In the presence of nirmatrelvir, wild-type virus grew poorly, reaching only 3.8 × 104 PFU at 72 h post-infection, whereas Nsp5-L50F/E166V and Nsp5-L50F/E166A/L167F replicated similarly to in the absence of nirmatrelvir (Fig. 2b). The gene discussed is SPECC1; the disease is infection.