RESUMEN
Influenza A virus (IAV) is a lytic RNA virus that triggers receptor-interacting serine/threonine-protein kinase 3 (RIPK3)-mediated pathways of apoptosis and mixed lineage kinase domain-like pseudokinase (MLKL)-dependent necroptosis in infected cells. ZBP1 initiates RIPK3-driven cell death by sensing IAV RNA and activating RIPK3. Here, we show that replicating IAV generates Z-RNAs, which activate ZBP1 in the nucleus of infected cells. ZBP1 then initiates RIPK3-mediated MLKL activation in the nucleus, resulting in nuclear envelope disruption, leakage of DNA into the cytosol, and eventual necroptosis. Cell death induced by nuclear MLKL was a potent activator of neutrophils, a cell type known to drive inflammatory pathology in virulent IAV disease. Consequently, MLKL-deficient mice manifest reduced nuclear disruption of lung epithelia, decreased neutrophil recruitment into infected lungs, and increased survival following a lethal dose of IAV. These results implicate Z-RNA as a new pathogen-associated molecular pattern and describe a ZBP1-initiated nucleus-to-plasma membrane "inside-out" death pathway with potentially pathogenic consequences in severe cases of influenza.
Asunto(s)
Virus de la Influenza A/genética , Necroptosis/genética , Proteínas de Unión al ARN/metabolismo , Animales , Apoptosis/genética , Muerte Celular/genética , Línea Celular Tumoral , Femenino , Virus de la Influenza A/metabolismo , Masculino , Ratones , Ratones Endogámicos C57BL , Necrosis/metabolismo , Fosforilación , Proteínas Quinasas/metabolismo , ARN/metabolismo , ARN Bicatenario/genética , ARN Bicatenario/metabolismo , Proteínas de Unión al ARN/genética , Proteína Serina-Treonina Quinasas de Interacción con Receptores/metabolismo , Proteína Serina-Treonina Quinasas de Interacción con Receptores/fisiologíaRESUMEN
Antiviral responses are often accompanied by translation inhibition and formation of stress granules (SGs) in infected cells. However, the triggers for these processes and their role during infection remain subjects of active investigation. Copy-back viral genomes (cbVGs) are the primary inducers of the mitochondrial antiviral signaling (MAVS) pathway and antiviral immunity during Sendai virus (SeV) and respiratory syncytial virus (RSV) infections. The relationship between cbVGs and cellular stress during viral infections is unknown. Here, we show that SGs form during infections containing high levels of cbVGs, and not during infections with low levels of cbVGs. Moreover, using RNA fluorescent in situ hybridization to differentiate accumulation of standard viral genomes from cbVGs at a single-cell level during infection, we show that SGs form exclusively in cells that accumulate high levels of cbVGs. Protein kinase R (PKR) activation is increased during high cbVG infections and, as expected, is necessary for virus-induced SGs. However, SGs form independent of MAVS signaling, demonstrating that cbVGs induce antiviral immunity and SG formation through 2 independent mechanisms. Furthermore, we show that translation inhibition and SG formation do not affect the overall expression of interferon and interferon stimulated genes during infection, making the stress response dispensable for global antiviral immunity. Using live-cell imaging, we show that SG formation is highly dynamic and correlates with a drastic reduction of viral protein expression even in cells infected for several days. Through analysis of active protein translation at a single-cell level, we show that infected cells that form SGs show inhibition of protein translation. Together, our data reveal a new cbVG-driven mechanism of viral interference where cbVGs induce PKR-mediated translation inhibition and SG formation, leading to a reduction in viral protein expression without altering overall antiviral immunity.
Asunto(s)
Interferones , Proteínas Virales , Humanos , Proteínas Virales/genética , Proteínas Virales/metabolismo , Hibridación Fluorescente in Situ , Interferones/metabolismo , Biosíntesis de Proteínas , Genoma Viral , Gránulos Citoplasmáticos/metabolismo , Replicación Viral/genéticaRESUMEN
Much progress has been made in the identification of specific human gene variants that contribute to enhanced susceptibility or resistance to viral diseases. Herein we review multiple discoveries made with genome-wide or candidate gene approaches that have revealed significant insights into virus-host interactions. Genetic factors that have been identified include genes encoding virus receptors, receptor-modifying enzymes, and a wide variety of innate and adaptive immunity-related proteins. We discuss a range of pathogenic viruses, including influenza virus, respiratory syncytial virus, human immunodeficiency virus, human T cell leukemia virus, human papilloma virus, hepatitis B and C viruses, herpes simplex virus, norovirus, rotavirus, parvovirus, and Epstein-Barr virus. Understanding the genetic underpinnings that affect infectious disease outcomes should allow tailored treatment and prevention approaches in the future.
Asunto(s)
Inmunidad Adaptativa , Regulación de la Expresión Génica/inmunología , Predisposición Genética a la Enfermedad , Interacciones Huésped-Patógeno/genética , Inmunidad Innata , Virosis/genética , Citocinas/genética , Citocinas/inmunología , Estudio de Asociación del Genoma Completo , Interacciones Huésped-Patógeno/inmunología , Genética Humana , Humanos , Factores Reguladores del Interferón/genética , Factores Reguladores del Interferón/inmunología , Receptores KIR/genética , Receptores KIR/inmunología , Receptores Virales/genética , Receptores Virales/inmunología , Transducción de Señal , Péptidos y Proteínas Asociados a Receptores de Factores de Necrosis Tumoral/genética , Péptidos y Proteínas Asociados a Receptores de Factores de Necrosis Tumoral/inmunología , Virosis/inmunología , Virosis/patología , Virosis/virologíaRESUMEN
During viral replication, viruses carrying an RNA genome produce non-standard viral genomes (nsVGs), including copy-back viral genomes (cbVGs) and deletion viral genomes (delVGs), that play a crucial role in regulating viral replication and pathogenesis. Because of their critical roles in determining the outcome of RNA virus infections, the study of nsVGs has flourished in recent years, exposing a need for bioinformatic tools that can accurately identify them within next-generation sequencing data obtained from infected samples. Here, we present our data analysis pipeline, Viral Opensource DVG Key Algorithm 2 (VODKA2), that is optimized to run on a parallel computing environment for fast and accurate detection of nsVGs from large data sets.
Asunto(s)
Algoritmos , Genoma Viral , RNA-Seq , Biología Computacional/métodos , Replicación Viral , ARN Viral/genéticaRESUMEN
The henipaviruses, including Nipah virus (NiV) and Hendra virus (HeV), are biosafety level 4 (BSL-4) zoonotic pathogens that cause severe neurological and respiratory disease in humans. To study the replication machinery of these viruses, we developed robust minigenome systems that can be safely used in BSL-2 conditions. The nucleocapsid (N), phosphoprotein (P), and large protein (L) of henipaviruses are critical elements of their replication machinery and thus essential support components of the minigenome systems. Here, we tested the effects of diverse combinations of the replication support proteins on the replication capacity of the NiV and HeV minigenomes by exchanging the helper plasmids coding for these proteins among the two viruses. We demonstrate that all combinations including one or more heterologous proteins were capable of replicating both the NiV and HeV minigenomes. Sequence alignment showed identities of 92% for the N protein, 67% for P, and 87% for L. Notably, variations in amino acid residues were not concentrated in the N-P and P-L interacting regions implying that dissimilarities in amino acid composition among NiV and HeV polymerase complex proteins may not impact their interactions. The observed indiscriminate activity of NiV and HeV polymerase complex proteins is different from related viruses, which can support the replication of heterologous genomes only when the whole polymerase complex belongs to the same virus. This newly observed promiscuous property of the henipavirus polymerase complex proteins likely attributed to their conserved interaction regions could potentially be harnessed to develop universal anti-henipavirus antivirals.IMPORTANCEGiven the severity of disease induced by Hendra and Nipah viruses in humans and the continuous emergence of new henipaviruses as well as henipa-like viruses, it is necessary to conduct a more comprehensive investigation of the biology of henipaviruses and their interaction with the host. The replication of henipaviruses and the development of antiviral agents can be studied in systems that allow experiments to be performed under biosafety level 2 conditions. Here, we developed robust minigenome systems for the Nipah virus (NiV) and Hendra virus (HeV) that provide a convenient alternative for studying NiV and HeV replication. Using these systems, we demonstrate that any combination of the three polymerase complex proteins of NiV and HeV could effectively initiate the replication of both viral minigenomes, which suggests that the interaction regions of the polymerase complex proteins could be effective targets for universal and effective anti-henipavirus interventions.
Asunto(s)
Genoma Viral , Virus Nipah , Replicación Viral , Virus Nipah/genética , Virus Nipah/fisiología , Humanos , Proteínas Virales/metabolismo , Proteínas Virales/genética , Virus Hendra/genética , Virus Hendra/metabolismo , Virus Hendra/fisiología , Animales , Henipavirus/genética , Henipavirus/metabolismo , Infecciones por Henipavirus/virología , Fosfoproteínas/metabolismo , Fosfoproteínas/genética , Proteínas de la Nucleocápside/metabolismo , Proteínas de la Nucleocápside/genética , Línea CelularRESUMEN
Respiratory syncytial virus (RSV) is a common cause of respiratory infection that often leads to hospitalization of infected younger children and older adults. RSV is classified into two strains, A and B, each with several subgroups or genotypes. One issue with the definition of these subgroups is the lack of a unified method of identification or genotyping. We propose that genotyping strategies based on the genes coding for replication-associated proteins could provide critical information on the replication capacity of the distinct subgroups, while clearly distinguishing genotypes. Here, we analyzed the virus replication-associated genes N, P, M2, and L from de novo assembled RSV A sequences obtained from 31 newly sequenced samples from hospitalized patients in Philadelphia and 78 additional publicly available sequences from different geographic locations within the United States. In-depth analysis and annotation of variants in the replication-associated proteins identified the polymerase protein L as a robust target for genotyping RSV subgroups. Importantly, our analysis revealed non-synonymous variations in L that were consistently accompanied by conserved changes in its co-factor P or the M2-2 protein, suggesting associations and interactions between specific domains of these proteins. Similar associations were seen among sequences of the related human metapneumovirus. These results highlight L as an alternative to other RSV genotyping targets and demonstrate the value of in-depth analyses and annotations of RSV sequences as it can serve as a foundation for subsequent in vitro and clinical studies on the efficiency of the polymerase and fitness of different virus isolates.IMPORTANCEGiven the historical heterogeneity of respiratory syncytial virus (RSV) and the disease it causes, there is a need to understand the properties of the circulating RSV strains each season. This information would benefit from an informative and consensus method of genotyping the virus. Here, we carried out a variant analysis that shows a pattern of specific variations among the replication-associated genes of RSV A across different seasons. Interestingly, these variation patterns, which were also seen in human metapneumovirus sequences, point to previously defined interactions of domains within these genes, suggesting co-variation in the replication-associated genes. Our results also suggest a genotyping strategy that can prove to be particularly important in understanding the genotype-phenotype correlation in the era of RSV vaccination, where selective pressure on the virus to evolve is anticipated. More importantly, the categorization of pneumoviruses based on these patterns may be of prognostic value.
Asunto(s)
Genotipo , Infecciones por Virus Sincitial Respiratorio , Virus Sincitial Respiratorio Humano , Proteínas Virales , Replicación Viral , Humanos , Virus Sincitial Respiratorio Humano/genética , Virus Sincitial Respiratorio Humano/clasificación , Infecciones por Virus Sincitial Respiratorio/virología , Replicación Viral/genética , Proteínas Virales/genética , Filogenia , Variación Genética , Lactante , Estados Unidos , Preescolar , PhiladelphiaRESUMEN
Influenza A virus (IAV) preferentially infects conducting airway and alveolar epithelial cells in the lung. The outcome of these infections is impacted by the host response, including the production of various cytokines, chemokines, and growth factors. Fibroblast growth factor-9 (FGF9) is required for lung development, can display antiviral activity in vitro, and is upregulated in asymptomatic patients during early IAV infection. We therefore hypothesized that FGF9 would protect the lungs from respiratory virus infection and evaluated IAV pathogenesis in mice that overexpress FGF9 in club cells in the conducting airway epithelium (FGF9-OE mice). However, we found that FGF9-OE mice were highly susceptible to IAV and Sendai virus infection compared to control mice. FGF9-OE mice displayed elevated and persistent viral loads, increased expression of cytokines and chemokines, and increased numbers of infiltrating immune cells as early as 1 day post-infection (dpi). Gene expression analysis showed an elevated type I interferon (IFN) signature in the conducting airway epithelium and analysis of IAV tropism uncovered a dramatic shift in infection from the conducting airway epithelium to the alveolar epithelium in FGF9-OE lungs. These results demonstrate that FGF9 signaling primes the conducting airway epithelium to rapidly induce a localized IFN and proinflammatory cytokine response during viral infection. Although this response protects the airway epithelial cells from IAV infection, it allows for early and enhanced infection of the alveolar epithelium, ultimately leading to increased morbidity and mortality. Our study illuminates a novel role for FGF9 in regulating respiratory virus infection and pathogenesis.
Asunto(s)
Factor 9 de Crecimiento de Fibroblastos , Virus de la Influenza A , Gripe Humana , Interferón Tipo I , Infecciones por Orthomyxoviridae , Animales , Citocinas/metabolismo , Células Epiteliales/metabolismo , Factor 9 de Crecimiento de Fibroblastos/biosíntesis , Humanos , Virus de la Influenza A/metabolismo , Gripe Humana/metabolismo , Gripe Humana/virología , Interferón Tipo I/metabolismo , Ratones , Infecciones por Orthomyxoviridae/metabolismo , Infecciones por Orthomyxoviridae/virologíaRESUMEN
[This corrects the article DOI: 10.1371/journal.ppat.1007707.].
RESUMEN
Defective viral genomes of the copy-back type (cbDVGs) are the primary initiators of the antiviral immune response during infection with respiratory syncytial virus (RSV) both in vitro and in vivo. However, the mechanism governing cbDVG generation remains unknown, thereby limiting our ability to manipulate cbDVG content in order to modulate the host response to infection. Here we report a specific genomic signal that mediates the generation of a subset of RSV cbDVG species. Using a customized bioinformatics tool, we identified regions in the RSV genome frequently used to generate cbDVGs during infection. We then created a minigenome system to validate the function of one of these sequences and to determine if specific nucleotides were essential for cbDVG generation at that position. Further, we created a recombinant virus unable to produce a subset of cbDVGs due to mutations introduced in this sequence. The identified sequence was also found as a site for cbDVG generation during natural RSV infections, and common cbDVGs originated at this sequence were found among samples from various infected patients. These data demonstrate that sequences encoded in the viral genome determine the location of cbDVG formation and, therefore, the generation of cbDVGs is not a stochastic process. These findings open the possibility of genetically manipulating cbDVG formation to modulate infection outcome.
Asunto(s)
Antivirales/metabolismo , Virus Defectuosos/genética , Genoma Viral , ARN Viral/genética , Infecciones por Virus Sincitial Respiratorio/genética , Virus Sincitial Respiratorio Humano/genética , Replicación Viral , Células A549 , Niño , Regulación Viral de la Expresión Génica , Células HeLa , Secuenciación de Nucleótidos de Alto Rendimiento , Humanos , Mutación , Neoplasias Nasofaríngeas/genética , Neoplasias Nasofaríngeas/virología , Infecciones por Virus Sincitial Respiratorio/virología , Transcripción Genética , Interferencia Viral , Proteínas ViralesRESUMEN
Chronic obstructive pulmonary disease (COPD) and asthma remain prevalent human lung diseases. Variability in epithelial and inflammatory components that results in pathologic heterogeneity complicates the development of treatments for these diseases. Early childhood infection with parainfluenza virus or respiratory syncytial virus is strongly associated with the development of asthma and COPD later in life, and exacerbations of these diseases correlate with the presence of viral RNA in the lung. Well-characterized animal models of postviral chronic lung diseases are necessary to study the underlying mechanisms of viral-related COPD and asthma and to develop appropriate therapies. In this study, we cross-analyzed chronic lung disease caused by infection with Sendai virus (SeV) or influenza A virus in mice. Differences were observed in lesion composition and inflammatory profiles between SeV- and influenza A virus-induced long-term lung disease. In addition, a primary SeV infection led to worsened pathologic findings on secondary heterologous viral challenge, whereas the reversed infection scheme protected against disease in response to a secondary viral challenge >1 month after the primary infection. These data demonstrate the differential effect of primary viral infections in the susceptibility to disease exacerbation in response to a different secondary viral infection and highlight the usefulness of these viral models as tools to understand the underlying mechanisms that mediate distinct chronic postviral lung diseases.
Asunto(s)
Asma/patología , Virus de la Influenza A/fisiología , Gripe Humana/patología , Infecciones por Paramyxoviridae/patología , Paramyxoviridae/fisiología , Enfermedad Pulmonar Obstructiva Crónica/virología , Sobreinfección/patología , Animales , Asma/virología , Enfermedad Crónica , Progresión de la Enfermedad , Femenino , Humanos , Gripe Humana/virología , Pulmón/patología , Pulmón/virología , Ratones , Ratones Endogámicos C57BL , Infecciones por Paramyxoviridae/virología , Sobreinfección/virologíaRESUMEN
The ApoE ε4 allele is the most significant genetic risk factor for late-onset Alzheimer disease. The risk conferred by ε4, however, differs across populations, with populations of African ancestry showing lower ε4 risk compared to those of European or Asian ancestry. The cause of this heterogeneity in risk effect is currently unknown; it may be due to environmental or cultural factors correlated with ancestry, or it may be due to genetic variation local to the ApoE region that differs among populations. Exploring these hypotheses may lead to novel, population-specific therapeutics and risk predictions. To test these hypotheses, we analyzed ApoE genotypes and genome-wide array data in individuals from African American and Puerto Rican populations. A total of 1,766 African American and 220 Puerto Rican individuals with late-onset Alzheimer disease, and 3,730 African American and 169 Puerto Rican cognitively healthy individuals (> 65 years) participated in the study. We first assessed average ancestry across the genome ("global" ancestry) and then tested it for interaction with ApoE genotypes. Next, we assessed the ancestral background of ApoE alleles ("local" ancestry) and tested if ancestry local to ApoE influenced Alzheimer disease risk while controlling for global ancestry. Measures of global ancestry showed no interaction with ApoE risk (Puerto Rican: p-value = 0.49; African American: p-value = 0.65). Conversely, ancestry local to the ApoE region showed an interaction with the ApoE ε4 allele in both populations (Puerto Rican: p-value = 0.019; African American: p-value = 0.005). ApoE ε4 alleles on an African background conferred a lower risk than those with a European ancestral background, regardless of population (Puerto Rican: OR = 1.26 on African background, OR = 4.49 on European; African American: OR = 2.34 on African background, OR = 3.05 on European background). Factors contributing to the lower risk effect in the ApoE gene ε4 allele are likely due to ancestry-specific genetic factors near ApoE rather than non-genetic ethnic, cultural, and environmental factors.
Asunto(s)
Enfermedad de Alzheimer/genética , Apolipoproteína E4/genética , Negro o Afroamericano/genética , Hispánicos o Latinos/genética , Anciano , Anciano de 80 o más Años , Estudios de Casos y Controles , Femenino , Frecuencia de los Genes , Variación Genética , Genética de Población , Estudio de Asociación del Genoma Completo , Humanos , Masculino , Puerto Rico/etnología , Factores de RiesgoRESUMEN
Defective viral genomes (DVGs) generated during RNA virus replication determine infection outcome by triggering innate immunity, diminishing virulence, and, in many cases, facilitating the establishment of persistent infections. Despite their critical role during virus-host interactions, the mechanisms regulating the production and propagation of DVGs are poorly understood. Visualization of viral genomes using RNA fluorescent in situ hybridization revealed a striking difference in the intracellular localization of DVGs and full-length viral genomes during infections with the paramyxovirus Sendai virus. In cells enriched in full-length virus, viral genomes clustered in a perinuclear region and associated with cellular trafficking machinery, including microtubules and the GTPase Rab11a. However, in cells enriched in DVGs, defective genomes distributed diffusely throughout the cytoplasm and failed to interact with this cellular machinery. Consequently, cells enriched in full-length genomes produced both DVG- and full-length-genome-containing viral particles, while DVG-high cells poorly produced viral particles yet strongly stimulated antiviral immunity. These findings reveal the selective production of both standard and DVG-containing particles by a subpopulation of infected cells that can be differentiated by the intracellular localization of DVGs. This study highlights the importance of considering this functional heterogeneity in analyses of virus-host interactions during infection.IMPORTANCE Defective viral genomes (DVGs) generated during Sendai virus infections accumulate in the cytoplasm of some infected cells and stimulate antiviral immunity and cell survival. DVGs are packaged and released as defective particles and have a significant impact on infection outcome. We show that the subpopulation of DVG-high cells poorly engages the virus packaging and budding machinery and do not effectively produce viral particles. In contrast, cells enriched in full-length genomes are the primary producers of both standard and defective viral particles during infection. This study demonstrates heterogeneity in the molecular interactions occurring within infected cells and highlights distinct functional roles for cells as either initiators of immunity or producers and perpetuators of viral particles depending on their content of viral genomes and their intracellular localization.
Asunto(s)
Virus Defectuosos/genética , Virus Sendai/genética , Ensamble de Virus/genética , Células A549 , Animales , Línea Celular , Genoma Viral/genética , Humanos , Hibridación Fluorescente in Situ/métodos , Transporte de Proteínas/genética , Virus ARN/genética , ARN Viral/genética , Virión/genética , Replicación Viral/genéticaRESUMEN
Respiratory paramyxoviruses are important causes of morbidity and mortality, particularly of infants and the elderly. In humans, a T helper (Th)2-biased immune response to these infections is associated with increased disease severity; however, little is known about the endogenous regulators of these responses that may be manipulated to ameliorate pathology. IL-27, a cytokine that regulates Th2 responses, is produced in the lungs during parainfluenza infection, but its role in disease pathogenesis is unknown. To determine whether IL-27 limits the development of pathogenic Th2 responses during paramyxovirus infection, IL-27-deficient or control mice were infected with the murine parainfluenza virus Sendai virus (SeV). Infected IL-27-deficient mice experienced increased weight loss, more severe lung lesions, and decreased survival compared to controls. IL-27 deficiency led to increased pulmonary eosinophils, alternatively activated macrophages (AAMs), and the emergence of Th2 responses. In control mice, IL-27 induced a population of IFN-γ+/IL-10+ CD4+ T cells that was replaced by IFN-γ+/IL-17+ and IFN-γ+/IL-13+ CD4+ T cells in IL-27-deficient mice. CD4+ T cell depletion in IL-27-deficient mice attenuated weight loss and decreased AAMs. Elimination of STAT6 signaling in IL-27-deficient mice reduced Th2 responses and decreased disease severity. These data indicate that endogenous IL-27 limits pathology during parainfluenza virus infection by regulating the quality of CD4+ T cell responses and therefore may have therapeutic potential in paramyxovirus infections.
Asunto(s)
Linfocitos T CD4-Positivos/inmunología , Interleucinas/inmunología , Infecciones por Respirovirus/inmunología , Animales , Modelos Animales de Enfermedad , Citometría de Flujo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Reacción en Cadena en Tiempo Real de la Polimerasa , Virus Sendai/inmunologíaRESUMEN
Caspases regulate cell death programs in response to environmental stresses, including infection and inflammation, and are therefore critical for the proper operation of the mammalian immune system. Caspase-8 is necessary for optimal production of inflammatory cytokines and host defense against infection by multiple pathogens including Yersinia, but whether this is due to death of infected cells or an intrinsic role of caspase-8 in TLR-induced gene expression is unknown. Caspase-8 activation at death signaling complexes results in its autoprocessing and subsequent cleavage and activation of its downstream apoptotic targets. Whether caspase-8 activity is also important for inflammatory gene expression during bacterial infection has not been investigated. Here, we report that caspase-8 plays an essential cell-intrinsic role in innate inflammatory cytokine production in vivo during Yersinia infection. Unexpectedly, we found that caspase-8 enzymatic activity regulates gene expression in response to bacterial infection as well as TLR signaling independently of apoptosis. Using newly-generated mice in which caspase-8 autoprocessing is ablated (Casp8DA/DA), we now demonstrate that caspase-8 enzymatic activity, but not autoprocessing, mediates induction of inflammatory cytokines by bacterial infection and a wide variety of TLR stimuli. Because unprocessed caspase-8 functions in an enzymatic complex with its homolog cFLIP, our findings implicate the caspase-8/cFLIP heterodimer in control of inflammatory cytokines during microbial infection, and provide new insight into regulation of antibacterial immune defense.
Asunto(s)
Caspasa 8/inmunología , Citocinas/biosíntesis , Inmunidad Innata/inmunología , Transducción de Señal/inmunología , Yersiniosis/inmunología , Animales , Apoptosis , Caspasa 8/metabolismo , Modelos Animales de Enfermedad , Ensayo de Inmunoadsorción Enzimática , Citometría de Flujo , Regulación de la Expresión Génica/inmunología , Técnicas de Silenciamiento del Gen , Ratones , Ratones Endogámicos C57BL , Reacción en Cadena de la Polimerasa , Receptores Toll-Like/inmunologíaRESUMEN
Human respiratory syncytial virus (RSV) is a major cause of severe respiratory illness in children and susceptible adults. RSV blocks the development of the innate antiviral immune response and can grow to high titers in the respiratory tract. Here we demonstrate that immunostimulatory defective viral genomes (iDVGs) that are naturally generated during RSV replication are strong inducers of the innate antiviral response to RSV in mice and humans. In mice, RSV iDVGs stimulated the expression of antiviral genes, restricted viral replication, and prevented weight loss and lung inflammation. In human cells, the antiviral response to RSV iDVGs was dominated by the expression of IFN-λ1 over IFN-ß and was driven by rapid intranuclear accumulation of the transcription factor IRF1. RSV iDVGs were detected in respiratory secretions of hospitalized patients, and their amount positively correlated with the level of expression of antiviral genes in the samples. Infection of explanted human lung tissue from different donors revealed that most humans can respond to RSV iDVGs and that the rate of accumulation of iDVGs during infection directly correlates with the quality of the antiviral response. Taken together, our data establish iDVGs as primary triggers of robust antiviral responses to RSV and provide the first evidence for an important biological role for naturally occurring iDVGs during a paramyxovirus infection in humans.
Asunto(s)
Genoma Viral , Interacciones Huésped-Patógeno , Interferón beta/agonistas , Interleucinas/agonistas , Mucosa Respiratoria/virología , Infecciones por Virus Sincitial Respiratorio/virología , Virus Sincitial Respiratorio Humano/fisiología , Animales , Línea Celular , Chlorocebus aethiops , Femenino , Regulación Viral de la Expresión Génica , Humanos , Inmunidad Innata , Interferón beta/antagonistas & inhibidores , Interferón beta/genética , Interferón beta/metabolismo , Interferones , Interleucinas/antagonistas & inhibidores , Interleucinas/genética , Interleucinas/metabolismo , Pulmón/inmunología , Pulmón/patología , Pulmón/virología , Ratones Endogámicos BALB C , Nasofaringe/inmunología , Nasofaringe/patología , Nasofaringe/virología , Interferencia de ARN , Mucosa Respiratoria/inmunología , Mucosa Respiratoria/patología , Infecciones por Virus Sincitial Respiratorio/inmunología , Infecciones por Virus Sincitial Respiratorio/patología , Virus Sincitial Respiratorio Humano/genética , Virus Sincitial Respiratorio Humano/inmunología , Virus Sincitial Respiratorio Humano/aislamiento & purificación , Técnicas de Cultivo de Tejidos , Células Vero , Tropismo Viral , Replicación ViralRESUMEN
Viruses efficiently block the host antiviral response in order to replicate and spread before host intervention. The mechanism initiating antiviral immunity during stealth viral replication is unknown, but recent data demonstrate that defective viral genomes generated at peak virus replication are critical for this process in vivo. This article summarizes the supporting evidence and highlights gaps in our understanding of the mechanisms and impact of immunostimulatory defective viral genomes generated during natural infections.
Asunto(s)
Genoma Viral/inmunología , Virosis/inmunología , Virosis/virología , Replicación Viral/inmunología , Animales , Antivirales/inmunología , HumanosRESUMEN
The innate immune response to viruses is initiated when specialized cellular sensors recognize viral danger signals. Here we show that truncated forms of viral genomes that accumulate in infected cells potently trigger the sustained activation of the transcription factors IRF3 and NF-κB and the production type I IFNs through a mechanism independent of IFN signaling. We demonstrate that these defective viral genomes (DVGs) are generated naturally during respiratory infections in vivo even in mice lacking the type I IFN receptor, and their appearance coincides with the production of cytokines during infections with Sendai virus (SeV) or influenza virus. Remarkably, the hallmark antiviral cytokine IFNß is only expressed in lung epithelial cells containing DVGs, while cells within the lung that contain standard viral genomes alone do not express this cytokine. Together, our data indicate that DVGs generated during viral replication are a primary source of danger signals for the initiation of the host immune response to infection.
Asunto(s)
Genoma Viral/inmunología , Virus de la Influenza A/inmunología , Infecciones por Orthomyxoviridae/inmunología , Infecciones por Respirovirus/inmunología , Virus Sendai/inmunología , Transducción de Señal/inmunología , Animales , Cricetinae , Perros , Factor 3 Regulador del Interferón/genética , Factor 3 Regulador del Interferón/inmunología , Interferón beta/genética , Interferón beta/inmunología , Células de Riñón Canino Madin Darby , Ratones , Ratones Noqueados , FN-kappa B/genética , FN-kappa B/inmunología , Infecciones por Orthomyxoviridae/genética , Infecciones por Orthomyxoviridae/patología , Infecciones por Respirovirus/genética , Infecciones por Respirovirus/patología , Transducción de Señal/genéticaRESUMEN
RATIONALE: Respiratory viral infections can result in the establishment of chronic lung diseases. Understanding the early innate immune mechanisms that participate in the development of chronic postviral lung disease may reveal new targets for therapeutic intervention. The intracellular viral sensor protein melanoma differentiation-associated protein 5 (MDA5) sustains the acute immune response to Sendai virus, a mouse pathogen that causes chronic lung inflammation, but its role in the development of postviral chronic lung disease is unknown. OBJECTIVES: To establish the role of MDA5 in the development of chronic lung disease. METHODS: MDA5-deficient or control mice were infected with Sendai virus. The acute inflammatory response was evaluated by profiling chemokine and cytokine expression and by characterizing the composition of the cellular infiltrate. The impact of MDA5 on chronic lung pathology and function was evaluated through histological studies, degree of oxygen saturation, and responsiveness to carbachol. MEASUREMENTS AND MAIN RESULTS: MDA5 deficiency resulted in normal virus replication and in a distinct profile of chemokines and cytokines that associated with acute lung neutropenia and enhanced accumulation of alternatively activated macrophages. Diminished expression of neutrophil-recruiting chemokines was also observed in cells infected with influenza virus, suggesting a key role of MDA5 in driving the early accumulation of neutrophils at the infection site. The biased acute inflammatory response of MDA5-deficient mice led to an enhanced chronic lung inflammation, epithelial cell hyperplasia, airway hyperreactivity, and diminished blood oxygen saturation. CONCLUSIONS: MDA5 modulates the development of chronic lung inflammation by regulating the early inflammatory response in the lung.
Asunto(s)
ARN Helicasas DEAD-box/deficiencia , Neumonía Viral/enzimología , Infecciones por Respirovirus/enzimología , Virus Sendai , Animales , Biomarcadores/metabolismo , Líquido del Lavado Bronquioalveolar/química , Quimiocinas/metabolismo , Enfermedad Crónica , Citocinas/metabolismo , Citometría de Flujo , Inmunidad Innata , Helicasa Inducida por Interferón IFIH1 , Pulmón/enzimología , Pulmón/inmunología , Pulmón/metabolismo , Pulmón/patología , Ratones , Ratones Endogámicos C57BL , Neumonía Viral/inmunología , Neumonía Viral/patología , Reacción en Cadena en Tiempo Real de la Polimerasa , Infecciones por Respirovirus/inmunología , Infecciones por Respirovirus/patologíaRESUMEN
RNA viruses are some of the most successful biological entities due their ability to adapt and evolve. Despite their small genome and parasitic nature, RNA viruses have evolved many mechanisms to ensure their survival and maintenance in the host population. We propose that one of these mechanisms of survival is the generation of nonstandard viral genomes (nsVGs) that accumulate during viral replication. NsVGs are often considered to be accidental defective byproducts of the RNA virus replication, but their ubiquity and the plethora of roles they have during infection indicate that they are an integral part of the virus life cycle. Here we review the different types of nsVGs and discuss how their multiple roles during infection could be beneficial for RNA viruses to be maintained in nature. By shifting our perspectives on what makes a virus successful, we posit that nsVG generation is a conserved phenomenon that arose during RNA virus evolution as an essential component of a healthy virus community.