The emergence and global spread of SARS-CoV-2 variants has caused global concerns about increased virulence and decreased efficacy of medical countermeasures. Herein, we demonstrate that the newly emerged 501Y.V2 variant (also called the beta variant) is capable of infecting standard laboratory mice after intranasal instillation, unlike the earlier isolates. However, the infectivity in mice demonstrated in the laboratory may not occur in nature; indeed, there is no evidence of natural transmission of 501Y.V2 in mice to date. Most interestingly, the 501Y.V2 variant was quickly replaced by another variant—the delta variant—in the human population. Our results indicate that circulating SARS-CoV-2 has been evolving rapidly and that transient acquisition of cross-species infectivity in animals may occur. This phenomenon creates new challenges as well as opportunities in studying SARS-CoV-2 circulation and evolution.

中文翻译：

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SARS-CoV-2进化过程中跨物种传染性的瞬时获得

SARS-CoV-2 变种的出现和全球传播引起了全球对毒力增加和医疗对策有效性降低的担忧。在此，我们证明新出现的 501Y.V2 变体（也称为 beta 变体）能够在鼻内滴注后感染标准实验室小鼠，这与早期的分离株不同。然而，实验室证明的小鼠感染性可能不会在自然界发生；事实上，迄今为止，没有证据表明 501Y.V2 在小鼠中自然传播。最有趣的是，501Y.V2 变体很快被人群中的另一种变体——delta 变体所取代。我们的研究结果表明，循环中的 SARS-CoV-2 发展迅速，可能会在动物中发生短暂的跨物种感染。