Two of them, schematically shown on the left in Figure 1 and termed pRBD (Figure 1a) and pHEL (Figure 1c), respectively, are SVLS that display either the purified receptor-binding domain (RBD) of SARS-CoV-2, the causative agent of the COVID-19 pandemic [29], or a purified mutant version of hen egg lysozyme (HEL), a well-characterized protein Ag that has been used extensively in immunological studies [30]. The gene discussed is RENBP; the disease is COVID-19.