RESUMEN
The worldwide pandemic caused by SARS-CoV-2 has remained a human medical threat due to the continued evolution of multiple variants that acquire resistance to vaccines and prior infection. Therefore, it is imperative to discover monoclonal antibodies (mAbs) that neutralize a broad range of SARS-CoV-2 variants for therapeutic and prophylactic use. A stabilized autologous SARS-CoV-2 spike glycoprotein was used to enrich antigen-specific B cells from an individual with a primary Gamma variant infection. Five mAbs selected from those B cells showed considerable neutralizing potency against multiple variants of concern, with COVA309-35 being the most potent against the autologous virus, as well as against Omicron BA.1 and BA.2. When combining the COVA309 mAbs as cocktails or bispecific antibody formats, the breadth and potency was significantly improved against all tested variants. In addition, the mechanism of cross-neutralization of the COVA309 mAbs was elucidated by structural analysis. Altogether these data indicate that a Gamma-infected individual can develop broadly neutralizing antibodies.
RESUMEN
To prepare for future coronavirus (CoV) pandemics, it is desirable to generate vaccines capable of eliciting neutralizing antibody responses against multiple CoVs. Because of the phylogenetic similarity to humans, rhesus macaques are an animal model of choice for many virus-challenge and vaccine-evaluation studies, including SARS-CoV-2. Here, we show that immunization of macaques with SARS-CoV-2 spike (S) protein generates potent receptor binding domain cross- neutralizing antibody (nAb) responses to both SARS-CoV-2 and SARS-CoV-1, in contrast to human infection or vaccination where responses are typically SARS-CoV-2-specific. Furthermore, the macaque nAbs are equally effective against SARS-CoV-2 variants of concern. Structural studies show that different immunodominant sites are targeted by the two primate species. Human antibodies generally target epitopes strongly overlapping the ACE2 receptor binding site (RBS), whereas the macaque antibodies recognize a relatively conserved region proximal to the RBS that represents another potential pan-SARS-related virus site rarely targeted by human antibodies. B cell repertoire differences between the two primates appear to significantly influence the vaccine response and suggest care in the use of rhesus macaques in evaluation of vaccines to SARS-related viruses intended for human use. ONE SENTENCE SUMMARYBroadly neutralizing antibodies to an unappreciated site of conservation in the RBD in SARS- related viruses can be readily induced in rhesus macaques because of distinct properties of the naive macaque B cell repertoire that suggest prudence in the use of the macaque model in SARS vaccine evaluation and design.
RESUMEN
After first emerging in December 2019 in China, severe acute respiratory syndrome 2 (SARS-CoV-2) has since caused a pandemic leading to millions of infections and deaths worldwide. Vaccines have been developed and authorized but supply of these vaccines is currently limited. With new variants of the virus now emerging and spreading globally, it is essential to develop therapeutics that are broadly protective and bind conserved epitopes in the receptor binding domain (RBD) or the whole spike of SARS-CoV-2. In this study, we have generated mouse monoclonal antibodies (mAbs) against different epitopes on the RBD and assessed binding and neutralization against authentic SARS-CoV-2. We have demonstrated that antibodies with neutralizing activity, but not non-neutralizing antibodies, lower viral titers in the lungs when administered in a prophylactic setting in vivo in a mouse challenge model. In addition, most of the mAbs cross-neutralize the B.1.351 as well as the B.1.1.7 variants in vitro. ImportanceCrossneutralization of SARS-CoV-2 variants by RBD-targeting antibodies is still not well understood and very little is known about the potential protective effect of non-neutralizing antibodies in vivo. Using a panel of mouse monoclonal antibodies, we investigate both of these aspects.
RESUMEN
In vitro antibody selection against pathogens from naive combinatorial libraries can yield various classes of antigen-specific binders that are distinct from those evolved from natural infection1-4. Also, rapid neutralizing antibody discovery can be made possible by a strategy that selects for those interfering with pathogen and host interaction5. Here we report the discovery of antibodies that neutralize SARS-CoV-2, the virus responsible for the COVID-19 pandemic, from a highly diverse naive human Fab library. Lead antibody 5A6 blocks the receptor binding domain (RBD) of the viral spike from binding to the host receptor angiotensin converting enzyme 2 (ACE2), neutralizes SARS-CoV-2 infection of Vero E6 cells, and reduces viral replication in reconstituted human nasal and bronchial epithelium models. 5A6 has a high occupancy on the viral surface and exerts its neutralization activity via a bivalent binding mode to the tip of two neighbouring RBDs at the ACE2 interaction interface, one in the "up" and the other in the "down" position, explaining its superior neutralization capacity. Furthermore, 5A6 is insensitive to several spike mutations identified in clinical isolates, including the D614G mutant that has become dominant worldwide. Our results suggest that 5A6 could be an effective prophylactic and therapeutic treatment of COVID-19.
RESUMEN
The ongoing SARS-CoV-2 pandemic demands rapid identification of immunogenic targets for the design of efficient vaccines and serological detection tools. In this report, using pools of overlapping linear peptides and functional assays, we present two immunodominant regions on the spike glycoprotein that were highly recognized by neutralizing antibodies in the sera of COVID-19 convalescent patients. One is highly specific to SARS-CoV-2, and the other is a potential pan-coronavirus target.
