Viral Infections Of Central Nervous System Research Articles

Elevated phospholipids and acylcarnitines C4 and C5 in cerebrospinal fluid distinguish viral CNS infections from autoimmune neuroinflammation

BackgroundViral and autoimmune encephalitis may present with similar symptoms, but require different treatments. Thus, there is a need for biomarkers to improve diagnosis and understanding of pathogenesis. We hypothesized that virus-host cell interactions lead to different changes in central nervous system (CNS) metabolism than autoimmune processes and searched for metabolite biomarkers in cerebrospinal fluid (CSF) to distinguish between the two conditions.MethodsWe applied a targeted metabolomic/lipidomic analysis to CSF samples from patients with viral CNS infections (n = 34; due to herpes simplex virus [n = 9], varicella zoster virus [n = 15], enteroviruses [n = 10]), autoimmune neuroinflammation (n = 25; autoimmune anti-NMDA-receptor encephalitis [n = 8], multiple sclerosis [n = 17), and non-inflamed controls (n = 31; Gilles de la Tourette syndrome [n = 20], Bell’s palsy with normal CSF cell count [n = 11]). 85 metabolites passed quality screening and were evaluated as biomarkers. Standard diagnostic CSF parameters were assessed for comparison.ResultsOf the standard CSF parameters, the best biomarkers were: CSF cell count for viral infections vs. controls (area under the ROC curve, AUC = 0.93), Q-albumin for viral infections vs. autoimmune neuroinflammation (AUC = 0.86), and IgG index for autoimmune neuroinflammation vs. controls (AUC = 0.90). Concentrations of 2 metabolites differed significantly (p < 0.05) between autoimmune neuroinflammation and controls, with proline being the best biomarker (AUC = 0.77). In contrast, concentrations of 67 metabolites were significantly higher in viral infections than controls, with SM.C16.0 being the best biomarker (AUC = 0.94). Concentrations of 68 metabolites were significantly higher in viral infections than in autoimmune neuroinflammation, and the 10 most accurate metabolite biomarkers (AUC = 0.89–0.93) were substantially better than Q-albumin (AUC = 0.86). These biomarkers comprised six phosphatidylcholines (AUC = 0.89–0.92), two sphingomyelins (AUC = 0.89, 0.91), and acylcarnitines isobutyrylcarnitine (C4, AUC = 0.92) and isovalerylcarnitine (C5, AUC = 0.93). Elevated C4 and C5 concentrations suggested dysfunctional mitochondrial β-oxidation and correlated only moderately with CSF cell count (Spearman ρ = 0.41 and 0.44), indicating that their increase is not primarily driven by inflammation.ConclusionsChanges in CNS metabolism differ substantially between viral CNS infections and autoimmune neuroinflammation and reveal CSF metabolites as pathophysiologically relevant diagnostic biomarkers for the differentiation between the two conditions. In viral CNS infections, the observed higher concentrations of free phospholipids are consistent with disruption of host cell membranes, whereas the elevated short-chain acylcarnitines likely reflect compromised mitochondrial homeostasis and energy generation.

COVID-19 Recovery: Consistent Absence of Cerebrospinal Fluid Biomarker Abnormalities in Patients With Neurocognitive Post-COVID Complications.

To investigate evidence of residual viral infection, intrathecal immune activation, central nervous system (CNS) injury, and humoral responses in cerebrospinal fluid (CSF) and plasma in patients recovering from coronavirus disease 2019 (COVID-19), with or without neurocognitive post-COVID condition (PCC). Thirty-one participants (25 with neurocognitive PCC) underwent clinical examination, lumbar puncture, and venipuncture ≥3 months after COVID-19 symptom onset. Healthy volunteers were included. CSF and plasma severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleocapsid and spike antigen (N-Ag, S-Ag), and CSF biomarkers of immune activation and neuronal injury were analyzed. SARS-CoV-2 N-Ag or S-Ag were undetectable in all samples and no participant had pleocytosis. We detected no significant differences in CSF and plasma cytokine concentrations, albumin ratio, IgG index, neopterin, β2M, or in CSF biomarkers of neuronal injury and astrocytic damage. Furthermore, principal component analysis (PCA1) analysis did not indicate any significant differences between the study groups in the marker sets cytokines, neuronal markers, or anti-cytokine autoantibodies. We found no evidence of ongoing viral replication, immune activation, or CNS injury in plasma or CSF in patients with neurocognitive PCC compared with COVID-19 controls or healthy volunteers, suggesting that neurocognitive PCC is a consequence of events suffered during acute COVID-19 rather than persistent viral CNS infection or residual CNS inflammation.

Pathogenesis and outcome of VA1 astrovirus infection in the human brain are defined by disruption of neural functions and imbalanced host immune responses.

Astroviruses (AstVs) can cause of severe infection of the central nervous system (CNS) in immunocompromised individuals. Here, we identified a human AstV of the VA1 genotype, HAstV-NIH, as the cause of fatal encephalitis in an immunocompromised adult. We investigated the cells targeted by AstV, neurophysiological changes, and host responses by analyzing gene expression, protein expression, and cellular morphology in brain tissue from three cases of AstV neurologic disease (AstV-ND). We demonstrate that neurons are the principal cells targeted by AstV in the brain and that the cerebellum and brainstem have the highest burden of infection. Detection of VA1 AstV in interconnected brain structures such as thalamus, deep cerebellar nuclei, Purkinje cells, and pontine nuclei indicates that AstV may spread between connected neurons transsynaptically. We found transcriptional dysregulation of neural functions and disruption of both excitatory and inhibitory synaptic innervation of infected neurons. Importantly, transcriptional dysregulation of neural functions occurred in fatal cases, but not in a patient that survived AstV-ND. We show that the innate, but not adaptive immune response was transcriptionally driving host defense in the brain of immunocompromised patients with AstV-ND. Both transcriptome and molecular pathology studies showed that most of the cellular changes were associated with CNS-intrinsic cells involved in phagocytosis and injury repair (microglia, perivascular/parenchymal border macrophages, and astrocytes), but not CNS-extrinsic cells (T and B cells), suggesting an imbalance of innate and adaptive immune responses to AstV infection in the brain as a result of the underlying immunodeficiencies. These results show that VA1 AstV infection of the brain in immunocompromised humans is associated with imbalanced host defense responses, disruption of neuronal somatodendritic compartments and synapses and increased phagocytic cellular activity. Improved understanding of the response to viral infections of the human CNS may provide clues for how to manipulate these processes to improve outcomes.

The Worldwide Prevalence of Herpes Simplex Virus Encephalitis and Meningitis: A Systematic Review and Meta-Analysis.

Given the relatively high frequency of central nervous system infections and considerable mor- tality and morbidity reported to be caused by herpes simplex viruses among the other viral agents, having a clear knowledge about their epidemiological profile seems necessary. This systematic review and meta-analysis aimed to determine the relative frequency and preva- lence of herpes simplex encephalitis and meningitis in patients tested for viral etiologies. A comprehensive systematic review was performed in PubMed, Scopus, and Web of Science databases, searching for studies on the prevalence and relative frequency of herpes sim- plex virus 1 and herpes simplex virus 2 encephalitis and meningitis. Seventy-one studies were included. Overall, the prevalence of herpes simplex virus encephalitis among patients tested was 8% (95% confidence interval, 6%-11%; I2 = 98%) and the prevalence of herpes simplex virus meningitis among aseptic patients tested was 4% (95% confidence interval, 3%-7%; I2 = 95%), and a significant difference was observed by region. The results of our subgroup analysis for herpes simplex virus encephalitis revealed a prevalence of 8% for pediatric patients and ado- lescents and 12% for adults. The results for herpes simplex virus meningitis showed a prevalence of 4% for pediatric patients and adolescents and 9% for adults. We observed significant differ- ences in the frequency of herpes simplex virus 1 and herpes simplex virus 2 detection rates by region. Having high rates of missed cases due to inadequate, highly sensitive paraclinical tests performed on patients with suspected viral central nervous system infection is one of the pos- sible factors. More studies are needed to detect the possible flaws in the process of diagnosis in different regions.

Early autoimmunity and outcome in virus encephalitis: a retrospective study based on tissue-based assay

To explore the autoimmune response and outcome in the central nervous system (CNS) at the onset of viral infection and correlation between autoantibodies and viruses.MethodsA retrospective observational study was conducted...

Tick-borne encephalitis epidemiology and surveillance in Poland, and comparison with selected European countries before and during the COVID-19 pandemic, 2008 to 2020.

BackgroundTick-borne encephalitis (TBE) is the most common viral central nervous system (CNS) infection in Poland. Previous research suggests that its incidence was underestimated in the pre-pandemic period. The COVID-19 pandemic caused a considerable burden on surveillance systems, which could further impact reporting.AimWe aimed to assess the completeness of reporting of TBE in the years 2008 to 2020 and explore the potential impact of the COVID-19 pandemic on reporting to the epidemiological surveillance system, compared with hospitalisations for TBEV and other viral neuro-infections.MethodsWe compared the Polish epidemiology of TBE and other viral infections of the CNS from national surveillance reports with data on hospitalisations from 2008 to 2020 and data from selected European countries.ResultsBetween 2008 and 2020, 3,016 TBE cases were reported to surveillance compared with 3,620 hospitalisations. There was an increasing trend in hospitalisations, while surveillance data demonstrated the opposite, with the largest discrepancy observed in the first pandemic year (354 hospitalisations vs 159 cases reported to surveillance). Serological testing for TBE was used more in the known endemic region of north-eastern Poland and less in non-endemic areas. Other European countries reported higher TBE case numbers and an increase during the COVID-19 pandemic, whereas Poland observed an opposite trend.ConclusionThe sensitivity of TBE surveillance in Poland requires improvement. There are considerable regional differences. Regions that test for TBE intensively report most cases. Policymakers should be made aware of the value of quality epidemiological data for planning prophylactic measures in risk areas.

VEGFR-3 signaling restrains the neuron-macrophage crosstalk during neurotropic viral infection

Upon recognizing danger signals produced by virally infected neurons, macrophages in the central nervous system (CNS) secrete multiple inflammatory cytokines to accelerate neuron apoptosis. The understanding is limited about which key effectors regulate macrophage-neuron crosstalk upon infection. We have used neurotropic-virus-infected murine models to identify that vascular endothelial growth factor receptor 3 (VEGFR-3) is upregulated in the CNS macrophages and that virally infected neurons secrete the ligand VEGF-C. When cultured with VEGF-C-containing supernatants from virally infected neurons, VEGFR-3+ macrophages suppress tumor necrosis factor α (TNF-α) secretion to reduce neuron apoptosis. Vegfr-3ΔLBD/ΔLBD (deletion of ligand-binding domain in myeloid cells) mice or mice treated with the VEGFR-3 kinase inhibitor exacerbate the severity of encephalitis, TNF-α production, and neuron apoptosis post Japanese encephalitis virus (JEV) infection. Activating VEGFR-3 or blocking TNF-α can reduce encephalitis and neuronal damage upon JEV infection. Altogether, we show that the inducible VEGF-C/VEGFR-3 module generates protective crosstalk between neurons and macrophages to alleviate CNS viral infection.

Epidemiology and diagnosis of viral and bacterial central nervous system infections in Sri Lanka: A Narrative review

Bacterial central nervous system (CNS) infections are life-threatening diseases with high mortality and long-term neurological sequels, while viral CNS infections are mild and self-limited. In Sri Lanka, 1000-1500 and 150-250 patients with meningitis and encephalitis respectively are reported annually to the Epidemiology Unit. Haemophilus influenzae, Group B Streptococcus, Streptococcus pneumoniae, Escherichia coli, Mycobacterium tuberculosis, Neisseria meningitidis, Group D Streptococcus, Leptospira borgpetersenii serovar Tarasssovi, Listeria monocytogenes, Streptococcus bovis biotype 2, enterovirus, Herpes Simplex Virus type 1 and type 2, Varicella zoster virus and cytomegalovirus have been reported up to 2022 in patients with meningitis while dengue virus, Japanese encephalitis virus, Varicella zoster virus, West Nile virus, Human Bocavirus Type 1, 2 and 3, human adenovirus type 41, Echovirus type 9 and 25, Herpes Simplex Virus type 1 and Mycoplasma pneumoniae have been reported in patients with encephalitis and meningoencephalitis. However less than 10% of cases have a definitive aetiological diagnosis with conventional bacterial culture methods routinely used to diagnose bacterial CNS infections, while molecular assays are used only for selected common viral pathogens in government hospitals in Sri Lanka. Use of antibiotics prior to cerebrospinal fluid collection, delay in sample collection, and low volume of samples have been identified as factors for low sensitivity of test results. Scientists, microbiologists and virologists are responsible for developing new test methods to identify current and previously unidentified causative microorganisms to extend the spectrum of neurotropic organisms in Sri Lanka to enhance the aetiological diagnosis.

Viral, Bacterial, Metabolic, and Autoimmune Causes of Severe Acute Encephalopathy in Sub-Saharan Africa: A Multicenter Cohort Study

To assess whether viral, bacterial, metabolic, and autoimmune diseases are missed by conventional diagnostics among children with severe acute encephalopathy in sub-Saharan Africa. One hundred thirty-four children (6 months to 18years) presenting with nontraumatic coma or convulsive status epilepticus to 1 of 4 medical referral centers in Uganda, Malawi, and Rwanda were enrolled between 2015 and 2016. Locally available diagnostic tests could be supplemented in 117 patients by viral, bacterial, and 16s quantitative polymerase chain reaction testing, metagenomics, untargeted metabolomics, and autoimmune immunohistochemistry screening. Fourteen (12%) cases of viral encephalopathies, 8 (7%) cases of bacterial central nervous system (CNS) infections, and 4 (4%) cases of inherited metabolic disorders (IMDs) were newly identified by additional diagnostic testing as the most likely cause of encephalopathy. No confirmed cases of autoimmune encephalitis were found. Patients for whom additional diagnostic testing aided causal evaluation (aOR 3.59, 90% CI 1.57-8.36), patients with a viral CNS infection (aOR 7.91, 90% CI 2.49-30.07), and patients with an IMD (aOR 9.10, 90% CI 1.37-110.45) were at increased risk for poor outcome of disease. Viral and bacterial CNS infections and IMDs are prevalent causes of severe acute encephalopathy in children in Uganda, Malawi, and Rwanda that are missed by conventional diagnostics and are associated with poor outcome of disease. Improved diagnostic capacity may increase diagnostic yield and might improve outcome of disease.

The emerging mechanism behind viral infections and extracellular vesicles hypotheses leading to neuroinflammation and Alzheimer's disease pathology.

Despite decades of repeated and intense research, the etiology of sudden Alzheimer's disease (AD) symptoms is still unclear. AD progressive pathology mainly involves neuron damage, depositions of amyloid-beta (Aβ), and hyperphosphorylated tau protein. All these defects are manifested by exaggerated cytokine storm and neuroinflammation leading to irreversible brain damage in the long term. Despite the numerous risks and drawbacks associated with AD, it is believed that there is a hidden unknown causative and predisposing factors for AD. Extracellular vesicles (EVs) are small vesicles released by cells as a type of intercellular communication. Several pieces of evidence support the inclusion of viral components within EVs facilitating their penetration into the blood-brain barrier leading to neuroinflammation. In light of the SARS-CoV-19 pandemic and its related neurological complications, it is mandatory to highlight the possibility and viability of viral infections such as varicella-zoster virus (VZV) and herpes simplex virus (HSV) on the onset of AD. Herein, the author is investigating the potential role of VZV and HSV along with highlighting the suggested route of pathogenesis entry resulting in AD manifestations. Additionally, this review aims to summarize the role of EVs in mediating the central nervous system viral infections leading to AD.

Management of neonatal central nervous system viral infections: Knowledge gaps and research priorities.

Congenital CMV, enteroviruses, human parechovirus and herpes simplex virus are all common causes of severe central nervous system (CNS) infection in neonates. The introduction of screening (i.e. newborn hearing screening programme), integration of molecular syndromic testing (i.e. multiplex polymerase chain reaction assays) and increase in sexually transmitted infections (i.e. anogenital herpes) have contributed to increases in each of these infections over the last decade. However, therapeutic options are highly limited in part due to the lack of epidemiological data informing trials. This review will describe our current understanding of the clinical burden and epidemiology of these severe neonatal CNS infections, outline the novel antiviral and vaccines in the pipeline and suggest future research studies which could help develop new therapeutics.

Putting PLX5622 into perspective: microglia in central nervous system viral infection.

Putting PLX5622 into perspective: microglia in central nervous system viral infection.

Eradication of human immunodeficiency virus-1 reservoir in the brain microglia.

Eradication of human immunodeficiency virus-1 reservoir in the brain microglia.

Aetiologies and clinical presentation of central nervous system infections in Vietnamese patients: a prospective study

Knowledge of the clinical presentation of central nervous system (CNS) infections and the causative pathogens is crucial for appropriate diagnosis and rapid initiation of appropriate treatment to prevent severe neurological sequelae. The aim of this study is to understand the aetiology of CNS infections based on the clinical presentation of Vietnamese patients. A prospective hospital-based cohort study was conducted between May 2014 and May 2017. We screened 137 patients with clinically suspected CNS infection for fungal, bacterial and viral pathogens using their cerebrospinal fluid (CSF) and blood cultures. In addition, DNA or RNA extracted from CSF samples were subjected to nucleic acid testing (NAT) with a selective panel of bacterial, viral and fungal pathogens. At least one pathogen could be detected in 41% (n = 56) of the patients. The main pathogens causing CNS infections were Streptococcus suis (n = 16; 12%) and Neisseria meningitidis (n = 9; 7%), followed by Herpes simplex virus 1/2 (n = 4; 3%) and Klebsiella pneumoniae (n = 4; 3%). Other pathogens were only identified in a few cases. Patients with bacterial CNS infections were significantly older, had a worse outcome, a lower Glasgow Coma Scale (GCS), a higher rate of speech impairment and neck stiffness than patients with viral or tuberculous CNS infections. In northern Vietnam, adults are mostly affected by bacterial CNS infections, which have a severe clinical course and worse outcomes compared to viral or tuberculous CNS infections. Clinicians should be aware of the regional occurrence of pathogens to initiate rapid and appropriate diagnosis and treatment.

Epidemiology and Disease Burden of Hospitalized Children With Viral Central Nervous System Infections in China, 2016 to 2020

BackgroundViral central nervous system (CNS) infections seriously threaten the life and health of children, with a high mortality and severe sequelae in China and globally. Surveillance of viral CNS infections in children is important, especially in hospitalized children, to facilitate disease evaluation. MethodsIn this study, we collected the data on the discharged Face Sheet of Medical Records from database from 2016 to 2020 and analyzed the epidemiologic characteristics and disease burden of hospitalized children (≤18 years old) with viral CNS infections in China. We classified the discharge diagnosis of viral CNS infection as viral encephalitis (VE), viral meningitis (VM), viral meningoencephalitis (VME), viral encephalomyelitis (VEM), and viral meningomyelitis (VMM). ResultsA total of 42,641 cases of viral CNS infections were included in the database, consisting of 39,279 cases with VE (92.47%), 2011 cases with VM (4.73%), 1189 cases with VME (2.80%), 118 cases with VEM (0.28%), and 44 cases with VMM (0.10%). The number of hospitalized patients with viral CNS infections accounted for 0.74% (42,641 of 5,790,910) of all hospitalized cases. The onset of viral CNS infections presented seasonal characteristic, with peaks in June to July and December to January. Seizures are the most frequent complication of this disorder. Median length of stay and inpatient expenditures for patients with viral CNS infections were 9 days and 1144.36 USD. Causative viruses were identified in 4.33% (1848 of 42,641) of patients. ConclusionsThis study will help understand the clinical epidemiology and disease burden of hospitalized children with viral CNS infections in China.

Viral Infection

Viral central nervous system(CNS)infections due to direct viral infection in the CNS include encephalitis/myelitis and meningitis. Acute encephalopathy is a CNS disorder that is mainly associated with viral respiratory infections. This article outlines herpes encephalitis, poliomyelitis, enterovirus A71 brainstem encephalitis/myelitis, and enterovirus D68 paralytic myelitis as acute encephalitis/myelitis, enteroviral meningitis and mumps meningitis as acute viral meningitis, and influenza encephalopathy and HHV-6 encephalopathy as acute encephalopathy.

Overview of Research into mTOR Inhibitors.

The mammalian target of rapamycin (mTOR) is a serine/threonine kinase that belongs to the phosphoinositide 3-kinase (PI3K)-related kinase (PIKK) family. The kinase exists in the forms of two complexes, mTORC1 and mTORC2, and it participates in cell growth, proliferation, metabolism, and survival. The kinase activity is closely related to the occurrence and development of multiple human diseases. Inhibitors of mTOR block critical pathways to produce antiviral, anti-inflammatory, antiproliferative and other effects, and they have been applied to research in cancer, inflammation, central nervous system diseases and viral infections. Existing mTOR inhibitors are commonly divided into mTOR allosteric inhibitors, ATP-competitive inhibitors and dual binding site inhibitors, according to their sites of action. In addition, there exist several dual-target mTOR inhibitors that target PI3K, histone deacetylases (HDAC) or ataxia telangiectasia mutated and Rad-3 related (ATR) kinases. This review focuses on the structure of mTOR protein and related signaling pathways as well as the structure and characteristics of various mTOR inhibitors. Non-rapalog allosteric inhibitors will open new directions for the development of new therapeutics specifically targeting mTORC1. The applications of ATP-competitive inhibitors in central nervous system diseases, viral infections and inflammation have laid the foundation for expanding the indications of mTOR inhibitors. Both dual-binding site inhibitors and dual-target inhibitors are beneficial in overcoming mTOR inhibitor resistance.

B cells going viral in the CNS: Dynamics, complexities, and functions of B cells responding to viral encephalitis.

A diverse number of DNA and RNA viruses have the potential to invade the central nervous system (CNS), causing inflammation and injury to cells that have a limited capacity for repair and regeneration. While rare, viral encephalitis in humans is often fatal and survivors commonly suffer from permanent neurological sequelae including seizures. Established treatment options are extremely limited, predominantly relying on vaccines, antivirals, or supportive care. Many viral CNS infections are characterized by the presence of antiviral antibodies in the cerebral spinal fluid (CSF), indicating local maintenance of protective antibody secreting cells. However, the mechanisms maintaining these humoral responses are poorly characterized. Furthermore, while both viral and autoimmune encephalitis are associated with the recruitment of diverse B cell subsets to the CNS, their protective and pathogenic roles aside from antibody production are just beginning to be understood. This review will focus on the relevance of B cell responses to viral CNS infections, with an emphasis on the importance of intrathecal immunity and the potential contribution to autoimmunity. Specifically, it will summarize the newest data characterizing B cell activation, differentiation, migration, and localization in clinical samples as well as experimental models of acute and persistent viral encephalitis.

Efficacy of Vafidemstat in Experimental Autoimmune Encephalomyelitis Highlights the KDM1A/RCOR1/HDAC Epigenetic Axis in Multiple Sclerosis.

Lysine specific demethylase 1 (LSD1; also known as KDM1A), is an epigenetic modulator that modifies the histone methylation status. KDM1A forms a part of protein complexes that regulate the expression of genes involved in the onset and progression of diseases such as cancer, central nervous system (CNS) disorders, viral infections, and others. Vafidemstat (ORY-2001) is a clinical stage inhibitor of KDM1A in development for the treatment of neurodegenerative and psychiatric diseases. However, the role of ORY-2001 targeting KDM1A in neuroinflammation remains to be explored. Here, we investigated the effect of ORY-2001 on immune-mediated and virus-induced encephalomyelitis, two experimental models of multiple sclerosis and neuronal damage. Oral administration of ORY-2001 ameliorated clinical signs, reduced lymphocyte egress and infiltration of immune cells into the spinal cord, and prevented demyelination. Interestingly, ORY-2001 was more effective and/or faster acting than a sphingosine 1-phosphate receptor antagonist in the effector phase of the disease and reduced the inflammatory gene expression signature characteristic ofEAE in the CNS of mice more potently. In addition, ORY-2001 induced gene expression changes concordant with a potential neuroprotective function in the brain and spinal cord and reduced neuronal glutamate excitotoxicity-derived damage in explants. These results pointed to ORY-2001 as a promising CNS epigenetic drug able to target neuroinflammatory and neurodegenerative diseases and provided preclinical support for the subsequent design of early-stage clinical trials.

Discriminating between Lyme neuroborreliosis and other central nervous system infections by use of biomarkers CXCL13 and IL-6

CXCL13 in cerebrospinal fluid has gradually become an established biomarker for Lyme neuroborreliosis (LNB), however the diagnostic performance of CXCL13 may be improved by the addition of IL-6, a non-specific infection biomarker. The aim of this study was to measure the concentrations of CXCL13 and IL-6 in cerebrospinal fluid, in the attempt to evaluate the diagnostic performance of these two biomarkers, in the differentiation between definite and possible LNB, as well as between LNB and other neuroinfections. This study used a cross-sectional design to quantify the levels of CXCL13 and IL-6 in cerebrospinal fluid (CSF) specimens from consecutive patients examined for central nervous system (CNS) infections at Lillebaelt Hospital in the Region of Southern Denmark. CXCL13 and IL-6 were measured simultaneously using the Bio-Plex 200 multiplex Cytokine Immunoassay System (Bio-Rad). Based on clinical and paraclinical findings, we grouped patients into six separate groups: definite LNB, possible LNB, Viral CNS infection, non-Borrelia Bacterial CNS infection, Other CNS disease (with pleocytosis) and Negative (without pleocytosis). A combined interpretation of four variables (leukocyte cell counts, protein concentration, CXCL13 and IL-6 concentrations in CSF) is presented using principal component cluster analysis. We included by chart review 390 patients discharged with definite LNB (n = 31), possible LNB (n = 10), confirmed Viral or non-Borrelia Bacterial CNS infection (n = 34), Other CNS disease (n = 58), and Negative (n = 257) for CXCL13 and IL-6 analysis. Principal component analysis (PCA) revealed three distinct clusters based on leukocyte cell counts, protein concentration, CXCL13 and IL-6 concentrations in CSF from 380 included patients (10 possible LNB patients excluded). The clusters clearly differentiate the groups: definite LNB, non-Borrelia Bacterial CNS infection and Negative (without pleocytosis). A receiver operating characteristic (ROC) curve comparing LNB patients (n = 31) and all non-LNB conditions with CSF pleocytosis (n = 99) indicated an optimal CXCL13 cut-off value of 50.7 pg/mL, resulting in a sensitivity and a specificity of 93.6 and 91.1%, respectively. The ROC analysis comparing patients with confirmed non-LNB CNS infection (n = 34) and all others with CSF pleocytosis (n = 97) resulted in an optimal IL-6 cut-off value of 111.5 pg/mL, yielding a sensitivity and a specificity of 78.8% and 82.5% respectively. Of the ten possible LNB patients, three cases (with CXCL13 levels above cut-off) fall within the LNB cluster, and one case is just outside, providing some laboratory support for the diagnosis of LNB. The remaining six possible LNB patients (with CXCL13 levels below the 50.7 cut-off) had little support for the diagnosis of LNB in the PCA-plot. The results of this study confirm that CXCL13 is a valuable supplement for diagnosis of LNB, and that the combination of CXCL13 and IL-6 may be used to differentiate cases of LNB from other CNS infections. Furthermore, IL-6 can be of differential diagnostic value when evaluating patients with possible LNB.