COVID-19(16) SARS-CoV-2(15) plant(13) coronavirus(10) Vaccine(9) Nicotiana benthamiana(9) pandemic(9) Treatment(8) acute respiratory syndrome(8) expressed(8) RBD(8) in vitro(7) antibody(7) therapeutic(7) produced(7) caused(6) molecular farming(6) platform(6) Receptor binding domain(5) coronavirus disease(5) virus(5) develop(5) expression(5) Protein(5) transient expression(5) demonstrated(5) effective(4) molecular(4) tested(4) plants(4)