RESUMO
The tick-borne encephalitis virus (TBEV) strain C11-13 (GenBank acc. no. OQ565596) of the Siberian genotype was previously isolated from the brain of a deceased person. TBEV C11-13 variants obtained at passages 3 and 8 in SPEV cells were inoculated into the brains of white mice for subsequent passages. Full genome sequences of all virus variants were analyzed by high-throughput sequencing. A total of 41 single nucleotide substitutions were found to occur mainly in the genes for the nonstructural proteins NS3 and NS5 (GenBank MF043953, OP902894, and OP902895), and 12 amino acid substitutions were identified in the deduced protein sequences. Reverse nucleotide and amino acid substitutions were detected after three passages through mouse brains. The substitutions restored the primary structures that were characteristic of the isolate C11-13 from a human patient and changed during the eight subsequent passages in SPEV cells. In addition, the 3'-untranslated region (3'-UTR) of the viral genome increased by 306 nt. The Y3 and Y2 3'-UTR elements were found to contain imperfect L and R repeats, which were probably associated with inhibition of cellular XRN1 RNase and thus involved in the formation of subgenomic flaviviral RNAs (sfRNAs). All TBEV variants showed high-level reproduction in both cell cultures and mouse brains. The genomic changes that occurred during successive passages of TBEV are most likely due to its significant genetic variability, which ensures its efficient reproduction in various hosts and its broad distribution in various climatic zones.
Assuntos
Vírus da Encefalite Transmitidos por Carrapatos , Genoma Viral , Proteínas não Estruturais Virais , Vírus da Encefalite Transmitidos por Carrapatos/genética , Animais , Camundongos , Humanos , Proteínas não Estruturais Virais/genética , Proteínas não Estruturais Virais/metabolismo , Regiões 3' não Traduzidas/genética , Encefalite Transmitida por Carrapatos/virologia , Encefalite Transmitida por Carrapatos/genética , Substituição de Aminoácidos , Cultura de Vírus/métodos , Encéfalo/virologia , Encéfalo/metabolismo , Serina Endopeptidases/genética , Serina Endopeptidases/metabolismo , Linhagem Celular , Proteases Virais , Nucleosídeo-Trifosfatase , RNA Helicases DEAD-boxRESUMO
BACKGROUND: Ticks carry a variety of microorganisms, some of which are pathogenic to humans. The human risk of tick-borne diseases depends on, among others, the prevalence of pathogens in ticks biting humans. To follow-up on this prevalence over time, a Belgian study from 2017 was repeated in 2021. METHODS: During the tick season 2021, citizens were invited to have ticks removed from their skin, send them and fill in a short questionnaire on an existing citizen science platform for the notification of tick bites (TekenNet). Ticks were morphologically identified to species and life stage level and screened using multiplex qPCR targeting, among others, Borrelia burgdorferi (sensu lato), Anaplasma phagocytophilum, Borrelia miyamotoi, Neoehrlichia mikurensis, Babesia spp., Rickettsia helvetica and tick-borne encephalitis virus (TBEV). The same methodology as in 2017 was used. RESULTS: In 2021, the same tick species as in 2017 were identified in similar proportions; of 1094 ticks, 98.7% were Ixodes ricinus, 0.8% Ixodes hexagonus and 0.5% Dermacentor reticulatus. A total of 928 nymphs and adults could be screened for the presence of pathogens. Borrelia burgdorferi (s.l.) was detected in 9.9% (95% CI 8.2-12.0%), which is significantly lower than the prevalence of 13.9% (95% CI 12.2-15.7%) in 2017 (P = 0.004). The prevalences of A. phagocytophilum (4.7%; 95% CI 3.5-6.3%) and R. helvetica (13.3%; 95% CI 11.2-15.6%) in 2021 were significantly higher compared to 2017 (1.8%; 95% CI 1.3-2.7% and 6.8%; 95% CI 5.6-8.2% respectively) (P < 0.001 for both). For the other pathogens tested, no statistical differences compared to 2017 were found, with prevalences ranging between 1.5 and 2.9% in 2021. Rickettsia raoultii was again found in D. reticulatus ticks (n = 3/5 in 2021). Similar to 2017, no TBEV was detected in the ticks. Co-infections were found in 5.1% of ticks. When combining co-infection occurrence in 2017 and 2021, a positive correlation was observed between B. burgdorferi (s.l.) and N. mikurensis and B. burgdorferi (s.l.) and B. miyamotoi (P < 0.001 for both). CONCLUSIONS: Although the 2021 prevalences fell within expectations, differences were found compared to 2017. Further research to understand the explanations behind these differences is needed.
Assuntos
Anaplasma phagocytophilum , Borrelia burgdorferi , Borrelia , Vírus da Encefalite Transmitidos por Carrapatos , Ixodes , Animais , Bélgica/epidemiologia , Humanos , Prevalência , Vírus da Encefalite Transmitidos por Carrapatos/isolamento & purificação , Vírus da Encefalite Transmitidos por Carrapatos/genética , Borrelia/isolamento & purificação , Borrelia/genética , Borrelia/classificação , Ixodes/microbiologia , Ixodes/virologia , Borrelia burgdorferi/isolamento & purificação , Borrelia burgdorferi/genética , Anaplasma phagocytophilum/isolamento & purificação , Anaplasma phagocytophilum/genética , Babesia/isolamento & purificação , Babesia/genética , Rickettsia/isolamento & purificação , Rickettsia/genética , Rickettsia/classificação , Feminino , Doenças Transmitidas por Carrapatos/epidemiologia , Doenças Transmitidas por Carrapatos/microbiologia , Doenças Transmitidas por Carrapatos/virologia , Masculino , Dermacentor/microbiologia , Dermacentor/virologia , Ninfa/microbiologia , Ninfa/virologia , Carrapatos/microbiologia , Carrapatos/virologia , Picadas de Carrapatos/epidemiologiaRESUMO
Tick-borne encephalitis (TBE) virus (TBEV) is transmitted to humans via tick bites. Infection is benign in >90% of the cases but can cause mild (<5%), moderate (<4%), or severe (<1%) encephalitis. We show here that â¼10% of patients hospitalized for severe TBE in cohorts from Austria, Czech Republic, and France carry auto-Abs neutralizing IFN-α2, -ß, and/or -ω at the onset of disease, contrasting with only â¼1% of patients with moderate and mild TBE. These auto-Abs were found in two of eight patients who died and none of 13 with silent infection. The odds ratios (OR) for severe TBE in individuals with these auto-Abs relative to those without them in the general population were 4.9 (95% CI: 1.5-15.9, P < 0.0001) for the neutralization of only 100 pg/ml IFN-α2 and/or -ω, and 20.8 (95% CI: 4.5-97.4, P < 0.0001) for the neutralization of 10 ng/ml IFN-α2 and -ω. Auto-Abs neutralizing type I IFNs accounted for â¼10% of severe TBE cases in these three European cohorts.
Assuntos
Anticorpos Neutralizantes , Autoanticorpos , Encefalite Transmitida por Carrapatos , Interferon Tipo I , Humanos , Encefalite Transmitida por Carrapatos/imunologia , Interferon Tipo I/imunologia , Autoanticorpos/imunologia , Feminino , Masculino , Anticorpos Neutralizantes/imunologia , Pessoa de Meia-Idade , Adulto , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Idoso , Áustria/epidemiologia , República TchecaRESUMO
The aim of this study was to evaluate the clinical usefulness of VirClia IgM/IgG single-assay chemiluminescence tests for the diagnosis of tick-borne encephalitis (TBE) in an endemic part of Norway. Patients hospitalized at Vestfold or Telemark Hospitals with suspected infection in the central nervous system (CNS) in the period between May 2021 and December 2023 were included, with 85 TBE cases identified. The VirClia IgM assay was positive in the initial serum sample in 75/85 cases, giving a sensitivity of 88.2% (95% CI, 79.4-94.2). The ReaScan TBE IgM rapid test was positive in 80/85 cases, with an estimated sensitivity of 94.1% (95% CI, 86.8-98.1). Vaccine breakthrough infections were the predominant cause of non-reactive IgM cases. The calculated specificity for the VirClia IgM was 95.8% (95% CI, 92.5-98.0). In conclusion, the sensitivity of the VirClia IgM was non-inferior to the ReaScan TBE IgM rapid test. However, isolated IgM reactive results must be interpreted with caution, since false-reactive results occur.
Assuntos
Anticorpos Antivirais , Vírus da Encefalite Transmitidos por Carrapatos , Encefalite Transmitida por Carrapatos , Imunoglobulina G , Imunoglobulina M , Medições Luminescentes , Sensibilidade e Especificidade , Encefalite Transmitida por Carrapatos/diagnóstico , Encefalite Transmitida por Carrapatos/imunologia , Encefalite Transmitida por Carrapatos/epidemiologia , Humanos , Imunoglobulina M/sangue , Noruega/epidemiologia , Anticorpos Antivirais/sangue , Imunoglobulina G/sangue , Masculino , Medições Luminescentes/métodos , Feminino , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Pessoa de Meia-Idade , Idoso , Adulto , Doenças Endêmicas , Adulto Jovem , Idoso de 80 Anos ou mais , AdolescenteRESUMO
Tick-borne encephalitis outbreaks have been reported in Europe after consumption of raw milk products from infected animals. While molecular methods are commonly used in viral foodborne outbreak investigations due to their sensitivity, specificity and rapidity, there are very few methods to detect infectious tick-borne encephalitis virus (TBEV) in milk products for routine use/analyses. To address this gap, we developed a cell culture-based method to detect infectious TBEV in artificially contaminated raw goat milk and raw goat cheese, and evaluated the sensitivity of TBEV infectivity assays. Raw goat milk samples were spiked with TBEV to achieve inoculation levels ranging from 106 to 100 TCID50/mL, and Faisselle and Tomme cheese samples were spiked so their TBEV concentrations ranged from 9.28 × 105 to 9.28 × 101 TCID50 per 2.5g. To detect infectious TBEV, Vero cells were infected by raw goat milk. For cheese samples, after homogenisation and membrane filtration, Vero cells were infected with samples adsorbed on the filter (method A) or with samples eluted from the filter (method B). After 5 days, cytopathic effects (CPEs) were observed and TBEV replication in Vero cells was confirmed by an increase in the number of genome copies/mL that were detected in cell supernatant. Infected Vero cells exhibited CPEs for both milk and cheese samples. Infectious TBEV was detected to 103 TCID50/mL in raw milk samples and to 9.28 × 101 TCID50 from Faisselle samples using both methods A and B. For Tomme samples, method A was able to detect TBEV to 9.28 × 102 TCID50/2.5g and method B to 9.28 × 103 TCID50/2.5g. The number of positive samples detected was slightly higher with method A than with method B. To conclude, this qualitative cell culture-based method can detect infectious TBEV artificially inoculated into raw milk and cheese; it should be further evaluated during foodborne outbreak investigations to detect infectious TBEV from naturally contaminated milk and cheese.
Assuntos
Queijo , Vírus da Encefalite Transmitidos por Carrapatos , Contaminação de Alimentos , Cabras , Leite , Animais , Leite/virologia , Vírus da Encefalite Transmitidos por Carrapatos/isolamento & purificação , Células Vero , Chlorocebus aethiops , Queijo/virologia , Contaminação de Alimentos/análise , Encefalite Transmitida por Carrapatos/virologia , Técnicas de Cultura de CélulasRESUMO
Tick-borne encephalitis virus (TBEV) is a pathogen that causes febrile infectious diseases and neurological damage to humans. TBEVs are prevalent from Europe to Far Eastern Asia, including Northeastern China. The understanding of TBEV phylogeny in China has been limited owing to insufficient genomic data on Chinese TBEV strains. Here, six TBEV strains were isolated from ticks collected in Inner Mongolia. The transmission electron microscopy revealed spherical particles with an enveloped structure of 50-60 nm in diameter. Phylogenetic analysis showed that, two strains were classified as the Siberian subtype, while the remaining four were identified as the Far Eastern subtype. Migration analyses based on TBEV ORF and envelope (E) protein sequences revealed that Chinese TBEV strains were migrated from Russia and/or Kazakhstan into China. Hulun Buir and Mudanjiang, the northeastern region of China, are considered hotspots with multiple import and export routes of Chinese TBEV strains. These results promote the understanding of TBEV genetic variations and phylogeny in China and suggest the importance of improving investigation of TBEV prevalence, which would instrumental for vaccine design strategies and better preparation for controlling TBEV infection in humans.
Assuntos
Vírus da Encefalite Transmitidos por Carrapatos , Variação Genética , Filogenia , Animais , Humanos , China/epidemiologia , Vírus da Encefalite Transmitidos por Carrapatos/genética , Vírus da Encefalite Transmitidos por Carrapatos/classificação , Encefalite Transmitida por Carrapatos/virologia , Encefalite Transmitida por Carrapatos/epidemiologia , Genoma Viral , Proteínas do Envelope Viral/genéticaRESUMO
Tick-borne encephalitis (TBE) virus is the most prevalent tick-transmitted orthoflavivirus in Europe. Due to the nonspecific nature of its symptoms, TBE is primarily diagnosed by ELISA-based detection of specific antibodies in the patient serum. However, cross-reactivity between orthoflaviviruses complicates the diagnosis. Specificity issues may be mitigated by serum neutralization assays (SNT), although the handling of clinically relevant orthoflaviviruses requires biosafety level (BSL) 3 conditions and they have highly divergent viral kinetics and cell tropisms. In the present study, we established a reporter virus particle (RVP)-based SNT in which the infectivity is measured by luminescence and that can be performed under BSL-2 conditions. The RVP-based SNT for TBEV exhibited a highly significant correlation with the traditional virus-based SNT (R2 = 0.8637, p < 0.0001). The RVP-based assay demonstrated a sensitivity of 92.3% (95% CI: 79.7%-97.4%) and specificity of 100% (95% CI: 81.6%-100%). We also tested the cross-reactivity of serum samples in RVP-based assays against other orthoflaviviruses (yellow fever virus, dengue virus type 2, Zika virus, West Nile virus and Japanese encephalitis virus). Interestingly, all serum samples which had tested TBEV-positive by ELISA but negative by RVP-based SNT were reactive for antibodies against other orthoflaviviruses. Thus, the RVP-based seroneutralization assay provides an added value in clinical diagnostics as well as in epidemiological studies.
Assuntos
Anticorpos Antivirais , Reações Cruzadas , Vírus da Encefalite Transmitidos por Carrapatos , Encefalite Transmitida por Carrapatos , Ensaio de Imunoadsorção Enzimática , Testes de Neutralização , Sensibilidade e Especificidade , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Humanos , Anticorpos Antivirais/sangue , Testes de Neutralização/métodos , Encefalite Transmitida por Carrapatos/diagnóstico , Encefalite Transmitida por Carrapatos/virologia , Ensaio de Imunoadsorção Enzimática/métodos , Vírion/imunologia , Anticorpos Neutralizantes/sangue , Anticorpos Neutralizantes/imunologia , AnimaisRESUMO
Hemorrhagic fever with renal syndrome (HFRS) and tick-borne encephalitis (TBE) are the most common viral diseases in Russia. HFRS is caused by six different types of hantaviruses: Hantaan, Amur, Seoul, Puumala, Kurkino, and Sochi, which are transmitted to humans through small mammals of the Muridae and Cricetidae families. TBE is caused by viruses belonging to five different phylogenetic subtypes. The similarities in the ecology of HFRS and TBE pathogens is presented here. Hantavirus-infected small mammals can transmit the virus to uninfected animals, and ticks can also transmit hantavirus to other ticks and mammals. Hantavirus transmission from ticks to humans is possible only hypothetically based on indirect data. Over the past 23 years, 164,582 cases of HFRS (4.9 per 105 people) and 71,579 cases of TBE (2.5 per 105 people) were registered in Russia. The mortality rate was 0.4% (668 cases) in HFRS and 1.6% deaths (1136 cases) in TBE. There were 4030 HFRS (2.5%) and 9414 TBE (13%) cases in children under 14 years old. HFRS and TBE cases were registered in 42 out of 85 Russian regions; in 18-only HFRS, in 13-only TBE, and 12 had no reported cases. The prospects of applying a combined vaccine for HFRS and TBE prevention are shown in this paper.
Assuntos
Encefalite Transmitida por Carrapatos , Febre Hemorrágica com Síndrome Renal , Vacinas Virais , Encefalite Transmitida por Carrapatos/prevenção & controle , Encefalite Transmitida por Carrapatos/epidemiologia , Encefalite Transmitida por Carrapatos/virologia , Encefalite Transmitida por Carrapatos/transmissão , Federação Russa/epidemiologia , Febre Hemorrágica com Síndrome Renal/epidemiologia , Febre Hemorrágica com Síndrome Renal/prevenção & controle , Febre Hemorrágica com Síndrome Renal/virologia , Humanos , Animais , Vacinas Virais/imunologia , Vacinas Virais/administração & dosagem , Orthohantavírus/imunologia , Orthohantavírus/genética , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Vírus da Encefalite Transmitidos por Carrapatos/genética , Vacinas Combinadas/imunologia , Vacinas Combinadas/administração & dosagem , Carrapatos/virologiaRESUMO
Tick-borne encephalitis virus (TBEV) is a neurotropic member of the genus Orthoflavivirus (former Flavivirus) and is of significant health concern in Europe and Asia. TBEV pathogenesis may occur directly via virus-induced damage to neurons or through immunopathology due to excessive inflammation. While primary cells isolated from the host can be used to study the immune response to TBEV, it is still unclear how well these reflect the immune response elicited in vivo. Here, we compared the transcriptional response to TBEV and the less pathogenic tick-borne flavivirus, Langat virus (LGTV), in primary monocultures of neurons, astrocytes and microglia in vitro, with the transcriptional response in vivo captured by single-nuclei RNA sequencing (snRNA-seq) of a whole mouse cortex. We detected similar transcriptional changes induced by both LGTV and TBEV infection in vitro, with the lower response to LGTV likely resulting from slower viral kinetics. Gene set enrichment analysis showed a stronger transcriptional response in vivo than in vitro for astrocytes and microglia, with a limited overlap mainly dominated by interferon signaling. Together, this adds to our understanding of neurotropic flavivirus pathogenesis and the strengths and limitations of available model systems.
Assuntos
Astrócitos , Vírus da Encefalite Transmitidos por Carrapatos , Encefalite Transmitida por Carrapatos , Microglia , Neurônios , Animais , Astrócitos/virologia , Microglia/virologia , Vírus da Encefalite Transmitidos por Carrapatos/genética , Vírus da Encefalite Transmitidos por Carrapatos/fisiologia , Vírus da Encefalite Transmitidos por Carrapatos/patogenicidade , Camundongos , Neurônios/virologia , Encefalite Transmitida por Carrapatos/virologia , Infecções por Flavivirus/virologia , Infecções por Flavivirus/imunologia , Células Cultivadas , Flavivirus/fisiologia , Flavivirus/genética , Camundongos Endogâmicos C57BL , Transcrição GênicaRESUMO
A case of Powassan encephalitis occurred in Manitoba, Canada, after the bite of a black-legged tick. Awareness of this emerging tickborne illness is needed because the number of vector tick species is growing. No specific treatment options exist, and cases with illness and death are high. Prevention is crucial.
Assuntos
Vírus da Encefalite Transmitidos por Carrapatos , Encefalite Transmitida por Carrapatos , Picadas de Carrapatos , Animais , Humanos , Pessoa de Meia-Idade , Encefalite Transmitida por Carrapatos/epidemiologia , Encefalite Transmitida por Carrapatos/diagnóstico , Manitoba/epidemiologiaRESUMO
Tick-borne encephalitis virus (TBEV) infection may cause acute central nervous system inflammation varying in clinical manifestations and severity. A possible correlation of TBEV-specific antibody and cell-mediated immune responses, shortly after infection, with clinical manifestations, severity and long-term outcome has been poorly investigated. In a cohort of thirty early tick-borne encephalitis (TBE) patients, we assessed the magnitude, specificity and functional properties of TBEV-specific T-cell and antibody responses. These responses early during disease were assessed in view of clinical manifestations, severity and long-term outcome. TBEV-specific T-cell responses to C, E, NS1, and NS5 proteins were significantly lower in patients with severe acute illness than in patients with mild TBE. Lower T-cell responses to E, NS1, and NS5 proteins also correlated with the development of meningoencephalomyelitis. Virus-specific antibody titres early after infection did not correlate with disease severity, clinical manifestations, or long-term outcome in this study, possibly due to the small number of patients of which matching serum and peripheral blood mononuclear cells were available. The findings suggest that virus-specific T cells afford a certain degree of protection against the development of severe TBEV-induced disease.
Assuntos
Anticorpos Antivirais , Vírus da Encefalite Transmitidos por Carrapatos , Encefalite Transmitida por Carrapatos , Linfócitos T , Encefalite Transmitida por Carrapatos/imunologia , Encefalite Transmitida por Carrapatos/virologia , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Humanos , Linfócitos T/imunologia , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Masculino , Feminino , Pessoa de Meia-Idade , Adulto , Índice de Gravidade de Doença , Idoso , Proteínas não Estruturais Virais/imunologiaRESUMO
Powassan virus is a tick-borne flavivirus that can cause severe neuroinvasive disease, with areas of endemicity in the Northeast and Midwest United States, Canada, and Russia. Diagnosis is challenging and relies on a high index of suspicion and choosing the right test based on duration of infection and the patient's immune status. This review covers laboratory testing for Powassan virus, including historical considerations, modern options, and methods being developed in the research space.
Assuntos
Vírus da Encefalite Transmitidos por Carrapatos , Encefalite Transmitida por Carrapatos , Humanos , Encefalite Transmitida por Carrapatos/diagnóstico , Encefalite Transmitida por Carrapatos/epidemiologia , Encefalite Transmitida por Carrapatos/virologia , Vírus da Encefalite Transmitidos por Carrapatos/isolamento & purificação , Técnicas de Laboratório Clínico/métodos , História do Século XXI , História do Século XX , Animais , Canadá/epidemiologia , Anticorpos Antivirais/sangueRESUMO
Powassan virus (POWV) is an emergent tick-borne flavivirus that causes fatal encephalitis in the elderly and long-term neurologic sequelae in survivors. How age contributes to severe POWV encephalitis remains an enigma, and no animal models have assessed age-dependent POWV neuropathology. Inoculating C57BL/6 mice with a POWV strain (LI9) currently circulating in Ixodes ticks resulted in age-dependent POWV lethality 10-20 dpi. POWV infection of 50-week-old mice was 82% fatal with lethality sequentially reduced by age to 7.1% in 10-week-old mice. POWV LI9 was neuroinvasive in mice of all ages, causing acute spongiform CNS pathology and reactive gliosis 5-15 dpi that persisted in survivors 30 dpi. High CNS viral loads were found in all mice 10 dpi. However, by 15 dpi, viral loads decreased by 2-4 logs in 10- to 40-week-old mice, while remaining at high levels in 50-week-old mice. Age-dependent differences in CNS viral loads 15 dpi occurred concomitantly with striking changes in CNS cytokine responses. In the CNS of 50-week-old mice, POWV induced Th1-type cytokines (IFNγ, IL-2, IL-12, IL-4, TNFα, IL-6), suggesting a neurodegenerative pro-inflammatory M1 microglial program. By contrast, in 10-week-old mice, POWV-induced Th2-type cytokines (IL-10, TGFß, IL-4) were consistent with a neuroprotective M2 microglial phenotype. These findings correlate age-dependent CNS cytokine responses and viral loads with POWV lethality and suggest potential neuroinflammatory therapeutic targets. Our results establish the age-dependent lethality of POWV in a murine model that mirrors human POWV severity and long-term CNS pathology in the elderly. IMPORTANCE: Powassan virus is an emerging tick-borne flavivirus causing lethal encephalitis in aged individuals. We reveal an age-dependent POWV murine model that mirrors human POWV encephalitis and long-term CNS damage in the elderly. We found that POWV is neuroinvasive and directs reactive gliosis in all age mice, but at acute stages selectively induces pro-inflammatory Th1 cytokine responses in 50-week-old mice and neuroprotective Th2 cytokine responses in 10-week-old mice. Our findings associate CNS viral loads and divergent cytokine responses with age-dependent POWV lethality and survival outcomes. Responses of young mice suggest potential therapeutic targets and approaches for preventing severe POWV encephalitis that may be broadly applicable to other neurodegenerative diseases. Our age-dependent murine POWV model permits analysis of vaccines that prevent POWV lethality, and therapeutics that resolve severe POWV encephalitis.
Assuntos
Citocinas , Modelos Animais de Doenças , Vírus da Encefalite Transmitidos por Carrapatos , Encefalite Transmitida por Carrapatos , Camundongos Endogâmicos C57BL , Neuroglia , Carga Viral , Animais , Camundongos , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Encefalite Transmitida por Carrapatos/imunologia , Encefalite Transmitida por Carrapatos/virologia , Encefalite Transmitida por Carrapatos/mortalidade , Encefalite Transmitida por Carrapatos/patologia , Citocinas/metabolismo , Citocinas/imunologia , Neuroglia/virologia , Neuroglia/imunologia , Neuroglia/patologia , Feminino , Fatores Etários , Ixodes/virologia , Ixodes/imunologia , Sistema Nervoso Central/virologia , Sistema Nervoso Central/imunologia , Sistema Nervoso Central/patologia , Encéfalo/virologia , Encéfalo/patologia , Encéfalo/imunologiaRESUMO
Ticks are important vectors of disease, particularly in the context of One Health, where tick-borne diseases (TBDs) are increasingly prevalent worldwide. TBDs often involve co-infections, where multiple pathogens co-exist in a single host. Patients with chronic Lyme disease often have co-infections with other bacteria or parasites. This study aimed to create a co-infection model with Borrelia afzelii and tick-borne encephalitis virus (TBEV) in C3H mice and to evaluate symptoms, mortality, and pathogen level compared to single infections. Successful co-infection of C3H mice with B. afzelii and TBEV was achieved. Outcomes varied, depending on the timing of infection. When TBEV infection followed B. afzelii infection by 9 days, TBEV symptoms worsened and virus levels increased. Conversely, mice infected 21 days apart with TBEV showed milder symptoms and lower mortality. Simultaneous infection resulted in mild symptoms and no deaths. However, our model did not effectively infect ticks with TBEV, possibly due to suboptimal dosing, highlighting the challenges of replicating natural conditions. Understanding the consequences of co-infection is crucial, given the increasing prevalence of TBD. Co-infected individuals may experience exacerbated symptoms, highlighting the need for a comprehensive understanding through refined animal models. This study advances knowledge of TBD and highlights the importance of exploring co-infection dynamics in host-pathogen interactions.
Assuntos
Coinfecção , Modelos Animais de Doenças , Vírus da Encefalite Transmitidos por Carrapatos , Encefalite Transmitida por Carrapatos , Doença de Lyme , Camundongos Endogâmicos C3H , Animais , Coinfecção/microbiologia , Coinfecção/virologia , Camundongos , Vírus da Encefalite Transmitidos por Carrapatos/fisiologia , Vírus da Encefalite Transmitidos por Carrapatos/patogenicidade , Doença de Lyme/microbiologia , Encefalite Transmitida por Carrapatos/virologia , Grupo Borrelia Burgdorferi , FemininoRESUMO
Omsk hemorrhagic fever virus (OHFV) is a member of the tick-borne encephalitis virus (TBEV) complex of the Flaviviridae family. Currently, there are no data on the cross-reactivity of antibodies to the NS1 proteins of OHFV and TBEV. Such data are of major interest for monitoring viral encephalitis of unknown etiology due to the increasing geographical distribution of OHFV. In this study, a recombinant OHFV NS1 protein was produced using the Escherichia coli expression system and purified. The recombinant OHFV NS1 protein was recognized by specific mice immune ascetic fluids to the native OHFV NS1 protein. A Western blot analysis and ELISA of the recombinant NS1 proteins of OHFV and TBEV were used to study the cross-reactivity of antibodies from immune ascites fluid obtained from OHFV-infected mice and mAbs against TBEV NS1. Anti-TBEV NS1 mouse monoclonal antibodies (mAbs) have been shown to not be cross-reactive to the OHFV NS1 protein. Sera from patients with confirmed tick-borne encephalitis (TBE) were examined by ELISA using recombinant OHFV NS1 and TBEV NS1 proteins as antigens. It was shown for the first time that cross-reactive antibodies to the OHFV NS1 protein were not detected in the sera of TBE patients, whereas the sera contained antibodies to the TBEV NS1 protein.
Assuntos
Anticorpos Antivirais , Reações Cruzadas , Vírus da Encefalite Transmitidos por Carrapatos , Encefalite Transmitida por Carrapatos , Proteínas Recombinantes , Proteínas não Estruturais Virais , Proteínas não Estruturais Virais/imunologia , Encefalite Transmitida por Carrapatos/imunologia , Encefalite Transmitida por Carrapatos/virologia , Encefalite Transmitida por Carrapatos/sangue , Reações Cruzadas/imunologia , Vírus da Encefalite Transmitidos por Carrapatos/imunologia , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Animais , Humanos , Camundongos , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/genética , Ensaio de Imunoadsorção Enzimática , Escherichia coli/genética , Camundongos Endogâmicos BALB C , FemininoRESUMO
CONTEXT: Flaviviruses cause severe encephalitic or hemorrhagic diseases in humans. Its members, Kyasanur forest disease virus (KFDV) and Alkhumra hemorrhagic fever virus (ALKV), cause hemorrhagic fever and are prevalent in India and Saudi Arabia, respectively, while the tick-borne encephalitis virus (TBEV) causes a dangerous encephalitic infection in Europe and Asia. However, little information is available about the targets of immune responses for these deadly viruses. Here, we predict potential antigenic peptide epitopes of viral envelope protein for inducing a cell-mediated and humoral immune response. METHODS: Using the Immune Epitope Database and Analysis Resource (IEDB-AR), we identified 13 MHC-I and two MHC-II dominant conserved epitopes in KFDV and ALKV and six MHC-I and three MHC-II epitopes in TBEV envelope proteins. Parallelly, we also predicted B-cell linear and discontinuous envelope protein epitopes for these viruses. Interestingly, the epitopes are conserved in all three viral envelope proteins. Further, the discontinuous epitopes are structurally compared with the available DENV, ZIKV, WNV, TBEV, and LIV envelope protein antibody structures. Overall structural comparison analyses highlight (i) lateral ridge epitope in the ED-III domain of E protein, and (ii) envelope dimer epitope (EDE) could be targeted for developing potent vaccine candidates as well as therapeutic antibody production. Moreover, existing structural and biochemical functions of the same epitopes in homologous viruses are predicted to have a reduced antibody-dependent enhancement (ADE) effect on flaviviral infection.
Assuntos
Flavivirus , Flavivirus/imunologia , Humanos , Proteínas do Envelope Viral/imunologia , Proteínas do Envelope Viral/química , Biologia Computacional , Sequência de Aminoácidos , Epitopos de Linfócito B/imunologia , Epitopos de Linfócito B/química , Homologia de Sequência de Aminoácidos , Epitopos/imunologia , Epitopos/química , Modelos Moleculares , Vírus da Encefalite Transmitidos por Carrapatos/imunologiaRESUMO
Tick-borne encephalitis virus (TBEV), a zoonotic pathogen, can cause severe neurological complications and fatal outcomes in humans. Early diagnosis of TBEV infection is crucial for clinical practice. Although serological assays are frequently employed for detection, the lack of antibodies in the early stages of infection and the cross-reactivity of antibodies limit their efficacy. Conventional molecular diagnostic methods such as RT-qPCR can achieve early and accurate identification but require specialized instrumentation and professionals, hindering their application in resource-limited areas. Our study developed a rapid and visual TBEV molecular detection method by combining RT-recombinase-aided amplification, the CRISPR/Cas13a system, and lateral flow dipsticks. The diagnostic sensitivity of this method is 50 CFU/ml, with no cross-reactivity with a variety of viruses. The detection can be carried out within 1 h at a temperature between 37 and 42 °C, and the results can be visually determined without the need for complex instruments and professionals. Subsequently, this assay was used to analyze clinical samples from 15 patients suspected of TBEV infection and 10 healthy volunteers, and its sensitivity and specificity reached 100 %, which was consistent with the results of RT-qPCR. These results indicate that this new method can be a promising point-of-care test for the diagnosis of tick-borne encephalitis.
Assuntos
Sistemas CRISPR-Cas , Vírus da Encefalite Transmitidos por Carrapatos , Recombinases , Vírus da Encefalite Transmitidos por Carrapatos/genética , Humanos , Recombinases/metabolismo , Técnicas de Amplificação de Ácido Nucleico/métodos , Encefalite Transmitida por Carrapatos/diagnóstico , Encefalite Transmitida por Carrapatos/virologia , Encefalite Transmitida por Carrapatos/sangue , Sensibilidade e Especificidade , RNA Viral/genética , Técnicas de Diagnóstico Molecular/métodosRESUMO
Tick-borne Encephalitis (TBE) is a zoonotic disease caused by the Tick-borne Encephalitis virus (TBEV), which affects the central nervous system of both humans and animals. Currently, there is no specific therapy for patients with TBE, with symptomatic treatment being the primary approach. In this study, the effects of minocycline (MIN), which is a kind of tetracycline antibiotic, on TBEV propagation and cellular protection in TBEV-infected cell lines were evaluated. Indirect immunofluorescence, virus titers, and RT-qPCR results showed that 48 h post-treatment with MIN, TBEV replication was significantly inhibited in a dose-dependent manner. In addition, the inhibitory effect of MIN on different TBEV multiplicities of infection (MOIs) in Vero cells was studied. Furthermore, the transcriptomic analysis and RT-qPCR results indicate that after incubation with MIN, the levels of TBEV and CALML4 were decreased, whereas the levels of calcium channel receptors, such as RYR2 and SNAP25, were significantly increased. MIN also regulated MAPK-ERK-related factors, including FGF2, PDGFRA, PLCB2, and p-ERK, and inhibited inflammatory responses. These data indicate that administering MIN to TBEV-infected cells can reduce the TBEV level, regulate calcium signaling pathway-associated proteins, and inhibit the MAPK-ERK signaling pathway and inflammatory responses. This research offers innovative strategies for the advancement of anti-TBEV therapy.
Assuntos
Vírus da Encefalite Transmitidos por Carrapatos , Minociclina , Replicação Viral , Animais , Vírus da Encefalite Transmitidos por Carrapatos/efeitos dos fármacos , Vírus da Encefalite Transmitidos por Carrapatos/fisiologia , Minociclina/farmacologia , Chlorocebus aethiops , Células Vero , Replicação Viral/efeitos dos fármacos , Humanos , Antivirais/farmacologia , Encefalite Transmitida por Carrapatos/virologia , Encefalite Transmitida por Carrapatos/tratamento farmacológico , Linhagem Celular , Transdução de Sinais/efeitos dos fármacosRESUMO
We present structures of three immature tick-borne encephalitis virus (TBEV) isolates. Our atomic models of the major viral components, the E and prM proteins, indicate that the pr domains of prM have a critical role in holding the heterohexameric prM3E3 spikes in a metastable conformation. Destabilization of the prM furin-sensitive loop at acidic pH facilitates its processing. The prM topology and domain assignment in TBEV is similar to the mosquito-borne Binjari virus, but is in contrast to other immature flavivirus models. These results support that prM cleavage, the collapse of E protein ectodomains onto the virion surface, the large movement of the membrane domains of both E and M, and the release of the pr fragment from the particle render the virus mature and infectious. Our work favors the collapse model of flavivirus maturation warranting further studies of immature flaviviruses to determine the sequence of events and mechanistic details driving flavivirus maturation.