RESUMO
BACKGROUND: Torque teno virus (TTV) is part of the human virome. TTV load was related to the immune status in patients after organ transplantation. We hypothesize that TTV load could be an additional marker for immune function in people living with HIV (PLWH). METHODS: In this analysis, serum samples of PLWH from the RESINA multicenter cohort were reanalyzed for TTV. Investigated clinical and epidemiological parameters included human pegivirus load, patient age and sex, HIV load, CD4+ T-cell count (Centers for Disease Control and Prevention [CDC] stage 1, 2, or 3), and CDC clinical stage (1993 CDC classification system; stage A, B, or C) before initiation of antiretroviral therapy. Regression analysis was used to detect possible associations among parameters. RESULTS: Our analysis confirmed TTV as a strong predictor of CD4+ T-cell count and CDC class 3. This relationship was used to propose a first classification of TTV load with regard to clinical stage. We found no association with clinical CDC stages A-C. The human pegivirus load was inversely correlated with HIV load but not TTV load. CONCLUSIONS: TTV load was associated with immunodeficiency in PLWH. Neither TTV nor HIV load were predictive for the clinical categories of HIV infection.
Assuntos
Infecções por Vírus de DNA , Infecções por HIV , Torque teno virus , Carga Viral , Humanos , Torque teno virus/isolamento & purificação , Masculino , Feminino , Contagem de Linfócito CD4 , Adulto , Pessoa de Meia-Idade , Infecções por HIV/imunologia , Infecções por HIV/virologia , Infecções por HIV/tratamento farmacológico , Infecções por HIV/complicações , Infecções por Vírus de DNA/virologia , Infecções por Vírus de DNA/imunologia , Infecções por Vírus de DNA/epidemiologia , Estados Unidos/epidemiologia , Centers for Disease Control and Prevention, U.S. , Flaviviridae/imunologia , Estudos de Coortes , Síndrome da Imunodeficiência Adquirida/imunologia , Síndrome da Imunodeficiência Adquirida/virologiaRESUMO
A novel blood-borne human pegivirus (HPgV), HPgV-2, was recently identified in hepatitis C virus (HCV)-infected individuals and individuals who had received multiple transfusions. Robust serological assays capable of detecting antibodies in HPgV-2-infected individuals are needed to establish global seroprevalence rates and potential disease associations. The two objectives of this study were to determine the utility of mammalian cell-expressed HPgV-2 E2 glycoprotein or bacterium-expressed nonstructural protein 4AB (NS4AB) in detecting past or present infections and to compare the total prevalence (antibody and RNA positive) of HPgV-2 with that of the other human pegivirus, HPgV-1 (GB virus C [GBV-C]). HPgV-2 E2 antibodies were detected in 13 (92.86%) of 14 HPgV-2-viremic cases, and NS4AB antibodies were detected in 8 (57.14%) of 14 cases. The HPgV-2 seroprevalence was significantly higher (P < 0.0001) among HCV-infected individuals (3.31% [24 of 726 samples]) than among non-HCV-infected individuals (0.30% [4 of 1,348 samples]). Of 31 anti-E2-positive samples, 22 had supplemental supporting data; 12 samples were HPgV-2 RNA positive and 10 nonviremic samples were antibody positive for peptides or NS4AB. The total prevalence of HPgV-1 (35.00%) was significantly higher than that of HPgV-2 (1.33%) in all populations tested (P < 0.0001). For HPgV-1, codetection of antibodies to E2 and RNA was infrequent (5.88%). In contrast, antibodies to E2 were detected in most HPgV-2-viremic individuals (92.86%), as is observed among individuals chronically infected with HCV, most of whom are antibody positive for HCV E2. Our studies indicate that HPgV-2 circulates with HCV and displays a profile similar to the serological profile of HCV-infected persons, although the pathogenicity of this virus has yet to be established.
Assuntos
Anticorpos Antivirais/sangue , Infecções por Flaviviridae/epidemiologia , Infecções por Flaviviridae/virologia , Flaviviridae/imunologia , Antígenos Virais/genética , Antígenos Virais/imunologia , Infecções por Flaviviridae/imunologia , Humanos , Proteínas Recombinantes/genética , Proteínas Recombinantes/imunologia , Estudos SoroepidemiológicosRESUMO
UNLABELLED: Zika virus (ZIKV) is an emerging arbovirus of the Flaviviridae family, which includes dengue, West Nile, yellow fever, and Japanese encephalitis viruses, that causes a mosquito-borne disease transmitted by the Aedes genus, with recent outbreaks in the South Pacific. Here we examine the importance of human skin in the entry of ZIKV and its contribution to the induction of antiviral immune responses. We show that human dermal fibroblasts, epidermal keratinocytes, and immature dendritic cells are permissive to the most recent ZIKV isolate, responsible for the epidemic in French Polynesia. Several entry and/or adhesion factors, including DC-SIGN, AXL, Tyro3, and, to a lesser extent, TIM-1, permitted ZIKV entry, with a major role for the TAM receptor AXL. The ZIKV permissiveness of human skin fibroblasts was confirmed by the use of a neutralizing antibody and specific RNA silencing. ZIKV induced the transcription of Toll-like receptor 3 (TLR3), RIG-I, and MDA5, as well as several interferon-stimulated genes, including OAS2, ISG15, and MX1, characterized by strongly enhanced beta interferon gene expression. ZIKV was found to be sensitive to the antiviral effects of both type I and type II interferons. Finally, infection of skin fibroblasts resulted in the formation of autophagosomes, whose presence was associated with enhanced viral replication, as shown by the use of Torin 1, a chemical inducer of autophagy, and the specific autophagy inhibitor 3-methyladenine. The results presented herein permit us to gain further insight into the biology of ZIKV and to devise strategies aiming to interfere with the pathology caused by this emerging flavivirus. IMPORTANCE: Zika virus (ZIKV) is an arbovirus belonging to the Flaviviridae family. Vector-mediated transmission of ZIKV is initiated when a blood-feeding female Aedes mosquito injects the virus into the skin of its mammalian host, followed by infection of permissive cells via specific receptors. Indeed, skin immune cells, including dermal fibroblasts, epidermal keratinocytes, and immature dendritic cells, were all found to be permissive to ZIKV infection. The results also show a major role for the phosphatidylserine receptor AXL as a ZIKV entry receptor and for cellular autophagy in enhancing ZIKV replication in permissive cells. ZIKV replication leads to activation of an antiviral innate immune response and the production of type I interferons in infected cells. Taken together, these results provide the first general insights into the interaction between ZIKV and its mammalian host.
Assuntos
Células Dendríticas/virologia , Flaviviridae/fisiologia , Queratinócitos/virologia , Internalização do Vírus , Replicação Viral , Aedes/virologia , Animais , Autofagia/imunologia , Moléculas de Adesão Celular/genética , Moléculas de Adesão Celular/metabolismo , Células Cultivadas , Chlorocebus aethiops , Citocinas/biossíntese , Proteína DEAD-box 58 , RNA Helicases DEAD-box/genética , RNA Helicases DEAD-box/metabolismo , Células Dendríticas/imunologia , Fibroblastos/virologia , Flaviviridae/imunologia , Infecções por Flaviviridae/imunologia , Infecções por Flaviviridae/virologia , Células HEK293 , Receptor Celular 1 do Vírus da Hepatite A , Humanos , Insetos Vetores/virologia , Helicase IFIH1 Induzida por Interferon , Interferon beta/biossíntese , Interferon beta/imunologia , Lectinas Tipo C/genética , Lectinas Tipo C/metabolismo , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Proteínas de Resistência a Myxovirus/biossíntese , Fagossomos/imunologia , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Interferência de RNA , RNA Interferente Pequeno , Receptores Proteína Tirosina Quinases/genética , Receptores Proteína Tirosina Quinases/metabolismo , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Receptores Imunológicos , Receptores Virais/genética , Receptores Virais/metabolismo , Pele/imunologia , Pele/virologia , Receptor 3 Toll-Like/genética , Receptor 3 Toll-Like/imunologia , Receptor 3 Toll-Like/metabolismo , Receptor 7 Toll-Like/imunologia , Ubiquitinas/biossíntese , Células Vero , Receptor Tirosina Quinase AxlRESUMO
The family Flaviviridae comprises a wide variety of viruses that are distributed worldwide, some of which are associated with high rates of morbidity and mortality. There are neither vaccines nor antivirals for most flavivirus infections, reinforcing the importance of research on different aspects of the viral life cycle. During infection, cytoplasmic accumulation of RNA fragments mainly originating from the 3' UTRs, which have been designated subgenomic flavivirus RNAs (sfRNAs), has been detected. It has been shown that eukaryotic exoribonucleases are involved in viral sfRNA production. Additionally, viral and human small RNAs (sRNAs) have also been found in flavivirus-infected cells, especially microRNAs (miRNAs). miRNAs were first described in eukaryotic cells and in a mature and functional state present as single-stranded 18-24 nt RNA fragments. Their main function is the repression of translation through base pairing with cellular mRNAs, besides other functions, such as mRNA degradation. Canonical miRNA biogenesis involves Drosha and Dicer, however miRNA can also be generated by alternative pathways. In the case of flaviviruses, alternative pathways have been suggested. Both sfRNAs and miRNAs are involved in viral infection and host cell response modulation, representing interesting targets of antiviral strategies. In this review, we focus on the generation and function of viral sfRNAs, sRNAs and miRNAs in West Nile, dengue, Japanese encephalitis, Murray Valley encephalitis and yellow fever infections, as well as their roles in viral replication, translation and cell immune response evasion. We also give an overview regarding other flaviviruses and the generation of cellular miRNAs during infection.
Assuntos
Infecções por Flavivirus/imunologia , Infecções por Flavivirus/virologia , Interações Hospedeiro-Patógeno , MicroRNAs/análise , RNA Viral/análise , Animais , Flaviviridae/genética , Flaviviridae/imunologia , Flaviviridae/fisiologia , Regulação da Expressão Gênica , Humanos , MicroRNAs/genética , RNA Viral/genética , Replicação ViralRESUMO
Duck Tembusu virus (DTMUV) is a newly emerging pathogenic flavivirus that has caused massive economic losses to the duck industry in China. Envelope (E) protein of DTMUV is an important structural protein, which is able to induce protective immune response in target animals and can be used as specific serological diagnosis tool. In this study, a novel monoclonal antibody, designated mAb 3E9, was generated against DTMUV E protein. It is positive in indirect ELISA against both His-E protein and the purified whole viral antigen. Also, this mAb showed positive reaction with DTMUV in Western blot and indirect immunofluorescence assay, and the isotype was IgG1. End-point neutralizing assay performed in BHK-21 cells revealed that the neutralization titer of 3E9 against DTMUV JS804 strain reached 1:50. Furthermore, functional studies revealed that 3E9 blocks infection of DTMUV at a step on viral attachment. The anti-E mAbs produced in the present work may be valuable in developing an antigen-capture ELISA test for antigen detection or a competitive ELISA test for antibody detection or therapeutic medicine for DTMUV in poultry.
Assuntos
Anticorpos Monoclonais , Patos , Flaviviridae/imunologia , Proteínas do Envelope Viral/fisiologia , Animais , Linhagem Celular Tumoral , Cricetinae , Feminino , Flaviviridae/metabolismo , Regulação Viral da Expressão Gênica , Camundongos , Camundongos Endogâmicos BALB C , Testes de NeutralizaçãoRESUMO
Assays with the ability to detect multiple antibodies in parallel have a wide range of potential applications in epidemiologic research. Here, a multiplex enzyme-linked immunosorbent assay-based protein array (ELISA-array) was developed to simultaneously detect five Flaviviridae infections. The platform was based on an indirect ELISA and 15 antigens were constructed for specific antibody detection against five Flaviviridae viruses (Japanese B, tick-borne encephalitis, West Nile, dengue, and yellow fever viruses) and four serotypes of dengue virus. The specificity was evaluated by calculating the signal value cross-reacting with serum immunized with other viruses, and the sensitivity of antigens was compared with conventional ELISAs using immunized rabbit polyclonal antisera. IgG and IgM calibration curves were constructed to evaluate the reproducibility of the platform. Finally, 24 dengue fever (DF) infection and 15 tick-borne encephalitis (TBE) infection clinical sera were used to compare the advantage of ELISA-array to ELISA. After initial screening, 9 out of 15 antigens were chosen for ELISA-array printing. By using different virus-immunized rabbit antiserum, 7 out of 9 antigens showed good specificity in the ELISA-array. Eight out of 9 antigens showed four-fold greater sensitivity in ELISA-array compared to that in conventional ELISAs. The coefficients of determination (r (2)) close to 1 showed high reproducibility, and clinical sera test showed that ELISA-array had higher specificity and sensitivity than traditional ELISA. ELISA-array was a good platform for antigen screening and this multiplexed assay might be a useful and convenient tool for multiple immunological detection of infectious viral antibodies.
Assuntos
Antígenos Virais/imunologia , Ensaio de Imunoadsorção Enzimática , Infecções por Flaviviridae/diagnóstico , Infecções por Flaviviridae/imunologia , Flaviviridae/imunologia , Análise Serial de Proteínas , Animais , Flaviviridae/genética , Infecções por Flaviviridae/virologia , Humanos , Soros Imunes/imunologia , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Imunoglobulina M/sangue , Imunoglobulina M/imunologia , Coelhos , Reprodutibilidade dos Testes , Sensibilidade e EspecificidadeRESUMO
Non-primate hepacivirus (NPHV), equine pegivirus (EPgV) and Theiler's disease associated virus (TDAV) are newly discovered members of two genera in the Flaviviridae family, Hepacivirus and Pegivirus respectively, that include human hepatitis C virus (HCV) and human pegivirus (HPgV). To investigate their epidemiology, persistence and clinical features of infection, large cohorts of horses and other mammalian species were screened for NPHV, EPgV and TDAV viraemia and for past exposure through serological assays for NPHV and EPgV-specific antibodies. NPHV antibodies were detected in 43% of 328 horses screened for antibodies to NS3 and core antibodies, of which three were viraemic by PCR. All five horses that were stablemates of a viraemic horse were seropositive, as was a dog on the same farm. With this single exception, all other species were negative for NPHV antibodies and viraemia: donkeys (n=100), dogs (n=112), cats (n=131), non-human primates (n=164) and humans (n=362). EPgV antibodies to NS3 were detected in 66.5% of horses, including 10 of the 12 horses that had EPgV viraemia. All donkey samples were negative for EPgV antibody and RNA. All horse and donkey samples were negative for TDAV RNA. By comparing viraemia frequencies in horses with and without liver disease, no evidence was obtained that supported an association between active NPHV and EPgV infections with hepatopathy. The study demonstrates that NPHV and EPgV infections are widespread and enzootic in the study horse population and confirms that NPHV and potentially EPgV have higher frequencies of viral clearance than HCV and HPgV infections in humans.
Assuntos
Anticorpos Antivirais/sangue , Infecções por Flaviviridae/veterinária , Flaviviridae/imunologia , Flaviviridae/isolamento & purificação , Infecções por Flavivirus/veterinária , Doenças dos Cavalos/epidemiologia , Viremia/epidemiologia , Animais , Doenças do Cão/epidemiologia , Doenças do Cão/virologia , Cães , Infecções por Flaviviridae/epidemiologia , Infecções por Flaviviridae/virologia , Infecções por Flavivirus/epidemiologia , Infecções por Flavivirus/virologia , Doenças dos Cavalos/virologia , Cavalos , Dados de Sequência Molecular , Análise de Sequência de DNA , Estudos SoroepidemiológicosRESUMO
Interferon (IFN) signaling is initiated by the recognition of viral components by host pattern recognition receptors. Dengue virus (DEN) triggers IFN-beta induction through a molecular mechanism involving the cellular RIG-I/MAVS signaling pathway. Here we report that the MAVS protein level is reduced in DEN-infected cells and that caspase-1 and caspase-3 cleave MAVS at residue D429. In addition to its well-known function in IFN induction, MAVS is also a proapoptotic molecule that triggers disruption of the mitochondrial membrane potential and activation of caspases. Although different domains are required for the induction of cytotoxicity and IFN, caspase cleavage at residue 429 abolished both functions of MAVS. The apoptotic role of MAVS in viral infection and double-stranded RNA (dsRNA) stimulation was demonstrated in cells with reduced endogenous MAVS expression induced by RNA interference. Even though IFN-beta promoter activation was largely suppressed, DEN production was not affected greatly in MAVS knockdown cells. Instead, DEN- and dsRNA-induced cell death and caspase activation were delayed and attenuated in the cells with reduced levels of MAVS. These results reveal a new role of MAVS in the regulation of cell death beyond its well-known function of IFN induction in antiviral innate immunity.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/imunologia , Caspases/metabolismo , Interferons/imunologia , Potencial da Membrana Mitocondrial/fisiologia , Transdução de Sinais/imunologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Morte Celular/imunologia , Linhagem Celular , Dengue/imunologia , Ativação Enzimática , Flaviviridae/imunologia , Humanos , Imunidade Inata , Indutores de Interferon/imunologia , Isoenzimas/metabolismo , Camundongos , Poli I-C/imunologia , Interferência de RNA , RNA de Cadeia Dupla/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismoRESUMO
Two viruses, GB virus A (GBV-A) and GB virus B (GBV-B), were recently identified in the GB hepatitis agent. Human sera containing antibodies that recognize GBV-A and/or GBV-B recombinant proteins were subjected to polymerase chain reaction studies with degenerate oligonucleotides capable of amplifying a segment of the putative helicase genes from GBV-A, GBV-B or hepatitis C virus. Novel sequences related to members of the Flaviviridae were identified in sera from 12 individuals including 4 individuals with hepatitis. The limited nucleotide sequence identity between GBV-A, GBV-B and HCV sequences suggests that a novel virus, tentatively named GB virus C, may be responsible for some cases of non-A, non-B, non-C, non-D, non-E hepatitis.
Assuntos
Flaviviridae/isolamento & purificação , Vírus de Hepatite/isolamento & purificação , Hepatite Viral Humana/virologia , Viremia/virologia , Adulto , África Oriental/epidemiologia , África Ocidental/epidemiologia , Sequência de Aminoácidos , Anticorpos Antivirais/sangue , Sequência de Bases , Canadá/epidemiologia , Comorbidade , DNA Helicases/genética , Feminino , Flaviviridae/genética , Flaviviridae/imunologia , Vírus de Hepatite/genética , Vírus de Hepatite/imunologia , Hepatite Viral Humana/sangue , Hepatite Viral Humana/epidemiologia , Humanos , Masculino , Programas de Rastreamento , Dados de Sequência Molecular , Filogenia , Reação em Cadeia da Polimerase , Prevalência , Fatores de Risco , Alinhamento de Sequência , Homologia de Sequência , Abuso de Substâncias por Via Intravenosa/epidemiologia , Abuso de Substâncias por Via Intravenosa/virologia , Proteínas não Estruturais Virais/genéticaAssuntos
Aedes , Doenças Transmissíveis Emergentes/epidemiologia , Epidemias , Insetos Vetores/virologia , Infecção por Zika virus/epidemiologia , Zika virus , América/epidemiologia , Animais , Pesquisa Biomédica , Doenças Transmissíveis Emergentes/diagnóstico , Doenças Transmissíveis Emergentes/imunologia , Doenças Transmissíveis Emergentes/virologia , Flaviviridae/imunologia , Humanos , Zika virus/classificação , Zika virus/imunologia , Infecção por Zika virus/diagnóstico , Infecção por Zika virus/imunologia , Infecção por Zika virus/transmissãoRESUMO
Many mosquito-borne viruses (arboviruses) are endemic in Africa, contributing to systemic and neurological infections in various geographical locations on the continent. While most arboviral infections do not lead to neuroinvasive diseases of the central nervous system, neurologic diseases caused by arboviruses include flaccid paralysis, meningitis, encephalitis, myelitis, encephalomyelitis, neuritis, and post-infectious autoimmune or memory disorders. Here we review endemic members of the Flaviviridae and Togaviridae families that cause neurologic infections, their neuropathogenesis and host neuroimmunological responses in Africa. We also discuss the potential for neuroimmune responses to aide in the development of new diagnostics and therapeutics, and current knowledge gaps to be addressed by arbovirus research.
Assuntos
Infecções por Arbovirus/imunologia , Arbovírus/imunologia , Sistema Nervoso Central/imunologia , Encefalite por Arbovirus/imunologia , África/epidemiologia , Animais , Infecções por Arbovirus/epidemiologia , Infecções por Arbovirus/virologia , Arbovírus/classificação , Arbovírus/fisiologia , Bunyaviridae/imunologia , Bunyaviridae/fisiologia , Sistema Nervoso Central/virologia , Encefalite por Arbovirus/epidemiologia , Encefalite por Arbovirus/virologia , Epidemias , Flaviviridae/imunologia , Flaviviridae/fisiologia , Humanos , Togaviridae/imunologia , Togaviridae/fisiologiaRESUMO
Innate immunity has evolved complex molecular pathways to protect organisms from viral infections. One pivotal line of cellular defense is the induction of the antiviral effect of interferon. To circumvent this primary response and achieve their own replication, viruses have developed complex molecular strategies. Here, we provide a systems-level study of the human type I interferon system subversion by the viral proteome, by reconstructing the underlying protein-protein interaction network. At this network level, viruses establish a massive and a gradual attack, from receptors to transcription factors, by interacting preferentially with highly connected and central proteins as well as interferon-induced proteins. We also demonstrate that viruses significantly target 22% of the proteins directly interacting with the type I interferon system network, suggesting the relevance of our network-based method to identify new candidates involved in the regulation of the antiviral response. Finally, based on the comparative analysis of interactome profiles across four viral families, we provide evidence of common and differential targeting strategies.
Assuntos
Interações Hospedeiro-Patógeno/imunologia , Interferon Tipo I/imunologia , Mapeamento de Interação de Proteínas/métodos , Biologia de Sistemas/métodos , Vírus/imunologia , Bases de Dados Genéticas , Flaviviridae/imunologia , Herpesviridae/imunologia , Humanos , Papillomaviridae/imunologia , Retroviridae/imunologia , Transdução de Sinais , Estatísticas não ParamétricasRESUMO
Ticks transmit a wide variety of pathogens including bacteria, parasites and viruses. Over the last decade, numerous novel viruses have been described in arthropods, including ticks, and their characterization has provided new insights into RNA virus diversity and evolution. However, little is known about their ability to infect vertebrates. As very few studies have described the diversity of viruses present in ticks from the Caribbean, we implemented an RNA-sequencing approach on Amblyomma variegatum and Rhipicephalus microplus ticks collected from cattle in Guadeloupe and Martinique. Among the viral communities infecting Caribbean ticks, we selected four viruses belonging to the Chuviridae, Phenuiviridae and Flaviviridae families for further characterization and designing antibody screening tests. While viral prevalence in individual tick samples revealed high infection rates, suggesting a high level of exposure of Caribbean cattle to these viruses, no seropositive animals were detected. These results suggest that the Chuviridae- and Phenuiviridae-related viruses identified in the present study are more likely tick endosymbionts, raising the question of the epidemiological significance of their occurrence in ticks, especially regarding their possible impact on tick biology and vector capacity. The characterization of these viruses might open the door to new ways of preventing and controlling tick-borne diseases.
Assuntos
Doenças dos Bovinos , Flaviviridae/isolamento & purificação , Ixodidae/virologia , Vírus de RNA/classificação , Vírus de RNA/isolamento & purificação , Rhipicephalus/virologia , Infestações por Carrapato/veterinária , Animais , Anticorpos Antivirais/sangue , Bovinos/imunologia , Doenças dos Bovinos/imunologia , Doenças dos Bovinos/parasitologia , Suscetibilidade a Doenças , Flaviviridae/genética , Flaviviridae/imunologia , Genoma Viral , Martinica , Filogenia , Vírus de RNA/genética , Vírus de RNA/imunologia , RNA Viral/análise , RNA Viral/genética , Estudos Soroepidemiológicos , Infestações por Carrapato/imunologia , Índias OcidentaisRESUMO
Alpha/beta interferon immune defenses are essential for resistance to viruses and can be triggered through the actions of the cytoplasmic helicases retinoic acid-inducible gene I (RIG-I) and melanoma differentiation-associated gene 5 (MDA5). Signaling by each is initiated by the recognition of viral products such as RNA and occurs through downstream interaction with the IPS-1 adaptor protein. We directly compared the innate immune signaling requirements of representative viruses of the Flaviviridae, Orthomyxoviridae, Paramyxoviridae, and Reoviridae for RIG-I, MDA5, and interferon promoter-stimulating factor 1 (IPS-1). In cultured fibroblasts, IPS-1 was essential for innate immune signaling of downstream interferon regulatory factor 3 activation and interferon-stimulated gene expression, but the requirements for RIG-I and MDA5 were variable. Each was individually dispensable for signaling triggered by reovirus and dengue virus, whereas RIG-I was essential for signaling by influenza A virus, influenza B virus, and human respiratory syncytial virus. Functional genomics analyses identified cellular genes triggered during influenza A virus infection whose expression was strictly dependent on RIG-I and which are involved in processes of innate or adaptive immunity, apoptosis, cytokine signaling, and inflammation associated with the host response to contemporary and pandemic strains of influenza virus. These results define IPS-1-dependent signaling as an essential feature of host immunity to RNA virus infection. Our observations further demonstrate differential and redundant roles for RIG-I and MDA5 in pathogen recognition and innate immune signaling that may reflect unique and shared biologic properties of RNA viruses whose differential triggering and control of gene expression may impact pathogenesis and infection.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/imunologia , RNA Helicases DEAD-box/imunologia , Imunidade Inata/fisiologia , Vírus de RNA/imunologia , Transdução de Sinais/imunologia , Animais , Células Cultivadas , Proteína DEAD-box 58 , Fibroblastos/imunologia , Fibroblastos/virologia , Flaviviridae/imunologia , Regulação da Expressão Gênica , Fator Regulador 3 de Interferon/biossíntese , Helicase IFIH1 Induzida por Interferon , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Orthomyxoviridae/imunologia , Paramyxoviridae/imunologia , Reoviridae/imunologiaRESUMO
BACKGROUND: Alongshan virus (ALSV) is a novel discovered segmented flavivirus associated with human febrile illness in northeastern China. Ixodes persulcatus is considered as a candidate vector of ALSV in the endemic regions. However, the role of domesticated animals in the circulation and transmission of ALSV have not been investigated. To evaluate the prevalence of ALSV infections in domesticated animals, viral RNA and viral specific antibodies were detected in sheep and cattle in Hulunbuir of northeastern Inner Mongolia. The findings contribute to the understanding of the ecology and transmission of ALSV among different natural hosts. METHODS: A total of 480 animal serum samples were collected in Hulunbuir of northeastern China in May, 2017. Viral specific antibodies were tested by indirect enzyme-linked immunosorbent assay (ELISA) with a purified E. coli recombinant capsid protein (VP2) of ALSV (strain H3) and further detected by viral neutralization test (VNT). RNA in serum samples were extracted and detected for ALSV sequence by quantitative real-time RT-PCR. ALSV RNA positive samples were used for virus isolation. RESULTS: ALSV-specific antibodies were detected in 9.2% (22/240) of examined sheep and 4.6% (11/240) of examined cattle by ELISA, while lower serological positivity with 4.2% (10/240) for sheep and 1.7% (4/240) for cattle was confirmed by VNT. In contrast, the prevalence of ALSV RNA was much higher, ranging from 26.3% (63/240) in sheep to 27.5% (66/240) in cattle. The partial S1 (NS5-like) and S3 (NS3-like) segments of ALSVs in sheep and cattle shared high identities of more than 98% to the human and tick isolates in the studied regions. CONCLUSIONS: These results suggest that the natural infection of ALSV can be found in sheep and cattle in the endemic regions.
Assuntos
Anticorpos Antivirais/sangue , Doenças dos Bovinos/epidemiologia , Reservatórios de Doenças/virologia , Infecções por Flaviviridae/veterinária , Flaviviridae/isolamento & purificação , RNA Viral/sangue , Doenças dos Ovinos/epidemiologia , Animais , Bovinos , Doenças dos Bovinos/virologia , China/epidemiologia , Ensaio de Imunoadsorção Enzimática , Flaviviridae/genética , Flaviviridae/imunologia , Infecções por Flaviviridae/epidemiologia , Infecções por Flaviviridae/virologia , Testes de Neutralização , Prevalência , Reação em Cadeia da Polimerase em Tempo Real , Ovinos , Doenças dos Ovinos/virologiaRESUMO
The paper reviews the known facts on the immunological response in infections with viral haemorrhagic fevers--dangerous pathogens for life and health of people. Immunological process registered in infections with viruses from Arenaviridae, Bunyaviridae, Filoviridae and Flaviviridae have been described. Moreover, the immunological response in infection with the RHD (rabbit haemorrhagic disease) virus from Caliciviridae family have been shown as a potential model for laboratory research on the duration and pathogenesis of viral haemorrhagic fevers.
Assuntos
Arenaviridae/imunologia , Bunyaviridae/imunologia , Filoviridae/imunologia , Flaviviridae/imunologia , Vírus da Doença Hemorrágica de Coelhos/imunologia , Febres Hemorrágicas Virais/imunologia , Animais , Anticorpos Monoclonais/imunologia , Arenaviridae/patogenicidade , Bunyaviridae/patogenicidade , Filoviridae/patogenicidade , Flaviviridae/patogenicidade , Febres Hemorrágicas Virais/virologia , Humanos , PesquisaRESUMO
Infections with viruses in the Flaviviridae family have a vast global and economic impact because of the high morbidity and mortality. The pathogenesis of Flaviviridae infections is very complex and not fully understood because these viruses can inhibit multiple immune pathways including the complement system, NK cells, and IFN induction and signalling pathways. The non-structural (NS) 5 and 5A proteins of Flaviviridae viruses are highly conserved and play an important role in resisting host immunity through various evasion mechanisms. This review summarizes the strategies used by the NS5 and 5A proteins of Flaviviridae viruses for evading the innate immune response by inhibiting pattern recognition receptor (PRR) signalling pathways (TLR/MyD88, IRF7), suppressing interferon (IFN) signalling pathways (IFN-γRs, STAT1, STAT2), and impairing the function of IFN-stimulated genes (ISGs) (e.g. protein kinase R [PKR], oligoadenylate synthase [OAS]). All of these immune evasion mechanisms depend on the interaction of NS5 or NS5A with cellular proteins, such as MyD88 and IRF7, IFN-αRs, IFN-γRs, STAT1, STAT2, PKR and OAS. NS5 is the most attractive target for the discovery of broad spectrum compounds against Flaviviridae virus infection. The methyltransferase (MTase) and RNA-dependent RNA polymerase (RdRp) activities of NS5 are the main therapeutic targets for antiviral drugs against Flaviviridae virus infection. Based on our site mapping, the sites involved in immune evasion provide some potential and promising targets for further novel antiviral therapeutics.
Assuntos
Antivirais/farmacologia , Infecções por Flaviviridae/tratamento farmacológico , Flaviviridae/imunologia , Animais , Desenvolvimento de Medicamentos/métodos , Infecções por Flaviviridae/imunologia , Humanos , Evasão da Resposta Imune/imunologia , Imunidade Inata , Transdução de Sinais/efeitos dos fármacos , Proteínas não Estruturais Virais/imunologiaRESUMO
Virus invasion triggers host immune responses, in particular, innate immune responses. Pathogen-associated molecular patterns of viruses (such as dsRNA, ssRNA, or viral proteins) released during virus replication are detected by the corresponding pattern-recognition receptors of the host, and innate immune responses are induced. Through production of type-I and type-III interferons as well as various other cytokines, the host innate immune system forms the frontline to protect host cells and inhibit virus infection. Not surprisingly, viruses have evolved diverse strategies to counter this antiviral system. In this review, we discuss the multiple strategies used by proteases of positive-sense single-stranded RNA viruses of the families Picornaviridae, Coronaviridae, and Flaviviridae, when counteracting host innate immune responses.
Assuntos
Evasão da Resposta Imune , Imunidade Inata , Interferons/imunologia , Receptores Toll-Like/imunologia , Proteínas Virais/imunologia , Viroses/imunologia , Animais , Coronaviridae/genética , Coronaviridae/imunologia , Citocinas/genética , Citocinas/imunologia , Flaviviridae/genética , Flaviviridae/imunologia , Regulação da Expressão Gênica , Humanos , Interferons/genética , Picornaviridae/genética , Picornaviridae/imunologia , Estrutura Secundária de Proteína , Transdução de Sinais , Receptores Toll-Like/genética , Proteínas Virais/química , Proteínas Virais/genética , Viroses/genética , Viroses/patologia , Replicação ViralRESUMO
BACKGROUND: All hepatotropic viruses are known to cause fulminant hepatic failure (FHF). However, in 30% to 40% of patients with FHF, the precise cause remains unknown. We aimed to better define this subgroup. METHODS: We evaluated the clinical course and outcome of 7 patients admitted during a 22-month period with fulminant viral hepatitis leading to liver transplantation; none had serologic or molecular evidence of hepatitis A, B, C, D, E, or G viral infection, thus the term non-A-G viral hepatitis. All known etiologies of FHF were excluded. RESULTS: All patients had prodromal symptoms suggestive of viral causes. Mean age was 30 years. The interval between onset of jaundice and appearance of encephalopathy was 23 days (range, 4-50 days). Five patients had grade III/IV encephalopathy. Serum alanine aminotransferase levels showed a single peak of activity. The duration between first symptoms and liver transplantation was 28 days (range, 12-71 days). Results of histological study of the explanted liver showed submassive (4 patients) or massive (3 patients) hepatocyte necrosis. In all patients, results of polymerase chain reaction analysis did not detect hepatitis B virus DNA, hepatitis C virus RNA, or hepatitis G virus RNA in the explanted liver. After transplantation, 2 patients showed (6 months later) increased liver enzyme levels of undetermined cause, and results of a liver biopsy showed mild lobular hepatitis; 1 patient had lymphoproliferative disorder (Epstein-Barr virus-originated); and 1 patient, aplastic anemia, which is known to be associated with seronegative viral hepatitis. The latter patient died, whereas the other 6 patients are alive (survival rate, 86%). CONCLUSIONS: Our patients with non-A-G viral hepatitis had a severe acute onset with progressive FHF requiring liver transplantation. There is some suggestion of recurrent viral disease after transplantation implicating other unknown viruses in the etiology.
Assuntos
Hepatite Viral Humana/complicações , Falência Hepática/etiologia , Transplante de Fígado , Adolescente , Adulto , Anticorpos Antivirais/análise , DNA Viral/análise , Feminino , Flaviviridae/genética , Flaviviridae/imunologia , Hepatite Viral Humana/virologia , Hepatovirus/genética , Hepatovirus/imunologia , Humanos , Falência Hepática/cirurgia , Masculino , Estudos Retrospectivos , Resultado do TratamentoRESUMO
BACKGROUND: Auxiliary liver transplantation offers an alternative method to conventional transplantation in acute liver failure. It is especially challenging for children because lifelong immunosuppression may be avoided. However, experience with this procedure is rare and there is controversy about whether to place the graft orthotopically or heterotopically. METHODS: We present the case of a 3-year-old boy with acute liver failure due to non-ABC hepatitis complicated by aplastic anemia who underwent auxiliary liver transplantation. Segments 2 and 3 of the graft were implanted heterotopically in the right lower abdomen. RESULTS: Good liver function was immediately restored. Aplastic anemia resolved 3 weeks after transplantation. Immunosuppressive therapy was discontinued after 14 months, and the graft was left to atrophy. Thirty-nine months after transplantation the boy is alive and well with normal liver function tests and normal blood cell counts. CONCLUSIONS: Heterotopic auxiliary liver transplantation allowed recovery of the native liver in a child with acute liver failure and aplastic anemia due to non-ABC hepatitis.