PROS1 and infection: Recombinant SARS-CoV-2 with the S protein of the B-1 P30 strain (Δ68–76, H655Y, P812L, and Q853L) and the double mutation (Δ68–76 and H655Y) caused milder body weight loss than that caused by the wild-type virus at 5 days post-infection (dpi).