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 (LD₅₀) of each variant, increasing viral loads (10⁰–10⁴ plaque-forming units [PFU]) were administered intranasally. Mouse weight and survival were monitored for 14 days. The LD₅₀ 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.

本研究使用 K18-人血管紧张素转换酶 2 杂合小鼠比较了属于 S、V、L、G、GH 和 GR 进化枝的严重急性呼吸系统综合症冠状病毒 2 变体的致死率。为了估计每个变体的 50% 致死剂量 (LD ₅₀ )，增加病毒载量（10 ⁰ –10 ⁴噬菌斑形成单位 [PFU]）经鼻内给药。监测小鼠体重和存活 14 天。GH 和 GR 进化枝的 LD ₅₀在 50 PFU 时显着低于其他进化枝。这些发现表明，全球普遍存在的 GH 和 GR 进化枝比其他进化枝更具毒性。