Search Results (157)

Pediatric seronegative immune-mediated cerebellar ataxia (IMCA) remains a poorly defined and often under-recognized diagnosis, particularly in young children, where symptoms are frequently misattributed to self-limited post-infectious processes. We report the case of a 2.5-year-old girl who presented with acute-onset ataxia (mSARA score: 14). Cerebrospinal fluid analysis revealed pleocytosis and positive oligoclonal bands, while serial brain imaging and extensive autoantibody panels were unremarkable. However, indirect immunohistochemistry (TIIF/IHC) demonstrated a positive intracellular signal in cerebellar Purkinje cells, supporting the diagnosis of isolated seronegative IMCA. The patient showed sustained clinical improvement with prolonged corticosteroid therapy (mSARA score: 1). To date, only a few similar cases have been reported in the literature. It remains unclear whether these presentations fall within the spectrum of autoimmune encephalitis (AIE) or represent a distinct pediatric phenotype, potentially expanding the age range of primary autoimmune cerebellar ataxia previously described in adults. We recommend incorporating TIIF/IHC into the diagnostic workup of both isolated and combined pediatric cerebellar ataxia syndromes to support diagnosis and guide individualized treatment. Additionally, neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) are emerging as promising biomarkers in this context and warrant further investigation. Full article

(1) Background: To report two cases of severe tick-borne encephalitis (TBE) in elderly patients presenting with a previously undescribed subarachnoid T2/FLAIR hyperintensity on repeated MRI examinations, which may serve as an early imaging biomarker of disease severity. (2) Methods: Two unvaccinated 82-year-old patients (one male and one female) presented with acute encephalitis and required intensive care. Serial brain MRI, EEG, CSF analysis, and neurophysiological assessments were performed. (3) Results: Both patients showed rapid progressive neurological deterioration in the context of TBE, confirmed by elevated serum and CSF IgM and IgG titers. Early follow-up MRI revealed striking sulcal hyperintensities on T2/FLAIR sequences, interpreted as protein-rich subarachnoid inflammatory changes. These changes paralleled clinical worsening and resolved on follow-up imaging. The male patient developed meningoencephalomyeloradiculitis, remained comatose, and died from respiratory failure (the brain and spinal cord were examined postmortem). The female patient had meningoencephaloradiculitis with severe dysphagia and was discharged with a modified Rankin Scale score of four. Both patients demonstrated epileptiform EEG activity. The CSF analysis revealed markedly elevated total protein, lactate, tau protein, and CXCL13, as evidence of blood–brain barrier disruption and inflammatory neurodegeneration. (4) Conclusions: We describe acute subarachnoid T2/FLAIR hyperintensity in TBE as an imaging feature that may correlate with severe systemic inflammation and a poor prognosis. This radiological finding could serve as a potential early prognostic marker in TBE. Full article

Background/Objectives: Meningoencephalitis (ME) is a life-threatening infectious disease; therefore, prompt and accurate diagnosis is lifesaving. Traditional diagnostic methods, such as culture, have several limitations related to sensitivity and specificity. Emerging multiplex ME-PCR panels are a comprehensive and rapid tool in a single test. The Bio-Speedy Meningitis/Encephalitis RT-qPCR MX-17 panel (Bioeksen R&D Technologies Inc., Turkey) enables testing for 17 targets. To evaluate the performance of the panel compared to clinical and CSF parameters. Methods: A total of 403 patients with a preliminary diagnosis of ME were reviewed between January 2019 and September 2023. Following revision, 72 patients with clinical, CSF, and laboratory findings were included. The tested panel was used to detect targeted pathogens in CSF samples. The 30-day survival rate and prolonged stay were analyzed. Results: The median CSF protein value was 59.5 mg/dL (14.2–1471 mg/dL) and glucose was 61.95 mg/dL (0.083–165 mg/dL). Forty-one (56.9%) ME panel results were positive, among which 38.9% (28) were viral and 19.4% (14) were bacterial. HHV-6 ranked first with a rate of 15.3%. The Bio-Speedy panel test results outperformed the CSF culture (p < 0.001). The correlation of the Bio-Speedy panel with impaired consciousness was statistically significant (p = 0.004). Six (8.3%) patients from the study group died within 30 days. Conclusions: Compared to traditional methods, Bio-Speedy panel was effective in identifying the causative agents of ME. The Bio-Speedy ME RT-qPCR MX-17 panel offers accurate detection of ME-causing pathogens. The implementation of the panel in clinical practice can impact patient management and improve outcomes. Full article

Ixodid ticks are blood-sucking ectoparasites of vertebrates. They constitute an integral part of natural foci and are responsible for the worldwide transmission of infections to humans, which can result in severe symptoms. For instance, the Tomsk region, where three abundant tick species (Dermacentor reticulatus, Ixodes pavlovskyi, I. persulcatus) occur, is an endemic area for tick-borne encephalitis virus (TBEV). An increasing number of novel infectious agents carried by ticks have been identified using metagenomic sequencing. A notable example is the Yezo virus (Orthonairovirus yezoense, YEZV), which was discovered in patients with fever after tick bites in Japan and China between 2014 and 2025. For the first time, we have performed metagenomic sequencing of the virome of ticks collected in the Tomsk region. In a sample obtained from a pool of I. pavlovskyi ticks, all three segments of the YEZV genome were detected. The phylogenetic analysis showed that the newly identified isolate formed a sister group to previously described virus isolates, indicating the presence of a new genetic variant. This study presents the first report of YEZV detection in I. pavlovskyi ticks in the Tomsk region, thereby expanding the geographical range and number of vector species for YEZV and highlighting the importance of monitoring viral agents circulating among ticks in Western Siberia. Full article

Inborn errors of immunity (IEI) encompass a diverse group of genetic disorders that often present with complex and multifaceted clinical features, including neuroinflammation. CTLA-4 deficiency (CTLA-4d), caused by monoallelic germline mutations in the CTLA4 gene, manifests with autoimmune phenomena, lymphoproliferation, infections, and neurological involvement in up to 30% of patients, with a broad clinical spectrum, ranging from encephalitis to demyelination and lymphocytic infiltration. Imaging typically shows multifocal contrast-enhancing lesions. Early recognition of CTLA-4d is crucial to guide clinical management. Herein, we report the case of a 15-year-old girl presenting with severe multifocal neuroinflammatory lesions, recurrent infections, and systemic granulomatous disease. After extensive infectious and immunological workup, a heterozygous de novo CTLA4 variant c.394G>A_p.Glu132Lys was identified and its pathogenicity confirmed by transendocytosis functional assays. Based on the genetic diagnosis, the patient was started on abatacept, with brilliant clinical and radiological results after dose adjustment. This report describes a new pathogenic variant of the CTLA4 gene and highlights the importance of considering IEIs, such as CTLA-4d, in patients with unexplained severe neuroinflammation. Also, it highlights the efficacy and tolerability of abatacept as a targeted therapy for neuroinflammation in CTLA4-d. Full article

Encephalitis is a potentially life-threatening condition with long-term neurological sequelae. However, data on early clinical, demographic, and diagnostic predictors of functional outcomes remain limited. We performed a retrospective monocentric study including 98 patients diagnosed with infectious encephalitis of various etiologies treated in the University Hospital Ulm between January 2014 and December 2024. Ordinal logistic regression models were applied to evaluate associations between admission characteristics and functional outcome at discharge, as measured by the modified Rankin Scale. Three multivariate models incorporating clinical, demographic, and MRI/EEG variables explained up to 53% of the variance in mRS at discharge (p < 0.001), outperforming models based solely on CSF parameters. Key predictors of poor functional outcome included ‘altered consciousness’ (OR 7.08, p < 0.001), higher ‘mRS at admission’ (OR 0.03–0.07 across categories, p < 0.001), ‘focal/generalized EEG slowing’ (OR 9.97, p < 0.001), ‘epileptiform EEG activity’ (OR 17.49, p < 0.001), ‘MRI: myelitis’ (OR 16.44, p = 0.004), and ‘intrathecal IgM synthesis’ (OR 8.93, p = 0.018). Conversely, ‘longer hospitalization’ (OR 0.13–0.17 for different intervals, p < 0.006) and ‘intrathecal IgG synthesis’ (OR 0.05, p = 0.03) were associated with more favorable outcomes. Despite the single-center and retrospective aspects of this study, our findings underscore a multifactorial pattern of outcome determinants in infectious encephalitis, highlighting the prognostic relevance of initial neurological status, electrophysiological abnormalities, and neuroimaging features. Full article

Japanese encephalitis virus (JEV) is a mosquito-borne zoonotic flavivirus that circulates primarily within animal populations and occasionally spills over to humans, causing severe neurological disease. While humans are terminal hosts, veterinary species such as pigs and birds play essential roles in viral amplification and maintenance, making JEV fundamentally a veterinary infectious disease with zoonotic potential. This review summarizes the current understanding of JEV transmission dynamics from a veterinary and ecological perspective, emphasizing the roles of amplifying hosts and animal surveillance in controlling viral circulation. Recent genotype shifts and viral evolution have raised concerns regarding vaccine effectiveness and regional emergence. National surveillance systems and animal-based monitoring strategies are examined for their predictive value in detecting outbreaks early. Veterinary and human vaccination strategies are also reviewed, highlighting the importance of integrated One Health approaches. Advances in modeling and climate-responsive surveillance further underscore the dynamic and evolving landscape of JEV transmission. By managing the infection in animal reservoirs, veterinary interventions form the foundation of sustainable zoonotic disease control. Full article

Japanese encephalitis virus (JEV) is a mosquito-borne orthoflavivirus and a major cause of human encephalitis throughout Asia, although it is currently not reported in Europe. To assess the potential impact of climate change, such as increased temperatures, and the potential for native Cx. pipiens to transmit JEV genotype I in the United Kingdom (UK), we have investigated vector competence at two different temperatures. Culex pipiens f. pipiens were provided a bloodmeal containing JEV genotype I at 7.8 × 10⁸ PFU/mL. Mosquitoes were maintained for 14 days at 21 °C or 25 °C, and rates of infection, dissemination, and transmission potential were assessed. There was no evidence for virus infection, dissemination, or potential for transmission at 21 °C. However, at 25 °C, virus infection was detected in 5 of 36 mosquitoes (13.9%). Of these, JEV disseminated to legs and wings in three specimens (3/5) and viral RNA was detected in saliva from one specimen (1/3). These data indicate that at elevated temperatures of 25 °C, UK Cx. pipiens f. pipiens could transmit JEV genotype 1. Full article

Tick-Borne Encephalitis Virus (TBEV) is impacting public health in the Eurasian region, with increasing case numbers. There is, therefore, a need to expand research efforts and the corresponding infrastructure capacity. Since TBEV is classified as a risk group 3 organism in Switzerland, handling infectious material containing the virus is restricted to biosafety level 3 laboratories. In some instances, downstream analyses may need to be performed outside of the containment facility. It is, therefore, essential to validate effective inactivation protocols compatible with the safe and accurate processing of samples. This study evaluated UV irradiation, chemical treatment with detergents, and mechanical filtration as candidate methods to inactivate TBEV infectious samples, including culture supernatants and tissue homogenates, while preserving their compatibility for different assays. Among the methods tested, 45 s of UV irradiation or Triton-X100 at concentrations between 0.05% and 0.1% effectively inactivated TBEV while mostly preserving the integrity of the processed samples for immuno- or enzymatic assays. These findings establish safe and reliable procedures for advancing TBEV research beyond high-containment settings. Full article

Arboviruses, transmitted by blood-sucking arthropods, are responsible for significant human and animal diseases, including fever, hemorrhagic fever, and encephalitis, posing a serious threat to global public health. Nevertheless, research on the mechanisms of arbovirus infection and the development of therapeutic interventions has been impeded. This delay is primarily due to the limitations inherent in current in vitro research models, including cell cultures and animal models. The simplicity of cell types and interspecies differences present significant obstacles to advancing our understanding of arbovirus infection mechanisms and the development of effective drugs. Human brain organoids, derived from human pluripotent stem cells or human embryonic stem cells and cultured in three-dimensional systems, more accurately replicate the extensive neuronal cellular diversity and key characteristics of human neurodevelopment. These organoids serve as an ideal model for investigating the intricate interactions between viruses and human hosts, and providing a novel platform for the development of antiviral drugs. In this review, we summarize how brain organoid models complement classical approaches to accelerate research into the infection mechanisms of arboviruses, with a particular focus on the types of neural cells, key factors, and cellular signaling pathways involved in the arbovirus infection of brain organoids that have been reported. Furthermore, we examine the development of brain organoids, address their current limitations, and propose future directions to enhance the application of brain organoids in the study of arboviral infectious diseases. Full article

Encephalitis, a severe neurological condition caused by human-to-human (H2H) transmitted viruses, such as herpes simplex virus (HSV), requires a rigorous mathematical framework to understand its transmission dynamics. This study develops a nonlinear compartmental model, SEITR (Susceptible–Exposed–Infected–Treated–Recovered), to characterize the progression of viral encephalitis. The basic reproduction number (R₀) is derived using the next-generation matrix method, serving as a threshold parameter determining disease persistence. The local and global stability of the disease-free and endemic equilibria are established through a rigorous mathematical analysis. Additionally, a sensitivity analysis quantifies the impact of key parameters on R₀, offering more profound insights into their mathematical significance. Numerical simulations validate the theoretical results, demonstrating the system’s dynamical behavior under varying epidemiological conditions. This study provides a mathematically rigorous approach to modeling viral encephalitis transmission, filling a gap in the literature and offering a foundation for future research in infectious disease dynamics. Full article

Handling cultured isolates and clinical, environmental, or wildlife surveillance samples containing Risk Group 3 and 4 pathogens presents considerable biosafety challenges in minimizing human exposure during processing and transport. Safe handling typically requires high- or maximum-containment facilities, demanding substantial logistical planning and resources. We evaluated PrimeStore Molecular Transport Medium (PS-MTM), a guanidine-based solution created to kill pathogens and preserve nucleic acids at ambient temperatures, for inactivating Crimean-Congo hemorrhagic fever, eastern equine encephalitis, Ebola, Hendra, Japanese encephalitis, Lassa, Marburg, Nipah, Rift Valley fever, and West Nile viruses. To mimic diagnostic conditions, human whole blood spiked with any of these viruses was incubated with PS-MTM for 20-, 30-, or 60-min. Samples with titers up to 10⁷ PFU/mL exposed to PS-MTM at all time points resulted in complete loss of infectivity judged by plaque assays. A 30-min incubation provided a 50% safety margin over the minimum inactivation time and was used for quantification with the tissue culture infectious dose (TCID₅₀) assay, enabling evaluation of PS-MTM’s activity for viruses that do or do not produce well-defined plaques. Results confirmed that PS-MTM inactivated all tested viruses at titers up to 10⁷ TCID₅₀/mL, underscoring its reliability for enhancing biosafety in diagnostics, outbreak management, and surveillance. Full article

Janus kinase inhibitors (JAKis) represent a relatively new class of immunomodulatory drugs with potent effects on various cytokine signalling pathways. They have revolutionized the treatment landscape for autoimmune diseases such as rheumatoid arthritis, psoriatic arthritis, and ulcerative colitis. However, their ability to modulate immune responses presents a dual-edged nature, influencing both protective immunity and pathological inflammation. This review explores the complex role of JAKis in infectious settings, highlighting both beneficial and detrimental effects. On the one hand, experimental models suggest that JAK inhibition can impair host defence mechanisms, increasing susceptibility to certain bacterial and viral infections. For example, tofacitinib-treated mice exhibited more severe joint erosions in Staphylococcus aureus (S. aureus) septic arthritis and showed impaired viral clearance in herpes simplex encephalitis. Additionally, clinical data confirm an increased risk of herpes zoster in patients receiving JAKis, underscoring the need for rigorous monitoring. On the other hand, JAK inhibition has demonstrated protective effects in certain infectious and hyperinflammatory conditions. In sepsis models, including cecal ligation and puncture (CLP) and S. aureus bacteraemia, tofacitinib improved survival by attenuating excessive inflammation. Furthermore, JAKis, particularly baricitinib, have shown substantial efficacy in mitigating cytokine storms during severe COVID-19 infections, leading to improved clinical outcomes and reduced mortality. These observations suggest that JAKis have a role in modulating hyperinflammatory responses in select infectious contexts. In conclusion, JAKis present a complex interplay between immunosuppression and immunomodulation. While they increase the risk of certain infections, they also show potential in managing hyperinflammatory conditions such as cytokine storms. The key challenge is determining which patients and situations benefit most from JAKis while minimizing risks, requiring a careful and personalized treatment approach. Full article

Transient gene expression (TGE) is commonly employed for protein production, but its reliance on plasmid transfection makes it challenging to scale up. In this paper, an alternative TGE method is presented, utilizing pseudoinfectious alphavirus as an expression vector. Pseudoinfectious viruses (PIV) and a replicable helper construct were derived from the genome of the Venezuelan equine encephalitis virus. The PIV carries a mutant capsid protein that prevents packaging into infectious particles, while the replicable helper encodes a wild-type capsid protein but lacks other viral structural proteins. Although PIV and the helper cannot independently spread infection, their combination results in increased titers in cell cultures, enabling easier scale-up of producing cultures. The PIV-driven production of a model protein outperforms that of alphavirus replicon vectors or simple plasmid vectors. Another described feature of the expression system is the modification to immobilized metal affinity chromatography (IMAC), allowing purification of His-tagged recombinant proteins from a conditioned medium in the presence of substances that can strip metal from the IMAC columns. The PIV-based expression system allows for the production of milligram quantities of recombinant proteins in static cultures, without the need for complex equipment such as bioreactors, and complies with regulatory requirements due to its distinction from common recombinant viruses. Full article

Chimeric orthoflaviviruses derived from the insect-specific Binjari virus (BinJV) offer a promising basis for safe orthoflavivirus vaccines. However, these vaccines have so far only been produced using adherent C6/36 Aedes albopictus mosquito cell cultures grown in serum-supplemented media, limiting their scalable manufacture. To address this, we adapted C6/36 cells for serum-free suspension culture using Sf900-III medium, achieving high peak cell densities (up to 2.5 × 10⁷ cells/mL). Higher agitation rates reduced cell aggregation, and cryopreservation and direct-to-suspension revival were successful, confirming the adapted line’s stability for research and industrial applications. Despite this, BinJV-based chimeric orthoflaviviruses, including BinJV/WNV_KUN, a candidate vaccine for West Nile virus, and similar vaccines (BinJV/DENV2 and BinJV/JEV_NSW22) for dengue 2 virus and Japanese encephalitis virus, respectively, exhibited substantially reduced titres in C6/36 cultures infected in Sf900-III, a phenomenon attributed to the medium’s acidic pH. Switching to the more alkaline, serum-free CD-FortiCHO medium enhanced the replication of these chimeric viruses to peak titres between 1.7 × 10⁷ and 7.6 × 10⁹ infectious units per mL whilst preserving viral integrity. These findings suggest that suspension-adapted C6/36 cultures in CD-FortiCHO medium can support high-yield vaccine production for various orthoflaviviruses and highlight the important role of cell culture media pH for orthoflavivirus bioprocessing. This scalable mosquito cell-based system could reduce production costs and improve vaccine accessibility, supporting efforts to combat arbovirus-related public health challenges. Full article