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PubMed2025

Plasma Proteomic Profiles of Pediatric Patients With Human Herpesvirus 6B Encephalitis Following Umbilical Cord Blood Transplantation.

Human herpesvirus 6B (HHV-6B) encephalitis is a rare but severe complication of hematopoietic cell transplantation. This study investigated the pathogenesis of HHV-6B encephalitis by comparing plasma proteomic profiles of four pediatric patients with HHV-6B encephalitis to three with asymptomatic HHV-6B reactivation following umbilical cord blood transplantation (UCBT). Plasma proteomic profiling was conducted using liquid chromatography-mass spectrometry. Overall, 260 proteins were identified and quantified in plasma samples. At the onset of HHV-6B encephalitis and asymptomatic reactivation, 20 and 24 proteins, respectively, were significantly upregulated compared to their respective pre-onset levels. Of these, 11 proteins were uniquely upregulated in HHV-6B encephalitis. S100-A9 and S100-A8 were the most and second-most upregulated proteins in HHV-6B encephalitis, respectively. Elevated plasma S100A8/A9 heterodimer levels were confirmed via enzyme-linked immunosorbent assay in three of the four patients with HHV-6B encephalitis. Pathway analysis identified neutrophil degranulation as the most enriched category among upregulated proteins in HHV-6B encephalitis. Additionally, proteins related to the protein-lipid complex remodeling pathway were more prominently upregulated in HHV-6B encephalitis than in asymptomatic reactivation. Proteomic analysis revealed distinct plasma protein profiles between HHV-6B encephalitis and asymptomatic HHV-6B reactivation in pediatric UCBT recipients. The inflammatory response mediated by S100A8/A9 proteins may play a critical role in the pathogenesis of HHV-6B encephalitis. These findings indicate that proteomic analysis may provide novel insights into the host response to HHV-6B reactivation and the subsequent development of HHV-6B encephalitis.

Humans↗
PubMed2026

Rashless varicella-zoster virus encephalitis diagnosed by metagenomic next-generation sequencing: two case reports.

BACKGROUND: Varicella-zoster virus (VZV) can cause a range of central nervous system (CNS) infections, but early diagnosis is difficult when typical skin rash is absent. Rashless VZV encephalitis may present with nonspecific clinical, cerebrospinal fluid (CSF), and neuroimaging findings and can mimic autoimmune encephalitis, primary central nervous system lymphoma, or other disorders. We report two cases of rashless VZV encephalitis diagnosed by CSF metagenomic next-generation sequencing (mNGS), with subsequent neurological complications. CASE PRESENTATION: Case 1 was a 68-year-old man admitted with fever, seizures, and impaired consciousness. Brain magnetic resonance imaging (MRI) showed multifocal abnormal signals. CSF analysis revealed marked pleocytosis and elevated protein levels, and CSF cytology showed suspected atypical lymphocytes, leading to early consideration of autoimmune encephalitis and primary central nervous system lymphoma. CSF mNGS detected VZV, and rashless VZV encephalitis was diagnosed. The patient improved after intravenous acyclovir combined with a short course of dexamethasone. On day 45 after disease onset, follow-up MRI showed a new acute cerebral infarction adjacent to the posterior horn of the left lateral ventricle. Recurrent CSF pleocytosis and persistent protein elevation suggested possible VZV-associated vasculopathy. After repeated antiviral treatment, he improved again, and no recurrence was observed during more than 3 years of follow-up. Case 2 was a 74-year-old man admitted with fever, low back pain, vomiting, and impaired consciousness. Brain MRI showed multifocal abnormal signals, and CSF analysis revealed marked inflammatory changes. CSF mNGS detected VZV, supporting the etiological diagnosis of rashless VZV encephalitis. The patient improved after intravenous acyclovir combined with a short course of dexamethasone. On day 14 after disease onset, he developed urinary retention, impaired defecation sensation, and bilateral lower-limb weakness, suggesting possible lumbosacral nerve root or cauda equina involvement. Suspected VZV-related Elsberg syndrome was considered. His urinary and bowel dysfunction recovered at 2 months after disease onset. CONCLUSIONS: Rashless VZV encephalitis may be diagnostically challenging because early clinical, CSF, and neuroimaging findings are nonspecific. CSF mNGS can support etiological diagnosis, and careful follow-up is needed to detect delayed vascular and lumbosacral nerve root complications.

Humans↗
PubMed2025

Diagnostic and phylogenetic perspectives of the 2023 Murray Valley encephalitis virus outbreak in Australia: an observational study.

BACKGROUND: An outbreak of Murray Valley encephalitis virus (MVEV), the largest since 1974, was observed in Australia between Jan 1 and July 31, 2023. This study aims to characterise the utility of diagnostic platforms, testing algorithms, and genomic characteristics of MVEV to facilitate a comprehensive framework for MVEV testing and surveillance in the outbreak setting. METHODS: In this observational study, we assessed flavivirus diagnostics for all patients with suspected Murray Valley encephalitis in Australia from Jan 1 to July 31, 2023. We included all patients with confirmed Murray Valley encephalitis, probable Murray Valley encephalitis, or acute unspecified flavivirus infection using the Communicable Diseases Network Australia case definition. Cases were excluded if an alternative diagnosis was identified. We collected blood, serum, cerebrospinal fluid, brain tissue, urine, or a combination of these samples, as appropriate and at the discretion of the treating clinician. We conducted multimodal diagnostic testing, which included flavivirus-specific serological and nucleic acid amplification testing. Metagenomic next-generation sequencing, including next-generation deep sequencing, target-enrichment, and targeted amplification, was conducted on human and representative mosquito-derived samples obtained from established mosquito population surveillance programmes for phylogenetic analysis. FINDINGS: 27 patients with encephalitis were assessed for MVEV between Jan 1, 2023, and July 31, 2023, 23 (85%) of whom fulfilled national case definitions for confirmed Murray Valley encephalitis. Patient ages ranged from 6 weeks to 83 years (median 62·0 years [IQR 31·0-67·5]) and patients were mostly male (21 [78%] male patients and six [22%] female patients). Incidence varied widely by geographical region and was highest in the Northern Territory (32·0 per 1 000 000 population). Diagnostic specimen collection generally occurred promptly (median 6·0 days [IQR 4·0-14·5] from symptom onset to diagnostic specimen collection). In seven patients, case assignation relied on convalescent serum samples to assess for seroconversion or an appropriate rise in antibody titre (to four times the initial value or greater), or both. MVEV-specific IgM was detectable in serum samples of 17 (81%) of 21 patients tested by day 7 and MVEV IgG or total antibody (TAb) were detected in 18 (100%) of 18 patients tested by day 30. MVEV-specific IgM (or TAb) and MVEV RNA were detected in cerebrospinal fluid collected within 14 days of symptom onset in nine (39%) of 23 patients and seven (28%) of 25 patients, respectively. Phylogenetic analysis revealed two circulating MVEV genotypes, G1A and G2, in mosquitoes and humans in 2023. In southeast Australia, only G1A was detected and probably introduced from enzootic foci in northern Australia. INTERPRETATION: This study provides a comprehensive overview of the diagnostic workflows and phylogenetic evaluations used during the 2023 MVEV outbreak in Australia, emphasising the importance of a multimodal approach for accurate and timely confirmation of flavivirus infection. Further One Health surveillance for MVEV and other zoonotic flaviviruses is key, given potential expanded ecological niches in the context of episodic climatic events. FUNDING: None.

Humans↗
PubMed2026

Metagenomic sequencing in encephalitis diagnostics: Challenges and opportunities in clinical settings.

The primary aim of this study was to determine whether metagenomic next-generation sequencing (mNGS) can identify potential microbial agents responsible for encephalitis of unknown origin in immunocompetent patients, thereby enhancing clinical diagnostics. Cerebrospinal fluid samples from well-characterized patients (n = 17) diagnosed with encephalitis of unknown origin, according to Swedish national guidelines, were sequenced using mNGS using the Ion Torrent platform and analyzed using bioinformatic platforms. Samples from patients with known viral CNS infections i.e. HSV-2 meningitis (n = 4), VZV CNS infections (n = 3), enterovirus meningitis (n = 2), JCV CNS infection (n = 2) were used as controls for the methodology (n = 11). No viral agents were detected in 16/17 CSF samples from patients with encephalitis of unknown etiology. 13/17 CSF samples were analysed for the most common autoimmune antibodies and were negative. In one CSF sample from patients with encephalitis of unknown origin a Human pegivirus (HPgV) was detected. In 9/11 control CSF samples from patients with CNS infections, RNA or DNA of the known virus were detected. The main conclusion in this study was that the negative results were related to that the majority of included patients were immunocompetent. The finding of HPgV in a patient with unknown encephalitis was judged as a bystander. However, mNGS might detect more pathogens in other patient cohorts and this study implicates that a close collaboration between the clinical laboratory and the clinicians enables a safe implementation of metagenomics.

Humans↗
PubMed2025

Proteome Profiling in Cerebrospinal Fluid Reveals Increased Levels of Peroxiredoxin 2 Discriminating Japanese Encephalitis Virus and Scrub Typhus Infection.

Japanese encephalitis virus (JEV) and scrub typhus (ST) are major etiological agents of acute encephalitis syndrome (AES) in India and South Asia. The pathophysiological changes at the molecular level caused by JEV and ST have yet to be studied in detail. The cerebrospinal fluid (CSF) proteomic landscape is a critical indicator of CNS pathology. Here, we conducted label-free quantitative proteomics on CSF from AES patients (n = 15) to identify etiology-specific differentially expressed proteins (DEPs) linked to encephalitis. The key DEPs were validated via ELISA in CSF (n = 49) and serum (n = 33). Our findings revealed 50 proteins exhibited differential expression across JEV and ST groups, with a notable subset of three proteins, PRDX2, KLK6, and TTR. PRDX2 and KLK6 were markedly elevated in JEV CSF (AUC: 0.8933 and 0.9689) but not in ST or non-JEV AES, while TTR was reduced in JEV yet elevated in ST (AUC: 0.5619 vs. 0.8238). Further, PRDX2 upregulation was validated in JEV-infected mouse brains and cortical neurons. Overexpression of PRDX2 in human neuroblastoma cells correlated with enhanced antiviral gene expression, p-STAT1, p-AKT (ser473), and viral replication. Thus, our comprehensive proteomic analysis of CSF identifies PRDX2 as an important circulatory protein, differentially expressed between JEV and ST, with high specificity and enhancing viral propagation, underscoring its role in viral propagation and pathogenesis.

Humans↗
PubMed2026

Protein Profiling Identifies Biomarkers for Predicting Disease Severity in Anti-NMDAR Encephalitis.

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a severe autoimmune neurological disorder characterized by pathogenic antibodies against the NMDAR. A systematic protein profiling approach is warranted to identify biomarkers capable of predicting disease status. An Olink proximity extension assay (PEA) profiled 91 inflammation-related proteins from anti-NMDAR encephalitis patients. Disease severity or prognosis were assessed by CASE score or mRS score at 6-month follow-up. Patients were stratified into distinct molecular clusters using unsupervised clustering. Logistic regression models incorporating selected biomarkers were developed to predict disease severity and prognosis, followed by absolute quantification using ELISA. Patients were classified into four consensus clusters. Clusters 1 and 2 corresponded to the mild group, while Cluster 3 represented the severe group, consistent with CASE score above 6. Cluster 4 showed heterogeneous clinical features. Elevated serum levels of IL-10, IL-6, and SIRT2, as well as increased CSF levels of CXCL10, CXCL11, and MMP10, were positively associated with severe disease. Conversely, several proteins including LTA and CCL11, CCL8, TGFB1, CXCL6 were associated with severe disease or unfavorable 6-month outcomes. A logistic regression model combining serum CXCL6 and CCL11 with CSF MMP10 achieved an area under the curve (AUC) of 0.95 for predicting disease severity. Serum CCL11 alone showed predictive value for 6-month prognosis, with an AUC of 0.79. These findings delineate distinct protein signatures associated with clinical heterogeneity of anti-NMDAR encephalitis. Prediction models incorporating multiple biomarkers may provide an approach for disease severity stratification and prognosis forecast.

Humans↗
PubMed2026

Bergamottin, a bioactive component of bergamot: dual inhibition of Japanese encephalitis virus internalization and genome replication.

Japanese encephalitis virus (JEV) is associated with high mortality and severe neurological sequelae, and existing prevention and control strategies remain insufficient. Therefore, the development of novel antiviral agents is of critical public health importance. This study systematically evaluated the antiviral activity and underlying mechanism of bergamottin, a natural product. Bergamottin exhibited significant dose-dependent inhibitory effects against JEV in multiple cell lines, including BHK-21, HuH-7, and Vero cells, demonstrating potent antiviral efficacy. Mechanistic investigations revealed that bergamottin primarily targeted the internalization and replication stages of the JEV life cycle, thereby effectively suppressing viral proliferation. Additionally, adaptive mutation screening indicated that the D389G mutation in envelope protein E confers drug resistance by potentially changing E protein conformation or reducing endocytic efficiency. In vivo experiment, bergamottin significantly reduced viral loads in mouse brain tissue and effectively improved the survival rate of infected mice. Our findings indicated that bergamottin exerted antiviral activity by dual targeting of key steps in the viral life cycle, making it a highly promising candidate for anti-JEV therapy. Further exploration of the antiviral properties of bergamottin is expected to facilitate its clinical development as a treatment for JEV infection.

Animals↗
PubMed2025

Key virulence factors responsible for differences in pathogenicity between clinically proven live-attenuated Japanese encephalitis vaccine SA14-14-2 and its pre-attenuated highly virulent parent SA14.

Japanese encephalitis virus (JEV), a neuroinvasive and neurovirulent orthoflavivirus, can be prevented in humans with the SA14-14-2 vaccine, a live-attenuated version derived from the wild-type SA14 strain. To determine the viral factors responsible for the differences in pathogenicity between SA14 and SA14-14-2, we initially established a reverse genetics system that includes a pair of full-length infectious cDNAs for both strains. Using this cDNA pair, we then systematically exchanged genomic regions between SA14 and SA14-14-2 to generate 20 chimeric viruses and evaluated their replication capability in cell culture and their pathogenic potential in mice. Our findings revealed the following: (i) The single envelope (E) protein of SA14-14-2, which contains nine mutations (eight in the ectodomain and one in the stem region), is both necessary and sufficient to render SA14 non-neuroinvasive and non-neurovirulent. (ii) Conversely, the E protein of SA14 alone is necessary for SA14-14-2 to become highly neurovirulent, but it is not sufficient to make it highly neuroinvasive. (iii) The limited neuroinvasiveness of an SA14-14-2 derivative that contains the E gene of SA14 significantly increases (approaching that of the wild-type strain) when two viral nonstructural proteins are replaced by their counterparts from SA14: (a) NS1/1', which has four mutations on the external surface of the core β-ladder domain; and (b) NS2A, which has two mutations in the N-terminal region, including two non-transmembrane α-helices. In line with their roles in viral pathogenicity, the E, NS1/1', and NS2A genes all contribute to the enhanced spread of the virus in cell culture. Collectively, our data reveal for the first time that the E protein of JEV has a dual function: It is the master regulator of viral neurovirulence and also the primary initiator of viral neuroinvasion. After the initial E-mediated neuroinvasion, the NS1/1' and NS2A proteins act as secondary promoters, further amplifying viral neuroinvasiveness.

Animals↗
PubMed2025

Infectious Subgenomic Amplicon Strategies for Japanese Encephalitis and West Nile Viruses.

Classical methods for constructing infectious cDNA clones of flaviviruses are often hindered by instability and toxicity. The Infectious-Subgenomic-Amplicons (ISA) method is an advancement which utilizes overlapping DNA fragments representing viral genomic sequence and in-cell recombination to bypass bacterial plasmid assembly. However, the ISA method has limitations due to the toxicity of some ISA DNA fragments in bacteria during synthetic production. We validated modified ISA strategies for producing toxic ISA Japanese encephalitis virus (JEV) and West Nile virus (WNV) DNA fragments. Three approaches were explored, including subdividing toxic DNA fragments into two sub-fragments for synthetic clonal production, using a low-copy bacterial plasmid, and subdividing the toxic DNA fragments into four short overlapping sub-fragments, each up to 1.8 kb. The latter novel approach in ISA applications enabled the synthesis of entirely bacteria-free ISA DNA fragments. Our results demonstrate that subdividing toxic fragments into sub-fragments smaller than 1.8 kb for synthesis is the efficient strategy, circumventing the need for bacterial plasmids and ensuring rapid production of synthetic flaviviruses. This method also shortens the production timeline. We also compared the efficacy of JEV and WNV ISA in zinc finger antiviral protein 1 (ZAP) wild-type and knockout cells and found that knockout cells may be more effective for ISA rescue of flaviviruses, including CpG-enriched strains for live attenuated vaccines. The validated modified ISA strategies provide an efficient approach for producing synthetic JEV and WNV. This will enable rapid research during outbreaks of emerging flaviviruses by facilitating the quick generation of new virus variants.

West Nile virus↗
PubMed2024

Role of RNA G-Quadruplexes in the Japanese Encephalitis Virus Genome and Their Recognition as Prospective Antiviral Targets.

G-quadruplexes (GQs) have been primarily studied in the context of cancer and neurodegenerative pathologies. However, recent research has shifted focus to their existence and functional roles in viral genomes, revealing GQ-regulated key pathways in various human pathogenic viruses. While GQ structures have been reported in the genomes of emerging and re-emerging viruses, RNA viruses have been understudied compared to DNA viruses, including notable examples such as human immunodeficiency virus-1, hepatitis C virus, Ebola virus, Nipah virus, Zika virus, and SARS-CoV-2. The flavivirus family, comprising the Japanese encephalitis virus (JEV), poses a significant global threat due to recurring outbreaks yet lacks approved antivirals. In this study, we identified and characterized eight putative G-quadruplex-forming motifs within essential genes involved in genome replication, assembly, and internalization in the host cell, conserved across different JEV isolates. The formation and stability of these motifs were validated through a multitude of biophysical and cell-based assays. The interaction and binding affinity of these motifs with the known GQ-binding ligand BRACO-19 were supported by biophysical assays, confirming the capability of these motifs to form GQ structures. Notably, BRACO-19 also exerted antiviral properties through reduction of viral replication and infectious virus titers as well as inhibition of viral protein expression, as evaluated by the cell-based assays. This comprehensive molecular characterization of G-quadruplex structures within the JEV genome highlights their potential as promising antiviral targets for intervention strategies against JEV infection through GQ-specific ligands.

G-Quadruplexes↗
PubMed2025

Genetic diversity of Murray Valley encephalitis virus 1951-2020 identified via phylogenetic and evolutionary analyses.

Murray Valley encephalitis virus (MVEV) is a mosquito-borne orthoflavivirus endemic to Australia that can cause fatal neurological disease. The enzootic focus of MVEV is believed to reside in northern Western Australia (WA). We sequenced whole genomes of 70 MVEV sampled over 51 years, 1969-2020, from locations across Australia and Papua New Guinea (PNG) and identified greater MVEV diversity than previously recognized. Genotype 1 (G1) demonstrated greatest intra-genotype diversity and was predominant over the sampling period with sub-lineage G1B circulating in WA and seeding activity across Australia. G1A included viruses sampled across northern WA, as well as the Northern Territory (NT). A newly identified sub-lineage G1C circulated in northern WA in 1993 and was detected again in 2003. G2 viruses were distributed across the Kimberley and Pilbara regions of northern WA, and in the NT. Although no new G3 and G4 viruses, previously identified only in PNG, were detected in the present study, other MVEV originating in PNG clustered with G1A. We confirm MVEV is enzootic in northern WA, with transmission occurring more frequently and across a wider geographical area than previously recognised. Additionally, we identify evidence of regular genotype replacement that has occurred over many decades where the major genotypes G1 and G2 have circulated in northern WA since the late 1960s. We also show that WA MVEV likely seeded an MVE outbreak in Victoria in 1974, further supporting the notion that the enzootic focus of MVEV lies in northern WA. Recent increases in MVEV detections, MVE cases and deaths in WA and across Australia highlight the need for enhanced surveillance and more frequent sampling to understand viral origin and genomic diversity, to identify potential virulence motifs, and to understand the ecological drivers that determine emergence of MVEV in northern WA and movement of MVEV across the country.

Encephalitis Virus, Murray Valley↗
PubMed2026

Japanese encephalitis virus hijacks the host purine biosynthetic network to promote viral replication in neurons.

Japanese encephalitis virus (JEV) is an important neurotropic orthoflavivirus that poses a threat to both human and animal health. However, the mechanism underlying its rapid replication in the central nervous system (CNS) remains poorly understood. In this study, we conducted metabolomic profiling of JEV-infected mouse brains and neurons, revealing a profound reprogramming of central carbon metabolism, particularly an enhancement in nucleotide synthesis. Integrated multi-omics analyses confirmed that JEV infection transcriptionally upregulates key enzymes involved in de novo purine biosynthesis (DNPB), one-carbon (1C) metabolism, and the pentose phosphate pathway (PPP) in neurons. Pharmacological inhibition of the core DNPB enzymes potently suppressed JEV replication in neurons and reduced both viral loads and neuroinflammation in JEV-infected mice, suggesting the essential role of DNPB in JEV replication within CNS. Mechanistically, we delineated the critical functions of both the non-oxidative PPP and MTHFD2-mediated 1C metabolism, which jointly supply essential precursors, such as ribose-5-phosphate and formyl groups, for the de novo biosynthesis of purines required for viral RNA replication. These findings unveil a strategy by which JEV co-opts the host's purine biosynthetic machinery to fulfill the nucleotide demands for its genomic replication, establishing DNPB and its supporting pathways as promising therapeutic targets for infections caused by JEV and other neurotropic viruses.

Animals↗
PubMed2026

Field-isolate recombinant tick-borne encephalitis viruses define reporter-stability guidelines for antiviral testing in flaviviruses.

As arthropod-borne viruses continue to threaten populations globally, there is a pressing need for experimental systems that enable rapid antiviral discovery. Reverse-genetics platforms producing recombinant reporter orthoflaviviruses have been developed to address this gap. Here, we present two new recombinant tick-borne encephalitis viruses (TBEVrec) generated on a European-subtype Haselmühl Tiho1 isolate backbone. A reporter gene, either eGFP or Nluc, was inserted in the capsid-coding region of the genome downstream of the capsid RNA regulatory signal and separated from the complete viral polyprotein by a 2A self-cleaving peptide. TBEVrec was better rescued using the circular polymerase extension reaction (CPER) than with the infectious subgenomic amplicon (ISA) method. TBEVrec replicated efficiently in relevant human cell lines, with comparable replication to wild-type TBEV in a neuronal cell line and moderately reduced titers and RNA levels in immune-derived cell lines. Using either eGFP or Nluc, we illustrate how TBEVrec enabled high-content RNAi screening, highlighting Nucleolin and PRKD1 as potential TBEV host factors, and drug testing on a benchtop plate reader. Nanopore sequencing of the eGFP insert revealed that the reporter is excised without affecting flanking regions. Comparative analysis of eGFP and Nluc further shows that this instability is time- and cell type-dependent, and that Nluc is comparatively more stable. From these observations, we outline safeguards and design principles that are broadly applicable both to the rescue of existing constructs and to the design of future recombinant reporter virus platforms.

CPER↗
PubMed2026

Multi-omics profiling of cerebrospinal fluid in autoimmune encephalitis: insights into pathogenesis and therapeutic targets.

BACKGROUND: Autoimmune encephalitis (AIE) is a rare, severe inflammatory brain disease, with its pathogenesis not yet fully elucidated. This study aimed to characterize proteomic and metabolomic alterations in the cerebrospinal fluid (CSF) of AIE patients and identify potential therapeutic targets. METHODS: 65 consecutive AIE patients and age-matched concurrent controls were enrolled, respectively. Clinical characteristics, including blood and CSF laboratory findings, were compared between the two groups, and CSF samples were collected for multi-omics analysis. Differentially expressed proteins (DEPs) and metabolites (DEMs) between AIE patients and controls were identified using data-independent acquisition-based proteomics and targeted liquid chromatography-mass spectrometry-based metabolomics, followed by integrated multi-omics analysis. RESULTS: Compared with controls, AIE patients had lower levels of triglyceride and C1q, but higher HDL-CH levels, neutrophil counts, and eosinophil counts in blood. CSF leukocyte, erythrocyte, lymphocyte, and mononuclear cell counts were also elevated in AIE patients. Proteomic analysis identified 163 DEPs, with enrichment of 87 canonical pathways primarily associated with immune-inflammatory responses, neuronal-synaptic dysfunction, and cell signaling and metabolic pathways. Metabolomic analysis recognized 21 DEMs, predominantly amino acids, lipids, and carbohydrates, which were involved in lipid-carbohydrate metabolism and immune regulation. Integrated multi-omics analysis validated these findings and identified several potential therapeutic targets for AIE, including the IL6-STAT3 axis. CONCLUSIONS: Integrated multi-omics analysis systematically delineates cellular and molecular alterations underlying AIE. Immune-inflammatory response and lipid metabolism are pivotal in AIE progression and the IL6-STAT3 axis holds promise as a potential therapeutic target.

Humans↗
PubMed2026

Comparative dynamics of Japanese encephalitis virus adaptation in porcine macrophages and insect cells.

BACKGROUND: Japanese encephalitis virus (JEV) is a zoonotic mosquito-borne Orthoflavivirus that circulates primarily in birds and pigs. Previous observations of vector-free transmission between pigs indicates the possibility of single-host cycling in swine. Therefore, the aim of this work was to investigate the evolutionary pressure of single host cycling using a relevant primary cell culture model. METHODS: To investigate whether such single-host cycles affect viral infectivity, fitness and genomic adaptations, two strains and a reverse genetic cDNA-derived clone of JEV were serially passaged 12 times in primary porcine monocyte-derived macrophages (MDMs), in Aedes albopictus-derived C6/36 cells, and alternately between both cell types. Next-generation sequencing analysis was used to identify selected single nucleotide variants (SNVs) and haplotypes. Phenotype-to-genotype connections were confirmed using reverse genetics. RESULTS: For all viruses, serial passaging in MDMs - but not in C6/36 cells - led to a rapid increase in relative infectivity toward MDMs, accompanied by reduced plaque sizes in porcine endothelial cells. In contrast to C6/36 cells, MDM imposed a strong selective pressure, rapidly favoring selection of many SNVs and viral haplotypes. In addition, we identified a dominant selection of mutants with glutamic acid to lysine substitutions at positions 49 or 138 in the E protein, which explained the small plaque phenotype and caused viral sensitivity to heparin-mediated inhibition of attachment, indicating enhanced virus binding to glycosaminoglycans (GAG). The E138K mutant also explained the increased relative infectivity for MDM. CONCLUSION: This work demonstrates a high evolutionary pressure on JEV in MDM causing rapid selections of minor haplotypes. Furthermore, the efficient selection of E49K and E138K SNV, which were responsible for the phenotype, are likely caused by a selective pressure for GAG binding, observed in vitro with other mammalian cells.

Animals↗
PubMed2025

Microbiological Investigations for Chikungunya Virus in Children With Acute Encephalitis Syndrome in a Non-Outbreak Setting in Southern India.

Chikungunya virus (CHIKV) is an emerging cause of acute encephalitis syndrome (AES) in India, with limited data on its role in childhood AES in southern India. We systematically evaluated children with AES in southern India during a non-epidemic period for CHIKV. Serum and cerebrospinal fluid (CSF) samples were tested for CHIKV using IgM ELISA and real-time reverse transcriptase PCR. Amplicon sequencing was performed on PCR-positive samples. Clinical and laboratory features were compared between children with and without CSF CHIKV positivity (PCR/IgM antibodies). Of 376 children with AES, 20 (5.3%) had positive CHIKV tests. Co-infections were common, particularly with scrub typhus. Children presented with diverse symptoms affecting various organ systems. Neurological manifestations included meningism, seizures, cerebellar signs, behavioral abnormalities, cranial nerve involvement, involuntary movements, and hemiparesis/hemiplegia. Children with CSF CHIKV positivity showed more focal neurological deficits and transaminitis, and less musculoskeletal symptoms. Sequencing confirmation of CHIKV was made in all patients with positive CHIKV PCR, revealing a close relationship with 2016 Kenyan and Indian strains, albeit in a different clade within the East/Central/South African genotype. Along with important mutations known to impact CHIKV infectivity, four novel amino acid substitutions were detected in envelope protein coding regions. Our findings underscore the importance of routine and comprehensive CHIKV testing for children with AES, irrespective of season/outbreak. The high rate of co-infections warrants further research. Continued genomic surveillance is essential to monitor emerging mutations with epidemic potential, increased severity and the risk of neurological disease.

Humans↗
PubMed2026

Widespread circulation of Alongshan virus in Austria and serological evidence for infection in humans: a nationwide molecular and serological observational study.

BACKGROUND: Alongshan virus, a segmented RNA virus in the Jingmenvirus group of flaviviruses, was first identified in 2017 in China in patients with tick-borne encephalitis-like illness. Alongshan virus has since been detected in ticks and mammals in several European countries. In this study, we aimed to characterise the temporal and geographical distribution of Alongshan virus in Austria through nationwide tick surveillance combined with serological and molecular screening in individuals with suspected tick-borne encephalitis or tick exposure. METHODS: In this nationwide molecular and serological observational study, we conducted a PCR-based screening of ticks collected across Austria in 2024, using flagging, animal hosts, and citizen submissions. We also collated genomic data from stored nucleic acid extracts from ticks collected in Austria in 2005 and 2013 in previous surveillance studies and stored extracts of paired tick-human samples collected between 2015 and 2018. Alongshan virus-positive tick samples were subjected to whole-genome sequencing and phylogenetic analysis. In addition to tick samples, blood samples from Austrian patients with reported tick bite or suspected tick-borne encephalitis, submitted to the National Reference Center for Human Arbovirus Infections, Austria, were screened for Alongshan virus infection and subjected to serological and molecular testing. FINDINGS: 2952 ticks were collected between Feb 1, 2024, and Dec 6, 2024, from 29 (83%) of 35 NUTS-3 regions in Austria; the median detection rate for Alongshan virus was 1·2% (IQR 0·4-3·5). In addition, 1816 archived tick samples were analysed, with three testing positive for Alongshan virus. For the virus-positive samples, phylogenetic analysis showed that sequences from Austria grouped within the European clade, with Austrian sequences from the same region showing high sequence similarity. 1361 human serum samples collected between March 1, 2023, and May 16, 2025, were assessed for anti-Alongshan virus IgG antibodies. Two individuals had high antibody titres against Alongshan virus proteins VP1a and VP2. INTERPRETATION: Our study shows detection of Alongshan virus in archived tick samples dating back to 2005, representing the earliest documented occurrence of the virus to date and suggesting that Alongshan virus has been circulating in Austria for at least two decades. The detection of Alongshan virus-specific antibody titres in two individuals suggests past infection and previously unrecognised exposure. These results highlight the need for continued molecular surveillance of tick populations and serological monitoring in humans to define the epidemiology and public health relevance of Alongshan virus in Europe. FUNDING: One Health surveillance and Vector monitoring for cross-border pathogens (OH SURVector) and UNITED4Surveillance.

Adolescent↗