Bioinformatic evaluation of the potential animal models for studying SARS-Cov-2.

Recently, the severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2), a novel coronavirus, which results in corona virus disease 2019 (COVID-19), has caused over 40 millions of people infected and over 1 million fatalities, challenging the public health. The recognition of its functional receptor, angiotensin converting enzyme 2 (ACE2), have facilitated the antivirus drugs testing and vaccines development. Due to the natural resistance of mouse model to SARS-Cov-2, there is an urgent need to find out the alternative animal model. Considering the crucial role of ACE2 in the host cell entry, we analyzed the phylogeny and expression pattern of ACE2 from various mammals. Firstly, crab-eating macaque possesses all of the 5 identical hotspot residues with human, suggesting high likelihood of interaction between ACE2 and spike protein of SARS-CoV-2 to occur. Cattle and pig show 4 identical sites. Ferret, cat and dog possess 3 identical sites. Bat and mouse only share 2 same amino acids with human. Secondly, in humans, ACE2 is widely present, with particularly high expression in adipose, thyroid, lung and colon tissues. In crab-eating macaque, liver, lung, thyroid and colon showed high expression level of ACE2. For dog, ACE2 is most highly expressed in colon with obvious differential expression level between female and male group. The results would provide clues for establishing the appropriate animal model in the research and clinical cure of COVID-19.