Bispecific IgG neutralizes SARS-CoV-2 variants and prevents escape in mice

Abstract

Neutralizing antibodies that target the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein are among the most promising approaches against COVID-19 1,2 . A bispecific IgG1-like molecule (CoV-X2) has been developed on the basis of C121 and C135, two antibodies derived from donors who had recovered from COVID-19 3 . Here we show that CoV-X2 simultaneously binds two independent sites on the RBD and, unlike its parental antibodies, prevents detectable spike binding to the cellular receptor of the virus, angiotensin-converting enzyme 2 (ACE2). Furthermore, CoV-X2 neutralizes wild-type SARS-CoV-2 and its variants of concern, as well as escape mutants generated by the parental monoclonal antibodies. We also found that in a mouse model of SARS-CoV-2 infection with lung inflammation, CoV-X2 protects mice from disease and suppresses viral escape. Thus, the simultaneous targeting of non-overlapping RBD epitopes by IgG-like bispecific antibodies is feasible and effective, and combines the advantages of antibody cocktails with those of single-molecule approaches.The COVID-19 pandemic has prompted substantial efforts to develop effective countermeasures against SARS-CoV-2. Preclinical data and phase-III clinical studies indicate that monoclonal antibodies could be effectively deployed for prevention or treatment during the viral symptoms phase of the disease 1,2 . Cocktails of two or more monoclonal antibodies are preferred over a single antibody as these cocktails result in increased efficacy and the prevention of viral escape. However, this approach requires increased manufacturing costs and volumes, which are problematic at a time when the supply chain is under pressure to meet the high demand for COVID-19 therapeutic agents, vaccines and biologics in general 4 . Cocktails also complicate formulation 5,6 and hinder strategies such as antibody delivery by viral vectors or by nonvectored nucleic acids 7,8 . One alternative is to use multispecific antibodies, which have the advantages of cocktails and single-molecule strategies.To this end, we used structural information 9 and computational simulations to design bispecific antibodies that would simultaneously bind to (i) independent sites on the same RBD and (ii) distinct RBDs on a spike (S) trimer. We evaluated several designs using atomistic molecular dynamics simulations, and produced four constructs: of these, CoV-X2 was the most potent neutralizer of SARS-CoV-2 pseudovirus, and had a half-maximal inhibitory concentration (IC 50 ) of 0.04 nM (5.8 ng ml −1 ) (Extended Data Fig. 1). CoV-X2 is a human-derived IgG1-like bispecific antibody in the CrossMAb format 10 that is the result of the combination of the Fragment antigen binding (Fab) of the monoclonal antibodies C121 and C135, which are two potent neutralizers of SARS-CoV-2 3 . Structural predictions showed that CoV-X2-but not its parental monoclonal antibodies-can bind bivalently to all RBD conformations on the S trimer, which prevents the binding of ACE2 receptor 11 (Fig. 1a, Extended Data Fig. 2).CoV-X2 bou...

Naturally enhanced neutralizing breadth against SARS-CoV-2 one year after infection

“…SARS-CoV-2 infection produces a memory compartment that continues to evolve over 12 months after infection with accumulation of somatic mutations, emergence of new clones, and increasing affinity all of which is consistent with long-term persistence of germinal centers. The increase in activity against SARS-CoV-2 mutants parallels the increase in affinity and is consistent with the finding that increasing the apparent affinity of anti-SARS-CoV-2 antibodies by dimerization or by creating bi-specific antibodies also increases resistance to RBD mutations [37][38][39][40] .…”

Naturally enhanced neutralizing breadth to SARS-CoV-2 after one year

“…SARS-CoV-2 infection produces a memory compartment that continues to evolve over months after infection with accumulation of somatic mutations, emergence of new clones, and increasing affinity all of which is consistent with long-term persistence of germinal centers. The increase in activity against SARS-CoV-2 mutants parallels the increase in affinity and is consistent with the finding that increasing the apparent affinity of anti-SARS-CoV-2 antibodies by dimerization or by creating bi-specific antibodies also increases resistance to RBD mutations [37][38][39][40] .…”

Recent progress on the mutations of SARS-CoV-2 spike protein and suggestions for prevention and controlling of the pandemic

“…As reported, the S2 subunit, RBD, NTD, M protein, and E protein of SARS-CoV2 are effective target sites for developing the suitable vaccine for COVID-19 by comparing the genomes of various coronavirus strains ( Kaur et al, 2021 ). A recent report showed that bispecific IgG based on two antibodies from COVID-19 convalescent donors can effectively neutralize SARS-CoV-2 and its variants, and prevent the animal from disease and inhibit viral escape in mice models ( De Gasparo et al, 2021 ). Moreover, mosaic-RBD-nanoparticles elicited robust antibodies with superior cross-reactive recognition of heterologous RBDs than that of homotypic nanoparticles or COVID-19 convalescent human plasmas ( Cohen et al, 2021 ).…”