Transcriptome analysis following neurotropic virus infection reveals faulty innate immunity and delayed antigen presentation in mice susceptible to virus-induced demyelination

Viral infections of the central nervous system cause acute or delayed neuropathology and clinical consequences ranging from asymptomatic courses to chronic, debilitating diseases. The outcome of viral encephalitis is partially determined by genetically programed immune response patterns of the host. Experimental infection of mice with Theiler's murine encephalomyelitis virus (TMEV) causes diverse neurologic diseases, including TMEV‐induced demyelinating disease (TMEV‐IDD), depending on the used mouse strain. The aim of the present study was to compare initial transcriptomic changes occurring in the brain of TMEV‐infected SJL (TMEV‐IDD susceptible) and C57BL/6 (TMEV‐IDD resistant) mice. Animals were infected with TMEV and sacrificed 4, 7, or 14 days post infection. RNA was isolated from brain tissue and analyzed by whole‐transcriptome sequencing. Selected differences were confirmed on a protein level by immunohistochemistry. In mock‐infected SJL and C57BL/6 mice, >200 differentially expressed genes (DEGs) were detected. Following TMEV‐infection, the number of DEGs increased to >700. Infected C57BL/6 mice showed a higher expression of transcripts related to antigen presentation via major histocompatibility complex (MHC) I, innate antiviral immune responses and cytotoxicity, compared with infected SJL animals. Expression of many of those genes was weaker or delayed in SJL mice, associated with a failure of viral clearance in this mouse strain. SJL mice showed prolonged elevation of MHC II and chemotactic genes compared with C57BL/6 mice, which presumably facilitates the induction of chronic demyelinating disease. In addition, elevated expression of several genes associated with immunomodulatory or –suppressive functions was observed in SJL mice. The exploratory study confirms previous observations in the model and provides an extensive list of new immunologic parameters potentially contributing to different outcomes of viral encephalitis in two mouse strains.

Determination of Etiology and Epidemiology of Viral Central Nervous System Infections by Quantitative Real-Time Polymerase Chain Reaction in Central India Population

Introduction

Viral infections of the central nervous system (CNS) are the most common cause of hospital admission in worldwide and remain a challenging disease for diagnosis and treatment. The most common infectious agents associated with viral CNS infections are cytomegalovirus (CMV), Epstein-Barr virus (EBV), varicella zoster virus (VZV), Japanese encephalitis virus (JEV), Dengue virus (DENV),West Nile virus(WNV), and Chandipura virus(CHPV). The aim of the present work was to find the etiology of CNS viral infection in the Central India population by transcriptase PCR (RT-PCR) comparing real-time polymerase chain reaction (PCR) method [one-step and two-step reverse transcriptase (RT-PCR)] in cerebrospinal fluid (CSF) and blood samples of CNS viral infections patients.

Materials and Methods

One-step and two-step real-time PCR assays were evaluated in CSF and parallel blood samples from patients with viral CNS infections for detection of DNA and RNA viruses. A comparative analysis was also done between gDNA, gRNA, cDNA, and plasmid-based real-time PCR methods for an efficient quantitation of viral particles in clinical samples for determination of viral etiology.

Result

On evaluation of 150 CSF and 50 parallel blood samples from suspected cases of viral CNS infections, a viral etiology was confirmed in 21 (14%) cases, including 3% for EBV, 1% of CMV, and 5% for VZV and JEV. The one-step RT-PCR has a higher detection limit for detection and quantitation of viral RNA in comparison to two-step RT-PCR.

Conclusion

Our result reveals that VZV and JEV are the most usual cases of CNS viral infection in hospitalized patients in the Central India population and one-step RT-PCR shows higher viral load detection limits for quantitation of viral genome and more sensitivity in comparison to two-step RT-PCR.

Psychotic Agitation in a Patient with COVID-19: Pathogenesis or Iatrogenesis?

The pathophysiological underpinnings of central nervous system (CNS) involvement in SARS-CoV-2 infection, as well as the profile of adverse neuropsychiatric effects of pharmacological agents employed in the management of COVID-19, are yet to be elucidated. Here, we report a 43-year-old female patient who suffered from COVID-19 and who developed new-onset psychotic agitated behavior which may be related to either the COVID-19 infection itself or to the drugs that were used in the treatment. On her third day of treatment with oseltamivir, hydroxychloroquine, and azithromycin, the patient, who had no previous background of neurological or psychiatric diagnosis, presented with a new-onset psychomotor agitation with auditory hallucinations and insomnia. Her psychiatric symptoms have improved with oral olanzapine 5 mg/d. This report underscores the importance of neuropsychiatric monitoring in patients with COVID-19. Clinicians should be aware of the limited knowledge on the neuropsychiatric safety profile of the medication used for COVID-19 treatment, while they have focused on the neuropsychiatric outcomes of COVID-19 itself.

Varicella Zoster Virus Encephalitis in Denmark From 2015 to 2019-A Nationwide Prospective Cohort Study

BACKGROUND

Knowledge of the epidemiology and clinical characteristics of varicella zoster virus (VZV) encephalitis remains limited.

METHODS

Nationwide prospective cohort study of adults treated for microbiologically confirmed VZV encephalitis at Danish departments of infectious diseases from 2015 to 2019. Modified Poisson regression analysis was used to compute adjusted relative risks (RRs) of unfavorable outcome.

RESULTS

We identified 92 adults (49% female) with VZV encephalitis, yielding an incidence of 5.3/1 000 000 per year (95% CI, 4.2-6.6). Median age was 75 years (IQR, 67-83) and immunocompromising conditions were frequent (39%). Predominant symptoms were confusion (76%), headache (56%), nausea (45%), gait disturbance (42%), and personality changes (41%). Cranial imaging showed cerebral vasculitis (including infarction and hemorrhage) in 14 (16%) patients and encephalitic abnormalities in 11 (13%) with predilection for the brainstem and deep brain structures. Intravenous acyclovir treatment was initiated a median (IQR) of 13.4 hours (5.2-46.3) since admission, while cranial imaging and lumbar puncture were performed after 6.3 hours (2.5-31.0) and 18.5 hours (4.9-42.0). In-hospital, 1-month, and 3-month mortalities were 4%, 9%, and 11%, respectively. Unfavorable outcome (Glasgow Outcome Score of 1-4) was found in 69% at discharge, with age (adjusted RR [aRR], 1.02; 95% CI, 1.01-1.03), vasculitis (aRR, 1.38; 95% CI, 1.02-1.86), and Glasgow Coma Scale (GCS) <15 (aRR, 1.32; 95% CI, 1.01-1.73) identified as independent risk factors.

CONCLUSIONS

VZV encephalitis occurs primarily in elderly or immunocompromised patients with a higher incidence than previously estimated. The diagnosis is often delayed; risk factors for unfavorable outcome are age, cerebral vasculitis, and GCS <15.

Fitness selection of hyperfusogenic measles virus F proteins associated with neuropathogenic phenotypes

Measles virus (MeV) is resurgent and caused >200,000 deaths in 2019. MeV infection can establish a chronic latent infection of the brain that can recrudesce months to years after recovery from the primary infection. Recrudescent MeV leads to fatal subacute sclerosing panencephalitis (SSPE) or measles inclusion body encephalitis (MIBE) as the virus spreads across multiple brain regions. Most clinical isolates of SSPE/MIBE strains show mutations in the fusion (F) gene that result in a hyperfusogenic phenotype in vitro and allow for efficient spread in primary human neurons. Wild-type MeV receptor-binding protein is indispensable for manifesting these mutant F phenotypes, even though neurons lack canonical MeV receptors (CD150/SLAMF1 or nectin-4). How such hyperfusogenic F mutants are selected and whether they confer a fitness advantage for efficient neuronal spread is unresolved. To better understand the fitness landscape that allows for the selection of such hyperfusogenic F mutants, we conducted a screen of ≥3.1 × 10⁵ MeV-F point mutants in their genomic context. We rescued and amplified our genomic MeV-F mutant libraries in BSR-T7 cells under conditions in which MeV-F-T461I (a known SSPE mutant), but not wild-type MeV, can spread. We recovered known SSPE mutants but also characterized at least 15 hyperfusogenic F mutations with an SSPE phenotype. Structural mapping of these mutants onto the prefusion MeV-F trimer confirm and extend our understanding of the F regulatory domains in MeV-F. Our list of hyperfusogenic F mutants is a valuable resource for future studies into MeV neuropathogenesis and the regulation of paramyxovirus F.

The roles of microglia in viral encephalitis: from sensome to therapeutic targeting

Viral encephalitis is a devastating disease with high mortality, and survivors often suffer from severe neurological complications. Microglia are innate immune cells of the central nervous system (CNS) parenchyma whose turnover is reliant on local proliferation. Microglia express a diverse range of proteins, which allows them to continuously sense the environment and quickly react to changes. Under inflammatory conditions such as CNS viral infection, microglia promote innate and adaptive immune responses to protect the host. However, during viral infection, a dysregulated microglia-T-cell interplay may result in altered phagocytosis of neuronal synapses by microglia that causes neurocognitive impairment. In this review, we summarize the current knowledge on the role of microglia in viral encephalitis, propose questions to be answered in the future and suggest possible therapeutic targets.

Neurological risks and benefits of cytokine-based treatments in coronavirus disease 2019: from preclinical to clinical evidence

Immunodeficiency and hyperinflammation are responsible for the most frequent and life-threatening forms of coronavirus disease 2019 (COVID-19). Therefore, cytokine-based treatments targeting immuno-inflammatory mechanisms are currently undergoing clinical scrutiny in COVID-19-affected patients. In addition, COVID-19 patients also exhibit a wide range of neurological manifestations (neuro-COVID), which may also benefit from cytokine-based treatments. In fact, such drugs have shown some clinical efficacy also in neuroinflammatory diseases. On the other hand, anti-cytokine drugs are endowed with significant neurological risks, mainly attributable to their immunodepressant effects. Therefore, the aim of the present manuscript is to briefly describe the role of specific cytokines in neuroinflammation, to summarize the efficacy in preclinical models of neuroinflammatory diseases of drugs targeting these cytokines and to review the clinical data regarding the neurological effects of these drugs currently being investigated against COVID-19, in order to raise awareness about their potentially beneficial and/or detrimental neurological consequences.

Crosstalk Between Covid-19 and Associated Neurological Disorders: A Review

COVID-19 is a global pandemic, primarily affecting the pulmonary system but its effects on other systems are not certain. Coronavirus, the causative organism, binds with angiotensinconverting enzyme 2 (ACE2) receptors in the lungs and produces pneumonia-like symptoms. Other than lungs, ACE2 receptors are also seen in the endothelium of blood vessels. Therefore, viruses can bind to the ACE2 that is present in the endothelium of brain blood vessels and thus can invade BBB, leading to neuronal damage. It is also believed that olfactory cells rich in ACE2 receptors may act as the main route of viral spread into various parts of the brain. The reported neurological effects of SARS-CoV-2 include cerebrovascular diseases, ageusia and anosmia, Guillain Barre Syndrome, and viral encephalitis. The extent of neurological involvement in SARS-CoV-2 infection warrants the necessity of further research to systematically classify neurological complications associated with SARS-CoV-2 infection, its diagnosis, and treatment. As ACE2 receptors are present in various other organs, it is obligatory to study the effect of coronavirus on other organs also. Since the long-lasting effects of the COVID-19 are unclear, more studies should be conducted to confirm the effect of the virus on the central nervous system. This review highlights the reported neurological manifestations of SARS-CoV-2 and its mechanism.

Insights into the biomarkers of viral encephalitis from clinical patients

BACKGROUND

biomarkers can be helpful in identifying patients who may profit by explicit treatments or evaluating the reaction to the treatment of specific disease. Finding unique biomarkers in the process of disease could help clinicians in identifying serious disease in the early stage, so as to improve prognosis.

OBJECTIVE

these investigations, nonetheless, have made constrained progress. Numerous infections are known to cause intense viral encephalitis (VE) in people which can cause a variable level of meningeal just as parenchymal aggravation. Initial clinical manifestations in most encephalitis are nonspecific, resembling a viral-like illness. However, with disease progression, symptoms can become quite severe and fatal, including prominent cranial hypertension, cognitive problems, cerebral hernia and respiratory failure. Forwards: the clinical and research center discoveries in huge numbers of those viral issues are to a great extent comparable and in this way increasingly explicit biomarkers for indicative and prognostic intentions are justified. These biomarkers are progressively significant in the acknowledgment and treatment of the viral central nervous system (CNS) issue.

CONCLUSION

Clinical manifestations have been the indicative approaches for analysis of viral encephalitis. Lots of studies have been endeavored to distinguish progressively objective laboratory-based quantitative CSF biomarkers for VE.

Neuroprotective versus Neuroinflammatory Roles of Complement: From Development to Disease

Complement proteins are ancient components of innate immunity that have emerged as crucial regulators of neural networks. We discuss these roles in the context of the CNS development, acute CNS viral infections, and post-infectious and noninfectious CNS disorders, with an emphasis on microglia-mediated loss of synapses. Despite extensive examples that implicate classical complement proteins and their receptors in CNS dysfunction, recent data suggest that they exert neuroprotective roles in CNS homeostasis through continued refinement of synaptic connections. Thorough understanding of the mechanisms involved in these processes may lead to novel targets for the treatment of CNS diseases involving aberrant complement-mediated synapse loss.

The curious case of an atypical headache, a case report and review of literature

Atypical headaches are uncommon and require special consideration by a primary care physician. We report the case of a 37-year-old male, who presented to the family medicine practice with persistent headaches which subsided postprandial and was later hospitalized for stroke-like symptoms. The lumbar puncture (LP) suggested viral etiology; however, cerebrospinal fluid (CSF) yielded no evidence of a specific virus. The patient computed tomography (CT) was non-diagnostic and magnetic resonance imaging (MRI) confirmed no acute intracranial abnormalities. Electroencephalogram (EEG) showed no definite epileptiform discharges, electrographic seizures, or evidence of non-convulsive status epilepticus. He was started empirically on intravenous (IV) acyclovir 800 mg Q6 for 10 days, followed by another 10 days of oral valacyclovir 500 mg twice a day (BID) antivirals leading to a complete resolution of his symptoms and confirming the diagnosis as viral encephalitis. This case is unique in its presentation due to the postprandial resolution of the patient's headache with no evidence of a specific virus in the CSF. In primary care setting, headaches are often referred routinely to neurologist for further management. However, more insidious causes for a headache, such as viral infections, should not be ruled out; and if the symptoms are acute and severe, an immediate inpatient work-up with empiric treatment for the most probable etiology may be warranted, despite unequivocal exam and laboratory findings.

COVID-19 and the Brain: Acute Encephalitis as a Clinical Manifestation

Central nervous system (CNS) viral infections result in the clinical syndromes of aseptic meningitis or encephalitis. Although the primary target of coronavirus disease 2019 (COVID-19) is the respiratory system, it is increasingly being recognized as a neuropathogen. The hallmark clinical feature is altered mental status, ranging from mild confusion to deep coma. Most patients with encephalopathy or encephalitis are critically ill. We present a case of COVID-19-related encephalitis who presented with acute delirium and new-onset seizures. The patient responded well to treatment with intravenous immunoglobulins and rituximab.

Evaluating spectral cytometry for immune profiling in viral disease

In conventional fluorescence cytometry, each fluorophore present in a panel is measured in a target detector, through the use of wide band-pass optical filters. In contrast, spectral cytometry uses a large number of detectors with narrow band-pass filters to measure a fluorophore's signal across the spectrum, creating a more detailed fluorescent signature for each fluorophore. The spectral approach shows promise in adding flexibility to panel design and improving the measurement of fluorescent signal. However, few comparisons between conventional and spectral systems have been reported to date. We therefore sought to compare a modern conventional cytometry system with a modern spectral system, and to assess the quality of resulting datasets from the point of view of a flow cytometry user. Signal intensity, spread, and resolution were compared between the systems. Subsequently, the different methods of separating fluorophore signals were compared, where compensation mathematically separates multiple overlapping fluorophores and unmixing relies on creating a detailed fluorescent signature across the spectrum to separate the fluorophores. Within the spectral data set, signal spread and resolution were comparable between compensation and unmixing. However, for some highly overlapping fluorophores, unmixing resolved the two fluorescence signals where compensation did not. Finally, data from mid- to large-size panels were acquired and were found to have comparable resolution for many fluorophores on both instruments, but reduced levels of spreading error on our spectral system improved signal resolution for a number of fluorophores, compared with our conventional system. Furthermore, autofluorescence extraction on the spectral system allowed for greater population resolution in highly autofluorescent samples. Overall, the implementation of a spectral cytometry approach resulted in data that are comparable to that generated on conventional systems, with a number of potential advantages afforded by the larger number of detectors, and the integration of the spectral unmixing approach. © 2020 International Society for Advancement of Cytometry.

Cytosolic DNA Sensors and CNS Responses to Viral Pathogens

Viral central nervous system (CNS) infections can lead to life threatening encephalitis and long-term neurological deficits in survivors. Resident CNS cell types, such as astrocytes and microglia, are known to produce key inflammatory and antiviral mediators following infection with neurotropic DNA viruses. However, the mechanisms by which glia mediate such responses remain poorly understood. Recently, a class of intracellular pattern recognition receptors (PRRs), collectively known as DNA sensors, have been identified in both leukocytic and non-leukocytic cell types. The ability of such DNA sensors to initiate immune mediator production and contribute to infection resolution in the periphery is increasingly recognized, but our understanding of their role in the CNS remains limited at best. In this review, we describe the evidence for the expression and functionality of DNA sensors in resident brain cells, with a focus on their role in neurotropic virus infections. The available data indicate that glia and neurons can constitutively express, and/or can be induced to express, various disparate DNA sensing molecules previously described in peripheral cell types. Furthermore, multiple lines of investigation suggest that these sensors are functional in resident CNS cells and are required for innate immune responses to viral infections. However, it is less clear whether DNA sensormediated glial responses are beneficial or detrimental, and the answer to this question appears to dependent on the context of the infection with regard to the identity of the pathogen, host cell type, and host species. Defining such parameters will be essential if we are to successfully target these molecules to limit damaging inflammation while allowing beneficial host responses to improve patient outcomes.

Uveal Effusion Associated with Presumed Viral Encephalitis

Background Uveal effusion is a rare disease that is characterized by exudative detachment of the ciliary body and choroid. Herein, we report a rare case of uveal effusion associated with viral encephalitis, which resolved following the treatment of the viral encephalitis and administration of corticosteroids.Case presentation A 67-year-old man who was hospitalized for viral encephalitis was referred to our clinic. He had been treated for herpes zoster ophthalmicus in his left eye 3 weeks previously. Choroidal detachment and uveal effusion between the ciliary body and sclera were observed. He was prescribed oral and topical steroids and cycloplegics to treat uveal effusion, and an antiviral agent (Acyclovir) to treat viral encephalitis. After 4 weeks, the choroidal detachment resolved completely.Conclusions Uveal effusion syndrome can develop in association with viral encephalitis and be treated successfully with oral and topical steroids; we suggest that medical treatment should be attempted prior to surgery.Abbreviations ADEM: Acute disseminated encephalomyelitis; BCVA: Best corrected visual acuity; CSF: Cerebrospinal fluid; CT: Computed tomography; MRI: Magnetic resonance imaging; WBC: White blood cell.

Twice Negative PCR in a Patient With Herpes Simplex Virus Type 1 (HSV-1) Encephalitis

Untreated herpes simplex virus type 1 (HSV-1) encephalitis is associated with high mortality. Missed cases can have devastating consequences. Detection of HSV-1 in cerebrospinal fluid (CSF) with polymerase chain reaction (PCR) is reported to have high sensitivity and specificity and is considered the diagnostic gold standard for HSV-1 encephalitis. In this article, we report a case of autopsy-confirmed HSV-1 encephalitis where CSF PCR returned negative on 2 occasions. A 64-year-old man presented with fever, left-sided weakness, and altered level of consciousness. Magnetic resonance imaging demonstrated right mesial temporal lobe diffusion restriction and electroencephalography showed right lateralized periodic discharges. Lumbar puncture was performed on day 1 for which CSF PCR returned negative for HSV-1. Empiric antiviral and antibiotic treatments were continued due to high clinical suspicion of HSV-1 encephalitis. Repeat lumbar puncture on day 5 was unchanged and empiric treatments were discontinued. On day 13, he developed status epilepticus requiring intensive care unit admission. A third CSF sample returned positive for HSV-1. Acyclovir was restarted but he continued to clinically worsen and supportive care was withdrawn. Autopsy confirmed widespread HSV-1 meningoencephalitis. Negative CSF PCR should be interpreted with caution in cases where there is high clinical suspicion of HSV-1 encephalitis. Current guidelines suggest repeating CSF HSV-1 PCR within 3 to 7 days in suspicious cases while continuing empiric therapy. However, missed cases can occur even with repeated testing. Empiric treatment with acyclovir should be considered in cases with high clinical suspicion of HSV-1 encephalitis, while investigations for alternate treatable diagnoses are continued.

Analysis of exotic squirrel trade and detection of human infections with variegated squirrel bornavirus 1, Germany, 2005 to 2018

Following the discovery in 2015 of the variegated squirrel bornavirus 1 (VSBV-1) in fatal encephalitis cases among exotic squirrel breeders and a zoo animal caretaker in Germany, a case definition was developed. It was employed during trace-back animal trade investigations and sero-epidemiological studies among breeders and zoo animal caretakers of holdings with VSBV-1 infected squirrels. During the investigation, two possible human cases who had died of encephalitis were identified retrospectively among the squirrel breeders. Moreover, one probable human case was detected among the breeders who had a positive memory T-cell response to VSBV-1 antigen and antibodies against VSBV-1. The low rate of seropositivity found among living persons in risk groups that handle exotic squirrels privately or at zoos may reflect rareness of exposure to VSBV-1 during animal contact, a high lethality of infection or a combination of these factors. As a precaution against human exposure, testing of exotic squirrels for VSBV-1 infection and/or avoiding direct contact with exotic squirrels in zoos and private holdings is strongly advised.

Human herpesvirus 6B encephalitis in a liver transplant recipient: A case report and review of the literature

Human herpesvirus 6B (HHV‐6B) encephalitis in a liver transplant recipient is rarely reported. In this report, we presented a case of HHV‐6B encephalitis in a liver transplant recipient and reviewed the relevant literature. A 56‐year‐old man was admitted to the intensive care unit (ICU) with an acute headache and intermittent convulsion 17 days after liver transplantation. Next‐generation sequencing (NGS) of the cerebrospinal fluid (CSF) revealed 30691 sequence reads of HHV‐6B and real‐time polymerase chain reaction (real‐time PCR) of the CSF detected HHV‐6B DNA at 12 000 copies/mL, so the patient was diagnosed with HHV‐6B encephalitis and received ganciclovir treatment promptly. The condition of the patient improved well and returned to the general ward with no neurologic deficits. This case indicated that adequate awareness, early diagnosis, and timely treatment are crucial to a good prognosis of HHV‐6B encephalitis after liver transplantation.

Update on T cells in the virally infected brain: friends and foes

PURPOSE OF REVIEW

The present review will outline neuroprotective and neurotoxic effects of central nervous system (CNS) infiltrating T cells during viral infections. Evidence demonstrating differential roles for antiviral effector and resident memory T-cell subsets in virologic control and immunopathology in the CNS will be discussed. Potential therapeutic targets emanating from a growing understanding of T-cell-initiated neuropathology that impacts learning and memory will also be delineated.

RECENT FINDINGS

The critical role for T cells in preventing and clearing CNS infections became incontrovertible during the era of acquired immunodeficiency syndrome. Recent studies have further defined differential roles of T-cell subsets, including resident memory T cells (Trm), in antiviral immunity and, unexpectedly, in postinfectious cognitive dysfunction. Mechanisms of T-cell-mediated effects include differential innate immune signaling within neural cells that are virus-specific.

SUMMARY

T-cell cytokines that are essential for cell-mediated virologic control during neurotropic viral infections have recently been identified as potential targets to prevent post-infection memory disorders. Further identification of T-cell subsets, their antigen specificity, and postinfection localization of Trm will enhance the efficacy of immunotherapies through minimization of immunopathology.

The Innate Immune Response to Herpes Simplex Virus 1 Infection Is Dampened in the Newborn Brain and Can Be Modulated by Exogenous Interferon Beta To Improve Survival

Herpes simplex virus (HSV) is a ubiquitous human pathogen affecting 50 to 80% of the population in North America and Europe. HSV infection is commonly asymptomatic in the adult population but can result in fatal encephalitis in the newborn. Current treatment with acyclovir has improved mortality in the newborn; however, severe neurologic sequelae are still a major concern following HSV encephalitis. For this reason, there is a critical need to better understand the underlying differences in the immune response between the two age groups that could be used to develop more effective treatments. In this study, we investigated differences in the innate immune response to viral infection in the brains of newborn and adult mice. We found that, similar to humans, newborn mice are more susceptible to HSV infection than the adult. Increased susceptibility was associated with dampened innate immune responses in the newborn brain that could be rescued by administering interferon beta.

Newborns are particularly susceptible to severe forms of herpes simplex virus 1 (HSV-1) infection, including encephalitis and multisystemic disseminated disease. The underlying age-dependent differences in the immune response that explain this increased susceptibility relative to the adult population remain largely understudied. Using a murine model of HSV-1 infection, we found that newborn mice are largely susceptible to intracranial and intraperitoneal challenge while adult mice are highly resistant. This age-dependent difference correlated with differential basal-level expression of components of innate immune signaling pathways, which resulted in dampened interferon (IFN) signaling in the newborn brain. To explore the possibility of modulating the IFN response in the newborn brain to recapitulate the adult phenotype, we administered exogenous IFN-β in the context of disseminated HSV-1 infection. IFN-β treatment resulted in significantly increased survival and delayed viral neuroinvasion in the newborn. These effects were associated with changes in the type I IFN response in the brain, reduced viral replication in the periphery, and the stabilization of the blood-brain barrier (BBB). Our study reveals important age-dependent differences in the innate immune response to HSV-1 infection and suggests a contribution of the BBB and the brain parenchyma in mediating the increased susceptibility to HSV-1 infection observed in the newborn. These results could provide the basis for potential new therapeutic strategies for life-threatening HSV-1 infection in newborns.

Hashimoto's Encephalopathy Mimicking Viral Encephalitis: A Case Report

Hashimoto's encephalopathy (HE) is a rare neuropsychiatric syndrome characterized by elevated levels of anti-thyroid antibodies. Diverse manifestations make timely diagnosis of HE difficult. Herein, we report a case of HE, in which the clinical symptoms and laboratory test results mimicked viral encephalitis. A 59-year-old male patient, who presented with a fever, headache, slow and unclear speech, sentence confusion, elevated levels of anti-thyroid antibodies in the serum, an increased white blood cell count, and positivity for anti-thyroid antibodies in the CSF, was finally diagnosed with HE and responded well to a small dose of methylprednisolone. This report helps bring the attention of clinicians to the fact that HE should be considered when cases of unexplained encephalopathy are encountered.

Cerebral HSV-1 Vasculitis as a Fatal Complication of Immunosuppression in Non-Hodgkin´s Lymphoma: A Case Report and Review of the Literature

Patients with lymphoma are predisposed to infection because of the immunocompromised state related to the disease itself and as a consequence of chemo-/radiotherapy. Here, we report a case of Herpes-simplex virus encephalitis (HSE) in an immunosuppressed patient with splenic marginal zone lymphoma (SMZL), a rare indolent variant of non-Hodgkin´s lymphoma (NHL). The course was complicated febrile neutropenia and HSV-1-related cerebral vasculitis causing progressive ischemic stroke. This case illustrates the expanding spectrum of atypical clinical and radiological manifestations of HSE in patients treated with myelotoxic drugs. Moreover, we summarize the few central nervous system manifestations of SMZL reported in the literature and discuss distinct causes of neurological deterioration in patients with NHL.

The longitudinal health economic impact of viral encephalitis in the United States

Introduction. Previous studies of viral encephalitis have focused on acute costs, estimating incidence at 7.3 per 100 000 and total US annual charges at $2 billion in 2010.Aim. We aim to quantify the most updated longitudinal health economic impact of viral encephalitis in the USA from 2008 to 2015.Methodology. Data on patients diagnosed with viral encephalitis were obtained from the Truven Health Analytics MarketScan database. Patients with a primary diagnosis of viral encephalitis, from herpetic viruses and other viral aetiologies (e.g. West Nile fever) were included in the analysis. Data concerning healthcare resource utilization, inpatient mortality, length of stay and accrued healthcare costs were collected for up to 5 years.Results. Among 3985 patients with continuous enrolment for 13 months prior to the encephalitis diagnosis, more non-herpes simplex encephalitis (61.7 %) than herpes simplex encephalitis (HSE; 38.3 %) cases were recorded, with the majority concentrated in the southern USA (29.2 %). One-year inpatient mortality was 6.2 %, which over a 5-year period rose to 8.9 % for HSE and 5.8 % for all other viral encephalitides. HSE resulted in longer cumulative stays in the hospital (11 days vs. 4 days; P=0.0025), and accrued 37 % higher first-year costs, after adjusting for known confounders [P<0.001, cost ratio=1.37, 95 % confidence interval (1.20, 1.57)]. Additionally, HSE was associated with greater 5-year cumulative median charges ($125 338 vs. $82 317, P=0.0015).Conclusion. The health economic impact and long-term morbidity of viral encephalitis in the USA are substantial.