Comparison of SARS-CoV-2 variant lethality in human angiotensin-converting enzyme 2 transgenic mice

This study compared the lethality of severe acute respiratory syndrome coronavirus 2 variants belonging to the S, V, L, G, GH, and GR clades using K18-human angiotensin-converting enzyme 2 heterozygous mice. To estimate the 50% lethal dose (LD(50)) of each variant, increasing viral loads (10(0)–10(4) plaque-forming units [PFU]) were administered intranasally. Mouse weight and survival were monitored for 14 days. The LD(50) of the GH and GR clades was significantly lower than that of other clades at 50 PFU. These findings suggest that the GH and GR clades, which are prevalent worldwide, are more virulent than the other clades.