RESUMO
Clinical manifestations of COVID-19 caused by the new coronavirus SARS-CoV-2 are associated with age1,2. Adults develop respiratory symptoms, which can progress to acute respiratory distress syndrome (ARDS) in the most severe form, while children are largely spared from respiratory illness but can develop a life-threatening multisystem inflammatory syndrome (MIS-C)3-5. Here, we show distinct antibody responses in children and adults after SARS-CoV-2 infection. Adult COVID-19 cohorts had anti-spike (S) IgG, IgM and IgA antibodies, as well as anti-nucleocapsid (N) IgG antibody, while children with and without MIS-C had reduced breadth of anti-SARS-CoV-2-specific antibodies, predominantly generating IgG antibodies specific for the S protein but not the N protein. Moreover, children with and without MIS-C had reduced neutralizing activity as compared to both adult COVID-19 cohorts, indicating a reduced protective serological response. These results suggest a distinct infection course and immune response in children independent of whether they develop MIS-C, with implications for developing age-targeted strategies for testing and protecting the population.
Assuntos
Anticorpos Antivirais/imunologia , Formação de Anticorpos/imunologia , COVID-19/imunologia , Proteínas do Nucleocapsídeo/imunologia , SARS-CoV-2/imunologia , Glicoproteína da Espícula de Coronavírus/imunologia , Adolescente , Adulto , Idoso , COVID-19/virologia , Criança , Pré-Escolar , Feminino , Humanos , Imunoglobulina A/imunologia , Imunoglobulina G/imunologia , Imunoglobulina M/imunologia , Masculino , Pessoa de Meia-Idade , SARS-CoV-2/fisiologia , Adulto JovemRESUMO
Interferon (IFN) type I plays a critical role in the protection of mice from lethal Nipah virus (NiV) infection, but mechanisms responsible for IFN-I induction remain unknown. In the current study, we demonstrated the critical role of the mitochondrial antiviral signaling protein signaling pathway in IFN-I production and NiV replication in murine embryonic fibroblasts in vitro, and the redundant but essential roles of both mitochondrial antiviral signaling protein and myeloid differentiation primary response 88 adaptors, but not toll/interleukin-1 receptor/resistance [TIR] domain-containing adaptor-inducing IFN-ß (TRIF), in the control of NiV infection in mice. These results reveal potential novel targets for antiviral intervention and help in understanding NiV immunopathogenesis.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Infecções por Henipavirus/imunologia , Infecções por Henipavirus/virologia , Fator 88 de Diferenciação Mieloide/metabolismo , Vírus Nipah , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Proteína DEAD-box 58/genética , Proteína DEAD-box 58/metabolismo , Regulação da Expressão Gênica/imunologia , Interferon Tipo I/genética , Interferon Tipo I/metabolismo , Interferon beta/genética , Interferon beta/metabolismo , Camundongos , Camundongos Knockout , Camundongos Transgênicos , Fator 88 de Diferenciação Mieloide/genética , Receptores Toll-Like/genética , Receptores Toll-Like/metabolismoRESUMO
We conducted an in-depth characterization of the Nipah virus (NiV) isolate previously obtained from a Pteropus lylei bat in Cambodia in 2003 (CSUR381). We performed full-genome sequencing and phylogenetic analyses and confirmed CSUR381 is part of the NiV-Malaysia genotype. In vitro studies revealed similar cell permissiveness and replication of CSUR381 (compared with 2 other NiV isolates) in both bat and human cell lines. Sequence alignments indicated conservation of the ephrin-B2 and ephrin-B3 receptor binding sites, the glycosylation site on the G attachment protein, as well as the editing site in phosphoprotein, suggesting production of nonstructural proteins V and W, known to counteract the host innate immunity. In the hamster animal model, CSUR381 induced lethal infections. Altogether, these data suggest that the Cambodia bat-derived NiV isolate has high pathogenic potential and, thus, provide insight for further studies and better risk assessment for future NiV outbreaks in Southeast Asia.
Assuntos
Quirópteros/virologia , Infecções por Henipavirus/veterinária , Vírus Nipah/patogenicidade , Animais , Camboja , Genoma Viral/genética , Infecções por Henipavirus/epidemiologia , Infecções por Henipavirus/virologia , Humanos , Vírus Nipah/genética , Filogenia , RNA Viral/genética , Reação em Cadeia da Polimerase em Tempo Real , Sequenciamento Completo do GenomaRESUMO
Ebola virus (EBOV) is among the most devastating pathogens causing fatal hemorrhagic fever in humans. The epidemics from 2013 to 2016 resulted in more than 11,000 deaths, and another outbreak is currently ongoing. Since there is no FDA-approved drug so far to fight EBOV infection, there is an urgent need to focus on drug discovery. Considering the tight correlation between the high EBOV virulence and its ability to suppress the type I interferon (IFN-I) system, identifying molecules targeting viral protein VP24, one of the main virulence determinants blocking the IFN response, is a promising novel anti-EBOV therapy approach. Hence, in the effort to find novel EBOV inhibitors, a screening of a small set of flavonoids was performed; it showed that quercetin and wogonin can suppress the VP24 effect on IFN-I signaling inhibition. The mechanism of action of the most active compound, quercetin, showing a half-maximal inhibitory concentration (IC50) of 7.4 µM, was characterized to significantly restore the IFN-I signaling cascade, blocked by VP24, by directly interfering with the VP24 binding to karyopherin-α and thus restoring P-STAT1 nuclear transport and IFN gene transcription. Quercetin significantly blocked viral infection, specifically targeting EBOV VP24 anti-IFN-I function. Overall, quercetin is the first identified inhibitor of the EBOV VP24 anti-IFN function, representing a molecule interacting with a viral binding site that is very promising for further drug development aiming to block EBOV infection at the early steps.
Assuntos
Ebolavirus , Doença pelo Vírus Ebola , Interferons , Quercetina , Antivirais/farmacologia , Antivirais/uso terapêutico , Ebolavirus/efeitos dos fármacos , Doença pelo Vírus Ebola/tratamento farmacológico , Humanos , Quercetina/farmacologia , Proteínas Virais/antagonistas & inibidoresRESUMO
Fatal neurological syndromes can occur after measles virus (MeV) infection of the brain. The mechanisms controlling MeV spread within the central nervous system (CNS) remain poorly understood. We analyzed the role of type I interferon (IFN-I) receptor (IFNAR) signaling in the control of MeV infection in a murine model of brain infection. Using organotypic brain cultures (OBC) from wild-type and IFNAR-knockout (IFNARKO) transgenic mice ubiquitously expressing the human SLAM (CD150) receptor, the heterogeneity of the permissiveness of different CNS cell types to MeV infection was characterized. In the absence of IFNAR signaling, MeV propagated significantly better in explant slices. In OBC from IFNAR-competent mice, while astrocytes and microglia were infected on the day of explant preparation, they became refractory to infection with time, in contrast to neurons and oligodendrocytes, which remained permissive to infection. This selective loss of permissiveness to MeV infection was not observed in IFNARKO mouse OBC. Accordingly, the development of astrogliosis related to the OBC procedure was exacerbated in the presence of IFNAR signaling. In the hippocampus, this astrogliosis was characterized by a change in the astrocyte phenotype and by an increase of IFN-I transcripts. A proteome analysis showed the upregulation of 84 out of 111 secreted proteins. In the absence of IFNAR, only 27 secreted proteins were upregulated, and none of these were associated with antiviral activities. Our results highlight the essential role of the IFN-I response in astrogliosis and in the permissiveness of astrocytes and microglia that could control MeV propagation throughout the CNS.IMPORTANCE Measles virus (MeV) can infect the central nervous system (CNS), with dramatic consequences. The mechanisms controlling MeV invasion of the CNS remain ill-defined since most previous data were obtained from postmortem analysis. Here, we highlight for the first time the crucial role of the type I interferon (IFN-I) response not only in the control of CNS invasion but also in the early permissiveness of glial cells to measles virus infection.
Assuntos
Astrócitos/virologia , Vírus do Sarampo/metabolismo , Sarampo/metabolismo , Microglia/virologia , Receptor de Interferon alfa e beta/metabolismo , Transdução de Sinais/fisiologia , Animais , Antivirais/farmacologia , Astrócitos/patologia , Encéfalo/virologia , Sistema Nervoso Central/virologia , Citocinas , Feminino , Hipocampo/patologia , Hipocampo/virologia , Humanos , Masculino , Sarampo/patologia , Sarampo/virologia , Camundongos , Camundongos Knockout , Neurônios/virologia , Oligodendroglia/virologia , Receptor de Interferon alfa e beta/genética , Transdução de Sinais/genética , Membro 1 da Família de Moléculas de Sinalização da Ativação Linfocitária/metabolismoRESUMO
During a measles virus (MeV) epidemic in 2009 in South Africa, measles inclusion body encephalitis (MIBE) was identified in several HIV-infected patients. Years later, children are presenting with subacute sclerosing panencephalitis (SSPE). To investigate the features of established MeV neuronal infections, viral sequences were analyzed from brain tissue samples of a single SSPE case and compared with MIBE sequences previously obtained from patients infected during the same epidemic. Both the SSPE and the MIBE viruses had amino acid substitutions in the ectodomain of the F protein that confer enhanced fusion properties. Functional analysis of the fusion complexes confirmed that both MIBE and SSPE F protein mutations promoted fusion with less dependence on interaction by the viral receptor-binding protein with known MeV receptors. While the SSPE F required the presence of a homotypic attachment protein, MeV H, in order to fuse, MIBE F did not. Both F proteins had decreased thermal stability compared to that of the corresponding wild-type F protein. Finally, recombinant viruses expressing MIBE or SSPE fusion complexes spread in the absence of known MeV receptors, with MIBE F-bearing viruses causing large syncytia in these cells. Our results suggest that alterations to the MeV fusion complex that promote fusion and cell-to-cell spread in the absence of known MeV receptors is a key property for infection of the brain.IMPORTANCE Measles virus can invade the central nervous system (CNS) and cause severe neurological complications, such as MIBE and SSPE. However, mechanisms by which MeV enters the CNS and triggers the disease remain unclear. We analyzed viruses from brain tissue of individuals with MIBE or SSPE, infected during the same epidemic, after the onset of neurological disease. Our findings indicate that the emergence of hyperfusogenic MeV F proteins is associated with infection of the brain. We also demonstrate that hyperfusogenic F proteins permit MeV to enter cells and spread without the need to engage nectin-4 or CD150, known receptors for MeV that are not present on neural cells.
Assuntos
Vírus do Sarampo/genética , Panencefalite Esclerosante Subaguda/genética , Proteínas Virais de Fusão/genética , Substituição de Aminoácidos , Animais , Encéfalo/virologia , Moléculas de Adesão Celular/metabolismo , Chlorocebus aethiops , Epidemias , Feminino , Genótipo , Células Gigantes/virologia , Células HEK293 , Humanos , Masculino , Sarampo/epidemiologia , Sarampo/metabolismo , Sarampo/virologia , Mutação , Neurônios/virologia , África do Sul , Panencefalite Esclerosante Subaguda/virologia , Células Vero , Proteínas Virais de Fusão/metabolismoRESUMO
A clinical isolate of measles virus (MeV) bearing a single amino acid alteration in the viral fusion protein (F; L454W) was previously identified in two patients with lethal sequelae of MeV central nervous system (CNS) infection. The mutation dysregulated the viral fusion machinery so that the mutated F protein mediated cell fusion in the absence of known MeV cellular receptors. While this virus could feasibly have arisen via intrahost evolution of the wild-type (wt) virus, it was recently shown that the same mutation emerged under the selective pressure of small-molecule antiviral treatment. Under these conditions, a potentially neuropathogenic variant emerged outside the CNS. While CNS adaptation of MeV was thought to generate viruses that are less fit for interhost spread, we show that two animal models can be readily infected with CNS-adapted MeV via the respiratory route. Despite bearing a fusion protein that is less stable at 37°C than the wt MeV F, this virus infects and replicates in cotton rat lung tissue more efficiently than the wt virus and is lethal in a suckling mouse model of MeV encephalitis even with a lower inoculum. Thus, either during lethal MeV CNS infection or during antiviral treatment in vitro, neuropathogenic MeV can emerge, can infect new hosts via the respiratory route, and is more pathogenic (at least in these animal models) than wt MeV.IMPORTANCE Measles virus (MeV) infection can be severe in immunocompromised individuals and lead to complications, including measles inclusion body encephalitis (MIBE). In some cases, MeV persistence and subacute sclerosing panencephalitis (SSPE) occur even in the face of an intact immune response. While they are relatively rare complications of MeV infection, MIBE and SSPE are lethal. This work addresses the hypothesis that despite a dysregulated viral fusion complex, central nervous system (CNS)-adapted measles virus can spread outside the CNS within an infected host.
Assuntos
Sistema Nervoso Central/virologia , Encefalite Viral , Corpos de Inclusão Viral , Pulmão/virologia , Vírus do Sarampo/fisiologia , Sarampo , Mutação de Sentido Incorreto , Proteínas Virais de Fusão , Replicação Viral , Substituição de Aminoácidos , Animais , Sistema Nervoso Central/metabolismo , Chlorocebus aethiops , Modelos Animais de Doenças , Encefalite Viral/genética , Encefalite Viral/metabolismo , Encefalite Viral/transmissão , Humanos , Corpos de Inclusão Viral/genética , Corpos de Inclusão Viral/metabolismo , Pulmão/metabolismo , Sarampo/metabolismo , Sarampo/transmissão , Camundongos , Camundongos Transgênicos , Sigmodontinae , Células Vero , Proteínas Virais de Fusão/genética , Proteínas Virais de Fusão/metabolismoRESUMO
Background: The emerging zoonotic paramyxovirus Nipah virus (NiV) causes severe respiratory and neurological disease in humans, with high fatality rates. Nipah virus can be transmitted via person-to-person contact, posing a high risk for epidemic outbreaks. However, a broadly applicable approach for human NiV outbreaks in field settings is lacking. Methods: We engineered new antiviral lipopeptides and analyzed in vitro fusion inhibition to identify an optimal candidate for prophylaxis of NiV infection in the lower respiratory tract, and we assessed antiviral efficiency in 2 different animal models. Results: We show that lethal NiV infection can be prevented with lipopeptides delivered via the respiratory route in both hamsters and nonhuman primates. By targeting retention of peptides for NiV prophylaxis in the respiratory tract, we avoid its systemic delivery in individuals who need only prevention, and thus we increase the safety of treatment and enhance utility of the intervention. Conclusions: The experiments provide a proof of concept for the use of antifusion lipopeptides for prophylaxis of lethal NiV. These results advance the goal of rational development of potent lipopeptide inhibitors with desirable pharmacokinetic and biodistribution properties and a safe effective delivery method to target NiV and other pathogenic viruses.
Assuntos
Quimioprevenção/métodos , Infecções por Henipavirus/prevenção & controle , Lipopeptídeos/administração & dosagem , Vírus Nipah/fisiologia , Doenças dos Primatas/prevenção & controle , Proteínas do Envelope Viral/antagonistas & inibidores , Inibidores de Proteínas Virais de Fusão/administração & dosagem , Animais , Broncopneumonia/prevenção & controle , Broncopneumonia/veterinária , Chlorocebus aethiops , Modelos Animais de Doenças , Feminino , Humanos , Masculino , MesocricetusRESUMO
UNLABELLED: Nonsegmented negative-stranded RNA viruses, or members of the order Mononegavirales, share a conserved gene order and the use of elaborate transcription and replication machinery made up of at least four molecular partners. These partners have coevolved with the acquisition of the permanent encapsidation of the entire genome by the nucleoprotein (N) and the use of this N-RNA complex as a template for the viral polymerase composed of the phosphoprotein (P) and the large enzymatic protein (L). Not only is P required for polymerase function, but it also stabilizes the L protein through an unknown underlying molecular mechanism. By using NVP-AUY922 and/or 17-dimethylaminoethylamino-17-demethoxygeldanamycin as specific inhibitors of cellular heat shock protein 90 (HSP90), we found that efficient chaperoning of L by HSP90 requires P in the measles, Nipah, and vesicular stomatitis viruses. While the production of P remains unchanged in the presence of HSP90 inhibitors, the production of soluble and functional L requires both P and HSP90 activity. Measles virus P can bind the N terminus of L in the absence of HSP90 activity. Both HSP90 and P are required for the folding of L, as evidenced by a luciferase reporter insert fused within measles virus L. HSP90 acts as a true chaperon; its activity is transient and dispensable for the activity of measles and Nipah virus polymerases of virion origin. That the cellular chaperoning of a viral polymerase into a soluble functional enzyme requires the assistance of another viral protein constitutes a new paradigm that seems to be conserved within the Mononegavirales order. IMPORTANCE: Viruses are obligate intracellular parasites that require a cellular environment for their replication. Some viruses particularly depend on the cellular chaperoning apparatus. We report here that for measles virus, successful chaperoning of the viral L polymerase mediated by heat shock protein 90 (HSP90) requires the presence of the viral phosphoprotein (P). Indeed, while P protein binds to the N terminus of L independently of HSP90 activity, both HSP90 and P are required to produce stable, soluble, folded, and functional L proteins. Once formed, the mature P+L complex no longer requires HSP90 to exert its polymerase functions. Such a new paradigm for the maturation of a viral polymerase appears to be conserved in several members of the Mononegavirales order, including the Nipah and vesicular stomatitis viruses.
Assuntos
RNA Polimerases Dirigidas por DNA/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Infecções por Henipavirus/metabolismo , Sarampo/metabolismo , Fosfoproteínas/metabolismo , Dobramento de Proteína , Animais , Chlorocebus aethiops , Proteínas de Choque Térmico HSP90/química , Células HeLa , Infecções por Henipavirus/virologia , Humanos , Sarampo/virologia , Vírus do Sarampo/fisiologia , Camundongos , Vírus Nipah/fisiologia , Nucleoproteínas/metabolismo , Ligação Proteica , Infecções por Rhabdoviridae/metabolismo , Infecções por Rhabdoviridae/virologia , Células Vero , Vesiculovirus/fisiologia , Proteínas Virais/metabolismo , Vírion/fisiologia , Replicação ViralRESUMO
UNLABELLED: Human herpesvirus 6 (HHV-6) is widely spread in the human population and has been associated with several neuroinflammatory diseases, including multiple sclerosis. To develop a small-animal model of HHV-6 infection, we analyzed the susceptibility of several lines of transgenic mice expressing human CD46, identified as a receptor for HHV-6. We showed that HHV-6A (GS) infection results in the expression of viral transcripts in primary brain glial cultures from CD46-expressing mice, while HHV-6B (Z29) infection was inefficient. HHV-6A DNA persisted for up to 9 months in the brain of CD46-expressing mice but not in the nontransgenic littermates, whereas HHV-6B DNA levels decreased rapidly after infection in all mice. Persistence in the brain was observed with infectious but not heat-inactivated HHV-6A. Immunohistological studies revealed the presence of infiltrating lymphocytes in periventricular areas of the brain of HHV-6A-infected mice. Furthermore, HHV-6A stimulated the production of a panel of proinflammatory chemokines in primary brain glial cultures, including CCL2, CCL5, and CXCL10, and induced the expression of CCL5 in the brains of HHV-6A-infected mice. HHV-6A-induced production of chemokines in the primary glial cultures was dependent on the stimulation of toll-like receptor 9 (TLR9). Finally, HHV-6A induced signaling through human TLR9 as well, extending observations from the murine model to human infection. Altogether, this study presents a first murine model for HHV-6A-induced brain infection and suggests a role for TLR9 in the HHV-6A-initiated production of proinflammatory chemokines in the brain, opening novel perspectives for the study of virus-associated neuropathology. IMPORTANCE: HHV-6 infection has been related to neuroinflammatory diseases; however, the lack of a suitable small-animal infection model has considerably hampered further studies of HHV-6-induced neuropathogenesis. In this study, we have characterized a new model for HHV-6 infection in mice expressing the human CD46 protein. Infection of CD46 transgenic mice with HHV-6A resulted in long-term persistence of viral DNA in the brains of infected animals and was followed by lymphocyte infiltration and upregulation of the CCL5 chemokine in the absence of clinical signs of disease. The secretion of a panel of chemokines was increased after infection in primary murine brain glial cultures, and the HHV-6-induced chemokine expression was inhibited when TLR9 signaling was blocked. These results describe the first murine model for HHV-6A-induced brain infection and suggest the importance of the TLR9 pathway in HHV-6A-initiated neuroinflammation.
Assuntos
Encéfalo/virologia , Quimiocinas/imunologia , Modelos Animais de Doenças , Herpesvirus Humano 6/isolamento & purificação , Proteína Cofatora de Membrana/genética , Infecções por Roseolovirus/imunologia , Receptor Toll-Like 9/imunologia , Animais , Encéfalo/patologia , Células Cultivadas , DNA Viral/isolamento & purificação , Humanos , Imuno-Histoquímica , Proteína Cofatora de Membrana/metabolismo , Camundongos , Camundongos Transgênicos , Neuroglia/imunologia , Neuroglia/virologia , Receptores Virais/genética , Receptores Virais/metabolismo , Infecções por Roseolovirus/patologia , Infecções por Roseolovirus/virologiaRESUMO
Measles virus (MV) infection causes an acute childhood disease that can include infection of the central nervous system and can rarely progress to severe neurological disease for which there is no specific treatment. We generated potent antiviral peptide inhibitors of MV entry and spreading and MV-induced cell fusion. Dimers of MV-specific peptides derived from the C-terminal heptad repeat region of the MV fusion protein, conjugated to cholesterol, efficiently protect SLAM transgenic mice from fatal MV infection. Fusion inhibitors hold promise for the prophylaxis of MV infection in unvaccinated and immunocompromised people, as well as potential for the treatment of grave neurological complications of measles.
Assuntos
Antivirais/farmacologia , Encéfalo/virologia , Vírus do Sarampo/efeitos dos fármacos , Sarampo/prevenção & controle , Proteínas Virais de Fusão/antagonistas & inibidores , Animais , Encéfalo/efeitos dos fármacos , Linhagem Celular , Humanos , Sarampo/tratamento farmacológico , Sarampo/mortalidade , Sarampo/virologia , Vírus do Sarampo/genética , Vírus do Sarampo/fisiologia , Camundongos , Camundongos Transgênicos , Proteínas Virais de Fusão/genética , Proteínas Virais de Fusão/metabolismo , Internalização do Vírus/efeitos dos fármacosRESUMO
The paramyxovirus entry machinery consists of two glycoproteins that tightly cooperate to achieve membrane fusion for cell entry: the tetrameric attachment protein (HN, H, or G, depending on the paramyxovirus genus) and the trimeric fusion protein (F). Here, we explore whether receptor-induced conformational changes within morbillivirus H proteins promote membrane fusion by a mechanism requiring the active destabilization of prefusion F or by the dissociation of prefusion F from intracellularly preformed glycoprotein complexes. To properly probe F conformations, we identified anti-F monoclonal antibodies (MAbs) that recognize conformation-dependent epitopes. Through heat treatment as a surrogate for H-mediated F triggering, we demonstrate with these MAbs that the morbillivirus F trimer contains a sufficiently high inherent activation energy barrier to maintain the metastable prefusion state even in the absence of H. This notion was further validated by exploring the conformational states of destabilized F mutants and stabilized soluble F variants combined with the use of a membrane fusion inhibitor (3g). Taken together, our findings reveal that the morbillivirus H protein must lower the activation energy barrier of metastable prefusion F for fusion triggering.
Assuntos
Hemaglutininas Virais/química , Hemaglutininas Virais/metabolismo , Morbillivirus/fisiologia , Proteínas Virais de Fusão/química , Proteínas Virais de Fusão/metabolismo , Internalização do Vírus , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Antivirais/imunologia , Linhagem Celular , Epitopos/imunologia , Humanos , Ligação Proteica , Conformação ProteicaRESUMO
Hendra virus (HeV) and Nipah virus (NiV) are closely related, recently emerged paramyxoviruses that form Henipavirus genus and are capable of causing considerable morbidity and mortality in a number of mammalian species, including humans. However, in contrast to many other species and despite expression of functional virus entry receptors, mice are resistant to henipavirus infection. We report here the susceptibility of mice deleted for the type I interferon receptor (IFNAR-KO) to both HeV and NiV. Intraperitoneally infected mice developed fatal encephalitis, with pathology and immunohistochemical features similar to what was found in humans. Viral RNA was found in the majority of analyzed organs, and sublethally infected animals developed virus-specific neutralizing antibodies. Altogether, these results reveal IFNAR-KO mice as a new small animal model to study HeV and NiV pathogenesis, prophylaxis, and treatment and suggest the critical role of type I interferon signaling in the control of henipavirus infection.
Assuntos
Anticorpos Antivirais/imunologia , Encefalite Viral/prevenção & controle , Infecções por Henipavirus/prevenção & controle , Henipavirus/imunologia , Interferon Tipo I/genética , Animais , Anticorpos Neutralizantes , Especificidade de Anticorpos , Encéfalo/virologia , Células Cultivadas , Modelos Animais de Doenças , Encefalite Viral/imunologia , Encefalite Viral/mortalidade , Encefalite Viral/virologia , Vírus Hendra/genética , Vírus Hendra/imunologia , Vírus Hendra/patogenicidade , Henipavirus/genética , Henipavirus/patogenicidade , Infecções por Henipavirus/imunologia , Infecções por Henipavirus/mortalidade , Infecções por Henipavirus/virologia , Humanos , Interferon Tipo I/imunologia , Camundongos , Camundongos Knockout , Neuroglia/virologia , Vírus Nipah/genética , Vírus Nipah/imunologia , Vírus Nipah/patogenicidade , RNA Viral/análise , Transdução de Sinais , Análise de Sobrevida , Virulência , Internalização do Vírus , Replicação ViralRESUMO
Nipah virus (NiV) and Hendra virus (HeV) are closely related, recently emerged paramyxoviruses that are capable of causing considerable morbidity and mortality in several mammalian species, including humans. Henipavirus-specific vaccines are still commercially unavailable, and development of novel antiviral strategies to prevent lethal infections due to henipaviruses is highly desirable. Here we describe the development of adeno-associated virus (AAV) vaccines expressing the NiV G protein. Characterization of these vaccines in mice demonstrated that a single intramuscular AAV injection was sufficient to induce a potent and long-lasting antibody response. Translational studies in hamsters further demonstrated that all vaccinated animals were protected against lethal challenge with NiV. In addition, this vaccine induced a cross-protective immune response that was able to protect 50% of the animals against a challenge by HeV. This study presents a new efficient vaccination strategy against henipaviruses and opens novel perspectives on the use of AAV vectors as vaccines against emergent diseases.
Assuntos
Dependovirus/genética , Vetores Genéticos/genética , Infecções por Henipavirus/imunologia , Infecções por Henipavirus/prevenção & controle , Vacinas Sintéticas/imunologia , Vacinas Virais/imunologia , Animais , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Linhagem Celular Tumoral , Cricetinae , Modelos Animais de Doenças , Infecções por Henipavirus/virologia , Humanos , Imunidade Humoral , Imunoglobulina G/imunologia , Masculino , Camundongos , Vacinas Sintéticas/genética , Vacinas Virais/genéticaRESUMO
Measles virus is one of the most contagious airborne human viruses which keeps causing outbreaks in numerous countries over the world despite the existence of an efficient vaccine. Fusion inhibitory lipopeptides were shown to inhibit viral entry into target cells, and their adequate administration into the respiratory tract may provide a novel preventive approach against airborne infections. Aerosol delivery presents the best administration route to deliver such preventive compounds to the upper and lower respiratory tract. This approach offers a conceptually new strategy to protect the population at risk against infection by respiratory viruses, including measles. It is a noninvasive needle-free approach, which may be used when antiviral protection is required, without any medical assistance. In this chapter, we describe the nebulization approach of lipopeptide compounds in nonhuman primates and the subsequent measles virus challenge.
Assuntos
Aerossóis , Modelos Animais de Doenças , Vírus do Sarampo , Sarampo , Animais , Sarampo/prevenção & controle , Lipopeptídeos/administração & dosagem , Humanos , Sistemas de Liberação de Medicamentos/métodosRESUMO
Nipah virus (NiV) has been recently ranked by the World Health Organization as being among the top eight emerging pathogens likely to cause major epidemics, whereas no therapeutics or vaccines have yet been approved. We report a method to deliver immunogenic epitopes from NiV through the targeting of the CD40 receptor of antigen-presenting cells by fusing a selected humanized anti-CD40 monoclonal antibody to the Nipah glycoprotein with conserved NiV fusion and nucleocapsid peptides. In the African green monkey model, CD40.NiV induces specific immunoglobulin A (IgA) and IgG as well as cross-neutralizing responses against circulating NiV strains and Hendra virus and T cell responses. Challenge experiments using a NiV-B strain demonstrate the high protective efficacy of the vaccine, with all vaccinated animals surviving and showing no significant clinical signs or virus replication, suggesting that the CD40.NiV vaccine conferred sterilizing immunity. Overall, results obtained with the CD40.NiV vaccine are highly promising in terms of the breadth and efficacy against NiV.
Assuntos
Vacinas Virais , Animais , Chlorocebus aethiops , Linfócitos T , Formação de Anticorpos , Células Apresentadoras de Antígenos , Replicação ViralRESUMO
Measles virus (MeV) presents a public health threat that is escalating as vaccine coverage in the general population declines and as populations of immunocompromised individuals, who cannot be vaccinated, increase. There are no approved therapeutics for MeV. Neutralizing antibodies targeting viral fusion are one potential therapeutic approach but have not yet been structurally characterized or advanced to clinical use. We present cryo-electron microscopy (cryo-EM) structures of prefusion F alone [2.1-angstrom (Å) resolution], F complexed with a fusion-inhibitory peptide (2.3-Å resolution), F complexed with the neutralizing and protective monoclonal antibody (mAb) 77 (2.6-Å resolution), and an additional structure of postfusion F (2.7-Å resolution). In vitro assays and examination of additional EM classes show that mAb 77 binds prefusion F, arrests F in an intermediate state, and prevents transition to the postfusion conformation. These structures shed light on antibody-mediated neutralization that involves arrest of fusion proteins in an intermediate state.
Assuntos
Anticorpos Monoclonais , Anticorpos Neutralizantes , Anticorpos Antivirais , Microscopia Crioeletrônica , Vírus do Sarampo , Proteínas Virais de Fusão , Anticorpos Neutralizantes/imunologia , Anticorpos Neutralizantes/química , Vírus do Sarampo/imunologia , Vírus do Sarampo/química , Proteínas Virais de Fusão/imunologia , Proteínas Virais de Fusão/química , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/química , Anticorpos Antivirais/imunologia , Anticorpos Antivirais/química , Humanos , Conformação ProteicaRESUMO
Nipah virus (NiV) is a highly pathogenic, negative-strand RNA paramyxovirus that has recently emerged from flying foxes to cause serious human disease. We have analyzed the role of the nonstructural NiV C protein in viral immunopathogenesis using recombinant virus lacking the expression of NiV C (NiVΔC). While wild-type NiV was highly pathogenic in the hamster animal model, NiVΔC was strongly attenuated. Replication of NiVΔC was followed by the production of NiV-specific antibodies and associated with higher recruitment of inflammatory cells and less intensive histopathological lesions in different organs than in wild-type-NiV-infected animals. To analyze the molecular basis of NiVΔC attenuation, we studied early changes in gene expression in infected primary human endothelial cells, a major cellular target of NiV infection. The transcriptomic approach revealed the striking difference between wild-type and mutant NiV in the expression of genes involved in immunity, with the particularly interesting differential patterns of proinflammatory cytokines. Compared to wild-type virus, NiVΔC induced increased expression of interleukin 1 beta (IL-1ß), IL-8, CXCL2, CXCL3, CXCL6, CCL20, and beta interferon. Furthermore, the expression of NiV C in stably transfected cells decreased the production of the same panel of cytokines, revealing a role of the C protein in the regulation of cytokine balance. Together, these results suggest that NiV C regulates expression of proinflammatory cytokines, therefore providing a signal responsible for the coordination of leukocyte recruitment and the chemokine-induced immune response and controlling the lethal outcome of the infection.
Assuntos
Fosfoproteínas/genética , Fosfoproteínas/fisiologia , Proteínas Virais/genética , Proteínas Virais/fisiologia , Animais , Cricetinae , Citocinas/metabolismo , Células Endoteliais/citologia , Células Endoteliais/virologia , Regulação Viral da Expressão Gênica , Células HEK293 , Humanos , Inflamação , Mesocricetus , Microcirculação , Vírus Nipah/metabolismo , Proteínas Recombinantes/química , Fatores de Tempo , Veias Umbilicais/citologia , VirulênciaRESUMO
While the function of cGAS/STING signalling axis in the innate immune response to DNA viruses is well deciphered, increasing evidence demonstrates its significant contribution in the control of RNA virus infections. After the first evidence of cGAS/STING antagonism by flaviviruses, STING activation has been detected following infection by various enveloped RNA viruses. It has been discovered that numerous viral families have implemented advanced strategies to antagonize STING pathway through their evolutionary path. This review summarizes the characterized cGAS/STING escape strategies to date, together with the proposed mechanisms of STING signalling activation perpetrated by RNA viruses and discusses possible therapeutic approaches. Further studies regarding the interaction between RNA viruses and cGAS/STING-mediated immunity could lead to major discoveries important for the understanding of immunopathogenesis and for the treatment of RNA viral infections.
Assuntos
Imunidade Inata , Vírus de RNA , Humanos , Nucleotidiltransferases/metabolismo , Transdução de SinaisRESUMO
The Nipah and Hendra viruses, belonging to henipavirus genus, are recently emerged zoonotic pathogens that cause severe and often fatal, neurologic, and/or respiratory diseases in both humans and various animals. As mice represent a small animal model convenient to study viral infections and provide a well-developed experimental toolbox for analysis in immunovirology, we describe in this chapter a few basic methods used in biosafety 4 level (BSL4) conditions to study henipavirus infection in mice.