Recombinant SARS-CoV2 S-Protein ACE2 Binding Domain

      There has been an enormous amount of interest in the novel virus SARS-CoV-2 for very obvious reasons. It is a corona virus, a member of a large family of spherical viruses with prominent spikes which give them the appearance of a cartoon sun, which is why they are called corona viruses. The SARS-CoV-2 virus was first identified in Wuhan, China, at the end of 2019 and almost certainly originated from bats, possibly infecting humans indirectly from another animal host (1,2). The virus transmits very readily and has a significant mortality with particular risk to individuals with comorbidities such as diabetes, hypertension, immune compromise and heart problems. While no age group seems to be safe the majority of patients who have serious symptoms or succumb are of advanced age. Much research has shown that a part of the “spike” or S protein on the surface of the virus has a high affinity binding site for angiotensin converting enzyme 2 (ACE2) a protein on the surface of human cells in the lung epitheliun and other tissues (3). This specific binding is required for internalization of the virus and is the first step in viral infection. Accordingly antibodies or other reagents which bind to the ACE2/SARS-CoV-2 interaction site may interfere with viral internalization and hence infection. Recent cryoEM studies have characterized the exact interface (4). We have therefore made two recombinant constructs, this one including the segment of the SARS-CoV-2 spike protein containing the ACE2 binding site, and also Prot-ACE2-bd, containing the extracellular domain of ACE2 including the SARS-CoV-2 binding domain.