ABSTRACT
Using an unbiased interrogation of the memory B cell repertoire of convalescent COVID-19 patients, we identified human antibodies that demonstrated robust antiviral activity in vitro and efficacy in vivo against all tested SARS-CoV-2 variants. Here, we describe the pre-clinical characterization of an antibody cocktail, IMM-BCP-01, that consists of three unique, patient-derived recombinant neutralizing antibodies directed at non-overlapping surfaces on the SARS-CoV-2 spike protein. Two antibodies, IMM20184 and IMM20190 directly block spike binding to the ACE2 receptor. Binding of the third antibody, IMM20253, to its unique epitope on the outer surface of RBD, alters the conformation of the spike trimer, promoting release of spike monomers. These antibodies decreased SARS-CoV-2 infection in the lungs of Syrian golden hamsters, and efficacy in vivo efficacy was associated with broad antiviral neutralizing activity against multiple SARS-CoV-2 variants and robust antiviral effector function response, including phagocytosis, ADCC, and complement pathway activation. Our pre-clinical data demonstrate that the three antibody cocktail IMM-BCP-01 shows promising potential for preventing or treating SARS-CoV-2 infection in susceptible individuals. One sentence summaryIMM-BCP-01 cocktail triggers Spike Trimer dissociation, neutralizes all tested variants in vitro, activates a robust effector response and dose-dependently inhibits virus in vivo.
ABSTRACT
SARS-CoV-2 can be disinfected using ultraviolet-C (UVC) light. For effective inactivation strategies, design and implementation, knowledge of UVC wavelength sensitivity, and disinfection rate of the relevant pathogen are required. This study aimed to determine the inactivation profile of SARS-CoV-2 using UVC irradiation with different wavelengths. Specifically, the study determined dosage, inactivation levels, and wavelength sensitivity of SARS-CoV-2. Assessment of SARS-CoV-2 (isolate USA/WA1-2020) inactivation at peak wavelengths of 259, 268, 270, 275 and 280 nm was performed using a plaque assay method. A UVC dose of 3.1 mJ/cm2 using 259 and 268 nm arrays yielded log reduction values (LRV) of 2.32 and 2.44, respectively. With a dose of 5 mJ/cm2, arrays of peak wavelengths at 259 and 268 nm obtained similar inactivation levels (LRV 2.97 and 2.80 respectively). The arrays of longer wavelength (270, 275 and 280 nm), demonstrated lower performances ([≤]LRV 2.0) when applying an irradiation dose of 5 mJ/cm2. Additional study with the 268 nm array revealed that a dose of 6.25 mJ/cm2 is enough to obtain a LRV of 3. These results suggest that 259 and 268 nm are the most efficient wavelengths for SARS-CoV-2 inactivation compared to longer UVC wavelengths, allowing the calculation of disinfection systems efficacy.
ABSTRACT
The SARS-CoV-2 viral spike (S) protein mediates attachment and entry into host cells and is a major target of vaccine and drug design. Potent SARS-CoV-2 neutralizing antibodies derived from closely related antibody heavy chain genes (IGHV3-53 or 3-66) have been isolated from multiple COVID-19 convalescent individuals. These usually contain minimal somatic mutations and bind the S receptor-binding domain (RBD) to interfere with attachment to the cellular receptor angiotensin-converting enzyme 2 (ACE2). We used antigen-specific single B cell sorting to isolate S-reactive monoclonal antibodies from the blood of a COVID-19 convalescent individual. The seven most potent neutralizing antibodies were somatic variants of the same IGHV3-53-derived antibody and bind the RBD with varying affinity. We report X-ray crystal structures of four Fab variants bound to the RBD and use the structures to explain the basis for changes in RBD affinity. We show that a germline revertant antibody binds tightly to the SARS-CoV-2 RBD and neutralizes virus, and that gains in affinity for the RBD do not necessarily correlate with increased neutralization potency, suggesting that somatic mutation is not required to exert robust antiviral effect. Our studies clarify the molecular basis for a heavily germline-biased human antibody response to SARS-CoV-2.
ABSTRACT
Effective intervention strategies are urgently needed to control the COVID-19 pandemic. Human angiotensin-converting enzyme 2 (ACE2) is a carboxypeptidase that forms a dimer and serves as the cellular receptor for SARS-CoV-2. It is also a key negative regulator of the renin-angiotensin system (RAS), conserved in mammals, which modulates vascular functions. We report here the properties of a trimeric ACE2 variant, created by a structure-based approach, with binding affinity of ~60 pM for the spike (S) protein of SARS-CoV-2, while preserving the wildtype peptidase activity as well as the ability to block activation of angiotensin II receptor type 1 in the RAS. Moreover, the engineered ACE2 potently inhibits infection of SARS-CoV-2 in cell culture. These results suggest that engineered, trimeric ACE2 may be a promising anti-SARS-CoV-2 agent for treating COVID-19.
