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1.
Nat Commun ; 13(1): 1976, 2022 04 08.
Article in English | MEDLINE | ID: covidwho-1783980

ABSTRACT

Global genomic surveillance of SARS-CoV-2 has identified variants associated with increased transmissibility, neutralization resistance and disease severity. Here we report the emergence of the PANGO lineage C.1.2, detected at low prevalence in South Africa and eleven other countries. The initial C.1.2 detection is associated with a high substitution rate, and includes changes within the spike protein that have been associated with increased transmissibility or reduced neutralization sensitivity in SARS-CoV-2 variants of concern or variants of interest. Like Beta and Delta, C.1.2 shows significantly reduced neutralization sensitivity to plasma from vaccinees and individuals infected with the ancestral D614G virus. In contrast, convalescent donors infected with either Beta or Delta show high plasma neutralization against C.1.2. These functional data suggest that vaccine efficacy against C.1.2 will be equivalent to Beta and Delta, and that prior infection with either Beta or Delta will likely offer protection against C.1.2.


Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Neutralizing , Antibodies, Viral , Humans , Neutralization Tests , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/genetics
2.
Cell Host Microbe ; 30(2): 154-162.e5, 2022 02 09.
Article in English | MEDLINE | ID: covidwho-1708092

ABSTRACT

Characterizing SARS-CoV-2 evolution in specific geographies may help predict properties of the variants that come from these regions. We mapped neutralization of a SARS-CoV-2 strain that evolved over 6 months from ancestral virus in a person with advanced HIV disease in South Africa; this person was infected prior to emergence of the Beta and Delta variants. We longitudinally tracked the evolved virus and tested it against self-plasma and convalescent plasma from ancestral, Beta, and Delta infections. Early virus was similar to ancestral, but it evolved a multitude of mutations found in Omicron and other variants. It showed substantial but incomplete Pfizer BNT162b2 escape, weak neutralization by self-plasma, and despite pre-dating Delta, it also showed extensive escape of Delta infection-elicited neutralization. This example is consistent with the notion that SARS-CoV-2 evolving in individual immune-compromised hosts, including those with advanced HIV disease, may gain immune escape of vaccines and enhanced escape of Delta immunity, and this has implications for vaccine breakthrough and reinfections.


Subject(s)
Antibodies, Neutralizing/blood , HIV Infections/pathology , Immune Evasion/immunology , Immunogenicity, Vaccine/immunology , SARS-CoV-2/immunology , Adult , Animals , Antibodies, Neutralizing/immunology , Antibodies, Viral/blood , Antibodies, Viral/immunology , COVID-19/immunology , COVID-19 Vaccines/immunology , Cell Line , Chlorocebus aethiops , Female , HIV-1/immunology , Humans , Immunocompromised Host/immunology , Neutralization Tests , SARS-CoV-2/isolation & purification , South Africa , Vaccination , Vero Cells
3.
Science ; 374(6575): 1621-1626, 2021 Dec 24.
Article in English | MEDLINE | ID: covidwho-1506414

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission leads to the emergence of variants, including the B.1.617.2 (Delta) variant of concern that is causing a new wave of infections and has become globally dominant. We show that these variants dampen the in vitro potency of vaccine-elicited serum neutralizing antibodies and provide a structural framework for describing their immune evasion. Mutations in the B.1.617.1 (Kappa) and Delta spike glycoproteins abrogate recognition by several monoclonal antibodies via alteration of key antigenic sites, including remodeling of the Delta amino-terminal domain. The angiotensin-converting enzyme 2 binding affinities of the Kappa and Delta receptor binding domains are comparable to the Wuhan-Hu-1 isolate, whereas B.1.617.2+ (Delta+) exhibits markedly reduced affinity.


Subject(s)
COVID-19 Vaccines/immunology , Immune Evasion , SARS-CoV-2/immunology , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/immunology , /immunology , Angiotensin-Converting Enzyme 2/metabolism , Antibodies, Neutralizing/blood , Antibodies, Neutralizing/immunology , Antibodies, Neutralizing/metabolism , Antibodies, Viral/blood , Antibodies, Viral/immunology , Antibodies, Viral/metabolism , Antigens, Viral/chemistry , Antigens, Viral/immunology , Cryoelectron Microscopy , Humans , Models, Molecular , Mutation , Protein Binding , Protein Conformation , Protein Domains , Protein Folding , Receptors, Coronavirus/metabolism , SARS-CoV-2/chemistry , SARS-CoV-2/genetics , SARS-CoV-2/pathogenicity , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/metabolism
4.
Cell ; 184(21): 5432-5447.e16, 2021 10 14.
Article in English | MEDLINE | ID: covidwho-1454060

ABSTRACT

Understanding vaccine-elicited protection against SARS-CoV-2 variants and other sarbecoviruses is key for guiding public health policies. We show that a clinical stage multivalent SARS-CoV-2 spike receptor-binding domain nanoparticle (RBD-NP) vaccine protects mice from SARS-CoV-2 challenge after a single immunization, indicating a potential dose-sparing strategy. We benchmarked serum neutralizing activity elicited by RBD-NPs in non-human primates against a lead prefusion-stabilized SARS-CoV-2 spike (HexaPro) using a panel of circulating mutants. Polyclonal antibodies elicited by both vaccines are similarly resilient to many RBD residue substitutions tested, although mutations at and surrounding position 484 have negative consequences for neutralization. Mosaic and cocktail nanoparticle immunogens displaying multiple sarbecovirus RBDs elicit broad neutralizing activity in mice and protect mice against SARS-CoV challenge even in the absence of SARS-CoV RBD in the vaccine. This study provides proof of principle that multivalent sarbecovirus RBD-NPs induce heterotypic protection and motivates advancing such broadly protective sarbecovirus vaccines to the clinic.

5.
Science ; 373(6555): 648-654, 2021 08 06.
Article in English | MEDLINE | ID: covidwho-1295161

ABSTRACT

A novel variant of concern (VOC) named CAL.20C (B.1.427/B.1.429), which was originally detected in California, carries spike glycoprotein mutations S13I in the signal peptide, W152C in the N-terminal domain (NTD), and L452R in the receptor-binding domain (RBD). Plasma from individuals vaccinated with a Wuhan-1 isolate-based messenger RNA vaccine or from convalescent individuals exhibited neutralizing titers that were reduced 2- to 3.5-fold against the B.1.427/B.1.429 variant relative to wild-type pseudoviruses. The L452R mutation reduced neutralizing activity in 14 of 34 RBD-specific monoclonal antibodies (mAbs). The S13I and W152C mutations resulted in total loss of neutralization for 10 of 10 NTD-specific mAbs because the NTD antigenic supersite was remodeled by a shift of the signal peptide cleavage site and the formation of a new disulfide bond, as revealed by mass spectrometry and structural studies.


Subject(s)
COVID-19/virology , Immune Evasion , SARS-CoV-2/immunology , SARS-CoV-2/pathogenicity , Spike Glycoprotein, Coronavirus/genetics , Spike Glycoprotein, Coronavirus/immunology , Amino Acid Substitution , Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/blood , Antibodies, Neutralizing/immunology , Antibodies, Viral/blood , Antibodies, Viral/immunology , Antigens, Viral/immunology , COVID-19/immunology , COVID-19 Vaccines/immunology , Cryoelectron Microscopy , Humans , Models, Molecular , Mutation , Neutralization Tests , Protein Conformation , Protein Domains , Protein Interaction Domains and Motifs , Protein Subunits/chemistry , SARS-CoV-2/genetics , Spike Glycoprotein, Coronavirus/chemistry
6.
PLoS One ; 16(4): e0250019, 2021.
Article in English | MEDLINE | ID: covidwho-1197380

ABSTRACT

SARS-CoV-2 has caused a global pandemic, and has taken over 1.7 million lives as of mid-December, 2020. Although great progress has been made in the development of effective countermeasures, with several pharmaceutical companies approved or poised to deliver vaccines to market, there is still an unmet need of essential antiviral drugs with therapeutic impact for the treatment of moderate-to-severe COVID-19. Towards this goal, a high-throughput assay was used to screen SARS-CoV-2 nsp15 uracil-dependent endonuclease (endoU) function against 13 thousand compounds from drug and lead repurposing compound libraries. While over 80% of initial hit compounds were pan-assay inhibitory compounds, three hits were confirmed as nsp15 endoU inhibitors in the 1-20 µM range in vitro. Furthermore, Exebryl-1, a ß-amyloid anti-aggregation molecule for Alzheimer's therapy, was shown to have antiviral activity between 10 to 66 µM, in Vero 76, Caco-2, and Calu-3 cells. Although the inhibitory concentrations determined for Exebryl-1 exceed those recommended for therapeutic intervention, our findings show great promise for further optimization of Exebryl-1 as an nsp15 endoU inhibitor and as a SARS-CoV-2 antiviral.


Subject(s)
Antiviral Agents/pharmacology , COVID-19/drug therapy , Drug Repositioning , Endoribonucleases/antagonists & inhibitors , SARS-CoV-2/drug effects , Small Molecule Libraries/pharmacology , Viral Nonstructural Proteins/antagonists & inhibitors , Animals , Antiviral Agents/chemistry , COVID-19/virology , Caco-2 Cells , Chlorocebus aethiops , Drug Repositioning/methods , Endoribonucleases/metabolism , High-Throughput Screening Assays/methods , Humans , Molecular Docking Simulation , SARS-CoV-2/metabolism , Small Molecule Libraries/chemistry , Vero Cells , Viral Nonstructural Proteins/metabolism
7.
Sci Rep ; 11(1): 4290, 2021 02 22.
Article in English | MEDLINE | ID: covidwho-1096333

ABSTRACT

Rapid generation of diagnostics is paramount to understand epidemiology and to control the spread of emerging infectious diseases such as COVID-19. Computational methods to predict serodiagnostic epitopes that are specific for the pathogen could help accelerate the development of new diagnostics. A systematic survey of 27 SARS-CoV-2 proteins was conducted to assess whether existing B-cell epitope prediction methods, combined with comprehensive mining of sequence databases and structural data, could predict whether a particular protein would be suitable for serodiagnosis. Nine of the predictions were validated with recombinant SARS-CoV-2 proteins in the ELISA format using plasma and sera from patients with SARS-CoV-2 infection, and a further 11 predictions were compared to the recent literature. Results appeared to be in agreement with 12 of the predictions, in disagreement with 3, while a further 5 were deemed inconclusive. We showed that two of our top five candidates, the N-terminal fragment of the nucleoprotein and the receptor-binding domain of the spike protein, have the highest sensitivity and specificity and signal-to-noise ratio for detecting COVID-19 sera/plasma by ELISA. Mixing the two antigens together for coating ELISA plates led to a sensitivity of 94% (N = 80 samples from persons with RT-PCR confirmed SARS-CoV-2 infection), and a specificity of 97.2% (N = 106 control samples).


Subject(s)
COVID-19/diagnosis , COVID-19/immunology , Enzyme-Linked Immunosorbent Assay/methods , Epitopes, B-Lymphocyte/immunology , SARS-CoV-2/pathogenicity , Humans , Real-Time Polymerase Chain Reaction , SARS-CoV-2/immunology , Signal-To-Noise Ratio
8.
Biomol NMR Assign ; 15(1): 107-116, 2021 04.
Article in English | MEDLINE | ID: covidwho-1002175

ABSTRACT

The Betacoronavirus SARS-CoV-2 non-structural protein Nsp9 is a 113-residue protein that is essential for viral replication, and consequently, a potential target for the development of therapeutics against COVID19 infections. To capture insights into the dynamics of the protein's backbone in solution and accelerate the identification and mapping of ligand-binding surfaces through chemical shift perturbation studies, the backbone 1H, 13C, and 15N NMR chemical shifts for Nsp9 have been extensively assigned. These assignments were assisted by the preparation of an ~ 70% deuterated sample and residue-specific, 15N-labelled samples (V, L, M, F, and K). A major feature of the assignments was the "missing" amide resonances for N96-L106 in the 1H-15N HSQC spectrum, a region that comprises almost the complete C-terminal α-helix that forms a major part of the homodimer interface in the crystal structure of SARS-CoV-2 Nsp9, suggesting this region either undergoes intermediate motion in the ms to µs timescale and/or is heterogenous. These "missing" amide resonances do not unambiguously appear in the 1H-15N HSQC spectrum of SARS-CoV-2 Nsp9 collected at a concentration of 0.0007 mM. At this concentration, at the detection limit, native mass spectrometry indicates the protein is exclusively in the monomeric state, suggesting the intermediate motion in the C-terminal of Nsp9 may be due to intramolecular dynamics. Perhaps this intermediate ms to µs timescale dynamics is the physical basis for a previously suggested "fluidity" of the C-terminal helix that may be responsible for homophilic (Nsp9-Nsp9) and postulated heterophilic (Nsp9-Unknown) protein-protein interactions.


Subject(s)
Magnetic Resonance Spectroscopy , RNA-Binding Proteins/chemistry , SARS-CoV-2/chemistry , Viral Nonstructural Proteins/chemistry , Binding Sites , Carbon Isotopes , Codon , Crystallography, X-Ray , Dimerization , Disulfides , Hydrogen , Hydrogen-Ion Concentration , Kinetics , Ligands , Nitrogen Isotopes , Protein Binding , Protein Domains , Protein Structure, Secondary
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