Expression of SARS-CoV-2 receptor ACE2 and the spike protein processing enzymes in developing human embryos

Colaco, Stacy; Chhabria, Karisma; Singh, Neha; Bhide, Anshul; Singh, Domdatt; Singh, Abhishek; Husein, Atahar; Mishra, Anuradha; Sharma, Richa; Ashary, Nancy; Modi, Deepak

The novel coronavirus disease, COVID-19 caused by Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2), has resulted in thousands of critically ill patients and poses a serious threat globally. To investigate if SARS-CoV-2 can affect early human embryos, we analysed scRNA-seq datasets of human embryos for the SARS-CoV-2 receptors ACE2 and BSG (CD147), the serine protease TMPRSS2 for viral spike protein priming, and the endosomal protease CTSL for spike protein activation via the endosomal route. The results reveal that ACE2 and TMPRSS2 are co-expressed in a proportion of epiblast cells, and both BSG and CTSL are expressed in all the stages of embryonic development. The cells of the blastocysts express genes encoding for other coronavirus receptors such as DPP4 and ANPEP as well. Interestingly, the cells of the epiblast also express genes involved in viral endocytosis and replication. We further identified 194 genes that are differentially expressed in ACE2- and TMPRSS2-positive cells as compared to ACE2- and TMPRSS2-negative cells of the epiblast. Our results show that developing human embryos express the receptors for SARS-CoV-2 and other coronaviruses; embryos also harbour the necessary machinery for viral internalization and replication. We suggest that couples be advised to avoid conceiving during the pandemic and that IVF procedures be kept to a minimum to prevent any possible hazard to the developing embryos.