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1.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-330892

ABSTRACT

Viruses are microscopic pathogens capable of causing disease and are responsible for a range of human mortality and morbidity worldwide. They can be rendered harmless or destroyed with a range of antiviral chemical compounds. Cucurbit[n]urils (CB[n]s) are a macrocycle chemical compound existing as a range of homologues;due to their structure they can bind to biological materials, acting as supramolecular “hosts” to “guests”, such as amino acids. Due to the increasing need for a non-toxic antiviral compound, we investigated whether cucurbit[n]urils could act in an antiviral manner. We have found that certain cucurbit[n]uril homologues do indeed have an antiviral effect against a range of viruses, including RSV and SARS-CoV-2. In particular, we demonstrate that CB[7] is the active homologue of CB[n] mixtures, having an antiviral effect against enveloped and non-enveloped species. High levels of efficacy were observed with five-minute contact times across different viruses. We also demonstrate that CB[7] acts with an extracellular virucidal mode of action via host-guest supramolecular interactions between viral surface proteins and the CB[n] cavity, rather than via cell internalisation or a virustatic mechanism. This finding demonstrates that CB[7] acts as a supramolecular virucidal antiviral (a mechanism distinct from other current extracellular antivirals) demonstrating the potential of supramolecular interactions for future antiviral disinfectants.

2.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-330185

ABSTRACT

Viruses are microscopic pathogens capable of causing disease and are responsible for a range of human mortality and morbidity worldwide. They can be rendered harmless or destroyed with a range of antiviral chemical compounds. Cucurbit[n]urils (CB[n]s) are a macrocycle chemical compound existing as a range of homologues;due to their structure they can bind to biological materials, acting as supramolecular host to guests, such as amino acids. Due to the increasing need for a non-toxic antiviral compound, we investigated whether cucurbit[n]urils could act in an antiviral manner. We have found that certain cucurbit[n]uril homologues do indeed have an antiviral effect against a range of viruses, including RSV and SARS-CoV-2. In particular, we demonstrate that CB[7] is the active homologue of CB[n] mixtures, having an antiviral effect against enveloped and non-enveloped species. High levels of efficacy were observed with five-minute contact times across different viruses. We also demonstrate that CB[7] acts with an extracellular virucidal mode of action via host-guest supramolecular interactions between viral surface proteins and the CB[n] cavity, rather than via cell internalisation or a virustatic mechanism. This finding demonstrates that CB[7] acts as a supramolecular virucidal antiviral (a mechanism distinct from other current extracellular antivirals) demonstrating the potential of supramolecular interactions for future antiviral disinfectants.

3.
Cell Host Microbe ; 30(1): 53-68.e12, 2022 01 12.
Article in English | MEDLINE | ID: covidwho-1536483

ABSTRACT

Alpha-B.1.1.7, Beta-B.1.351, Gamma-P.1, and Delta-B.1.617.2 variants of SARS-CoV-2 express multiple mutations in the spike protein (S). These may alter the antigenic structure of S, causing escape from natural or vaccine-induced immunity. Beta is particularly difficult to neutralize using serum induced by early pandemic SARS-CoV-2 strains and is most antigenically separated from Delta. To understand this, we generated 674 mAbs from Beta-infected individuals and performed a detailed structure-function analysis of the 27 most potent mAbs: one binding the spike N-terminal domain (NTD), the rest the receptor-binding domain (RBD). Two of these RBD-binding mAbs recognize a neutralizing epitope conserved between SARS-CoV-1 and -2, while 18 target mutated residues in Beta: K417N, E484K, and N501Y. There is a major response to N501Y, including a public IgVH4-39 sequence, with E484K and K417N also targeted. Recognition of these key residues underscores why serum from Beta cases poorly neutralizes early pandemic and Delta viruses.


Subject(s)
Antibodies, Viral/immunology , Antibody Formation/immunology , COVID-19/immunology , SARS-CoV-2/immunology , Animals , Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/immunology , Cells, Cultured , Chlorocebus aethiops , Female , HEK293 Cells , Humans , Male , Mice , Mice, Transgenic , Neutralization Tests/methods , Protein Binding/immunology , Spike Glycoprotein, Coronavirus/immunology , Vero Cells
4.
Nat Commun ; 12(1): 4629, 2021 07 30.
Article in English | MEDLINE | ID: covidwho-1333939

ABSTRACT

Since the outbreak of the SARS-CoV-2 pandemic, there have been intense structural studies on purified viral components and inactivated viruses. However, structural and ultrastructural evidence on how the SARS-CoV-2 infection progresses in the native cellular context is scarce, and there is a lack of comprehensive knowledge on the SARS-CoV-2 replicative cycle. To correlate cytopathic events induced by SARS-CoV-2 with virus replication processes in frozen-hydrated cells, we established a unique multi-modal, multi-scale cryo-correlative platform to image SARS-CoV-2 infection in Vero cells. This platform combines serial cryoFIB/SEM volume imaging and soft X-ray cryo-tomography with cell lamellae-based cryo-electron tomography (cryoET) and subtomogram averaging. Here we report critical SARS-CoV-2 structural events - e.g. viral RNA transport portals, virus assembly intermediates, virus egress pathway, and native virus spike structures, in the context of whole-cell volumes revealing drastic cytppathic changes. This integrated approach allows a holistic view of SARS-CoV-2 infection, from the whole cell to individual molecules.


Subject(s)
COVID-19/immunology , SARS-CoV-2/immunology , Virus Assembly/immunology , Virus Release/immunology , Virus Replication/immunology , Animals , COVID-19/epidemiology , COVID-19/virology , Chlorocebus aethiops , Cryoelectron Microscopy , Electron Microscope Tomography , Humans , Pandemics/prevention & control , SARS-CoV-2/physiology , SARS-CoV-2/ultrastructure , Vero Cells , Virus Assembly/physiology , Virus Release/physiology , Virus Replication/physiology
5.
ACS Cent Sci ; 7(4): 594-602, 2021 Apr 28.
Article in English | MEDLINE | ID: covidwho-1225486

ABSTRACT

Vaccine development against the SARS-CoV-2 virus focuses on the principal target of the neutralizing immune response, the spike (S) glycoprotein. Adenovirus-vectored vaccines offer an effective platform for the delivery of viral antigen, but it is important for the generation of neutralizing antibodies that they produce appropriately processed and assembled viral antigen that mimics that observed on the SARS-CoV-2 virus. Here, we describe the structure, conformation, and glycosylation of the S protein derived from the adenovirus-vectored ChAdOx1 nCoV-19/AZD1222 vaccine. We demonstrate native-like post-translational processing and assembly, and reveal the expression of S proteins on the surface of cells adopting the trimeric prefusion conformation. The data presented here confirm the use of ChAdOx1 adenovirus vectors as a leading platform technology for SARS-CoV-2 vaccines.

6.
Cell ; 184(8): 2183-2200.e22, 2021 04 15.
Article in English | MEDLINE | ID: covidwho-1086819

ABSTRACT

Antibodies are crucial to immune protection against SARS-CoV-2, with some in emergency use as therapeutics. Here, we identify 377 human monoclonal antibodies (mAbs) recognizing the virus spike and focus mainly on 80 that bind the receptor binding domain (RBD). We devise a competition data-driven method to map RBD binding sites. We find that although antibody binding sites are widely dispersed, neutralizing antibody binding is focused, with nearly all highly inhibitory mAbs (IC50 < 0.1 µg/mL) blocking receptor interaction, except for one that binds a unique epitope in the N-terminal domain. Many of these neutralizing mAbs use public V-genes and are close to germline. We dissect the structural basis of recognition for this large panel of antibodies through X-ray crystallography and cryoelectron microscopy of 19 Fab-antigen structures. We find novel binding modes for some potently inhibitory antibodies and demonstrate that strongly neutralizing mAbs protect, prophylactically or therapeutically, in animal models.


Subject(s)
Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/immunology , Antibodies, Viral/immunology , COVID-19/immunology , Spike Glycoprotein, Coronavirus/immunology , Animals , Binding Sites, Antibody , CHO Cells , Chlorocebus aethiops , Cricetulus , Epitopes , Female , HEK293 Cells , Humans , Male , Mice , Mice, Transgenic , Models, Molecular , Protein Binding , Protein Structure, Tertiary , SARS-CoV-2/immunology , Vero Cells
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