RESUMO
Severe fever with thrombocytopenia syndrome (SFTS) virus, a tick-borne bunyavirus, causes a severe/fatal disease termed SFTS; however, the viral virulence is not fully understood. The viral non-structural protein, NSs, is the sole known virulence factor. NSs disturbs host innate immune responses and an NSs-mutant SFTS virus causes no disease in an SFTS animal model. The present study reports a novel determinant of viral tropism as well as virulence in animal models, within the glycoprotein (GP) of SFTS virus and an SFTS-related tick-borne bunyavirus. Infection with mutant SFTS viruses lacking the N-linked glycosylation of GP resulted in negligible usage of calcium-dependent lectins in cells, less efficient infection, high susceptibility to a neutralizing antibody, low cytokine production in macrophage-like cells, and reduced virulence in Ifnar-/- mice, when compared with wildtype virus. Three SFTS virus-related bunyaviruses had N-glycosylation motifs at similar positions within their GP and a glycan-deficient mutant of Heartland virus showed in vitro and in vivo phenotypes like those of the SFTS virus. Thus, N-linked glycosylation of viral GP is a novel determinant for the tropism and virulence of SFTS virus and of a related virus. These findings will help us understand the process of severe/fatal diseases caused by tick-borne bunyaviruses.
Assuntos
Glicoproteínas , Phlebovirus , Tropismo Viral , Animais , Glicosilação , Camundongos , Virulência , Phlebovirus/patogenicidade , Phlebovirus/genética , Glicoproteínas/metabolismo , Glicoproteínas/genética , Humanos , Febre Grave com Síndrome de Trombocitopenia/virologia , Camundongos Endogâmicos C57BL , Infecções por Bunyaviridae/virologia , Infecções por Bunyaviridae/metabolismo , Carrapatos/virologia , Camundongos Knockout , Orthobunyavirus/patogenicidade , Orthobunyavirus/genética , Orthobunyavirus/metabolismoRESUMO
Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with high case mortality rates, which is caused by Dabie bandavirus (DBV), a novel pathogen also termed as SFTS virus (SFTSV). Currently, no specific therapeutic drugs or vaccines are available for SFTS. Myxovirus resistance protein A (MxA) has been shown to inhibit multiple viral pathogens; however, the role of MxA in DBV infection is unknown. Here, we demonstrated that DBV stimulates MxA expression which, in turn, restricts DBV infection. Mechanistic target analysis revealed that MxA specifically interacts with the viral nucleocapsid protein (NP) in a manner independent of RNA. Minigenome reporter assay showed that in agreement with its targeting of NP, MxA inhibits DBV ribonucleoprotein (RNP) activity. In detail, MxA interacts with the NP N-terminal and disrupts the interaction of NP with the viral RNA-dependent RNA polymerase (RdRp) but not NP multimerization, the critical activities of NP for RNP formation and function. Furthermore, MxA N-terminal domain was identified as the functional domain inhibiting DBV infection, and, consistently, then was shown to interact with NP and obstruct the NP-RdRp interaction. Additionally, threonine 103 within the N-terminal domain is important for MxA inhibition to DBV, and its mutation (T103A) attenuates MxA binding to NP and obstruction of the NP-RdRp interaction. This study uncovers MxA inhibition of DBV with a series of functional and mechanistical analyses, providing insights into the virus-host interactions and probably helping inform the development of antiviral agents in the future.IMPORTANCEDBV/SFTSV is an emerging high-pathogenic virus. Since its first identification in China in 2009, cases of DBV infection have been reported in many other countries, posing a significant threat to public health. Uncovering the mechanisms of DBV-host interactions is necessary to understand the viral pathogenesis and host response and may advance the development of antiviral therapeutics. Here, we found that host factor MxA whose expression is induced by DBV restricts the virus infection. Mechanistically, MxA specifically interacts with the viral NP and blocks the NP-RdRp interaction, inhibiting the viral RNP activity. Further studies identified the key domain and amino acid residue required for MxA inhibition to DBV. Consistently, they were then shown to be important for MxA targeting of NP and obstruction of the NP-RdRp association. These findings unravel the restrictive role of MxA in DBV infection and the underlying mechanism, expanding our knowledge of the virus-host interactions.
Assuntos
Phlebovirus , Febre Grave com Síndrome de Trombocitopenia , Humanos , Proteínas do Nucleocapsídeo , Ribonucleoproteínas/metabolismo , RNA Polimerase Dependente de RNA , Febre Grave com Síndrome de Trombocitopenia/metabolismo , Febre Grave com Síndrome de Trombocitopenia/virologia , Phlebovirus/fisiologia , Interações Hospedeiro-PatógenoRESUMO
Severe fever with thrombocytopenia syndrome (SFTS) virus and hantavirus are categorized under the Bunyavirales order. The severe disease progression in both SFTS and hemorrhagic fever with renal syndrome (HFRS) is associated with cytokine storms. This study aimed to explore the differences in cytokine profiles and immune responses between the two diseases. A cross-sectional, single-center study involved 100 participants, comprising 46 SFTS patients, 48 HFRS patients, and 6 healthy controls. The study employed the Luminex cytokine detection platform to measure 48 cytokines. The differences in cytokine profiles and immune characteristics between the two diseases were further analyzed using multiple linear regression, principal component analysis, and random forest method. Among the 48 cytokines tested, 30 showed elevated levels in SFTS and/or HFRS compared to the healthy control group. Furthermore, there were 19 cytokines that exhibited significant differences between SFTS and HFRS. Random forest analysis suggested that TRAIL and CTACK were predictive of SFTS, while IL2Ralpha, MIG, IL-8, IFNalpha2, HGF, SCF, MCP-3, and PDGFBB were more common with HFRS. It was further verified by the receiver operating characteristic with area under the curve >0.8 and P-values <0.05, except for TRAIL. Significant differences were observed in the cytokine profiles of SFTS and HFRS, with TRAIL, IL2Ralpha, MIG, and IL-8 being the top 4 cytokines that most clearly distinguished the two diseases. IMPORTANCE: SFTS and HFRS differ in terms of cytokine immune characteristics. TRAIL, IL-2Ralpha, MIG, and IL-8 were the top 4 that differed markedly between SFTS and HFRS.
Assuntos
Citocinas , Febre Hemorrágica com Síndrome Renal , Febre Grave com Síndrome de Trombocitopenia , Humanos , Febre Hemorrágica com Síndrome Renal/imunologia , Febre Hemorrágica com Síndrome Renal/virologia , Febre Hemorrágica com Síndrome Renal/sangue , Citocinas/sangue , Masculino , Febre Grave com Síndrome de Trombocitopenia/imunologia , Febre Grave com Síndrome de Trombocitopenia/virologia , Pessoa de Meia-Idade , Feminino , Estudos Transversais , Adulto , Idoso , Phlebovirus/imunologiaRESUMO
Severe fever with thrombocytopenia syndrome virus (SFTSV), which has been reported in China, Korea, Japan, Vietnam, and Taiwan, is a causative agent of severe fever thrombocytopenia syndrome. This virus has a high mortality and induces thrombocytopenia and leukocytopenia in humans, cats, and aged ferrets, whereas immunocompetent adult mice infected with SFTSV never show symptoms. Anti-SFTSV antibodies have been detected in several animals-including goats, sheep, cattle, and pigs. However, there are no reports of severe fever thrombocytopenia syndrome in these animals. Previous studies have reported that the nonstructural protein NSs of SFTSV inhibits the type I interferon (IFN-I) response through the sequestration of human signal transducer and activator of transcription (STAT) proteins. In this study, comparative analysis of the function of NSs as IFN antagonists in human, cat, dog, ferret, mouse, and pig cells revealed a correlation between pathogenicity of SFTSV and the function of NSs in each animal. Furthermore, we found that the inhibition of IFN-I signaling and phosphorylation of STAT1 and STAT2 by NSs depended on the binding ability of NSs to STAT1 and STAT2. Our results imply that the function of NSs in antagonizing STAT2 determines the species-specific pathogenicity of SFTSV.
Assuntos
Interferon Tipo I , Phlebovirus , Febre Grave com Síndrome de Trombocitopenia , Proteínas não Estruturais Virais , Idoso , Animais , Bovinos , Cães , Humanos , Camundongos , Furões , Interferon Tipo I/metabolismo , Phlebovirus/fisiologia , Febre Grave com Síndrome de Trombocitopenia/virologia , Ovinos , Transdução de Sinais , Suínos , Trombocitopenia/metabolismo , Proteínas não Estruturais Virais/metabolismoRESUMO
We isolated severe fever with thrombocytopenia syndrome virus (SFTSV) from farmed minks in China, providing evidence of natural SFTSV infection in farmed minks. Our findings support the potential role of farmed minks in maintaining SFTSV and are helpful for the development of public health interventions to reduce human infection.
Assuntos
Surtos de Doenças , Vison , Phlebovirus , Febre Grave com Síndrome de Trombocitopenia , Phlebovirus/genética , Phlebovirus/isolamento & purificação , Phlebovirus/classificação , China/epidemiologia , Febre Grave com Síndrome de Trombocitopenia/epidemiologia , Febre Grave com Síndrome de Trombocitopenia/virologia , Animais , Vison/virologia , Filogenia , Humanos , FazendasRESUMO
Severe fever with thrombocytopenia syndrome virus (SFTSV) is a newly identified phlebovirus associated with severe hemorrhagic fever in humans. Studies have shown that SFTSV nucleoprotein (N) induces BECN1-dependent autophagy to promote viral assembly and release. However, the function of other SFTSV proteins in regulating autophagy has not been reported. In this study, we identify SFTSV NSs, a nonstructural protein that forms viroplasm-like structures in the cytoplasm of infected cells as the virus component mediating SFTSV-induced autophagy. We found that SFTSV NSs-induced autophagy was inclusion body independent, and most phenuivirus NSs had autophagy-inducing effects. Unlike N protein-induced autophagy, SFTSV NSs was key in regulating autophagy by interacting with the host's vimentin in an inclusion body-independent manner. NSs interacted with vimentin and induced vimentin degradation through the K48-linked ubiquitin-proteasome pathway. This negatively regulating Beclin1-vimentin complex formed and promoted autophagy. Furthermore, we identified the NSs-binding domain of vimentin and found that overexpression of wild-type vimentin antagonized the induced effect of NSs on autophagy and inhibited viral replication, suggesting that vimentin is a potential antiviral target. The present study shows a novel mechanism through which SFTSV nonstructural protein activates autophagy, which provides new insights into the role of NSs in SFTSV infection and pathogenesis. IMPORTANCE Severe fever with thrombocytopenia syndrome virus (SFTSV) is a newly emerging tick-borne pathogen that causes multifunctional organ failure and even death in humans. As a housekeeping mechanism for cells to maintain steady state, autophagy plays a dual role in viral infection and the host's immune response. However, the relationship between SFTSV infection and autophagy has not been described in detail yet. Here, we demonstrated that SFTSV infection induced complete autophagic flux and facilitated viral proliferation. We also identified a key mechanism underlying NSs-induced autophagy, in which NSs interacted with vimentin to inhibit the formation of the Beclin1-vimentin complex and induced vimentin degradation through K48-linked ubiquitination modification. These findings may help us understand the new functions and mechanisms of NSs and may aid in the identification of new antiviral targets.
Assuntos
Autofagia , Phlebovirus , Febre Grave com Síndrome de Trombocitopenia , Vimentina , Proteínas não Estruturais Virais , Humanos , Autofagia/genética , Proteína Beclina-1/metabolismo , Phlebovirus/metabolismo , Febre Grave com Síndrome de Trombocitopenia/fisiopatologia , Febre Grave com Síndrome de Trombocitopenia/virologia , Vimentina/genética , Vimentina/metabolismo , Proteínas não Estruturais Virais/genética , Proteínas não Estruturais Virais/metabolismo , Replicação Viral/fisiologia , Regulação para Baixo , Domínios ProteicosRESUMO
Hemorrhagic fever with renal syndrome (HFRS) and severe fever with thrombocytopenia syndrome (SFTS) are both endemic in rural areas and some characteristics are similar between HFRS and SFTS, which usually lead to misdiagnosis. In this study, we summarized and compared some characteristics of HFRS and SFTS which will provide scientific information for differential diagnosis. From 2011 to 2022, a total of 4336 HFRS cases and 737 SFTS cases were reported in Zhejiang Province. Compared to SFTS, there was a higher proportion of males among HFRS cases (72.46% [3142/4336] vs. 50.88% [375/737], p = 0.000). The median age of all 4336 HFRS cases was 49 (39, 59), while the median age of SFTS cases was 66 (57, 74). In addition, the involved counties of HFRS were more than SFTS, but the number of counties affected by SFTS increased from 2011 to 2022. The majority of SFTS cases occurred in summer (from May to July), but besides summer, HFRS cases also showed a peak in winter. Finally, our results showed that the case fatality rate of SFTS was significantly higher than that of HFRS. Although there were some similarities between HFRS and SFTS, our study found several differences between them, such as gender distribution, age distribution, and seasonal distribution, which will provide scientific information for differential diagnosis of HFRS and SFTS. Further studies should be carried out to explore the mechanism of these differences.
Assuntos
Febre Hemorrágica com Síndrome Renal , Estações do Ano , Febre Grave com Síndrome de Trombocitopenia , Humanos , Febre Hemorrágica com Síndrome Renal/epidemiologia , Febre Hemorrágica com Síndrome Renal/diagnóstico , Masculino , Pessoa de Meia-Idade , Feminino , Adulto , Idoso , Febre Grave com Síndrome de Trombocitopenia/epidemiologia , Febre Grave com Síndrome de Trombocitopenia/virologia , Febre Grave com Síndrome de Trombocitopenia/diagnóstico , China/epidemiologia , Diagnóstico DiferencialRESUMO
Severe fever with thrombocytopenia syndrome (SFTS) is associated with a high death rate and lacks a targeted therapy plan. The ratio of blood urea nitrogen to albumin, known as BAR, is a valuable method for assessing the outlook of various infectious diseases. The objective of this research was to evaluate the effectiveness of BAR in forecasting the outcome of individuals with SFTS. Four hundred and thirty-seven patients with SFTS from two clinical centers were included in this study according to inclusion and exclusion criteria. Clinical characteristics and test parameters of SFTS patients were analyzed between survival and fatal groups. Least absolute shrinkage and selection operator (LASSO) regression and Cox regression suggested that BAR might serve as a standalone prognostic indicator for patients with SFTS in the initial phase (hazard ratio = 18.669, 95% confidence interval [CI]: 8.558-40.725, p < 0.001). And BAR had a better predictive effectiveness in clinical outcomes in patients with SFTS with an AUC of 0.832 (95% CI: 0.788-0.876, p < 0.001), a cutoff value of 0.19, a sensitivity of 0.812, and a specificity of 0.726 compared to C-reactive protein, procalcitonin, and platelet to lymphocyte ratio via receiver operating characteristic curve. KM (Kaplan Meier) curves demonstrated that high level of BAR was associated with poor survival condition in patients with SFTS. Furthermore, the high level of BAR was associated with long hospital stays and test paraments of kidney, liver, and coagulation function in survival patients. So, BAR could be used as a promising early warning biomarker of adverse outcomes in patients with SFTS.
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Nitrogênio da Ureia Sanguínea , Febre Grave com Síndrome de Trombocitopenia , Humanos , Feminino , Masculino , Pessoa de Meia-Idade , Febre Grave com Síndrome de Trombocitopenia/mortalidade , Febre Grave com Síndrome de Trombocitopenia/sangue , Febre Grave com Síndrome de Trombocitopenia/diagnóstico , Febre Grave com Síndrome de Trombocitopenia/virologia , Idoso , Prognóstico , Biomarcadores/sangue , Estudos Retrospectivos , Adulto , Idoso de 80 Anos ou maisRESUMO
Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease with a high mortality rate. Differentiating between SFTS and hemorrhagic fever with renal syndrome (HFRS) is difficult and inefficient. Retrospective analysis of the medical records of individuals with SFTS and HFRS was performed. Clinical and laboratory data were compared, and a diagnostic model was developed based on multivariate logistic regression analyzes. Receiver operating characteristic curve analysis was used to evaluate the diagnostic model. Among the 189 patients, 113 with SFTS and 76 with HFRS were enrolled. Univariate analysis revealed that more than 20 variables were significantly associated with SFTS. Multivariate logistic regression analysis revealed that gender, especially female gender (odds ratio [OR]: 4.299; 95% confidence interval [CI]: 1.163-15.887; p = 0.029), age ≥65 years (OR: 16.386; 95% CI: 3.043-88.245; p = 0.001), neurological symptoms (OR: 12.312; 95% CI: 1.638-92.530; p = 0.015), leukopenia (<4.0 × 109/L) (OR: 17.355; 95% CI: 3.920-76.839; p < 0.001), and normal Cr (OR: 97.678; 95% CI: 15.483-616.226; p < 0.001) were significantly associated with SFTS but not with HFRS. The area under the curve of the differential diagnostic model was 0.960 (95% CI: 0.936-0.984), which was significantly better than that of each single factor. In addition, the model exhibited very excellent sensitivity and specificity (92.9% and 85.5%, respectively). In cases where HFRS and SFTS are endemic, a diagnostic model based on five parameters, such as gender, age ≥65 years, neurological symptoms, leukopenia and normal Cr, will facilitate the differential diagnosis of SFTS and HFRS in medical institutions, especially in primary care settings.
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Febre Hemorrágica com Síndrome Renal , Curva ROC , Febre Grave com Síndrome de Trombocitopenia , Humanos , Feminino , Masculino , Febre Hemorrágica com Síndrome Renal/diagnóstico , Febre Hemorrágica com Síndrome Renal/virologia , Pessoa de Meia-Idade , Febre Grave com Síndrome de Trombocitopenia/diagnóstico , Febre Grave com Síndrome de Trombocitopenia/virologia , Estudos Retrospectivos , Idoso , Diagnóstico Diferencial , Adulto , Diagnóstico Precoce , Idoso de 80 Anos ou mais , Sensibilidade e EspecificidadeRESUMO
INTRODUCTION: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by the SFTS virus (SFTSV), which has a wide geographic distribution. The primary clinical manifestations of SFTS are fever and thrombocytopenia, with multiorgan failure being the leading cause of death. While most patients recover with treatment, little is known about the potential long-term metabolic effects of SFTSV infection. OBJECTIVES: This study aimed to shed light on dysregulated metabolic pathways and cytokine responses following SFTSV infection, which pose significant risks to the short-term and long-term health of affected individuals. METHODS: Fourteen laboratory-confirmed clinical SFTS cases and thirty-eight healthy controls including 18 SFTSV IgG-positive and 20 IgG-negative individuals were recruited from Taizhou city of Zhejiang province, Eastern China. Inclusion criteria of healthy controls included residing in the study area for at least one year, absence of fever or other symptoms in the past two weeks, and no history of SFTS diagnosis. Ultrahigh-performance liquid chromatography-mass spectrometry (UHPLC-MS) was used to obtain the relative abundance of plasma metabolites. Short-term metabolites refer to transient alterations present only during SFTSV infection, while long-term metabolites persistently deviate from normal levels even after recovery from SFTSV infection. Additionally, the concentrations of 12 cytokines were quantified through fluorescence intensity measurements. Differential metabolites were screened using orthogonal projections to latent structures discriminant analysis (OPLS-DA) and the Wilcoxon rank test. Metabolic pathway analysis was performed using MetaboAnalyst. Between-group differences of metabolites and cytokines were examined using the Wilcoxon rank test. Correlation matrices between identified metabolites and cytokines were analyzed using Spearman's method. RESULTS AND CONCLUSIONS: We screened 122 long-term metabolites and 108 short-term metabolites by analytical comparisons and analyzed their correlations with 12 cytokines. Glycerophospholipid metabolism (GPL) was identified as a significant short-term metabolic pathway suggesting that the activation of GPL might be linked to the self-replication of SFTSV, whereas pentose phosphate pathway and alanine, aspartate, and glutamate metabolism were indicated as significant long-term metabolic pathways playing a role in combating long-standing oxidative stress in the patients. Furthermore, our study suggests a new perspective that α-ketoglutarate could serve as a dietary supplement to protect recovering SFTS patients.
Assuntos
Citocinas , Phlebovirus , Febre Grave com Síndrome de Trombocitopenia , Humanos , Febre Grave com Síndrome de Trombocitopenia/metabolismo , Febre Grave com Síndrome de Trombocitopenia/virologia , Citocinas/metabolismo , Citocinas/sangue , Pessoa de Meia-Idade , Masculino , Feminino , Phlebovirus/metabolismo , Idoso , Adulto , Cromatografia Líquida de Alta Pressão , Metabolômica/métodos , Estudos de Casos e Controles , Redes e Vias Metabólicas , Espectrometria de Massas/métodos , ChinaRESUMO
BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by severe fever with thrombocytopenia syndrome virus (SFTSV). Previous studies have indicated that SFTS patients have a high mortality rate, which may be related to cytokine storm and immune dysfunction. In our study, we analyzed differences in cytokines and lymphocyte subsets between severe and non-severe SFTS patients, with the aim of identifying predictors of severity. METHODS: We retrospectively analyzed demographic characteristics, clinical data, cytokine profiles, and lymphocyte subsets from 96 laboratory confirmed SFTS patients between April 2021 and August 2023. RESULTS: A total of 96 SFTS patients were enrolled, with a mean age of 65.05 (± 7.92) years old. According to our grouping criteria, 35 (36.5%) of these patients were classified as severe group, while 61 (63.5%) were classified as non-severe group. Univariate analysis revealed that age, interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-10 (IL-10), interferon-α (IFN-α), CD4 + T cell, and CD8 + T cell counts were risk predictors for the severity of SFTS. Further multivariable logistic regression analysis confirmed age, IL-6 levels, and CD4 + T cell counts as independent predictors of SFTS severity. CONCLUSIONS: Severe SFTS patients may experience cytokine storms and immune dysfunction. Aging, elevated levels of IL-6, and decreased CD4 + T cell count may serve as independent predictors for the severity of SFTS.
Assuntos
Citocinas , Subpopulações de Linfócitos , Phlebovirus , Febre Grave com Síndrome de Trombocitopenia , Índice de Gravidade de Doença , Humanos , Masculino , Feminino , Febre Grave com Síndrome de Trombocitopenia/imunologia , Febre Grave com Síndrome de Trombocitopenia/virologia , Idoso , Pessoa de Meia-Idade , Citocinas/sangue , Estudos Retrospectivos , Phlebovirus/imunologia , Subpopulações de Linfócitos/imunologiaRESUMO
BACKGROUND: Epstein-Barr virus (EBV) can be reactivated and proliferated with fatal outcome in immuno-compromised people, but the clinical consequences of EBV infection in patients with severe fever with thrombocytopenia syndrome (SFTS) remain uncertain. In this study, we investigated the infection rate, the influence and the early predictors of EBV infection in SFTS patients. METHODS: In this retrospective study, SFTS patients who were treated in the First Affiliated Hospital of Nanjing Medical University from May 2011 to August 2021 were enrolled and divided into infected and non-infected groups. We compared the demographic characteristics, clinical manifestations and signs, laboratory tests and prognosis, and explored the risk factors of EBV infection by receiver operating characteristic (ROC) curve and logistic regression. RESULTS: A total of 120 hospitalized SFTS patients with EBV-DNA testing were enrolled in this study. Patients with EBV infection had statistically significant higher mortality rate (32.0% vs. 11.43%, P = 0.005). Compared with the non-infected group, the EBV-infected group had higher levels of C-reactive protein (CRP), creatine-kinase (CK), fasting blood glucose (FBG), blood urea nitrogen (BUN), D-dimer, and CD56+ cell counts, lower levels of immunoglobulin G (IgG), IgM, complement 3 (C3), and C4. The proportion of patients with age ≥ 60 years and ferritin > 1500.0 ng/ml in the EBV-infected group was significantly higher than that in the non-infected group. The results of ROC analysis showed that the cut-off values of CRP, IgG, C3, C4, and CD56+ cell counts to predict EBV infection were 13.2 mg/l, 12.5 g/l, 1.1 g/l, 0.6 g/l, 0.3 g/l, and 94.0 cells/µl. Multivariable logistic analysis showed that age ≥ 60 years old, CRP > 13.2 mg/l, BUN > 5.4 mmol/l, ferritin > 1500.0 ng/ml, IgG < 12.5 g/l, IgM < 1.1 g/l, C4 < 0.3 g/l, and CD56+ cell counts > 94.0 cells/µl were the independent risk factors of EBV infection in SFTS patients. CONCLUSIONS: SFTS combined with EBV infection is associated with high morbidity and mortality. It is necessary to strengthen screening for EBV infection and its early predictive markers after admission in SFTS patients.
Assuntos
Infecções por Vírus Epstein-Barr , Herpesvirus Humano 4 , Febre Grave com Síndrome de Trombocitopenia , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Infecções por Vírus Epstein-Barr/complicações , Infecções por Vírus Epstein-Barr/virologia , Estudos Retrospectivos , Febre Grave com Síndrome de Trombocitopenia/virologia , Febre Grave com Síndrome de Trombocitopenia/sangue , Febre Grave com Síndrome de Trombocitopenia/diagnóstico , Idoso , Herpesvirus Humano 4/genética , Herpesvirus Humano 4/isolamento & purificação , Fatores de Risco , Prognóstico , Adulto , Curva ROC , China/epidemiologia , Anticorpos Antivirais/sangue , DNA Viral/sangueRESUMO
BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease. SFTS virus (SFTSV) is transmitted by tick bites and contact with the blood or body fluids of SFTS patients. Animal-to-human transmission of SFTS has been reported in Japan, but not in China. In this study, the possible transmission route of two patients who fed and cared for farm-raised fur animals in a mink farm was explored. METHOD: An epidemiological investigation and a genetic analysis of patients, animals and working environment were carried out. RESULTS: It was found that two patients had not been bitten by ticks and had no contact with patients infected with SFTS virus, but both of them had skinned the dying animals. 54.55% (12/22) of the farm workers were positive for SFTS virus antibody. By analyzing the large, medium and small segments sequences, the viral sequences from the two patients, animals and environments showed 99.9% homology. CONCLUSION: It is suspected that the two patients may be directly infected by farm-raised animals, and that the virus may have been transmitted by aerosols when skinning dying animals. Transmission by direct blood contacts or animal bites cannot be ignored.
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Phlebovirus , Febre Grave com Síndrome de Trombocitopenia , Animais , Humanos , Anticorpos Antivirais/sangue , China/epidemiologia , Fazendeiros , Fazendas , Vison/virologia , Phlebovirus/genética , Phlebovirus/isolamento & purificação , Phlebovirus/classificação , Filogenia , RNA Viral/genética , Febre Grave com Síndrome de Trombocitopenia/transmissão , Febre Grave com Síndrome de Trombocitopenia/virologia , Febre Grave com Síndrome de Trombocitopenia/epidemiologiaRESUMO
BACKGROUND: Since its discovery, severe fever with thrombocytopenia syndrome (SFTS) has been characterized by rapid progression and poor prognosis, and no specific treatment is available. The aim of this study was to investigate the early warning indicators of mortality in SFTS patients. METHODS: This is a retrospective cross-sectional study. The study subjects were patients who were admitted to the hospital with a confirmed diagnosis of SFTS from January 2023 to October 2023, and their clinical symptoms and signs at the time of admission, as well as the laboratory indexes of the first blood collection after admission were collected, grouped according to the prognosis, and statistically analyzed. RESULTS: A total of 141 patients were collected, of which 27 patients died and 114 patients were in the survival group. Through statistical analysis, patients with combined hemorrhagic manifestations, disturbance of consciousness, lymphopenia, elevated lipase, and prolonged thrombin time on admission were independent risk factors for patients' death. By plotting the working characteristic curve of the subjects, as well as calculating the area under the curve, the results showed that the AUC of lymphopenia count was 0.670, 95% CI (0.563-0.776), P = 0.006; the AUC of elevated serum lipase index was 0.789, 95% CI (0.699-0.878), p < 0.001; the AUC of prolonged thrombin time was 0.749, 95% CI (0.645-0.854), p < 0.001. CONCLUSION: Patients with hemorrhagic manifestations, disturbance of consciousness, lymphocyte reduction, elevated serum lipase, and prolonged thrombin time on admission are more worthy of the clinician's attention, and require early and effective interventions to avoid further disease progression.
Assuntos
Febre Grave com Síndrome de Trombocitopenia , Humanos , Masculino , Feminino , Febre Grave com Síndrome de Trombocitopenia/mortalidade , Febre Grave com Síndrome de Trombocitopenia/sangue , Febre Grave com Síndrome de Trombocitopenia/virologia , Estudos Retrospectivos , Pessoa de Meia-Idade , Estudos Transversais , Idoso , Prognóstico , Fatores de Risco , Phlebovirus , Adulto , Idoso de 80 Anos ou maisRESUMO
Severe fever with thrombocytopenia syndrome (SFTS) is a fatal zoonosis caused by ticks in East Asia. As SFTS virus (SFTSV) is maintained between wildlife and ticks, seroepidemiological studies in wildlife are important to understand the behavior of SFTSV in the environment. Miyazaki Prefecture, Japan, is an SFTS-endemic area, and approximately 100 feral horses, called Misaki horses (Equus caballus), inhabit Cape Toi in Miyazaki Prefecture. While these animals are managed in a wild-like manner, their ages are ascertainable due to individual identification. In the present study, we conducted a seroepidemiological survey of SFTSV in Misaki horses between 2015 and 2023. This study aimed to understand SFTSV infection in horses and its transmission to wildlife. A total of 707 samples from 180 feral horses were used to determine the seroprevalence of SFTSV using enzyme-linked immunosorbent assay (ELISA). Neutralization testing was performed on 118 samples. In addition, SFTS viral RNA was detected in ticks from Cape Toi and feral horses. The overall seroprevalence between 2015 and 2023 was 78.5% (555/707). The lowest seroprevalence was 55% (44/80) in 2016 and the highest was 92% (76/83) in 2018. Seroprevalence was significantly affected by age, with 11% (8/71) in those less than one year of age and 96.7% (435/450) in those four years of age and older (p < 0.0001). The concordance between ELISA and neutralization test results was 88.9% (105/118). SFTS viral RNA was not detected in ticks (n = 516) or feral horses. This study demonstrated that horses can be infected with SFTSV and that age is a significant factor in seroprevalence in wildlife. This study provides insights into SFTSV infection not only in horses but also in wildlife in SFTS-endemic areas.
Assuntos
Doenças dos Cavalos , Phlebovirus , Febre Grave com Síndrome de Trombocitopenia , Animais , Cavalos , Estudos Soroepidemiológicos , Japão/epidemiologia , Doenças dos Cavalos/epidemiologia , Doenças dos Cavalos/virologia , Doenças dos Cavalos/sangue , Phlebovirus/isolamento & purificação , Febre Grave com Síndrome de Trombocitopenia/epidemiologia , Febre Grave com Síndrome de Trombocitopenia/veterinária , Febre Grave com Síndrome de Trombocitopenia/virologia , Feminino , Masculino , Anticorpos Antivirais/sangue , Carrapatos/virologia , Ensaio de Imunoadsorção Enzimática/veterinária , Animais Selvagens/virologiaRESUMO
In our prior investigations, we elucidated the role of the tryptophan-to-tyrosine substitution at the 61st position in the nonstructural protein NSsW61Y in diminishing the interaction between nonstructural proteins (NSs) and nucleoprotein (NP), impeding viral replication. In this study, we focused on the involvement of NSs in replication via the modulation of autophagosomes. Initially, we examined the impact of NP expression levels, a marker for replication, upon the infection of HeLa cells with severe fever thrombocytopenia syndrome virus (SFTSV), with or without the inhibition of NP binding. Western blot analysis revealed a reduction in NP levels in NSsW61Y-expressing conditions. Furthermore, the expression levels of the canonical autophagosome markers p62 and LC3 decreased in HeLa cells expressing NSsW61Y, revealing the involvement of individual viral proteins on autophagy. Subsequent experiments confirmed that NSsW61Y perturbs autophagy flux, as evidenced by reduced levels of LC3B and p62 upon treatment with chloroquine, an inhibitor of autophagosome-lysosome fusion. LysoTracker staining demonstrated a decrease in lysosomes in cells expressing the NS mutant compared to those expressing wild-type NS. We further explored the mTOR-associated regulatory pathway, a key regulator affected by NS mutant expression. The observed inhibition of replication could be linked to conformational changes in the NSs, impairing their binding to NP and altering mTOR regulation, a crucial upstream signaling component in autophagy. These findings illuminate the intricate interplay between NSsW61Y and the suppression of host autophagy machinery, which is crucial for the generation of autophagosomes to facilitate viral replication.
Assuntos
Autofagossomos , Autofagia , Phlebovirus , Triptofano , Tirosina , Proteínas não Estruturais Virais , Replicação Viral , Humanos , Proteínas não Estruturais Virais/metabolismo , Proteínas não Estruturais Virais/genética , Replicação Viral/genética , Autofagossomos/metabolismo , Células HeLa , Phlebovirus/genética , Phlebovirus/fisiologia , Phlebovirus/metabolismo , Autofagia/genética , Tirosina/metabolismo , Triptofano/metabolismo , Serina-Treonina Quinases TOR/metabolismo , Mutação , Substituição de Aminoácidos , Febre Grave com Síndrome de Trombocitopenia/metabolismo , Febre Grave com Síndrome de Trombocitopenia/virologia , Febre Grave com Síndrome de Trombocitopenia/genética , Lisossomos/metabolismo , Nucleoproteínas/metabolismo , Nucleoproteínas/genéticaRESUMO
Severe fever with thrombocytopenia syndrome (SFTS) is a tick-borne febrile disease caused by SFTS virus (SFTSV), or Dabie bandavirus, in the Phenuiviridae family. Clinically neurological disorders in SFTS have been commonly reported, but their neuropathogenesis has rarely been studied. Microglia are a type of neuroglia accounting for 10 to 12% of all cells in the brain. As resident immune cells, microglial cells are the first line of immune defense present in the central nervous system (CNS). Here, we report that SFTSV was able to infect microglial cells and stimulate interleukin 1ß (IL-1ß) secretion in the brains of infected neonatal BALB/c mice. We characterized the cell death induced in infected human microglial HMC3 cells, also susceptible to SFTSV, and found that the NOD-like receptor protein 3 (NLRP3) inflammasome was activated, leading to secretion of IL-1ß and pyroptosis. Knockdown of NLRP3 or inhibition of the NLRP3 inflammasome activation suppressed the viral replication, suggesting that the activation of the NLRP3 inflammasome may support SFTSV replication in microglial cells. Viral nonstructural protein NSs, a known modulator of immune responses, interacted and colocalized with NLRP3 for the inflammasome activation. It appeared that the N-terminal fragment, amino acids 1 to 66, of NSs was critical to promote the assembly of the inflammasome complex by interacting with NLRP3 for its activation in microglial cells. Our findings provide evidence that SFTSV may cause neurological disorders through infecting microglia and activating the inflammasome through its nonstructural protein NSs for neural cell death and inflammation. This study may have revealed a novel mechanism of SFTSV NSs in dysregulating host response. IMPORTANCE Encephalitis or encephalopathy during severe fever with thrombocytopenia syndrome (SFTS) is considered a critical risk factor leading to high mortality, but there have been no studies to date on the pathogenesis of encephalitis or encephalopathy caused by SFTS virus. Here, we report that SFTSV infection can active the NLRP3 inflammasome and induce IL-1ß secretion in the brains of infected newborn mice. In infected human HMC3 microglia, SFTSV activated the NLRP3 inflammasome via the viral nonstructural protein NSs through interaction with its N-terminal fragment. Notably, our findings suggest that the activation of the NLRP3 inflammasome may promote SFTSV replication in infected microglial cells. This study may reveal a novel mechanism by SFTSV to dysregulate host responses through its nonstructural protein, which could help us understand viral neuropathogenesis in SFTS patients.
Assuntos
Encefalite , Inflamassomos , Proteína 3 que Contém Domínio de Pirina da Família NLR , Phlebovirus , Piroptose , Proteínas não Estruturais Virais , Animais , Células Cultivadas , Humanos , Inflamassomos/metabolismo , Camundongos , Microglia/metabolismo , Proteína 3 que Contém Domínio de Pirina da Família NLR/genética , Proteína 3 que Contém Domínio de Pirina da Família NLR/metabolismo , Phlebovirus/metabolismo , Febre Grave com Síndrome de Trombocitopenia/imunologia , Febre Grave com Síndrome de Trombocitopenia/virologia , Proteínas não Estruturais Virais/metabolismoRESUMO
Severe fever with thrombocytopenia syndrome (SFTS) caused by a species Dabie bandavirus (formerly SFTS virus [SFTSV]) is an emerging hemorrhagic infectious disease with a high case-fatality rate. One of the best strategies for preventing SFTS is to develop a vaccine, which is expected to induce both humoral and cellular immunity. We applied a highly attenuated but still immunogenic vaccinia virus strain LC16m8 (m8) as a recombinant vaccine for SFTS. Recombinant m8s expressing SFTSV nucleoprotein (m8-N), envelope glycoprotein precursor (m8-GPC), and both N and GPC (m8-N+GPC) in the infected cells were generated. Both m8-GPC- and m8-N+GPC-infected cells were confirmed to produce SFTSV-like-particles (VLP) in vitro, and the N was incorporated in the VLP produced by the infection of cells with m8-N+GPC. Specific antibodies to SFTSV were induced in mice inoculated with each of the recombinant m8s, and the mice were fully protected from lethal challenge with SFTSV at both 103 TCID50 and 105 TCID50. In mice that had been immunized with vaccinia virus strain Lister in advance of m8-based SFTSV vaccine inoculation, protective immunity against the SFTSV challenge was also conferred. The pathological analysis revealed that mice immunized with m8-GPC or m8-N+GPC did not show any histopathological changes without any viral antigen-positive cells, whereas the control mice showed focal necrosis with inflammatory infiltration with SFTSV antigen-positive cells in tissues after SFTSV challenge. The passive serum transfer experiments revealed that sera collected from mice inoculated with m8-GPC or m8-N+GPC but not with m8-N conferred protective immunity against lethal SFTSV challenge in naïve mice. On the other hand, the depletion of CD8-positive cells in vivo did not abrogate the protective immunity conferred by m8-based SFTSV vaccines. Based on these results, the recombinant m8-GPC and m8-N+GPC were considered promising vaccine candidates for SFTS.
Assuntos
Antígenos Virais/imunologia , Nucleoproteínas/imunologia , Phlebovirus/imunologia , Febre Grave com Síndrome de Trombocitopenia/prevenção & controle , Vacinas Atenuadas/administração & dosagem , Vacinas Sintéticas/administração & dosagem , Proteínas do Envelope Viral/imunologia , Animais , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Febre Grave com Síndrome de Trombocitopenia/imunologia , Febre Grave com Síndrome de Trombocitopenia/virologiaRESUMO
Severe fever with thrombocytopenia syndrome virus (SFTSV) is a tick-borne emerging phlebovirus with high mortality rates of 6.0 to 30%. SFTSV infection is characterized by high fever, thrombocytopenia, leukopenia, hemorrhage and multiple organ failures. Currently, specific therapies and vaccines remain elusive. Suitable small animal models are urgently needed to elucidate the pathogenesis and evaluate the potential drug and vaccine for SFTSV infection. Previous models presented only mild or no pathogenesis of SFTS, limiting their applications in SFTSV infection. Therefore, it is an urgent need to develop a small animal model for the investigation of SFTSV pathogenesis and evaluation of therapeutics. In the current report, we developed a SFTSV infection model based on the HuPBL-NCG mice that recapitulates many pathological characteristics of SFTSV infection in humans. Virus-induced histopathological changes were identified in spleen, lung, kidney, and liver. SFTSV was colocalized with macrophages in the spleen and liver, suggesting that the macrophages in the spleen and liver could be the principle target cells of SFTSV. In addition, histological analysis showed that the vascular endothelium integrity was severely disrupted upon viral infection along with depletion of platelets. In vitro cellular assays further revealed that SFTSV infection increased the vascular permeability of endothelial cells by promoting tyrosine phosphorylation and internalization of the adhesion molecule vascular endothelial (VE)-cadherin, a critical component of endothelial integrity. In addition, we found that both virus infection and pathogen-induced exuberant cytokine release dramatically contributed to the vascular endothelial injury. We elucidated the pathogenic mechanisms of hemorrhage syndrome and developed a humanized mouse model for SFTSV infection, which should be helpful for anti-SFTSV therapy and pathogenesis study.
Assuntos
Modelos Animais de Doenças , Phlebovirus/patogenicidade , Febre Grave com Síndrome de Trombocitopenia/patologia , Doenças Transmitidas por Carrapatos/patologia , Animais , Plaquetas/patologia , Plaquetas/virologia , Moléculas de Adesão Celular/metabolismo , Células Endoteliais/patologia , Células Endoteliais/virologia , Feminino , Humanos , Leucócitos Mononucleares/patologia , Leucócitos Mononucleares/virologia , Macrófagos/patologia , Macrófagos/virologia , Camundongos , Fosforilação , Febre Grave com Síndrome de Trombocitopenia/virologia , Doenças Transmitidas por Carrapatos/virologiaRESUMO
Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by Dabie bandavirus (DBV), a novel Bandavirus in the family Phenuiviridae. The first case of SFTS was reported in China, followed by cases in Japan, South Korea, Taiwan and Vietnam. With clinical manifestations including fever, leukopenia, thrombocytopenia, and gastrointestinal symptoms, SFTS has a fatality rate of approximately 10%. In recent years, an increasing number of viral strains have been isolated and sequenced, and several research groups have attempted to classify the different genotypes of DBV. Additionally, accumulating evidence indicates certain correlations between the genetic makeup and biological/clinical manifestations of the virus. Here, we attempted to evaluate the genetic classification of different groups, align the genotypic nomenclature in different studies, summarize the distribution of different genotypes, and review the biological and clinical implications of DBV genetic variations.