Figure 1. Mouse-adaptation of SARS-CoV-2.

a) Schematic of adaptation of SARS-CoV-2 CMA3p20. One ten-week-old female Balb/c mice was infected with SARS-CoV-2 CMA3 for 1 day, euthanized, and lung tissues harvested for viral RNA and viral titer determination. Lung tissues were homogenized, clarified, and 50ul used to inoculate subsequent animals for 20 passages (p). b) Viral replication of CMA3 p1-p20 from lung homogenates isolated from infected mice 1 day post infection. c) Stock virus generated at passages 0, 10, 15, and 20 was used to infect 5 female Balb/c mice at 105 PFU and evaluated for weight loss over a 4-day time course. d). Schematic of engineered (red stars) and passage-acquired (blue stars) mutations in CMA3p20 stock virus. Table includes Sanger equivalent accumulation of mutations over passages p5, p10, p15, p20, and final stock used for subsequent studies. e) Modeling RBD spike mutations N501Y and K417N found in CMA3p20 with mouse ACE2.