RESUMEN
Emerging and re-emerging respiratory viral infections pose a tremendous threat to human society, as exemplified by the ongoing COVID-19 pandemic. Upon viral invasion of the respiratory tract, the host initiates coordinated innate and adaptive immune responses to defend against the virus and to promote repair of the damaged tissue. However, dysregulated host immunity can also cause acute morbidity, hamper lung regeneration, and/or lead to chronic tissue sequelae. Here, we review our current knowledge of the immune mechanisms regulating antiviral protection, host pathogenesis, inflammation resolution, and lung regeneration following respiratory viral infections, mainly using influenza virus and SARS-CoV-2 infections as examples. We hope that this review sheds light on future research directions to elucidate the cellular and molecular cross talk regulating host recovery and to pave the way to the development of pro-repair therapeutics to augment lung regeneration following viral injury.
Asunto(s)
COVID-19 , Humanos , Animales , Inmunidad Innata , Pandemias , SARS-CoV-2 , Inflamación/patologíaRESUMEN
Characterization of RNA modifications has identified their distribution features and molecular functions. Dynamic changes in RNA modification on various forms of RNA are essential for the development and function of the immune system. In this review, we discuss the value of innovative RNA modification profiling technologies to uncover the function of these diverse, dynamic RNA modifications in various immune cells within healthy and diseased contexts. Further, we explore our current understanding of the mechanisms whereby aberrant RNA modifications modulate the immune milieu of the tumor microenvironment and point out outstanding research questions.
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Adenosina , ARN , Humanos , Animales , Sistema InmunológicoRESUMEN
Pattern recognition receptors (PRRs) survey intra- and extracellular spaces for pathogen-associated molecular patterns (PAMPs) within microbial products of infection. Recognition and binding to cognate PAMP ligand by specific PRRs initiates signaling cascades that culminate in a coordinated intracellular innate immune response designed to control infection. In particular, our immune system has evolved specialized PRRs to discriminate viral nucleic acid from host. These are critical sensors of viral RNA to trigger innate immunity in the vertebrate host. Different families of PRRs of virus infection have been defined and reveal a diversity of PAMP specificity for wide viral pathogen coverage to recognize and extinguish virus infection. In this review, we discuss recent insights in pathogen recognition by the RIG-I-like receptors, related RNA helicases, Toll-like receptors, and other RNA sensor PRRs, to present emerging themes in innate immune signaling during virus infection.
Asunto(s)
Proteína 58 DEAD Box/metabolismo , Interacciones Huésped-Patógeno/genética , Interacciones Huésped-Patógeno/inmunología , Virosis/etiología , Virosis/metabolismo , Virus/inmunología , Animales , ARN Helicasas DEAD-box/metabolismo , Humanos , Procesamiento Proteico-Postraduccional , ARN Helicasas/metabolismo , ARN Viral/genética , ARN Viral/metabolismo , Receptores Inmunológicos , Transducción de Señal , Receptores Toll-Like/metabolismoRESUMEN
Senescent cell accumulation has been implicated in the pathogenesis of aging-associated diseases, including cancer. The mechanism that prevents the accumulation of senescent cells in aging human organs is unclear. Here, we demonstrate that a virus-immune axis controls the senescent fibroblast accumulation in the human skin. Senescent fibroblasts increased in old skin compared with young skin. However, they did not increase with advancing age in the elderly. Increased CXCL9 and cytotoxic CD4+ T cells (CD4 CTLs) recruitment were significantly associated with reduced senescent fibroblasts in the old skin. Senescent fibroblasts expressed human leukocyte antigen class II (HLA-II) and human cytomegalovirus glycoprotein B (HCMV-gB), becoming direct CD4 CTL targets. Skin-resident CD4 CTLs eliminated HCMV-gB+ senescent fibroblasts in an HLA-II-dependent manner, and HCMV-gB activated CD4 CTLs from the human skin. Collectively, our findings demonstrate HCMV reactivation in senescent cells, which CD4 CTLs can directly eliminate through the recognition of the HCMV-gB antigen.
Asunto(s)
Antineoplásicos , Infecciones por Citomegalovirus , Humanos , Anciano , Citomegalovirus , Linfocitos T Citotóxicos , Antígenos HLA , Linfocitos T CD4-Positivos , Senescencia CelularRESUMEN
CRISPR-Cas systems are host-encoded pathways that protect microbes from viral infection using an adaptive RNA-guided mechanism. Using genome-resolved metagenomics, we find that CRISPR systems are also encoded in diverse bacteriophages, where they occur as divergent and hypercompact anti-viral systems. Bacteriophage-encoded CRISPR systems belong to all six known CRISPR-Cas types, though some lack crucial components, suggesting alternate functional roles or host complementation. We describe multiple new Cas9-like proteins and 44 families related to type V CRISPR-Cas systems, including the Casλ RNA-guided nuclease family. Among the most divergent of the new enzymes identified, Casλ recognizes double-stranded DNA using a uniquely structured CRISPR RNA (crRNA). The Casλ-RNA-DNA structure determined by cryoelectron microscopy reveals a compact bilobed architecture capable of inducing genome editing in mammalian, Arabidopsis, and hexaploid wheat cells. These findings reveal a new source of CRISPR-Cas enzymes in phages and highlight their value as genome editors in plant and human cells.
Asunto(s)
Bacteriófagos , Sistemas CRISPR-Cas , Animales , Humanos , Microscopía por Crioelectrón , Edición Génica , Genoma , Bacteriófagos/genética , ADN , ARN , Mamíferos/genéticaRESUMEN
Many enveloped viruses require the endosomal sorting complexes required for transport (ESCRT) pathway to exit infected cells. This highly conserved pathway mediates essential cellular membrane fission events, which restricts the acquisition of adaptive mutations to counteract viral co-option. Here, we describe duplicated and truncated copies of the ESCRT-III factor CHMP3 that block ESCRT-dependent virus budding and arose independently in New World monkeys and mice. When expressed in human cells, these retroCHMP3 proteins potently inhibit release of retroviruses, paramyxoviruses, and filoviruses. Remarkably, retroCHMP3 proteins have evolved to reduce interactions with other ESCRT-III factors and have little effect on cellular ESCRT processes, revealing routes for decoupling cellular ESCRT functions from viral exploitation. The repurposing of duplicated ESCRT-III proteins thus provides a mechanism to generate broad-spectrum viral budding inhibitors without blocking highly conserved essential cellular ESCRT functions.
Asunto(s)
Citocinesis , Complejos de Clasificación Endosomal Requeridos para el Transporte/metabolismo , VIH-1/fisiología , Proteínas del Envoltorio Viral/metabolismo , Liberación del Virus , Animales , Muerte Celular , Supervivencia Celular , Complejos de Clasificación Endosomal Requeridos para el Transporte/ultraestructura , Células HEK293 , Células HeLa , Humanos , Interferones/metabolismo , Mamíferos/genética , Ratones Endogámicos C57BL , ARN/metabolismo , Transducción de Señal , Proteínas de Transporte Vesicular/metabolismo , Ensamble de Virus , Productos del Gen gag del Virus de la Inmunodeficiencia Humana/metabolismoRESUMEN
The biosafety level 3 (BSL-3) requirement to culture severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a bottleneck for research. Here, we report a trans-complementation system that produces single-round infectious SARS-CoV-2 that recapitulates authentic viral replication. We demonstrate that the single-round infectious SARS-CoV-2 can be used at BSL-2 laboratories for high-throughput neutralization and antiviral testing. The trans-complementation system consists of two components: a genomic viral RNA containing ORF3 and envelope gene deletions, as well as mutated transcriptional regulator sequences, and a producer cell line expressing the two deleted genes. Trans-complementation of the two components generates virions that can infect naive cells for only one round but does not produce wild-type SARS-CoV-2. Hamsters and K18-hACE2 transgenic mice inoculated with the complementation-derived virions exhibited no detectable disease, even after intracranial inoculation with the highest possible dose. Thus, the trans-complementation platform can be safely used at BSL-2 laboratories for research and countermeasure development.
Asunto(s)
COVID-19/virología , Contención de Riesgos Biológicos/métodos , SARS-CoV-2 , Células A549 , Animales , Chlorocebus aethiops , Cricetinae , Prueba de Complementación Genética/métodos , Genoma Viral , Células HEK293 , Humanos , Masculino , Ratones , Ratones Transgénicos , ARN Viral , SARS-CoV-2/genética , SARS-CoV-2/patogenicidad , SARS-CoV-2/fisiología , Células Vero , Virulencia , Replicación ViralRESUMEN
To control viral infection, vertebrates rely on both inducible interferon responses and less well-characterized cell-intrinsic responses composed of "at the ready" antiviral effector proteins. Here, we show that E3 ubiquitin ligase TRIM7 is a cell-intrinsic antiviral effector that restricts multiple human enteroviruses by targeting viral 2BC, a membrane remodeling protein, for ubiquitination and proteasome-dependent degradation. Selective pressure exerted by TRIM7 results in emergence of a TRIM7-resistant coxsackievirus with a single point mutation in the viral 2C ATPase/helicase. In cultured cells, the mutation helps the virus evade TRIM7 but impairs optimal viral replication, and this correlates with a hyperactive and structurally plastic 2C ATPase. Unexpectedly, the TRIM7-resistant virus has a replication advantage in mice and causes lethal pancreatitis. These findings reveal a unique mechanism for targeting enterovirus replication and provide molecular insight into the benefits and trade-offs of viral evolution imposed by a host restriction factor.
Asunto(s)
Enterovirus/fisiología , Enterovirus/patogenicidad , Proteínas de Motivos Tripartitos/metabolismo , Ubiquitina-Proteína Ligasas/metabolismo , Replicación Viral/fisiología , Adenosina Trifosfatasas/metabolismo , Animales , Línea Celular , Femenino , Humanos , Inflamación/patología , Ratones Endogámicos C57BL , Mutación/genética , Complejo de la Endopetidasa Proteasomal/metabolismo , Unión Proteica , Proteolisis , ARN Viral/metabolismo , Ubiquitina/metabolismo , Proteínas Virales/genéticaRESUMEN
Emerging evidence indicates a fundamental role for the epigenome in immunity. Here, we mapped the epigenomic and transcriptional landscape of immunity to influenza vaccination in humans at the single-cell level. Vaccination against seasonal influenza induced persistently diminished H3K27ac in monocytes and myeloid dendritic cells (mDCs), which was associated with impaired cytokine responses to Toll-like receptor stimulation. Single-cell ATAC-seq analysis revealed an epigenomically distinct subcluster of monocytes with reduced chromatin accessibility at AP-1-targeted loci after vaccination. Similar effects were observed in response to vaccination with the AS03-adjuvanted H5N1 pandemic influenza vaccine. However, this vaccine also stimulated persistently increased chromatin accessibility at interferon response factor (IRF) loci in monocytes and mDCs. This was associated with elevated expression of antiviral genes and heightened resistance to the unrelated Zika and Dengue viruses. These results demonstrate that vaccination stimulates persistent epigenomic remodeling of the innate immune system and reveal AS03's potential as an epigenetic adjuvant.
Asunto(s)
Epigenómica , Inmunidad/genética , Vacunas contra la Influenza/genética , Vacunas contra la Influenza/inmunología , Análisis de la Célula Individual , Transcripción Genética , Vacunación , Adolescente , Adulto , Antibacterianos/farmacología , Antígenos CD34/metabolismo , Antivirales/farmacología , Reprogramación Celular , Cromatina/metabolismo , Citocinas/biosíntesis , Combinación de Medicamentos , Femenino , Regulación de la Expresión Génica , Histonas/metabolismo , Humanos , Inmunidad Innata/genética , Subtipo H5N1 del Virus de la Influenza A/efectos de los fármacos , Subtipo H5N1 del Virus de la Influenza A/inmunología , Interferón Tipo I/metabolismo , Masculino , Células Mieloides/metabolismo , Polisorbatos/farmacología , Escualeno/farmacología , Receptores Toll-Like/metabolismo , Factor de Transcripción AP-1/metabolismo , Transcriptoma/genética , Adulto Joven , alfa-Tocoferol/farmacologíaRESUMEN
SARS-CoV-2 infection can cause severe respiratory COVID-19. However, many individuals present with isolated upper respiratory symptoms, suggesting potential to constrain viral pathology to the nasopharynx. Which cells SARS-CoV-2 primarily targets and how infection influences the respiratory epithelium remains incompletely understood. We performed scRNA-seq on nasopharyngeal swabs from 58 healthy and COVID-19 participants. During COVID-19, we observe expansion of secretory, loss of ciliated, and epithelial cell repopulation via deuterosomal cell expansion. In mild and moderate COVID-19, epithelial cells express anti-viral/interferon-responsive genes, while cells in severe COVID-19 have muted anti-viral responses despite equivalent viral loads. SARS-CoV-2 RNA+ host-target cells are highly heterogenous, including developing ciliated, interferon-responsive ciliated, AZGP1high goblet, and KRT13+ "hillock"-like cells, and we identify genes associated with susceptibility, resistance, or infection response. Our study defines protective and detrimental responses to SARS-CoV-2, the direct viral targets of infection, and suggests that failed nasal epithelial anti-viral immunity may underlie and precede severe COVID-19.
Asunto(s)
COVID-19/inmunología , COVID-19/virología , Inmunidad , SARS-CoV-2/fisiología , Índice de Severidad de la Enfermedad , Adulto , Anciano , Efecto Espectador , COVID-19/genética , Estudios de Cohortes , Femenino , Humanos , Masculino , Persona de Mediana Edad , Nasofaringe/patología , Nasofaringe/virología , ARN Viral/análisis , ARN Viral/genética , Mucosa Respiratoria/patología , Mucosa Respiratoria/virología , Transcripción Genética , Carga ViralRESUMEN
RNA viruses generate defective viral genomes (DVGs) that can interfere with replication of the parental wild-type virus. To examine their therapeutic potential, we created a DVG by deleting the capsid-coding region of poliovirus. Strikingly, intraperitoneal or intranasal administration of this genome, which we termed eTIP1, elicits an antiviral response, inhibits replication, and protects mice from several RNA viruses, including enteroviruses, influenza, and SARS-CoV-2. While eTIP1 replication following intranasal administration is limited to the nasal cavity, its antiviral action extends non-cell-autonomously to the lungs. eTIP1 broad-spectrum antiviral effects are mediated by both local and distal type I interferon responses. Importantly, while a single eTIP1 dose protects animals from SARS-CoV-2 infection, it also stimulates production of SARS-CoV-2 neutralizing antibodies that afford long-lasting protection from SARS-CoV-2 reinfection. Thus, eTIP1 is a safe and effective broad-spectrum antiviral generating short- and long-term protection against SARS-CoV-2 and other respiratory infections in animal models.
Asunto(s)
Proteínas de la Cápside/genética , Virus Interferentes Defectuosos/metabolismo , Replicación Viral/efectos de los fármacos , Administración Intranasal , Animales , Antivirales/farmacología , Anticuerpos ampliamente neutralizantes/inmunología , Anticuerpos ampliamente neutralizantes/farmacología , COVID-19 , Proteínas de la Cápside/metabolismo , Línea Celular , Virus Interferentes Defectuosos/patogenicidad , Modelos Animales de Enfermedad , Genoma Viral/genética , Humanos , Gripe Humana , Interferones/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Poliovirus/genética , Poliovirus/metabolismo , Infecciones del Sistema Respiratorio/virología , SARS-CoV-2/efectos de los fármacos , SARS-CoV-2/patogenicidadRESUMEN
Many oncogenic insults deregulate RNA splicing, often leading to hypersensitivity of tumors to spliceosome-targeted therapies (STTs). However, the mechanisms by which STTs selectively kill cancers remain largely unknown. Herein, we discover that mis-spliced RNA itself is a molecular trigger for tumor killing through viral mimicry. In MYC-driven triple-negative breast cancer, STTs cause widespread cytoplasmic accumulation of mis-spliced mRNAs, many of which form double-stranded structures. Double-stranded RNA (dsRNA)-binding proteins recognize these endogenous dsRNAs, triggering antiviral signaling and extrinsic apoptosis. In immune-competent models of breast cancer, STTs cause tumor cell-intrinsic antiviral signaling, downstream adaptive immune signaling, and tumor cell death. Furthermore, RNA mis-splicing in human breast cancers correlates with innate and adaptive immune signatures, especially in MYC-amplified tumors that are typically immune cold. These findings indicate that dsRNA-sensing pathways respond to global aberrations of RNA splicing in cancer and provoke the hypothesis that STTs may provide unexplored strategies to activate anti-tumor immune pathways.
Asunto(s)
Antivirales/farmacología , Inmunidad/efectos de los fármacos , Empalmosomas/metabolismo , Neoplasias de la Mama Triple Negativas/inmunología , Neoplasias de la Mama Triple Negativas/patología , Inmunidad Adaptativa/efectos de los fármacos , Animales , Apoptosis/efectos de los fármacos , Línea Celular Tumoral , Citoplasma/efectos de los fármacos , Citoplasma/metabolismo , Femenino , Amplificación de Genes/efectos de los fármacos , Humanos , Intrones/genética , Ratones , Terapia Molecular Dirigida , Proteínas Proto-Oncogénicas c-myc/metabolismo , Empalme del ARN/efectos de los fármacos , Empalme del ARN/genética , ARN Bicatenario/metabolismo , Transducción de Señal/efectos de los fármacos , Empalmosomas/efectos de los fármacos , Neoplasias de la Mama Triple Negativas/genéticaRESUMEN
The causative agent of the coronavirus disease 2019 (COVID-19) pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has infected millions and killed hundreds of thousands of people worldwide, highlighting an urgent need to develop antiviral therapies. Here we present a quantitative mass spectrometry-based phosphoproteomics survey of SARS-CoV-2 infection in Vero E6 cells, revealing dramatic rewiring of phosphorylation on host and viral proteins. SARS-CoV-2 infection promoted casein kinase II (CK2) and p38 MAPK activation, production of diverse cytokines, and shutdown of mitotic kinases, resulting in cell cycle arrest. Infection also stimulated a marked induction of CK2-containing filopodial protrusions possessing budding viral particles. Eighty-seven drugs and compounds were identified by mapping global phosphorylation profiles to dysregulated kinases and pathways. We found pharmacologic inhibition of the p38, CK2, CDK, AXL, and PIKFYVE kinases to possess antiviral efficacy, representing potential COVID-19 therapies.
Asunto(s)
Betacoronavirus/metabolismo , Infecciones por Coronavirus/metabolismo , Evaluación Preclínica de Medicamentos/métodos , Neumonía Viral/metabolismo , Proteómica/métodos , Células A549 , Enzima Convertidora de Angiotensina 2 , Animales , Antivirales/farmacología , COVID-19 , Células CACO-2 , Quinasa de la Caseína II/antagonistas & inhibidores , Quinasa de la Caseína II/metabolismo , Chlorocebus aethiops , Infecciones por Coronavirus/virología , Quinasas Ciclina-Dependientes/antagonistas & inhibidores , Quinasas Ciclina-Dependientes/metabolismo , Células HEK293 , Interacciones Huésped-Patógeno , Humanos , Pandemias , Peptidil-Dipeptidasa A/genética , Peptidil-Dipeptidasa A/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Inhibidores de las Quinasa Fosfoinosítidos-3/farmacología , Fosforilación , Neumonía Viral/virología , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Proto-Oncogénicas/antagonistas & inhibidores , Proteínas Proto-Oncogénicas/metabolismo , Proteínas Tirosina Quinasas Receptoras/antagonistas & inhibidores , Proteínas Tirosina Quinasas Receptoras/metabolismo , SARS-CoV-2 , Glicoproteína de la Espiga del Coronavirus/metabolismo , Células Vero , Proteínas Quinasas p38 Activadas por Mitógenos/antagonistas & inhibidores , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo , Tirosina Quinasa del Receptor AxlRESUMEN
The coronavirus disease 2019 (COVID-19) pandemic, caused by the SARS-CoV-2 virus, has highlighted the need for antiviral approaches that can target emerging viruses with no effective vaccines or pharmaceuticals. Here, we demonstrate a CRISPR-Cas13-based strategy, PAC-MAN (prophylactic antiviral CRISPR in human cells), for viral inhibition that can effectively degrade RNA from SARS-CoV-2 sequences and live influenza A virus (IAV) in human lung epithelial cells. We designed and screened CRISPR RNAs (crRNAs) targeting conserved viral regions and identified functional crRNAs targeting SARS-CoV-2. This approach effectively reduced H1N1 IAV load in respiratory epithelial cells. Our bioinformatic analysis showed that a group of only six crRNAs can target more than 90% of all coronaviruses. With the development of a safe and effective system for respiratory tract delivery, PAC-MAN has the potential to become an important pan-coronavirus inhibition strategy.
Asunto(s)
Antivirales/farmacología , Betacoronavirus/efectos de los fármacos , Sistemas CRISPR-Cas , Subtipo H1N1 del Virus de la Influenza A/efectos de los fármacos , ARN Viral/antagonistas & inhibidores , Células A549 , Profilaxis Antibiótica/métodos , Secuencia de Bases , Betacoronavirus/genética , Betacoronavirus/crecimiento & desarrollo , COVID-19 , Repeticiones Palindrómicas Cortas Agrupadas y Regularmente Espaciadas , Simulación por Computador , Secuencia Conservada , Coronavirus/efectos de los fármacos , Coronavirus/genética , Coronavirus/crecimiento & desarrollo , Infecciones por Coronavirus/tratamiento farmacológico , Proteínas de la Nucleocápside de Coronavirus , ARN Polimerasa Dependiente de ARN de Coronavirus , Células Epiteliales/virología , Humanos , Subtipo H1N1 del Virus de la Influenza A/genética , Subtipo H1N1 del Virus de la Influenza A/crecimiento & desarrollo , Pulmón/patología , Pulmón/virología , Proteínas de la Nucleocápside/genética , Pandemias , Fosfoproteínas , Filogenia , Neumonía Viral/tratamiento farmacológico , ARN Polimerasa Dependiente del ARN/genética , SARS-CoV-2 , Proteínas no Estructurales Virales/genéticaRESUMEN
Programmed -1 ribosomal frameshifting (-1PRF) is a widely used translation recoding mechanism. HIV-1 expresses Gag-Pol protein from the Gag-coding mRNA through -1PRF, and the ratio of Gag to Gag-Pol is strictly maintained for efficient viral replication. Here, we report that the interferon-stimulated gene product C19orf66 (herein named Shiftless) is a host factor that inhibits the -1PRF of HIV-1. Shiftless (SFL) also inhibited the -1PRF of a variety of mRNAs from both viruses and cellular genes. SFL interacted with the -1PRF signal of target mRNA and translating ribosomes and caused premature translation termination at the frameshifting site. Downregulation of translation release factor eRF3 or eRF1 reduced SFL-mediated premature translation termination. We propose that SFL binding to target mRNA and the translating ribosome interferes with the frameshifting process. These findings identify SFL as a broad-spectrum inhibitor of -1PRF and help to further elucidate the mechanisms of -1PRF.
Asunto(s)
Proteínas de Fusión gag-pol/genética , VIH-1/genética , Secuencia de Bases , Sistema de Lectura Ribosómico/genética , Regulación Viral de la Expresión Génica/genética , Humanos , Conformación de Ácido Nucleico , Biosíntesis de Proteínas , ARN Mensajero/metabolismo , ARN Viral/metabolismo , Ribosomas/metabolismo , Replicación Viral/genéticaRESUMEN
The cGAS-STING intracellular DNA-sensing pathway has emerged as a key element of innate antiviral immunity and a promising therapeutic target. The existence of an innate immune sensor that can be activated by any double-stranded DNA (dsDNA) of any origin raises fundamental questions about how cGAS is regulated and how it responds to "foreign" DNA while maintaining tolerance to ubiquitous self-DNA. In this review, we summarize recent evidence implicating important roles for cGAS in the detection of foreign and self-DNA. We describe two recent and surprising insights into cGAS-STING biology: that cGAS is tightly tethered to the nucleosome and that the cGAMP product of cGAS is an immunotransmitter acting at a distance to control innate immunity. We consider how these advances influence our understanding of the emerging roles of cGAS in the DNA damage response (DDR), senescence, aging, and cancer biology. Finally, we describe emerging approaches to harness cGAS-STING biology for therapeutic benefit.
Asunto(s)
Nucleotidiltransferasas , Transducción de Señal , Nucleotidiltransferasas/metabolismo , Inmunidad Innata , ADNRESUMEN
In response to viral infection, how cells balance translational shutdown to limit viral replication and the induction of antiviral components like interferons (IFNs) is not well understood. Moreover, how distinct isoforms of IFN-induced oligoadenylate synthetase 1 (OAS1) contribute to this antiviral response also requires further elucidation. Here, we show that human, but not mouse, OAS1 inhibits SARS-CoV-2 replication through its canonical enzyme activity via RNase L. In contrast, both mouse and human OAS1 protect against West Nile virus infection by a mechanism distinct from canonical RNase L activation. OAS1 binds AU-rich elements (AREs) of specific mRNAs, including IFNß. This binding leads to the sequestration of IFNß mRNA to the endomembrane regions, resulting in prolonged half-life and continued translation. Thus, OAS1 is an ARE-binding protein with two mechanisms of antiviral activity: driving inhibition of translation but also a broader, non-canonical function of protecting IFN expression from translational shutdown.
Asunto(s)
2',5'-Oligoadenilato Sintetasa , Interferones , Oligorribonucleótidos , Virosis , Fiebre del Nilo Occidental , Animales , Humanos , Ratones , 2',5'-Oligoadenilato Sintetasa/genética , 2',5'-Oligoadenilato Sintetasa/metabolismo , Nucleótidos de Adenina , Antivirales/farmacología , Fiebre del Nilo Occidental/genética , Fiebre del Nilo Occidental/metabolismo , Virus del Nilo Occidental/metabolismo , Virus del Nilo Occidental/patogenicidadRESUMEN
Stem cells are highly resistant to viral infection compared to their differentiated progeny; however, the mechanism is mysterious. Here, we analyzed gene expression in mammalian stem cells and cells at various stages of differentiation. We find that, conserved across species, stem cells express a subset of genes previously classified as interferon (IFN) stimulated genes (ISGs) but that expression is intrinsic, as stem cells are refractory to interferon. This intrinsic ISG expression varies in a cell-type-specific manner, and many ISGs decrease upon differentiation, at which time cells become IFN responsive, allowing induction of a broad spectrum of ISGs by IFN signaling. Importantly, we show that intrinsically expressed ISGs protect stem cells against viral infection. We demonstrate the in vivo importance of intrinsic ISG expression for protecting stem cells and their differentiation potential during viral infection. These findings have intriguing implications for understanding stem cell biology and the evolution of pathogen resistance.
Asunto(s)
Inmunidad Innata , Células Madre Pluripotentes/inmunología , Virosis/inmunología , Animales , Células Cultivadas , Femenino , Células HEK293 , Humanos , Interferones/metabolismo , Masculino , Ratones , Ratones Endogámicos NOD , Células Madre Pluripotentes/virología , Especificidad de la EspecieRESUMEN
Bats harbor many viruses asymptomatically, including several notorious for causing extreme virulence in humans. To identify differences between antiviral mechanisms in humans and bats, we sequenced, assembled, and analyzed the genome of Rousettus aegyptiacus, a natural reservoir of Marburg virus and the only known reservoir for any filovirus. We found an expanded and diversified KLRC/KLRD family of natural killer cell receptors, MHC class I genes, and type I interferons, which dramatically differ from their functional counterparts in other mammals. Such concerted evolution of key components of bat immunity is strongly suggestive of novel modes of antiviral defense. An evaluation of the theoretical function of these genes suggests that an inhibitory immune state may exist in bats. Based on our findings, we hypothesize that tolerance of viral infection, rather than enhanced potency of antiviral defenses, may be a key mechanism by which bats asymptomatically host viruses that are pathogenic in humans.
Asunto(s)
Quirópteros/genética , Genoma , Inmunidad Innata/genética , Secuencia de Aminoácidos , Animales , Línea Celular , Quirópteros/clasificación , Quirópteros/inmunología , Mapeo Cromosómico , Reservorios de Enfermedades/virología , Egipto , Evolución Molecular , Variación Genética , Antígenos de Histocompatibilidad Clase I/clasificación , Antígenos de Histocompatibilidad Clase I/genética , Humanos , Interferón Tipo I/clasificación , Interferón Tipo I/genética , Enfermedad del Virus de Marburg/inmunología , Enfermedad del Virus de Marburg/patología , Marburgvirus/fisiología , Subfamília C de Receptores Similares a Lectina de Células NK/química , Subfamília C de Receptores Similares a Lectina de Células NK/clasificación , Subfamília C de Receptores Similares a Lectina de Células NK/genética , Subfamília D de Receptores Similares a Lectina de las Células NK/química , Subfamília D de Receptores Similares a Lectina de las Células NK/clasificación , Subfamília D de Receptores Similares a Lectina de las Células NK/genética , Filogenia , Alineación de SecuenciaRESUMEN
Ebola virus (EBOV) infection often results in fatal illness in humans, yet little is known about how EBOV usurps host pathways during infection. To address this, we used affinity tag-purification mass spectrometry (AP-MS) to generate an EBOV-host protein-protein interaction (PPI) map. We uncovered 194 high-confidence EBOV-human PPIs, including one between the viral transcription regulator VP30 and the host ubiquitin ligase RBBP6. Domain mapping identified a 23 amino acid region within RBBP6 that binds to VP30. A crystal structure of the VP30-RBBP6 peptide complex revealed that RBBP6 mimics the viral nucleoprotein (NP) binding to the same interface of VP30. Knockdown of endogenous RBBP6 stimulated viral transcription and increased EBOV replication, whereas overexpression of either RBBP6 or the peptide strongly inhibited both. These results demonstrate the therapeutic potential of biologics that target this interface and identify additional PPIs that may be leveraged for novel therapeutic strategies.