It is known that SARS-CoV-2 uses a cellular receptor, angiotensin converting enzyme II (ACE2), for cell entry. Besides being a virus receptor, ACE2 functions as an important regulator of the renin-angiotensin system (RAS). Studies have identified that the expression of virus dependency factors (VDFs) is needed for SARS-CoV-2 infection.sACE2-S complex and sACE2-s-vasopressin complex may be involved inthe receptor-mediated entry of the virus or endocytosis of the virus.  An analysis of the VDF revealed that disturbance of their functions could be related to clinical symptoms and complications of COVID-19. New research has shown the role of a soluble form of angiotensin converting enzyme 2 (ACE2) and vasopressin in mediating SARS-CoV-2 entry into susceptible cells. In a study, Yeung et al. showed that interaction of the SARS-CoV-2 spike protein with sACE2 or with a complex of sACE2 plus vasopressin facilitates receptor-mediated endocytosisof the virus through type 1 angiotensin and vasopressin V1b receptors, respectively.Further research demonstrated that SARS-CoV-2 employs receptor-mediated endocytosis via interaction between its spike with sACE2 or sACE2-vasopressin through AT1 or AVPR1B, respectively. 

This research has successfully identified (VDFs) that are significant for SARS-CoV-2 to establish a productive virus replication and also a correlation of clinical manifestation and complications of SARS-CoV-2 infection. The identification of VDFs and the regulatory effect of sACE2 on SARS-CoV-2 infection throws insight into pathogenesis and cell entry mechanisms of SARS-CoV-2 as well as potential treatment strategies for COVID-19. 

Reference: 

1. Yeung ML, Teng JLL, Jia L, et al. Soluble ACE2-mediated cell entry of SARS-CoV-2 via interaction with proteins related to the renin-angiotensin system. Cell. 2021; 184: 2212-2228.