Abstract
The coronavirus disease 2019 (COVID-19) pandemic, which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread to more than 222 countries and has put global public health at high risk. The world urgently needs a safe, cost-effective SARS-CoV-2 vaccine as well as therapeutic and antiviral drugs to combat COVID-19. Angiotensin-converting enzyme 2 (ACE2), as a key receptor for SARS-CoV-2 infections, has been proposed as a potential therapeutic tool in patients with COVID-19. In this study, we report a high-level production (about ∼0.75 g/kg leaf biomass) of human soluble (truncated) ACE2 in the Nicotiana benthamiana plant. After the Ni-NTA single-step, the purification yields of recombinant plant produced ACE2 protein in glycosylated and deglycosylated forms calculated as ∼0.4 and 0.5 g/kg leaf biomass, respectively. The plant produced recombinant human soluble ACE2s successfully bind to the SARS-CoV-2 spike protein. Importantly, both deglycosylated and glycosylated forms of ACE2 are stable at increased temperatures for extended periods of time and demonstrated strong anti-SARS-CoV-2 activities in vitro. The half maximal inhibitory concentration (IC50) values of glycosylated ACE2 (gACE2) and deglycosylated ACE2 (dACE2) were ∼1.0 and 8.48 μg/ml, respectively, for the pre-entry infection, when incubated with 100TCID50 of SARS-CoV-2. Therefore, plant produced soluble ACE2s are promising cost-effective and safe candidates as a potential therapeutic tool in the treatment of patients with COVID-19.
Highlights
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) is a novel and highly pathogenic coronavirus, which caused an outbreak in the city of Wuhan, China in 2019, and spread nationwide and spilled over to other countries, which resulted in hundreds of thousands of deaths worldwide
The N. benthamiana leaf samples were harvested at different post-infiltration days and expression levels of glycosylated and deglycosylated variants of Angiotensin-converting enzyme 2 (ACE2) reached the maximum level at 6 dpi
Our results showed that plant produced glycosylated ACE2 (gACE2) and deglycosylated ACE2 (dACE2) variants successfully bind to receptor binding domain (RBD) of SARSCoV-2 spike protein
Summary
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) is a novel and highly pathogenic coronavirus, which caused an outbreak in the city of Wuhan, China in 2019, and spread nationwide and spilled over to other countries, which resulted in hundreds of thousands of deaths worldwide. Since the angiotensin converting enzyme 2 (ACE2), the SARS-CoV-2 (COVID-19) receptor is a critical molecule in the entry process of the virus into host tissue cells, it could be a potential therapeutic agent. Similar to SARS-CoV, SARS-CoV-2 has been shown to bind to its functional receptor ACE2 via receptor binding domain (RBD) of SARS-CoV-2 spike protein as an initial step for entry into the cell (Li et al, 2003; Tai et al, 2020). It has been demonstrated that, ACE2 serves as the entry receptor for SARS-CoV or SARSCoV-2 but can prevent lung injuries (Imai et al, 2005; Kuba et al, 2005; Wösten-van Asperen et al, 2011; Yu et al, 2016; Zhou et al, 2020). Soluble ACE2 is described as a therapeutic candidate, which could neutralize the infection by acting as a decoy (Chan et al, 2020)
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