANOVA, Kruskal–Wallis test). b–e Blue circle, vehicle control; red square, pre-infection treatment; green triangle, post-infection treatment. Summary of Results: b, c No statistical significance in virus shedding (RT-PCR or TCID₅₀) between either of the two MK-4482 treatment groups and vehicle controls. d Significant difference in lung viral loads (RT-PCR) between pre-infection group compared to the vehicle control. Although post-infection group trended towards lower levels, no significant difference between this group and vehicle control. e Infectious titers in the lungs (TCID₅₀) were significantly different between both pre-infection and post-infection groups, compared to vehicle control group, but no significance was found between treatment groups from each other. One-way ANOVA followed by Kruskal–Wallis analysis and a pairwise Wilcox test was used to analyze differences among groups. *p < 0.05, **p < 0.008.