High level production and characterization of truncated human angiotensin converting enzyme 2 in Nicotiana benthamiana plant as a potential therapeutic target in COVID-19

The COVID-19 pandemic, which is caused by SARS-CoV-2 has rapidly spread to more than 222 countries and has put global public health at high risk. The world urgently needs safe, a cost-effective SARS-CoV-2 coronavirus vaccine, therapeutic and antiviral drugs to combat the COVID-19. Angiotensin-converting enzyme 2 (ACE2), as a key receptor for SARS-CoV-2 infections, has been proposed as a potential therapeutic target in COVID-19 patients. In this study, we report high level production (about ∼0.75 g /kg leaf biomass) of glycosylated and non-glycosylated forms of recombinant human truncated ACE2 in Nicotiana benthamiana plant. The plant produced recombinant human truncated ACE2s successfully bind to the SARC-CoV-2 spike protein, but deglycosylated ACE2 binds more strongly than the glycosylated counterpart. Importantly, both deglycosylated and glycosylated forms of AEC2 stable at elevated temperatures for prolonged periods and demonstrated strong anti-SARS-CoV-2 activity in vitro. The IC₅₀ values of glycosylated and deglycosylated AEC2 were 0.4 and 24 μg/ml, respectively, for the pre-entry infection, when incubated with 100TCID₅₀ of SARS-CoV-2. Thus, plant produced truncated ACE2s are promising cost-effective and safe candidate as a potential therapeutic targets in the treatment of COVID-19 patients.