Tissue distribution of ACE2 protein in Syrian golden hamster (Mesocricetus auratus) and its possible implications in SARS-CoV-2 related studies

Recently, the Syrian golden hamster (Mesocricetus auratus) has been demonstrated as a clinically relevant animal model for SARS-CoV-2 infection. However, lack of knowledge about the tissue-specific expression pattern of various proteins in these animals and the unavailability of reagents like antibodies against this species hampers optimal use of these models. The major objective of our current study was to analyze the tissue-specific expression pattern of angiotensin□converting enzyme 2 (ACE2), a proven functional receptor for SARS-CoV-2 in different organs of the hamster. We have adapted immunoblot analysis, immunohistochemistry, and immunofluorescence analysis techniques to evaluate the ACE2 expression pattern in different tissues of the Syrian golden hamster. We found that kidney, small intestine, esophagus, tongue, brain, and liver express ACE2. Epithelium of proximal tubules of kidney and surface epithelium of ileum expresses a very high amount of this protein. Surprisingly, analysis of stained tissue sections for ACE2 showed no detectable expression of ACE2 in the lung or tracheal epithelial cells. Similarly, all parts of the large intestine (caecum, colon, and rectum) were negative for ACE2 expression. Together, our findings corroborate some of the earlier reports related to ACE2 expression pattern in human tissues and also contradicts some others. We believe that the findings of this study will enable the appropriate use of the Syrian golden hamster to carryout SARS-CoV-2 related studies.