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1.
Front Immunol ; 12: 766821, 2021.
Article in English | MEDLINE | ID: covidwho-1581335

ABSTRACT

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants continue to emerge and spread around the world, antibodies and vaccines to confer broad and potent neutralizing activity are urgently needed. Through the isolation and characterization of monoclonal antibodies (mAbs) from individuals infected with SARS-CoV-2, we identified one antibody, P36-5D2, capable of neutralizing the major SARS-CoV-2 variants of concern. Crystal and electron cryo-microscopy (cryo-EM) structure analyses revealed that P36-5D2 targeted to a conserved epitope on the receptor-binding domain of the spike protein, withstanding the three key mutations-K417N, E484K, and N501Y-found in the variants that are responsible for escape from many potent neutralizing mAbs, including some already approved for emergency use authorization (EUA). A single intraperitoneal (IP) injection of P36-5D2 as a prophylactic treatment completely protected animals from challenge of infectious SARS-CoV-2 Alpha and Beta. Treated animals manifested normal body weight and were devoid of infection-associated death up to 14 days. A substantial decrease of the infectious virus in the lungs and brain, as well as reduced lung pathology, was found in these animals compared to the controls. Thus, P36-5D2 represents a new and desirable human antibody against the current and emerging SARS-CoV-2 variants.


Subject(s)
Antibodies, Monoclonal/pharmacology , Antibodies, Neutralizing/pharmacology , Antibodies, Viral/pharmacology , COVID-19/drug therapy , SARS-CoV-2/drug effects , Animals , Antibodies, Monoclonal/chemistry , Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/chemistry , Antibodies, Neutralizing/immunology , Antibodies, Viral/chemistry , Antibodies, Viral/immunology , HEK293 Cells , Humans , Immunization, Passive , Mice
2.
Cell Host Microbe ; 29(4): 551-563.e5, 2021 04 14.
Article in English | MEDLINE | ID: covidwho-1101147

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is characterized by a burst in the upper respiratory portal for high transmissibility. To determine human neutralizing antibodies (HuNAbs) for entry protection, we tested three potent HuNAbs (IC50 range, 0.0007-0.35 µg/mL) against live SARS-CoV-2 infection in the golden Syrian hamster model. These HuNAbs inhibit SARS-CoV-2 infection by competing with human angiotensin converting enzyme-2 for binding to the viral receptor binding domain (RBD). Prophylactic intraperitoneal or intranasal injection of individual HuNAb or DNA vaccination significantly reduces infection in the lungs but not in the nasal turbinates of hamsters intranasally challenged with SARS-CoV-2. Although postchallenge HuNAb therapy suppresses viral loads and lung damage, robust infection is observed in nasal turbinates treated within 1-3 days. Our findings demonstrate that systemic HuNAb suppresses SARS-CoV-2 replication and injury in lungs; however, robust viral infection in nasal turbinate may outcompete the antibody with significant implications to subprotection, reinfection, and vaccine.


Subject(s)
Antibodies, Neutralizing/therapeutic use , Antibodies, Viral/therapeutic use , COVID-19/therapy , SARS-CoV-2/immunology , Turbinates/virology , Angiotensin-Converting Enzyme 2/physiology , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/immunology , COVID-19/virology , Cricetinae , Female , HEK293 Cells , Humans , Male , Mesocricetus , Viral Load
3.
Natl Sci Rev ; 8(3): nwaa297, 2021 Mar.
Article in English | MEDLINE | ID: covidwho-990776

ABSTRACT

Receptor recognition and subsequent membrane fusion are essential for the establishment of successful infection by SARS-CoV-2. Halting these steps can cure COVID-19. Here we have identified and characterized a potent human monoclonal antibody, HB27, that blocks SARS-CoV-2 attachment to its cellular receptor at sub-nM concentrations. Remarkably, HB27 can also prevent SARS-CoV-2 membrane fusion. Consequently, a single dose of HB27 conferred effective protection against SARS-CoV-2 in two established mouse models. Rhesus macaques showed no obvious adverse events when administrated with 10 times the effective dose of HB27. Cryo-EM studies on complex of SARS-CoV-2 trimeric S with HB27 Fab reveal that three Fab fragments work synergistically to occlude SARS-CoV-2 from binding to the ACE2 receptor. Binding of the antibody also restrains any further conformational changes of the receptor binding domain, possibly interfering with progression from the prefusion to the postfusion stage. These results suggest that HB27 is a promising candidate for immuno-therapies against COVID-19.

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