SPP1 and COVID-19: Rattanapisit et al. (2017) reported that the geminiviral expression system could be used to produce human osteopontin and showed the potential of recombinant osteopontin to induce periodontal ligament differentiation. Recently, the receptor-binding domain (RBD) of SARS-CoV-2 and the anti-SARS-CoV mAbs, CR3022, H4, and B38, were rapidly produced in N. benthamiana during the COVID-19 pandemic (Rattanapisit et al., 2020; Shanmugaraj et al., 2020b).