Development of plant-produced subunit vaccine and therapeutic protein for COVID-19

Abstract

Due to the rapid transmission of the Coronavirus Disease 2019 (COVID-19) causing serious public health problems and economic burden, the development of effective therapeutic interventions is urgently needed for controlling the ongoing pandemic disease. In this study, we have transiently produced recombinant SARS-CoV-2 RBD and human ACE2 fused with the Fc region of human IgG1 in Nicotiana benthamianain in order to use as a preventive subunit vaccine and therapeutic against SARS-CoV-2. The recombinant SARS-CoV-2 RBD-Fc subunit vaccine was formulated with different commercially available adjuvants including aluminium hydroxide gel (Alum), AddaVaxTM (MF59), monophosphoryl lipid A from Salmonella Minnesota R595 (mPLA-SM), and polyinosinic-polycytidylic acid (poly(I:C)) and intramuscularly immunized in mice to appraise the immunogenicity as well as potent anti-SARS-CoV-2 activity of recombinant ACE2-Fc protein was assessed in vitro using Vero E6 cells. Importantly, the plant-produced recombinant SARS-CoV-2 RBD-Fc could exhibit effective immunogenicity profiles in terms of and specific potent antibodies vaccine-specific T-lymphocyte responses in mice. Additionally, plant-produced ACE2-Fc proteins could efficiently inhibit SARS-CoV-2 infection in vitro. Altogether, our results demonstrated that the plant-produced recombinant SARS-CoV-2 RBD-Fc and ACE2-Fc proteins have the potential to be used as an alternative subunit vaccine and therapeutic for COVID-19, which are possibly presented in the clinical trials for human uses in the near future.