SARS-CoV-1 and SARS-CoV-2 consensus sequences share about 80% identity (Tai et al., 2020). Thus, a wide range of SARS-CoV-1 nAbs have been tested for crossreactivity with SARS-CoV-2, as they could help speed up the development of potential COVID-19 treatments. In a recent study, antibodies were isolated from the memory B cells of an individual who recovered from SARS-CoV-1 infection. While 8 out of 25 isolated antibodies could bind SARS-CoV-2 S protein, one of them (s309; see Table 3 ) also neutralizes SARS-CoV-2 (Pinto et al., 2020). The combination of s309 with a weakly neutralizing antibody that could bind another RBD epitope led to enhanced neutralization potency. In addition, CR3022 (Table 3) was found to bind SARS-CoV-2 RBD (Tian et al., 2020b), but this antibody did not neutralize SARS-CoV-2 (Yuan et al., 2020). Computational simulations identified three amino acids that could be modified on CR3022 to enhance its binding affinity with SARS-CoV-2 RBD (Giron et al., 2020), potentially augmenting its neutralization potential.
Table 3 Strategies to Isolate SARS-CoV-2 Neutralizing Antibodies
Ab Source Clone Target Type of Antibody Neutralization Inhibition of ACE2/RBD Binding Reference
Derived from COVID-19 patients 31B532D4 RBD human monoclonal yes yes Chen et al., 2020a
P2C-2F6P2C-1F11 RBD human monoclonal yes yes Ju et al., 2020
Derived from SARS-CoV-1 patients CR3022 RBD human monoclonal no no Tian et al., 2020b, Yuan et al., 2020, Giron et al., 2020
S309 RBD human monoclonal yes no Pinto et al., 2020
Derived from SARS-CoV-1 or MERS-CoV-1 animal models R325R302R007 S1 rabbit monoclonal yes no Sun et al., 2020
47D11 S1 recombinant human monoclonal (derived from hybridomas of immunized transgenic H2L2 mice) yes no Wang et al., 2020a
VHH-72-Fc S Fc-fusion derived from camelids VHH yes yes Wrapp et al., 2020
S polyclonal mouse antibodies yes N/A Walls et al., 2020, Yuan et al., 2020
Other ACE2-Fc RBD ACE2-Fc fusion yes N/A Lei et al., 2020a, Li et al., 2020d
RBD-Fc ACE2 RBD-Fc fusion yes N/A Li et al., 2020d
N3130 S1 human monoclonal single domain antibody isolated by phage display yes no Wu et al., 2020c
IVIg N/A polyclonal human IVIg N/A N/A Díez et al., 2020, Shao et al., 2020
F(ab′)2 RBD horse polyclonal yes N/A Pan et al., 2020
N/A, not assessed.