Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 212
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
PLoS Pathog ; 17(1): e1009314, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33513212

RESUMO

Type 1 pili have long been considered the major virulence factor enabling colonization of the urinary bladder by uropathogenic Escherichia coli (UPEC). The molecular pathogenesis of pyelonephritis is less well characterized, due to previous limitations in preclinical modeling of kidney infection. Here, we demonstrate in a recently developed mouse model that beyond bladder infection, type 1 pili also are critical for establishment of ascending pyelonephritis. Bacterial mutants lacking the type 1 pilus adhesin (FimH) were unable to establish kidney infection in male C3H/HeN mice. We developed an in vitro model of FimH-dependent UPEC binding to renal collecting duct cells, and performed a CRISPR screen in these cells, identifying desmoglein-2 as a primary renal epithelial receptor for FimH. The mannosylated extracellular domain of human DSG2 bound directly to the lectin domain of FimH in vitro, and introduction of a mutation in the FimH mannose-binding pocket abolished binding to DSG2. In infected C3H/HeN mice, type 1-piliated UPEC and Dsg2 were co-localized within collecting ducts, and administration of mannoside FIM1033, a potent small-molecule inhibitor of FimH, significantly attenuated bacterial loads in pyelonephritis. Our results broaden the biological importance of FimH, specify the first renal FimH receptor, and indicate that FimH-targeted therapeutics will also have application in pyelonephritis.

2.
Proc Natl Acad Sci U S A ; 118(1)2021 Jan 05.
Artigo em Inglês | MEDLINE | ID: mdl-33372156

RESUMO

Macrophages activated with interferon-γ (IFN-γ) in combination with other proinflammatory stimuli, such as lipopolysaccharide or tumor necrosis factor-α (TNF-α), respond with transcriptional and cellular changes that enhance clearance of intracellular pathogens at the risk of damaging tissues. IFN-γ effects must therefore be carefully balanced with inhibitory mechanisms to prevent immunopathology. We performed a genome-wide CRISPR knockout screen in a macrophage cell line to identify negative regulators of IFN-γ responses. We discovered an unexpected role of the ubiquitin-fold modifier (Ufm1) conjugation system (herein UFMylation) in inhibiting responses to IFN-γ and lipopolysaccharide. Enhanced IFN-γ activation in UFMylation-deficient cells resulted in increased transcriptional responses to IFN-γ in a manner dependent on endoplasmic reticulum stress responses involving Ern1 and Xbp1. Furthermore, UFMylation in myeloid cells is required for resistance to influenza infection in mice, indicating that this pathway modulates in vivo responses to infection. These findings provide a genetic roadmap for the regulation of responses to a key mediator of cellular immunity and identify a molecular link between the UFMylation pathway and immune responses.

3.
Cell Metab ; 2020 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-33278339

RESUMO

Recent studies suggest that mitochondria can be transferred between cells to support the survival of metabolically compromised cells. However, whether intercellular mitochondria transfer occurs in white adipose tissue (WAT) or regulates metabolic homeostasis in vivo remains unknown. We found that macrophages acquire mitochondria from neighboring adipocytes in vivo and that this process defines a transcriptionally distinct macrophage subpopulation. A genome-wide CRISPR-Cas9 knockout screen revealed that mitochondria uptake depends on heparan sulfates (HS). High-fat diet (HFD)-induced obese mice exhibit lower HS levels on WAT macrophages and decreased intercellular mitochondria transfer from adipocytes to macrophages. Deletion of the HS biosynthetic gene Ext1 in myeloid cells decreases mitochondria uptake by WAT macrophages, increases WAT mass, lowers energy expenditure, and exacerbates HFD-induced obesity in vivo. Collectively, this study suggests that adipocytes and macrophages employ intercellular mitochondria transfer as a mechanism of immunometabolic crosstalk that regulates metabolic homeostasis and is impaired in obesity.

4.
Cell Rep ; 33(6): 108371, 2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-33176151

RESUMO

Transcription factor EB (TFEB) activates lysosomal biogenesis genes in response to environmental cues. Given implications of impaired TFEB signaling and lysosomal dysfunction in metabolic, neurological, and infectious diseases, we aim to systematically identify TFEB-directed circuits by examining transcriptional responses to TFEB subcellular localization and stimulation. We reveal that steady-state nuclear TFEB is sufficient to activate transcription of lysosomal, autophagy, and innate immunity genes, whereas other targets require higher thresholds of stimulation. Furthermore, we identify shared and distinct transcriptional signatures between mTOR inhibition and bacterial autophagy. Using a genome-wide CRISPR library, we find TFEB targets that protect cells from or sensitize cells to lysosomal cell death. BHLHE40 and BHLHE41, genes responsive to high, sustained levels of nuclear TFEB, act in opposition to TFEB upon lysosomal cell death induction. Further investigation identifies genes counter-regulated by TFEB and BHLHE40/41, adding this negative feedback to the current understanding of TFEB regulatory mechanisms.

5.
J Virol ; 2020 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-33087464

RESUMO

Engagement of cell-surface receptors by viruses is a critical determinant of viral tropism and disease. The reovirus attachment protein, σ1, binds sialylated glycans and proteinaceous receptors to mediate infection, but the specific requirements on different cell types are not entirely known. To identify host factors required for reovirus-induced cell death, we conducted a CRISPR-knockout screen targeting over 20,000 genes in murine microglial BV2 cells. Candidate genes required for reovirus to cause cell death were highly enriched for sialic acid synthesis and transport. Two of the top candidates identified, cytidine monophosphate N-acetylneuraminic acid synthetase (Cmas) and solute carrier family 35 member A1 (Slc35a1), promote sialic acid expression on the cell surface. Two reovirus strains that differ in the capacity to bind sialic acid, T3SA+ and T3SA-, were used to evaluate Cmas and Slc35a1 as potential host genes required for reovirus infection. Following CRISPR-Cas9 disruption of either gene, cell-surface expression of sialic acid was diminished. These results correlated with decreased binding of strain T3SA+, which is capable of engaging sialic acid. Disruption of either gene did not alter the low-level binding of T3SA-, which does not engage sialic acid. Furthermore, infectivity of T3SA+ was diminished to levels of T3SA- in cells lacking Cmas and Slc35a1 by CRISPR ablation. However, exogenous expression of Cmas and Slc35a1 into the respective null cells restored sialic acid expression and T3SA+ binding and infectivity. These results demonstrate that Cmas and Slc35a1, which mediate cell-surface expression of sialic acid, are required in murine microglial cells for efficient reovirus binding and infection.IMPORTANCE Attachment factors and receptors are important determinants of dissemination and tropism during reovirus-induced disease. In a CRISPR cell-survival screen, we discovered two genes, Cmas and Slc35a1, which encode proteins required for sialic acid expression on the cell surface, that mediate reovirus infection of microglial cells. This work elucidates host genes that render microglial cells susceptible to reovirus infection and expands current understanding of the receptors on microglial cells that are engaged by reovirus. Such knowledge may lead to new strategies to selectively target microglial cells for oncolytic applications.

6.
Nature ; 2020 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-33032297

RESUMO

Antibodies against viral pathogens represent promising therapeutic agents for the control of infection, and their antiviral efficacy has been shown to require the coordinated function of both the Fab and Fc domains1. The Fc domain engages a wide spectrum of receptors on discrete cells of the immune system to trigger the clearance of viruses and subsequent killing of infected cells1-4. Here we report that Fc engineering of anti-influenza IgG monoclonal antibodies for selective binding to the activating Fcγ receptor FcγRIIa results in enhanced ability to prevent or treat lethal viral respiratory infection in mice, with increased maturation of dendritic cells and the induction of protective CD8+ T cell responses. These findings highlight the capacity for IgG antibodies to induce protective adaptive immunity to viral infection when they selectively activate a dendritic cell and T cell pathway, with important implications for the development of therapeutic antibodies with improved antiviral efficacy against viral respiratory pathogens.

7.
mBio ; 11(5)2020 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-33024031

RESUMO

The intracellular protozoan parasite Toxoplasma gondii is capable of infecting most nucleated cells, where it survives in a specially modified compartment called the parasitophorous vacuole (PV). Interferon gamma (IFN-γ) is the major cytokine involved in activating cell-autonomous immune responses to inhibit parasite growth within this intracellular niche. In HeLa cells, IFN-γ treatment leads to ubiquitination of susceptible parasite strains, recruitment of the adaptors p62 and NDP52, and engulfment in microtubule-associated protein 1 light chain 3 (LC3)-positive membranes that restrict parasite growth. IFN-γ-mediated growth restriction depends on core members of the autophagy (ATG) pathway but not the initiation or degradative steps in the process. To explore the connection between these different pathways, we used permissive biotin ligation to identify proteins that interact with ATG5 in an IFN-γ-dependent fashion. Network analysis of the ATG5 interactome identified interferon-stimulated gene 15 (ISG15), which is highly upregulated by IFN treatment, as a hub connecting the ATG complex with other IFN-γ-induced genes, suggesting that it forms a functional link between the pathways. Deletion of ISG15 resulted in impaired recruitment of p62, NDP52, and LC3 to the PV and loss of IFN-γ-restricted parasite growth. The function of ISG15 required conjugation, and a number of ISGylated targets overlapped with the IFN-γ-dependent ATG5 interactome, including the adapter p62. Collectively, our findings establish a role for ISG15 in connecting the ATG pathway with IFN-γ-dependent restriction of T. gondii in human cells.IMPORTANCE Interferon(s) provide the primary defense against intracellular pathogens, a property ascribed to their ability to upregulate interferon-stimulated genes. Due to the sequestered niche occupied by Toxoplasma gondii, the host has elaborated intricate ways to target the parasite within its vacuole. One such mechanism is the recognition by a noncanonical autophagy pathway that envelops the parasite-containing vacuole and stunts growth in human cells. Remarkably, autophagy-dependent growth restriction requires interferon-γ, yet none of the classical components of autophagy are induced by interferon. Our studies draw a connection between these pathways by demonstrating that the antiviral protein ISG15, which is normally upregulated by interferons, links the autophagy-mediated control to ubiquitination of the vacuole. These findings suggest a similar link between interferon-γ signaling and autophagy that may underlie defense against other intracellular pathogens.

8.
Science ; 370(6519): 950-957, 2020 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-32972994

RESUMO

Efficient therapeutic options are needed to control the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that has caused more than 922,000 fatalities as of 13 September 2020. We report the isolation and characterization of two ultrapotent SARS-CoV-2 human neutralizing antibodies (S2E12 and S2M11) that protect hamsters against SARS-CoV-2 challenge. Cryo-electron microscopy structures show that S2E12 and S2M11 competitively block angiotensin-converting enzyme 2 (ACE2) attachment and that S2M11 also locks the spike in a closed conformation by recognition of a quaternary epitope spanning two adjacent receptor-binding domains. Antibody cocktails that include S2M11, S2E12, or the previously identified S309 antibody broadly neutralize a panel of circulating SARS-CoV-2 isolates and activate effector functions. Our results pave the way to implement antibody cocktails for prophylaxis or therapy, circumventing or limiting the emergence of viral escape mutants.


Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Betacoronavirus/imunologia , Infecções por Coronavirus/prevenção & controle , Pandemias/prevenção & controle , Peptidil Dipeptidase A/imunologia , Pneumonia Viral/prevenção & controle , Glicoproteína da Espícula de Coronavírus/antagonistas & inibidores , Motivos de Aminoácidos/imunologia , Animais , Anticorpos Neutralizantes/administração & dosagem , Anticorpos Neutralizantes/isolamento & purificação , Anticorpos Antivirais/administração & dosagem , Anticorpos Antivirais/isolamento & purificação , Células CHO , Infecções por Coronavirus/terapia , Cricetinae , Cricetulus , Microscopia Crioeletrônica , Células HEK293 , Humanos , Epitopos Imunodominantes/química , Epitopos Imunodominantes/imunologia , Microscopia Eletrônica , Pneumonia Viral/terapia , Domínios Proteicos/imunologia , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/imunologia
9.
Cell ; 183(4): 1024-1042.e21, 2020 11 12.
Artigo em Inglês | MEDLINE | ID: mdl-32991844

RESUMO

Analysis of the specificity and kinetics of neutralizing antibodies (nAbs) elicited by SARS-CoV-2 infection is crucial for understanding immune protection and identifying targets for vaccine design. In a cohort of 647 SARS-CoV-2-infected subjects, we found that both the magnitude of Ab responses to SARS-CoV-2 spike (S) and nucleoprotein and nAb titers correlate with clinical scores. The receptor-binding domain (RBD) is immunodominant and the target of 90% of the neutralizing activity present in SARS-CoV-2 immune sera. Whereas overall RBD-specific serum IgG titers waned with a half-life of 49 days, nAb titers and avidity increased over time for some individuals, consistent with affinity maturation. We structurally defined an RBD antigenic map and serologically quantified serum Abs specific for distinct RBD epitopes leading to the identification of two major receptor-binding motif antigenic sites. Our results explain the immunodominance of the receptor-binding motif and will guide the design of COVID-19 vaccines and therapeutics.


Assuntos
Anticorpos Neutralizantes/imunologia , Mapeamento de Epitopos/métodos , Glicoproteína da Espícula de Coronavírus/imunologia , Anticorpos Monoclonais/química , Anticorpos Monoclonais/genética , Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/sangue , Anticorpos Neutralizantes/química , Anticorpos Antivirais/sangue , Anticorpos Antivirais/química , Anticorpos Antivirais/imunologia , Reações Antígeno-Anticorpo , Betacoronavirus/imunologia , Betacoronavirus/isolamento & purificação , Betacoronavirus/metabolismo , Sítios de Ligação , Infecções por Coronavirus/patologia , Infecções por Coronavirus/virologia , Epitopos/química , Epitopos/imunologia , Humanos , Imunoglobulina A/sangue , Imunoglobulina A/imunologia , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Imunoglobulina M/sangue , Imunoglobulina M/imunologia , Cinética , Simulação de Dinâmica Molecular , Pandemias , Peptidil Dipeptidase A/química , Peptidil Dipeptidase A/metabolismo , Pneumonia Viral/patologia , Pneumonia Viral/virologia , Ligação Proteica , Domínios Proteicos/imunologia , Estrutura Quaternária de Proteína , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/genética , Glicoproteína da Espícula de Coronavírus/metabolismo
10.
Cell Host Microbe ; 28(3): 475-485.e5, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32735849

RESUMO

Antibody-based interventions against SARS-CoV-2 could limit morbidity, mortality, and possibly transmission. An anticipated correlate of such countermeasures is the level of neutralizing antibodies against the SARS-CoV-2 spike protein, which engages with host ACE2 receptor for entry. Using an infectious molecular clone of vesicular stomatitis virus (VSV) expressing eGFP as a marker of infection, we replaced the glycoprotein gene (G) with the spike protein of SARS-CoV-2 (VSV-eGFP-SARS-CoV-2) and developed a high-throughput-imaging-based neutralization assay at biosafety level 2. We also developed a focus-reduction neutralization test with a clinical isolate of SARS-CoV-2 at biosafety level 3. Comparing the neutralizing activities of various antibodies and ACE2-Fc soluble decoy protein in both assays revealed a high degree of concordance. These assays will help define correlates of protection for antibody-based countermeasures and vaccines against SARS-CoV-2. Additionally, replication-competent VSV-eGFP-SARS-CoV-2 provides a tool for testing inhibitors of SARS-CoV-2 mediated entry under reduced biosafety containment.


Assuntos
Anticorpos Neutralizantes/sangue , Anticorpos Antivirais/sangue , Betacoronavirus/imunologia , Infecções por Coronavirus/terapia , Peptidil Dipeptidase A/imunologia , Pneumonia Viral/terapia , Animais , Betacoronavirus/genética , Betacoronavirus/fisiologia , Chlorocebus aethiops , Infecções por Coronavirus/genética , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/virologia , Proteínas de Fluorescência Verde/genética , Interações entre Hospedeiro e Microrganismos/imunologia , Humanos , Imunização Passiva , Testes de Neutralização , Pandemias , Pneumonia Viral/imunologia , Pneumonia Viral/virologia , Glicoproteína da Espícula de Coronavírus/genética , Glicoproteína da Espícula de Coronavírus/imunologia , Células Vero , Vírus da Estomatite Vesicular Indiana/genética , Vírus da Estomatite Vesicular Indiana/imunologia , Internalização do Vírus , Replicação Viral
11.
Genes (Basel) ; 11(8)2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32824125

RESUMO

Drug development (target identification, advancing drug leads to candidates for preclinical and clinical studies) can be facilitated by genetic and genomic knowledge. Here, we review the contribution of population genomics to target identification, the value of bulk and single cell gene expression analysis for understanding the biological relevance of a drug target, and genome-wide CRISPR editing for the prioritization of drug targets. In genomics, we discuss the different scope of genome-wide association studies using genotyping arrays, versus exome and whole genome sequencing. In transcriptomics, we discuss the information from drug perturbation and the selection of biomarkers. For CRISPR screens, we discuss target discovery, mechanism of action and the concept of gene to drug mapping. Harnessing genetic support increases the probability of drug developability and approval.

12.
SSRN ; : 3606354, 2020 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-32714117

RESUMO

Antibody-based interventions against SARS-CoV-2 could limit morbidity, mortality, and possibly disrupt epidemic transmission. An anticipated correlate of such countermeasures is the level of neutralizing antibodies against the SARS-CoV-2 spike protein, yet there is no consensus as to which assay should be used for such measurements. Using an infectious molecular clone of vesicular stomatitis virus (VSV) that expresses eGFP as a marker of infection, we replaced the glycoprotein gene (G) with the spike protein of SARS-CoV-2 (VSV-eGFP-SARS-CoV-2) and developed a high-throughput imaging-based neutralization assay at biosafety level 2. We also developed a focus reduction neutralization test with a clinical isolate of SARS-CoV-2 at biosafety level 3. We compared the neutralizing activities of monoclonal and polyclonal antibody preparations, as well as ACE2-Fc soluble decoy protein in both assays and find an exceptionally high degree of concordance. The two assays will help define correlates of protection for antibody-based countermeasures including therapeutic antibodies, immune γ-globulin or plasma preparations, and vaccines against SARS-CoV-2. Replication-competent VSV-eGFP-SARS-CoV-2 provides a rapid assay for testing inhibitors of SARS-CoV-2 mediated entry that can be performed in 7.5 hours under reduced biosafety containment. Funding: This study was supported by NIH contracts and grants (75N93019C00062, HHSN272201700060C and R01 AI127828, R37 AI059371 and U01 AI151810) and the Defense Advanced Research Project Agency (HR001117S0019) and gifts from Washington University in Saint Louis. J.B.C. is supported by a Helen Hay Whitney Foundation postdoctoral fellowship. Conflict of Interest: M.S.D. is a consultant for Inbios, Vir Biotechnology, NGM Biopharmaceuticals, and on the Scientific Advisory Board of Moderna. D.C. and H.W.V. are employees of Vir Biotechnology Inc. and may hold shares in Vir Biotechnology Inc. S.P.J.W. and P.W.R. have filed a disclosure with Washington University for the recombinant VSV. Ethical Approval: This study was approved by the Mayo Clinic Institutional Review Board.

13.
Nature ; 584(7821): 353-363, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32659783

RESUMO

Antibody-dependent enhancement (ADE) of disease is a general concern for the development of vaccines and antibody therapies because the mechanisms that underlie antibody protection against any virus have a theoretical potential to amplify the infection or trigger harmful immunopathology. This possibility requires careful consideration at this critical point in the pandemic of coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Here we review observations relevant to the risks of ADE of disease, and their potential implications for SARS-CoV-2 infection. At present, there are no known clinical findings, immunological assays or biomarkers that can differentiate any severe viral infection from immune-enhanced disease, whether by measuring antibodies, T cells or intrinsic host responses. In vitro systems and animal models do not predict the risk of ADE of disease, in part because protective and potentially detrimental antibody-mediated mechanisms are the same and designing animal models depends on understanding how antiviral host responses may become harmful in humans. The implications of our lack of knowledge are twofold. First, comprehensive studies are urgently needed to define clinical correlates of protective immunity against SARS-CoV-2. Second, because ADE of disease cannot be reliably predicted after either vaccination or treatment with antibodies-regardless of what virus is the causative agent-it will be essential to depend on careful analysis of safety in humans as immune interventions for COVID-19 move forward.


Assuntos
Anticorpos Antivirais/efeitos adversos , Anticorpos Antivirais/imunologia , Anticorpos Facilitadores/imunologia , Betacoronavirus/imunologia , Betacoronavirus/patogenicidade , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/virologia , Pneumonia Viral/imunologia , Pneumonia Viral/virologia , Animais , Anticorpos Neutralizantes/efeitos adversos , Anticorpos Neutralizantes/imunologia , Anticorpos Neutralizantes/uso terapêutico , Anticorpos Antivirais/uso terapêutico , Infecções por Coronavirus/prevenção & controle , Vírus da Dengue/imunologia , Modelos Animais de Doenças , Células HEK293 , Humanos , Fragmentos Fab das Imunoglobulinas/imunologia , Fragmentos Fc das Imunoglobulinas/imunologia , Imunoglobulina G/imunologia , Macaca mulatta , Camundongos , Coronavírus da Síndrome Respiratória do Oriente Médio/imunologia , Orthomyxoviridae/imunologia , Pandemias , Ratos , Vírus da SARS/imunologia , Vacinas Virais/efeitos adversos , Vacinas Virais/imunologia
14.
Science ; 369(6502): 378, 2020 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-32703867
15.
bioRxiv ; 2020 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-32511354

RESUMO

SARS-CoV-2 is a newly emerged coronavirus responsible for the current COVID-19 pandemic that has resulted in more than one million infections and 73,000 deaths 1,2 . Vaccine and therapeutic discovery efforts are paramount to curb the pandemic spread of this zoonotic virus. The SARS-CoV-2 spike (S) glycoprotein promotes entry into host cells and is the main target of neutralizing antibodies. Here we describe multiple monoclonal antibodies targeting SARS-CoV-2 S identified from memory B cells of a SARS survivor infected in 2003. One antibody, named S309, potently neutralizes SARS-CoV-2 and SARS-CoV pseudoviruses as well as authentic SARS-CoV-2 by engaging the S receptor-binding domain. Using cryo-electron microscopy and binding assays, we show that S309 recognizes a glycan-containing epitope that is conserved within the sarbecovirus subgenus, without competing with receptor attachment. Antibody cocktails including S309 along with other antibodies identified here further enhanced SARS-CoV-2 neutralization and may limit the emergence of neutralization-escape mutants. These results pave the way for using S309 and S309-containing antibody cocktails for prophylaxis in individuals at high risk of exposure or as a post-exposure therapy to limit or treat severe disease.

16.
bioRxiv ; 2020 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-32511401

RESUMO

Antibody-based interventions against SARS-CoV-2 could limit morbidity, mortality, and possibly disrupt epidemic transmission. An anticipated correlate of such countermeasures is the level of neutralizing antibodies against the SARS-CoV-2 spike protein, yet there is no consensus as to which assay should be used for such measurements. Using an infectious molecular clone of vesicular stomatitis virus (VSV) that expresses eGFP as a marker of infection, we replaced the glycoprotein gene (G) with the spike protein of SARS-CoV-2 (VSV-eGFP-SARS-CoV-2) and developed a high-throughput imaging-based neutralization assay at biosafety level 2. We also developed a focus reduction neutralization test with a clinical isolate of SARS-CoV-2 at biosafety level 3. We compared the neutralizing activities of monoclonal and polyclonal antibody preparations, as well as ACE2-Fc soluble decoy protein in both assays and find an exceptionally high degree of concordance. The two assays will help define correlates of protection for antibody-based countermeasures including therapeutic antibodies, immune γ-globulin or plasma preparations, and vaccines against SARS-CoV-2. Replication-competent VSV-eGFP-SARS-CoV-2 provides a rapid assay for testing inhibitors of SARS-CoV-2 mediated entry that can be performed in 7.5 hours under reduced biosafety containment.

17.
Nature ; 583(7815): 290-295, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32422645

RESUMO

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a newly emerged coronavirus that is responsible for the current pandemic of coronavirus disease 2019 (COVID-19), which has resulted in more than 3.7 million infections and 260,000 deaths as of 6 May 20201,2. Vaccine and therapeutic discovery efforts are paramount to curb the pandemic spread of this zoonotic virus. The SARS-CoV-2 spike (S) glycoprotein promotes entry into host cells and is the main target of neutralizing antibodies. Here we describe several monoclonal antibodies that target the S glycoprotein of SARS-CoV-2, which we identified from memory B cells of an individual who was infected with severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003. One antibody (named S309) potently neutralizes SARS-CoV-2 and SARS-CoV pseudoviruses as well as authentic SARS-CoV-2, by engaging the receptor-binding domain of the S glycoprotein. Using cryo-electron microscopy and binding assays, we show that S309 recognizes an epitope containing a glycan that is conserved within the Sarbecovirus subgenus, without competing with receptor attachment. Antibody cocktails that include S309 in combination with other antibodies that we identified further enhanced SARS-CoV-2 neutralization, and may limit the emergence of neutralization-escape mutants. These results pave the way for using S309 and antibody cocktails containing S309 for prophylaxis in individuals at a high risk of exposure or as a post-exposure therapy to limit or treat severe disease.


Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/imunologia , Betacoronavirus/imunologia , Reações Cruzadas/imunologia , Vírus da SARS/imunologia , Síndrome Respiratória Aguda Grave/imunologia , Glicoproteína da Espícula de Coronavírus/imunologia , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/farmacologia , Anticorpos Neutralizantes/química , Anticorpos Neutralizantes/farmacologia , Anticorpos Antivirais/química , Anticorpos Antivirais/imunologia , Anticorpos Antivirais/farmacologia , Citotoxicidade Celular Dependente de Anticorpos/efeitos dos fármacos , Citotoxicidade Celular Dependente de Anticorpos/imunologia , Linfócitos B/imunologia , Betacoronavirus/química , Betacoronavirus/efeitos dos fármacos , Chlorocebus aethiops , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/prevenção & controle , Infecções por Coronavirus/terapia , Infecções por Coronavirus/virologia , Reações Cruzadas/efeitos dos fármacos , Microscopia Crioeletrônica , Epitopos de Linfócito B/química , Epitopos de Linfócito B/imunologia , Células HEK293 , Humanos , Evasão da Resposta Imune/imunologia , Fragmentos Fab das Imunoglobulinas/química , Fragmentos Fab das Imunoglobulinas/imunologia , Fragmentos Fab das Imunoglobulinas/farmacologia , Memória Imunológica/imunologia , Células Matadoras Naturais/efeitos dos fármacos , Células Matadoras Naturais/imunologia , Modelos Moleculares , Testes de Neutralização , Pandemias/prevenção & controle , Peptidil Dipeptidase A/química , Peptidil Dipeptidase A/metabolismo , Pneumonia Viral/imunologia , Pneumonia Viral/prevenção & controle , Pneumonia Viral/terapia , Pneumonia Viral/virologia , Vírus da SARS/química , Vírus da SARS/efeitos dos fármacos , Síndrome Respiratória Aguda Grave/virologia , Glicoproteína da Espícula de Coronavírus/química , Células Vero
18.
Proc Natl Acad Sci U S A ; 117(4): 1994-2003, 2020 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-31919280

RESUMO

The nucleotide-binding oligomerization domain-containing protein 2 (NOD2) agonist muramyl dipeptide (MDP), a peptidoglycan motif common to all bacteria, supports leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5)+ intestinal stem cell (ISC) survival through NOD2 activation upon an otherwise lethal oxidative stress-mediated signal. However, the underlying protective mechanisms remain unknown. Here, using irradiation as stressor and primarily murine-derived intestinal organoids as a model system, we show that MDP induced a significant reduction of total and mitochondrial reactive oxygen species (ROS) within ISCs, which was associated with mitophagy induction. ATG16L1 knockout (KO) and NOD2 KO organoids did not benefit from the MDP-induced cytoprotection. We confirmed the MDP-dependent induction of ISC mitophagy upon stress in vivo. These findings elucidate the NOD2-mediated mechanism of cytoprotection involving the clearance of the lethal excess of ROS molecules through mitophagy, triggered by the coordinated activation of NOD2 and ATG16L1 by a nuclear factor κB (NF-κB)-independent pathway.


Assuntos
Acetilmuramil-Alanil-Isoglutamina/farmacologia , Citoproteção , Intestinos/crescimento & desenvolvimento , Mitofagia/efeitos dos fármacos , Proteína Adaptadora de Sinalização NOD2/metabolismo , Espécies Reativas de Oxigênio , Células-Tronco/citologia , Animais , Células Cultivadas , Imunidade Inata/efeitos dos fármacos , Imunidade Inata/imunologia , Imunidade Inata/efeitos da radiação , Intestinos/efeitos dos fármacos , Intestinos/efeitos da radiação , Camundongos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Mitocôndrias/patologia , Mitofagia/efeitos da radiação , Proteína Adaptadora de Sinalização NOD2/genética , Estresse Oxidativo/efeitos dos fármacos , Receptores Acoplados a Proteínas-G/genética , Receptores Acoplados a Proteínas-G/metabolismo , Transdução de Sinais , Células-Tronco/efeitos dos fármacos , Células-Tronco/metabolismo , Células-Tronco/efeitos da radiação
19.
Nat Microbiol ; 5(2): 272-281, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31959973

RESUMO

Innate and adaptive immune responses that prime myeloid cells, such as macrophages, protect against pathogens1,2. However, if left uncontrolled, these responses may lead to detrimental inflammation3. Macrophages, particularly those resident in tissues, must therefore remain quiescent between infections despite chronic stimulation by commensal microorganisms. The genes required for quiescence of tissue-resident macrophages are not well understood. Autophagy, an evolutionarily conserved cellular process by which cytoplasmic contents are targeted for lysosomal digestion, has homeostatic functions including maintenance of protein and organelle integrity and regulation of metabolism4. Recent research has shown that degradative autophagy, as well as various combinations of autophagy genes, regulate immunity and inflammation5-12. Here, we delineate a function of the autophagy proteins Beclin 1 and FIP200-but not of other essential autophagy components ATG5, ATG16L1 or ATG7-in mediating quiescence of tissue-resident macrophages by limiting the effects of systemic interferon-γ. The perturbation of quiescence in mice that lack Beclin 1 or FIP200 in myeloid cells results in spontaneous immune activation and resistance to Listeria monocytogenes infection. While antibiotic-treated wild-type mice display diminished macrophage responses to inflammatory stimuli, this is not observed in mice that lack Beclin 1 in myeloid cells, establishing the dominance of this gene over effects of the bacterial microbiota. Thus, select autophagy genes, but not all genes essential for degradative autophagy, have a key function in maintaining immune quiescence of tissue-resident macrophages, resulting in genetically programmed susceptibility to bacterial infection.


Assuntos
Autofagia/genética , Listeria monocytogenes/patogenicidade , Macrófagos Peritoneais/imunologia , Animais , Autofagia/imunologia , Proteínas Relacionadas à Autofagia/deficiência , Proteínas Relacionadas à Autofagia/genética , Proteínas Relacionadas à Autofagia/imunologia , Proteína Beclina-1/deficiência , Proteína Beclina-1/genética , Proteína Beclina-1/imunologia , Proliferação de Células , Suscetibilidade a Doenças/imunologia , Feminino , Predisposição Genética para Doença , Interferon gama/imunologia , Listeria monocytogenes/imunologia , Listeriose/etiologia , Ativação de Macrófagos/genética , Ativação de Macrófagos/imunologia , Macrófagos Peritoneais/microbiologia , Macrófagos Peritoneais/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout
20.
J Virol ; 93(19)2019 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-31341042

RESUMO

Caliciviruses are single-stranded RNA viruses with 180 copies of capsid protein comprising the T=3 icosahedral capsids. The main capsid feature is a pronounced protruding (P) domain dimer formed by adjacent subunits on the icosahedral surface while the shell domain forms a tight icosahedral sphere around the genome. While the P domain in the crystal structure of human Norwalk virus (genotype I.1) was tightly associated with the shell surface, the cryo-electron microscopy (cryo-EM) structures of several members of the Caliciviridae family (mouse norovirus [MNV], rabbit hemorrhagic disease virus, and human norovirus genotype II.10) revealed a "floating" P domain that hovers above the shell by nearly 10 to 15 Å in physiological buffers. Since this unusual feature is shared among, and unique to, the Caliciviridae, it suggests an important biological role. Recently, we demonstrated that bile salts enhance cell attachment to the target cell and increase the intrinsic affinity between the P domain and receptor. Presented here are the cryo-EM structures of MNV-1 in the presence of bile salts (∼3 Å) and the receptor CD300lf (∼8 Å). Surprisingly, bile salts cause the rotation and contraction of the P domain onto the shell surface. This both stabilizes the P domain and appears to allow for a higher degree of saturation of receptor onto the virus. Together, these results suggest that, as the virus moves into the gut and the associated high concentrations of bile, the entire capsid face undergoes a conformational change to optimize receptor avidity while the P domain itself undergoes smaller conformational changes to improve receptor affinity.IMPORTANCE Mouse norovirus and several other members of the Caliciviridae have been shown to have a highly unusual structure with the receptor binding protruding (P) domain only loosely tethered to the main capsid shell. Recent studies demonstrated that bile salts enhance the intrinsic P domain/receptor affinity and is necessary for cell attachment. Presented here are the high-resolution cryo-EM structures of apo MNV, MNV/bile salt, and MNV/bile salt/receptor. Bile salts cause a 90° rotation and collapse of the P domain onto the shell surface that may increase the number of available receptor binding sites. Therefore, bile salts appear to be having several effects on MNV. Bile salts shift the structural equilibrium of the P domain toward a form that binds the receptor and away from one that binds antibody. They may also cause the entire P domain to optimize receptor binding while burying a number of potential epitopes.


Assuntos
Ácidos e Sais Biliares/metabolismo , Capsídeo/química , Norovirus/química , Animais , Capsídeo/efeitos dos fármacos , Microscopia Crioeletrônica , Evasão da Resposta Imune/efeitos dos fármacos , Camundongos , Norovirus/efeitos dos fármacos , Norovirus/fisiologia , Ligação Proteica , Conformação Proteica/efeitos dos fármacos , Receptores Imunológicos/química , Receptores Virais/química , Ligação Viral/efeitos dos fármacos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA