BACKGROUND: Tick-borne encephalitis virus (TBEV) is a significant threat to human health. The virus causes potentially fatal disease of the central nervous system (CNS), for which no treatments are available. TBEV infected individuals display a wide spectrum of neuronal disease, the determinants of which are undefined. Changes to host metabolism and virus-induced immunity have been postulated to contribute to the neuronal damage observed in infected individuals. In this study, we evaluated the cytokine, chemokine, and metabolic alterations in the cerebrospinal fluid (CSF) of symptomatic patients infected with TBEV presenting with meningitis or encephalitis. Our aim was to investigate the host immune and metabolic responses associated with specific TBEV infectious outcomes. METHODS: CSF samples of patients with meningitis (n = 27) or encephalitis (n = 25) were obtained upon consent from individuals hospitalised with confirmed TBEV infection in Brno. CSF from uninfected control patients was also collected for comparison (n = 12). A multiplex bead-based system was used to measure the levels of pro-inflammatory cytokines and chemokines. Untargeted metabolomics followed by bioinformatics and integrative omics were used to profile the levels of metabolites in the CSF. Human motor neurons (hMNs) were differentiated from induced pluripotent stem cells (iPSCs) and infected with the highly pathogenic TBEV-Hypr strain to profile the role(s) of identified metabolites during the virus lifecycle. Virus infection was quantified via plaque assay. RESULTS: Significant differences in proinflammatory cytokines (IFN-α2, TSLP, IL-1α, IL-1β, GM-CSF, IL-12p40, IL-15, and IL-18) and chemokines (IL-8, CCL20, and CXCL11) were detected between neurological-TBEV and control patients. A total of 32 CSF metabolites differed in TBE patients with meningitis and encephalitis. CSF S-Adenosylmethionine (SAM), Fructose 1,6-bisphosphate (FBP1) and Phosphoenolpyruvic acid (PEP) levels were 2.4-fold (range ≥ 2.3-≥3.2) higher in encephalitis patients compared to the meningitis group. CSF urocanic acid levels were significantly lower in patients with encephalitis compared to those with meningitis (p = 0.012209). Follow-up analyses showed fluctuations in the levels of O-phosphoethanolamine, succinic acid, and L-proline in the encephalitis group, and pyruvic acid in the meningitis group. TBEV-infection of hMNs increased the production of SAM, FBP1 and PEP in a time-dependent manner. Depletion of the metabolites with characterised pharmacological inhibitors led to a concentration-dependent attenuation of virus growth, validating the identified changes as key mediators of TBEV infection. CONCLUSIONS: Our findings reveal that the neurological disease outcome of TBEV infection is associated with specific and dynamic metabolic signatures in the cerebrospinal fluid. We describe a new in vitro model for in-depth studies of TBEV-induced neuropathogenesis, in which the depletion of identified metabolites limits virus infection. Collectively, this reveals new biomarkers that can differentiate and predict TBEV-associated neurological disease. Additionally, we have identified novel therapeutic targets with the potential to significantly improve patient outcomes and deepen our understanding of TBEV pathogenesis.

• Keywords
• Cerebrospinal fluid, Chemokines, Human motor neurons, Metabolomics, Neuroinflammation, Pro-inflammatory cytokines, Tick-borne encephalitis virus,
• MeSH
• Cytokines cerebrospinal fluid   MeSH
• Adult MeSH
• Encephalitis, Tick-Borne * cerebrospinal fluid   metabolism   MeSH
• Cells, Cultured MeSH
• Middle Aged MeSH
• Humans MeSH
• Metabolome * physiology   MeSH
• Metabolomics MeSH
• Young Adult MeSH
• Neurons * metabolism   virology   MeSH
• Aged MeSH
• Encephalitis Viruses, Tick-Borne * MeSH
• Check Tag
• Adult MeSH
• Middle Aged MeSH
• Humans MeSH
• Young Adult MeSH
• Male MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Cytokines MeSH

Tick-borne encephalitis (TBE) is a potentially fatal neuroinfection of humans caused by the TBE virus. There is no specific therapy for TBE, as treatment is only supportive. Therefore, efforts to develop an effective specific therapy for TBE are warranted. Small molecule inhibitors and monoclonal antibodies are under intense investigation as potential therapeutics to combat TBE in humans. Here we describe the basic methods that can be used to test small molecule antivirals or monoclonal antibodies against TBEV. These include in vitro methods such as plaque assays, neutralizing assays, immunofluorescence staining of viral antigen, and cell-based antiviral assays, as well as in vivo assays in mouse model of TBE.

• Keywords
• Antivirals, Immunofluorescence, Monoclonal antibodies, Mouse infection, Neutralization test, Plaque assay, Tick-borne encephalitis virus,
• MeSH
• Antiviral Agents * pharmacology   MeSH
• Cell Line MeSH
• Encephalitis, Tick-Borne * virology   drug therapy   immunology   MeSH
• Humans MeSH
• Disease Models, Animal MeSH
• Antibodies, Monoclonal immunology   MeSH
• Mice MeSH
• Neutralization Tests methods   MeSH
• Antibodies, Neutralizing * immunology   pharmacology   MeSH
• Viral Plaque Assay MeSH
• Antibodies, Viral * immunology   MeSH
• Encephalitis Viruses, Tick-Borne * drug effects   immunology   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Mice MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Antiviral Agents * MeSH
• Antibodies, Monoclonal MeSH
• Antibodies, Neutralizing * MeSH
• Antibodies, Viral * MeSH

The European subtype of tick-borne encephalitis virus (TBEV-Eur; species Orthoflavivirus encephalitidis, family Flaviviridae) was the only tick-borne flavivirus present in central Europe known to cause neurologic disease in humans and several animal species. Here, we report a tick-borne flavivirus isolated from Alpine chamois (Rupicapra rupicapra rupicapra) with encephalitis and attached ticks, present over a wide area in the Alps. Cases were detected in 2017 in Salzburg, Austria, and 2023 in Lombardy and Piedmont, Italy. The virus strains exhibit 94.8-97.3% nucleotide identities to each other and are more closely related to Louping ill viruses (LIV; Orthoflavivirus loupingi; 90-92% identities) than to TBEV-Eur (less than 88%). The chamois-derived virus strains, tentatively termed "Alpine chamois encephalitis virus", form a well-supported independent genetic clade with Spanish goat encephalitis virus, clearly separated from other LIV. This supports its designation as a new virus subtype with the proposed shared taxonomic name "Spanish goat and Alpine chamois encephalitis virus subtype" within the species Orthoflavivirus loupingi. The zoonotic potential of this newly identified virus subtype as well as its host range in other animal species including farm animals needs to be further investigated.

• Keywords
• Alpine chamois, Flaviviridae, Ixodes ricinus, Rupicapra rupicapra, Spanish goat encephalitis virus, encephalitis, flavivirus, louping ill virus, neurotropic, tick-borne encephalitis virus,
• MeSH
• Phylogeny MeSH
• Genome, Viral MeSH
• Ticks virology   MeSH
• Encephalitis, Tick-Borne * veterinary   virology   epidemiology   MeSH
• Rupicapra * virology   MeSH
• Encephalitis Viruses, Tick-Borne * genetics   isolation & purification   classification   MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Geographicals
• Italy epidemiology   MeSH
• Austria epidemiology   MeSH

Tick-borne encephalitis (TBE) is a disease caused by the tick-borne encephalitis virus (TBEV) [...].

• Publication type
• Editorial MeSH

Matrix metalloproteinases (MMPs) play an important role in central nervous system infections. We analysed the levels of 8 different MMPs in the cerebrospinal fluid (CSF) of 89 adult patients infected with tick-borne encephalitis (TBE) virus and compared them with the levels in a control group. MMP-9 was the only MMP that showed significantly increased CSF levels in TBE patients. Serum MMP-9 levels were subsequently measured in 101 adult TBE patients at various time points during the neurological phase of TBE and at follow-up. In addition, serum MMP-9 was analysed in 37 paediatric TBE patients. Compared with control levels, both paediatric and adult TBE patients had significantly elevated serum MMP-9 levels. In most adult patients, serum MMP-9 levels peaked at hospital admission, with higher serum MMP-9 levels observed in patients with encephalitis than in patients with meningitis. Elevated serum MMP-9 levels were observed throughout hospitalisation but decreased to normal levels at follow-up. Serum MMP-9 levels correlated with clinical course, especially in patients heterozygous for the single-nucleotide polymorphism rs17576 (A/G; Gln279Arg) in the MMP9 gene. The results highlight the importance of MMP-9 in the pathogenesis of TBE and suggest that serum MMP-9 may serve as a promising bioindicator of TBE in both paediatric and adult TBE patients.

• Keywords
• Cerebrospinal fluid, Matrix matalloproteinase, Neuroinfection, Tick-borne encephalitis,
• MeSH
• Biomarkers MeSH
• Child MeSH
• Adult MeSH
• Polymorphism, Single Nucleotide MeSH
• Encephalitis, Tick-Borne * diagnosis   cerebrospinal fluid   MeSH
• Humans MeSH
• Matrix Metalloproteinase 9 genetics   MeSH
• Encephalitis Viruses, Tick-Borne * genetics   MeSH
• Check Tag
• Child MeSH
• Adult MeSH
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Biomarkers MeSH
• Matrix Metalloproteinase 9 MeSH
• MMP9 protein, human MeSH Browser

The presence of a non-structural protein 1 (NS1) in tick-borne encephalitis (TBE) vaccines and the possible induction of an NS1-specific immune response in vaccinated individuals remains a somewhat controversial topic. Previously, we detected the presence of NS1 in the Encepur TBE vaccine by mass spectrometry and found the induction of NS1-specific IgG antibodies in mice vaccinated with the FSME-Immun TBE vaccine. Here, in this follow-up study, we examined the dynamics and extent of the NS1-specific IgG response in mice vaccinated with these two vaccines in more detail and compared it with the IgG response to the whole virus (WV). Mice were vaccinated at two-week intervals with a total of six doses of each vaccine, and levels of IgG antibodies to TBE virus WV and NS1 were measured by ELISA after each dose. Both vaccines elicited a robust anti-WV IgG response after two doses. The Encepur vaccine did not elicit NS1-specific IgG even after all six doses. In contrast, the FSME-Immun vaccine triggered the production of NS1-specific IgG after four doses. The results indicate that FSME-Immun is the only vaccine that elicits an NS1-specific antibody response in mice. However, compared to WV-specific IgG, the NS1-specific response is weaker, and a higher number of doses is required to induce detectable levels of NS1-specific IgG antibodies.

• Keywords
• non-structural protein 1, tick-borne encephalitis virus, vaccine,
• Publication type
• Journal Article MeSH