There is strong evidence that severe acute respiratory syndrome 2 virus (SARS-CoV-2), the causative agent of the coronavirus disease 2019 (COVID-19) pandemic, originated from an animal reservoir. However, the exact mechanisms of emergence, the host species involved, and the risk to domestic and agricultural animals are largely unknown. Some domestic animal species, including cats, ferrets, and minks, have been demonstrated to be susceptible to SARS-CoV-2 infection, while others, such as pigs and chickens, are not. Importantly, the susceptibility of ruminants to SARS-CoV-2 is unknown, even though they often live in close proximity to humans. We investigated the replication and tissue tropism of two different SARS-CoV-2 isolates in the respiratory tract of three farm animal species - cattle, sheep, and pigs - using respiratory ex vivo organ cultures (EVOCs). We demonstrate that the respiratory tissues of cattle and sheep, but not of pigs, sustain viral replication in vitro of both isolates and that SARS-CoV-2 is associated to ACE2-expressing cells of the respiratory tract of both ruminant species. Intriguingly, a SARS-CoV-2 isolate containing an amino acid substitution at site 614 of the spike protein (mutation D614G) replicated at higher magnitude in ex vivo tissues of both ruminant species, supporting previous results obtained using human cells. These results suggest that additional in vivo experiments involving several ruminant species are warranted to determine their potential role in the epidemiology of this virus.

有充分的证据表明，严重的急性呼吸综合症2病毒（SARS-CoV-2）是2019年冠状病毒病（COVID-19）大流行的病原，源于动物库。但是，确切的出现机理，所涉及的寄主物种以及对家畜和农业动物的风险尚不清楚。已证明某些家畜物种，包括猫和雪貂，很容易感染SARS-CoV-2，而其他动物，例如猪和鸡，则不易感染。重要的是，反刍动物对SARS-CoV-2的易感性尚不明确，尽管它们通常生活在人类附近。我们调查了两种不同的SARS-CoV-2分离株在三种农场动物（牛，绵羊和猪）的呼吸道中的复制和组织向性，方法是使用呼吸道离体器官培养（EVOC）。我们证明，牛和羊的呼吸组织，而不是猪的呼吸组织，在两种分离物中均维持病毒的体外复制，SARS-CoV-2与两种反刍动物呼吸道的ACE2表达细胞有效结合。有趣的是，在两个反刍动物的离体组织中都以较高的幅度复制了在峰值蛋白（突变蛋白D614 G）的位点614处含有氨基酸取代的SARS-CoV-2分离株，支持使用人类细胞获得的先前结果。这些结果表明，需要进行涉及几种反刍动物物种的其他体内实验，以确定这种病毒在流行病学中的潜在作用。