Characterization of neutralizing antibodies from a SARS-CoV-2 infected individual

Abstract

22B cells specific for the SARS-CoV-2 S envelope glycoprotein spike were isolated from a 23 COVID-19-infected subject using a stabilized spike-derived ectodomain (S2P) twenty-one 24 days post-infection. Forty-four S2P-specific monoclonal antibodies were generated, three 25 of which bound to the receptor binding domain (RBD). The antibodies were minimally 26 mutated from germline and were derived from different B cell lineages. Only two 27 antibodies displayed neutralizing activity against SARS-CoV-2 pseudo-virus. The most 28 potent antibody bound the RBD in a manner that prevented binding to the ACE2 receptor, 29 while the other bound outside the RBD. Our study indicates that the majority of antibodies 30 against the viral envelope spike that were generated during the first weeks of COVID-19 31 infection are non-neutralizing and target epitopes outside the RBD. Antibodies that disrupt 32 the SARS-CoV-2 spike-ACE2 interaction can potently neutralize the virus without 33 undergoing extensive maturation. Such antibodies have potential preventive/therapeutic 34 potential and can serve as templates for vaccine-design. 35 36 37 38 39 40 41 42 43 44 45 KEY WORDS 46 COVID-19, SARS, SARS-CoV-2, antibody, B cells, spike protein, receptor binding 47 RESULTS 105 Serology 106Serum and PBMC were collected twenty-one days after the onset of clinical disease. The 107 serum contained high titers of antibodies to the SARS-CoV-2 S2P (Fig. 1A). The 108 specificity of this response was confirmed by the absence of S2P reactivity by serum 109 antibodies isolated from donors collected prior to the SARS-CoV-2 pandemic, or donors 110 with confirmed infection by endemic coronaviruses. We also measured the serum 111 antibody response to RBD, and again observed specific high titers of binding antibodies 112 ( Fig. 1B). Isotype-specific ELISA revealed that the IgG titers were higher than the IgA and 113 the IgM titers to both S2P and RBD, suggesting a significant portion of the antibody 114 responses to SARS-CoV-2 S are IgG (Fig. 1C and D). The serum from the SARS-CoV-2 115 infected donor displayed potent neutralizing activity (Reciprocal ID50~3000)against a 116 pseudovirus expressing the S protein from SARS-CoV-2 isolate Wuhan-Hu-1 ( Fig 1E). 117 We concluded that this donor had developed strong binding and neutralizing antibody 118 responses within three weeks of disease onset. 119 B cell sorts and VH/VL sequencing 120 Fluorescently labeled S2P and RBD probes were used as baits to identify B cells specific 121 to the SARS-CoV-2 S protein that were circulating at this timepoint. S2P was labeled with 122 either phycoerythrin (PE) or brilliant violet 711 (BV711) and used to stain B cells 123 concurrently. This double labeling strategy helps to discriminate between bona fide S2P-124 specific B cells and non-specific background staining to the fluorophores. RBD was 125 labeled with alexa fluor 647 to identify B cells specific for that domain. : bioRxiv preprint 7Approximately 0.65% of total CD19+ B cells were S2P positive compared to 0.07%...

Structures of human antibodies bound to SARS-CoV-2 spike reveal common epitopes and recurrent features of antibodies

“…were over-represented . Other studies have also reported anti-SARS-CoV-2 mAbs derived from these genes (Brouwer et al, 2020;Cao et al, 2020;Chi et al, 2020;Ju et al, 2020;Rogers et al, 2020;Seydoux et al, 2020;Wu et al, 2020c;Zost et al, 2020).…”

Escape from neutralizing antibodies by SARS-CoV-2 spike protein variants

“…Recent studies have shown that related, potently neutralizing monoclonal antibodies that recognize the SARS-CoV-2 receptor binding domain (RBD) are often elicited in SARS-CoV-2 infection (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17). These antibodies have great potential to be clinically impactful in the treatment and prevention of SARS-CoV-2 infection.…”

High titers of multiple antibody isotypes against the SARS-CoV-2 spike receptor-binding domain and nucleoprotein associate with better neutralization

“…A number of studies have begun to unravel the antibody response to SARS-CoV-2 beyond a simple "yes or no" answer [9][10][11][12][13][14][15][16][17][18] . Here, we hypothesized that by examining the antibody profile in patient's serum in terms of antigens, antibody isotypes (IgG, IgM, and IgA), and neutralization, we would be able to identify specific signatures associated to effective SARS-CoV-2 neutralization.…”