Subacute sclerosing panencephalitis: an update

Multimodal Imaging for Subacute Sclerosing Panencephalitis: Including Anterior Segment

Subacute sclerosing panencephalitis (SSPE) is an irreversible and progressive neurological disorder. A 20-year-old woman with SSPE presented with a decline in visual acuity. Anterior segment was evaluated with slit lamp and in vivo confocal microscopy, revealing the presence of dendritiform keratic precipitates and +2 cells in the anterior chamber. In fundus examination, white-yellowish lesions involving the macula and periphery were observed, which gradually progressed into atrophy over time. Optical coherence tomography (OCT) imaging showed progression to atrophy of moth-eaten shaped cavities including all retinal layers due to necrotizing retinitis. OCT angiography (OCTA) further revealed reduced vessel densities and flow void areas. Notably, to the best of our knowledge, this is the first case documenting anterior segment findings in SSPE in detail. [Ophthalmic Surg Lasers Imaging Retina 2024;55:344-348.].

Pediatric Subacute Sclerosing Panencephalitis: A Narrative Review on Measles and the Future of Vaccination

Subacute sclerosing panencephalitis is a rare complication due to persistent measles infection, characterized by cognitive and motor deterioration. Because subacute sclerosing panencephalitis is considered a potentially fatal complication of measles and usually presents in young populations, particularly those with measles infection under the age of 2 years, new approaches to implement vaccination programs must be devised to help avoid the worsening of patient outcome. Until the disease is eradicated globally, children in all regions of the world remain at risk of measles infection and its respective complications, and therefore, the vaccine is considered the optimal preventative measure. The legacy of measles virus goes beyond the immediate complications. Our study, therefore, aims to provide a comprehensive review on the updated insights into subacute sclerosing panencephalitis as a complication, as well as the extent and future considerations pertaining to vaccination programs in the pediatric population.

Tau filaments from amyotrophic lateral sclerosis/parkinsonism-dementia complex adopt the CTE fold

The amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) of the island of Guam and the Kii peninsula of Japan is a fatal neurodegenerative disease of unknown cause that is characterized by the presence of abundant filamentous tau inclusions in brains and spinal cords. Here, we used electron cryo-microscopy to determine the structures of tau filaments from the cerebral cortex of three cases of ALS/PDC from Guam and eight cases from Kii, as well as from the spinal cord of two of the Guam cases. Tau filaments had the chronic traumatic encephalopathy (CTE) fold, with variable amounts of Type I and Type II filaments. Paired helical tau filaments were also found in three Kii cases and tau filaments with the corticobasal degeneration fold in one Kii case. We identified a new Type III CTE tau filament, where protofilaments pack against each other in an antiparallel fashion. ALS/PDC is the third known tauopathy with CTE-type filaments and abundant tau inclusions in cortical layers II/III, the others being CTE and subacute sclerosing panencephalitis. Because these tauopathies are believed to have environmental causes, our findings support the hypothesis that ALS/PDC is caused by exogenous factors.

Brain tropism acquisition: The spatial dynamics and evolution of a measles virus collective infectious unit that drove lethal subacute sclerosing panencephalitis

It is increasingly appreciated that pathogens can spread as infectious units constituted by multiple, genetically diverse genomes, also called collective infectious units or genome collectives. However, genetic characterization of the spatial dynamics of collective infectious units in animal hosts is demanding, and it is rarely feasible in humans. Measles virus (MeV), whose spread in lymphatic tissues and airway epithelia relies on collective infectious units, can, in rare cases, cause subacute sclerosing panencephalitis (SSPE), a lethal human brain disease. In different SSPE cases, MeV acquisition of brain tropism has been attributed to mutations affecting either the fusion or the matrix protein, or both, but the overarching mechanism driving brain adaptation is not understood. Here we analyzed MeV RNA from several spatially distinct brain regions of an individual who succumbed to SSPE. Surprisingly, we identified two major MeV genome subpopulations present at variable frequencies in all 15 brain specimens examined. Both genome types accumulated mutations like those shown to favor receptor-independent cell-cell spread in other SSPE cases. Most infected cells carried both genome types, suggesting the possibility of genetic complementation. We cannot definitively chart the history of the spread of this virus in the brain, but several observations suggest that mutant genomes generated in the frontal cortex moved outwards as a collective and diversified. During diversification, mutations affecting the cytoplasmic tails of both viral envelope proteins emerged and fluctuated in frequency across genetic backgrounds, suggesting convergent and potentially frequency-dependent evolution for modulation of fusogenicity. We propose that a collective infectious unit drove MeV pathogenesis in this brain. Re-examination of published data suggests that similar processes may have occurred in other SSPE cases. Our studies provide a primer for analyses of the evolution of collective infectious units of other pathogens that cause lethal disease in humans.

Place of magistral preparations to continue the treatment if the drug is commercially stopped worldwide? A case report of a 10-year-old child with subacute sclerosing panencephalitis (SSPE) requiring inosiplex

Subacute sclerosing panencephalitis (SSPE) is a late-onset and fatal viral disease caused by persistent infection of the central nervous system by measles virus (MeV). We present the case of a 10-year-old child from South Asia affected by SSPE, stabilized with a combination of intrathecal interferon-α2b (INF-α2b) injections and oral inosiplex and how we continued the treatment when inosiplex was commercially stopped worldwide.

Low glycemic index therapy in children with sub-acute sclerosing panencephalitis (SSPE): an experience from a measles-endemic country

INTRODUCTION

Sub-acute sclerosing panencephalitis (SSPE) is a chronic, progressive neurodegenerative disorder, commonly seen in measles-endemic countries leading to progressive neuronal loss and death. Currently, there is no proven cure for this devastating disease. We started a low glycemic index therapy (LGIT) in children with SSPE using the same principle as per its role in intractable epilepsy.

METHODOLOGY

Low glycemic index diet was started in children with a confirmed diagnosis of SSPE based on Dyken's criteria. All children were then classified into four stages according to disease progression. The response to diet was evaluated by improvement in their myoclonic jerks, motor activities, and changes in their stage of the disease.

RESULTS

A total of 12 children were enrolled. The mean age was 6.65 years (range 3.3-10 years), with a male-to-female ratio of 2:1. Five children were at stage IV, five were at stage III, and two were at stage II at the start of the diet. Nine (75%) children showed improvement in their stage of illness. Of three children who were at stage IV at the initiation of the diet, one improved to stage II and two to stage III. Four children at stage III reverted to stage II. Two children initiated at stage II went into total remission. Seven (58.3%) children showed a >50% reduction in myoclonic jerks with three (25%) having a 100% reduction. Three (25%) children died due to pneumonia.

CONCLUSION

LGIT may play an effective role in the management of SSPE and gives hope to families having children with this potentially life-threatening disease.

Suppression of viral RNA polymerase activity is necessary for persistent infection during the transformation of measles virus into SSPE virus

Subacute sclerosing panencephalitis (SSPE) is a fatal neurodegenerative disease caused by measles virus (MV), which typically develops 7 to 10 years after acute measles. During the incubation period, MV establishes a persistent infection in the brain and accumulates mutations that generate neuropathogenic SSPE virus. The neuropathogenicity is closely associated with enhanced propagation mediated by cell-to-cell fusion in the brain, which is principally regulated by hyperfusogenic mutations of the viral F protein. The molecular mechanisms underlying establishment and maintenance of persistent infection are unclear because it is impractical to isolate viruses before the appearance of clinical signs. In this study, we found that the L and P proteins, components of viral RNA-dependent RNA polymerase (RdRp), of an SSPE virus Kobe-1 strain did not promote but rather attenuated viral neuropathogenicity. Viral RdRp activity corresponded to F protein expression; the suppression of RdRp activity in the Kobe-1 strain because of mutations in the L and P proteins led to restriction of the F protein level, thereby reducing cell-to-cell fusion mediated propagation in neuronal cells and decreasing neuropathogenicity. Therefore, the L and P proteins of Kobe-1 did not contribute to progression of SSPE. Three mutations in the L protein strongly suppressed RdRp activity. Recombinant MV harboring the three mutations limited viral spread in neuronal cells while preventing the release of infectious progeny particles; these changes could support persistent infection by enabling host immune escape and preventing host cell lysis. Therefore, the suppression of RdRp activity is necessary for the persistent infection of the parental MV on the way to transform into Kobe-1 SSPE virus. Because mutations in the genome of an SSPE virus reflect the process of SSPE development, mutation analysis will provide insight into the mechanisms underlying persistent infection.

Diagnosing viral encephalitis and emerging concepts

PURPOSE OF REVIEW

This review offers a contemporary clinical approach to the diagnosis of viral encephalitis and discusses recent advances in the field. The neurologic effects of coronaviruses, including COVID-19, as well as management of encephalitis are not covered in this review.

RECENT FINDINGS

The diagnostic tools for evaluating patients with viral encephalitis are evolving quickly. Multiplex PCR panels are now in widespread use and allow for rapid pathogen detection and potentially reduce empiric antimicrobial exposure in certain patients, while metagenomic next-generation sequencing holds great promise in diagnosing challenging and rarer causes of viral encephalitis. We also review topical and emerging infections pertinent to neuroinfectious disease practice, including emerging arboviruses, monkeypox virus (mpox), and measles.

SUMMARY

Although etiological diagnosis remains challenging in viral encephalitis, recent advances may soon provide the clinician with additional tools. Environmental changes, host factors (such as ubiquitous use of immunosuppression), and societal trends (re-emergence of vaccine preventable diseases) are likely to change the landscape of neurologic infections that are considered and treated in clinical practice.

Tau Filaments from Amyotrophic Lateral Sclerosis/Parkinsonism-Dementia Complex (ALS/PDC) adopt the CTE Fold

The amyotrophic lateral sclerosis/parkinsonism-dementia complex (ALS/PDC) of the island of Guam and the Kii peninsula of Japan is a fatal neurodegenerative disease of unknown cause that is characterised by the presence of abundant filamentous tau inclusions in brains and spinal cords. Here we used electron cryo-microscopy (cryo-EM) to determine the structures of tau filaments from the cerebral cortex of three cases of ALS/PDC from Guam and eight cases from Kii, as well as from the spinal cord of two of the Guam cases. Tau filaments had the chronic traumatic encephalopathy (CTE) fold, with variable amounts of Type I and Type II filaments. Paired helical tau filaments were also found in two Kii cases. We also identified a novel Type III CTE tau filament, where protofilaments pack against each other in an anti-parallel fashion. ALS/PDC is the third known tauopathy with CTE-type filaments and abundant tau inclusions in cortical layers II/III, the others being CTE and subacute sclerosing panencephalitis. Because these tauopathies are believed to have environmental causes, our findings support the hypothesis that ALS/PDC is caused by exogenous factors.

The Enigma of Autoimmunity: A Case of Subacute Sclerosing Panencephalitis in a Patient Diagnosed With Systemic Lupus Erythematosus

Subacute sclerosing panencephalitis (SSPE) is a rare complication of measles characterized by progressive neurological deterioration. The onset usually occurs about seven to 10 years after the measles infection. Aside from an earlier age of measles infection, factors that may influence the susceptibility for its development is unknown. There is a paucity of data regarding the course of SSPE in the presence of concomitant autoimmune conditions such as systemic lupus erythematosus (SLE). We report a case of a 19-year-old female who presented with new onset recurrent generalized tonic-clonic seizures, malar rash, and cutaneous erythematous, maculopapular eruptions. Antinuclear antibodies (ANA) and anti-double stranded DNA (anti-dsDNA) serologic examination yielded positive results favoring the diagnosis of SLE. Further in the course of illness, the patient developed generalized myoclonic jerks and progressive decline in language, cognitive, and motor functions. Subsequent investigation showed an elevated anti-measles antibody titer in the cerebrospinal fluid, and periodic generalized, bilaterally synchronous, and symmetric high voltage slow-wave complexes in the EEG. These findings and the typical evolution of neurologic manifestations fulfilled two major and one minor Dyken's criteria for the diagnosis of SSPE. It is postulated that some autoimmune-mediated responses may contribute to the evolution of SSPE. Autoimmune complexes in SLE induce downregulation of T-cell responses which accelerate the loss of antibodies formed against other diseases such as the measles virus that may lead to increased susceptibility to infection. SSPE is hypothesized to result from the downregulation of host-immune responses which leads to incomplete measles viral clearance. To the best of the authors' knowledge, this is the first published case of SSPE with active SLE.

Association of NOD1 and NOD2 Polymorphisms With Susceptibility to Subacute Sclerosing Panencephalitis

Background: Subacute sclerosing panencephalitis is a progressive neurodegenerative disease that is a late complication of measles infection. However, to date, the pathogenesis of subacute sclerosing panencephalitis is still not explained; both viral and host factors seem to be associated. The present study aimed to investigate the relationship between NOD1 and NOD2 gene variants and subacute sclerosing panencephalitis. Methods: The gene variants of NOD1 (rs2075820 and rs2075818) and NOD2 (R334Q and R334W) were explored in 64 subacute sclerosing panencephalitis patients and 70 controls using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Results: The frequencies of the AA genotype and A allele of rs2075820 (NOD1; c.796G>A) polymorphism were lower in patients compared with controls (P = .022 and .014, respectively). The presence of the A allele of rs2075820 may be considered as a protective factor for subacute sclerosing panencephalitis. There was a significant difference between the groups in rs2075818 (NOD1 G/C) polymorphism, and the CC genotype increased the risk of subacute sclerosing panencephalitis by 3.471-fold. The carriers of the C allele of rs2075818 (G/C) had a 1.855-fold susceptibility to subacute sclerosing panencephalitis (P = .018). The GC genotype might be associated with subacute sclerosing panencephalitis susceptibility in the patients compared with patients without having that haplotype (P = .03). Conclusions: Thus, we identified an association between subacute sclerosing panencephalitis and the rs2075820 (NOD1 G/A) and rs2075818 (NOD1 G/C) polymorphisms. These findings implicate a possible effect of this genetic polymorphism in susceptibility to subacute sclerosing panencephalitis, which needs to be confirmed in bigger populations.

[Reactivation of latent viruses in Neurology]

After establishing latent infection, some viruses can be reactivated by the alteration of host immunological conditions. First, we reviewed viruses that can cause neuronal damage by reactivation. Then we focused on the herpes simplex virus (HSV). The reactivation leads to neuronal damages through two possible mechanisms; "reactivation of a latent herpes virus" by which viruses can cause direct virus neurotoxicity, and "post-infectious immune inflammatory response" by which a focal reactivation of HSV leads to an inflammatory reaction. The former is radiologically characterized by cortical lesions, the latter is characterized by subcortical white matter lesions. We experienced a female, who underwent the right posterior quadrantectomy and then developed recurrent herpes encephalitis caused by herpes simplex reactivation, which pathologically demonstrated inflammation in the white matter, suggesting a post-infectious immune inflammatory response. The patient was successfully treated with immunosuppressants. The reactivation of the HSV is extremely rare in Japan. Neurologists should recognize this condition because this disorder will increase as epilepsy surgery gains more popularity.

La panencéphalite sclérosante subaiguë de la rougeole

La panencéphalite sclérosante subaiguë (PESS), une complication tardive de la rougeole, est encore présente lors d’épidémies de cette maladie dues aux insuffisances de la vaccination. Après un rappel historique, nous aborderons la physiopathologie de la PESS et l’importance des critères diagnostiques. De nombreux travaux portant sur les paramètres de l’immunité innée et sur ceux des réponses interféron tendent à montrer une baisse de l’activité de l’immunité cellulaire au cours de cette maladie. Nous formulons ici plusieurs hypothèses s’appuyant sur des publications concernant différentes formes de la maladie : congénitales, périnatales, formes à incubation courte, semblables à l’encéphalite aiguë à inclusions (EAI), formes d’évolution rapide, formes retrouvées chez les immunodéprimés ou chez l’adulte. Des formes familiales ont également été identifiées, suggérant une origine génétique. Selon la durée de la période de latence entre rougeole et la PESS, deux groupes de patients ont été individualisés, incitant à des analyses rétrospective et prospective des exomes de ces malades. La connaissance des gènes participant à la maladie devrait être utile pour la compréhension de la physiopathologie de la PESS mais aussi d’autres infections neurologiques tardives dues à des virus à ARN.

Independent distribution between tauopathy secondary to subacute sclerotic panencephalitis and measles virus: An immunohistochemical analysis in autopsy cases including cases treated with aggressive antiviral therapies

Subacute sclerotic panencephalitis (SSPE) is a refractory neurological disorder after exposure to measles virus. Recently, SSPE cases have been treated with antiviral therapies, but data on the efficacy are inconclusive. Abnormal tau accumulation has been reported in the brain tissue of SSPE cases, but there are few reports in which this is amply discussed. Five autopsied cases diagnosed as definite SSPE were included in this study. The subject age or disease duration ranged from 7.6 to 40.9 years old or from 0.5 to 20.8 years, respectively. Cases 3 and 4 had been treated with antiviral therapies. All evaluated cases showed marked brain atrophy with cerebral ventricle dilatation; additionally, marked demyelination with fibrillary gliosis were observed in the cerebral white matter. The brainstem, cerebellum, and spinal cord were relatively preserved. Immunoreactivity (IR) against measles virus was seen in the brainstem tegmentum, neocortex, and/or limbic cortex of the untreated cases but was rarely seen in the two treated cases. Activated microglia were broadly observed from the cerebrum to the spinal cord and had no meaningful difference among cases. Neurofibrillary tangles characterized by a combination of 3‐ and 4‐repeat tau were observed mainly in the oculomotor nuclei, locus coeruleus, and limbic cortex. IR against phosphorylated tau was seen mainly in the cingulate gyrus, oculomotor nuclei, and pontine tegmentum, and tended to be observed frequently in cases with long disease durations but also tended to decrease along with neuronal loss, as in Case 5, which had the longest disease duration. Since the distribution of phosphorylated tau was independent from that of measles virus, the tauopathy following SSPE was inferred to be the result of diffuse brain inflammation triggered by measles rather than a direct result of measles virus. Moreover, antiviral therapies seemed to suppress measles virus but not the progression of tauopathy.

Subacute Sclerosing Panencephalitis in Children: The Archetype of Non-Vaccination

Subacute sclerosing panencephalitis (SSPE) is a late complication of measles virus infection that occurs in previously healthy children. This disease has no specific cure and is associated with a high degree of disability and mortality. In recent years, there has been an increase in its incidence in relation to a reduction in vaccination adherence, accentuated by the COVID-19 pandemic. In this article, we take stock of the current evidence on SSPE and report our personal clinical experience. We emphasise that, to date, the only effective protection strategy against this disease is vaccination against the measles virus.

Options in the Treatment of Subacute Sclerosing Panencephalitis: Implications for Low Resource Areas

Purpose of the review

Subacute sclerosing panencephalitis (SSPE) is a rare, slowly progressive, and frequently fatal neurodegenerative disorder caused by measles virus. The risk of SSPE remains significant globally, with fluctuating incidence noted in in tandem with measles vaccine uptake. This review aims to explore the current global status of SSPE, its treatment, and preventive measures.

Recent findings

An increase in measles cases have been reported in various parts of the world for different reasons related to the regional context of the outbreak. With reduction in measles vaccine doses since the onset of the COVID-19 pandemic, the future risk of SSPE can only accelerate. In recent years, subsequent cases of SSPE have been reported in the period following documented measles outbreaks in different settings. Concomitantly, there have been efforts to evaluate the efficacy of immunomodulatory, antiviral, and anti-seizure therapies that could ameliorate the devastating effects of this disease. This review elucidates on these approaches and their limitations, reasons for poor vaccine coverage in low- and middle-income countries, as well as the possible solutions to the prevention of measles and eventual avoidance of SSPE.

Summary

Prevention of measles virus infection with the resultant sequelae would be the most effective strategy for the management of SSPE. This approach would be particularly important in low resource setting that currently bears the double burden of widespread communicable diseases and malnutrition.

Subacute Sclerosing Panencephalitis (SSPE): Experience from a Tertiary-Care Pediatric Center

Introduction  Subacute sclerosing panencephalitis (SSPE) is a devastating neurodegenerative disease occurring as a complication of measles infection that is still prevalent in low-resource countries. Clinical and electrographical variability in SSPE can lead to diagnostic delays.

Methods  Children diagnosed with SSPE in a tertiary care pediatric hospital in India in a period of 8 years were included in the study. The diagnosis was established on the basis of Dyken's criteria. The demographic data, clinical presentations, investigations, treatment approaches, and outcomes were reviewed and recorded.

Results  Thirty-four patients were included in the analysis. Average age at symptom onset was 7 years, 5 months. Majority of the children were not vaccinated for measles. Most patients (80%) presented with stage 2 of illness. Nearly 25% presented with atypical clinical features. Myoclonus was the most predominant feature seen after diagnosis. Electroencephalography (EEG) was the most useful investigation for suspecting the diagnosis. All patients showed deterioration in neurological status with time and 20% died during follow-up.

Conclusion  Atypical presentations of SSPE must be recognized in areas with high incidence to institute timely treatment and establish prognosis. EEG findings were found to be the most important indicator for diagnosis. Measles eradication will pave the way for elimination of this dreaded disease.

Seroprevalence of Measles Antibodies in the Population of the Olomouc Region, Czech Republic—Comparison of the Results of Four Laboratories

Objectives: Although the incidence of measles has decreased globally since the introduction of regular vaccination, its frequency has increased again in recent years. The study is focused on data from the Olomouc Region in the Czech Republic analyzed in four laboratories. The obtained results were compared with already published data. Methods: The data were provided by individual laboratories in an anonymized form—age at the time of the examination, sex, and result of test. Samples were collected between June 2018 and September 2019 and evaluated on the scale positive–borderline–negative. Results: A total of 7962 sera samples were evaluated using three different methods—two types of ELISA tests and CLIA. Positive result was issued in a total of 62.6 percent of samples, but the results of individual laboratories varied widely from 55.5 to 70.8 percent. However, the same trend with the highest levels of antibodies in people born before beginning of vaccination was observed. Conclusions: Data show significantly different results depending on the individual laboratories and the detection kits used. The underestimation of the proportion of positive results can cause problems in selecting individuals for revaccination with a live vaccine, which may fail in weakly positive individuals.

Measles-Associated CNS Complications: A Review

Measles virus infection is a common infectious disease of childhood, incidence of which is still high in developing countries. Other than the morbidity associated with the acute systemic infection, the measles virus can cause serious fatal neural complications. It can either enter the brain leading to acute encephalitis like primary measles encephalitis and acute post infectious measles encephalomyelitis or it may persist in brain cells (as mutated virus) leading to long-term neurodegenerative diseases like measles inclusion body encephalitis and subacute sclerosing pan encephalitis. The patho-clinical features, treatment, and the outcomes of these complications are different and should be identified in time for early diagnosis and management.

Progression of myoclonus subtypes in subacute sclerosing panencephalitis

OBJECTIVES

Diagnostic criteria of subacute sclerosing panencephalitis (SSPE) include myoclonus, a well-recognized clinical feature. Here, we studied the electrophysiological features of myoclonus with regards to disease staging in SSPE patients.

METHODS

We included 10 patients diagnosed with SSPE between 2010 and 2018, along with 21 healthy subjects. All participants had detailed electrophysiological evaluation including polymyographic analysis, blink reflex after trigeminal stimulation, auditory startle response, startle response after somatosensory stimuli, F-waves, and long-loop reflexes. Clinical findings were retrieved from the medical records.

RESULTS

Patients were categorized into Gascon stage 2B (n = 5, 50%), 2A (n = 2, 20%), 3B (n = 2, 20%) and 4A (n = 1, 10%) at the time of electrophysiological evaluation. Two patients had cortical myoclonus, four had possible cortico-subcortical myoclonus, and four had brainstem myoclonus. Patients were categorized into Gascon stages 2a and 2b had possible cortico-subcortical myoclonus (85.7%). However, none of the patients with stage 3b or 4a had possible cortico-subcortical subtype but all had the brainstem subtype.

CONCLUSION

Association was seen between subtypes of myoclonus and clinical staging in SSPE. This suggests that myoclonus in SSPE may primarily involve the cortex and cortico-subcortical structures such as the thalamus at earlier stages of disease, and then involve more caudal structures as the disease progresses.

Expanding the Spectrum of EEG Periodic Discharges in Subacute Sclerosing Panencephalitis: A Case Report

Background Atypical electroencephalogram (EEG) abnormalities emerge in patients with subacute sclerosing panencephalitis (SSPE), especially in cases with an atypical clinical presentation that can lead to diagnostic difficulties.

Case Report In this article, we presented a case of SSPE with an atypical onset with epileptic seizures and Parkinson's features. The neurological examination during the initial evaluation of the patient showed extrapyramidal syndrome, hyperreflexia, intention tremor, and dysmetria. Cranial magnetic resonance imaging was normal. Video EEGs were performed in wakefulness and sleep. In wakefulness, multiple brief seizures (1–1.5 seconds were recorded, consisting of gradual bending of the body forward and to the right that lacked the sudden characteristic of myoclonia. During those episodes, we recorded generalized epileptiform activity of 4 or 5 sharp waves, with higher amplitude in the anterior regions, in some of the paroxysms superimposed on a slow wave or followed by a high amplitude slow wave. The paroxysms appeared periodically every 15 to 30 seconds. However, 2 months later, the EEG showed typical periodic generalized activity of biphasic/triphasic slow waves (Radermecker complexes), accompanied by myoclonias.

Conclusion We reported a peculiar EEG pattern in a patient with SSPE that consists of periodic generalized activity of sharp waves. Atypical EEG patterns can appear when the disease progresses, but initially too, before typical periodic complexes and can complicate the diagnostic process.

Comparable Infection Level and Tropism of Measles Virus and Canine Distemper Virus in Organotypic Brain Slice Cultures Obtained from Natural Host Species

Measles virus (MV) and canine distemper virus (CDV) are closely related members of the family Paramyxoviridae, genus Morbillivirus. MV infection of humans and non-human primates (NHPs) results in a self-limiting disease, which rarely involves central nervous system (CNS) complications. In contrast, infection of carnivores with CDV usually results in severe disease, in which CNS complications are common and the case-fatality rate is high. To compare the neurovirulence and neurotropism of MV and CDV, we established a short-term organotypic brain slice culture system of the olfactory bulb, hippocampus, or cortex obtained from NHPs, dogs, and ferrets. Slices were inoculated ex vivo with wild-type-based recombinant CDV or MV expressing a fluorescent reporter protein. The infection level of both morbilliviruses was determined at different times post-infection. We observed equivalent infection levels and identified microglia as main target cells in CDV-inoculated carnivore and MV-inoculated NHP brain tissue slices. Neurons were also susceptible to MV infection in NHP brain slice cultures. Our findings suggest that MV and CDV have comparable neurotropism and intrinsic capacity to infect CNS-resident cells of their natural host species.

Magnetic resonance imaging patterns of subacute sclerosing panencephalitis may mimic metabolic disorders: clinical, electroencephalographic and imaging features of six cases

Subacute sclerosing panencephalitis is a rare, devastating neurodegenerative encephalitis whose diagnosis and therapy are still in question. Atypical clinical presentation and heterogeneity of neuroimaging findings that have been initially confused with metabolic disorders have hampered early diagnosis. To describe a series of patients with subacute sclerosing panencephalitis with imaging findings mimicking metabolic disorders. A total of six patients with subacute sclerosing panencephalitis were diagnosed from January 2012 to December 2016 in whom a metabolic disorder was suspected on initial clinical and MRI findings. Detailed laboratory investigation was performed in all patients. All patients presented with atypical neurologic manifestations, including dystonia, syncopal attacks, involuntary limb movements, meaningless speech and ataxia. Magnetic resonance imaging abnormalities included bilateral putaminal, bilateral posterior periventricular white matter and diffuse or splenial corpus callosum involvement which are particularly unusual in SSPE and mostly observed in metabolic disorders. All patients had elevated cerebrospinal fluid Ig G measles antibodies. The diagnosis of subacute sclerosing panencephalitis through clinical and imaging features can be considerably challenging. It is crucial to differentiate it from metabolic disorders, since the management and clinical outcome are different.

Clinical and magnetic resonance study of a case of subacute sclerosing panencephalitis treated with ketogenic diet

Background

Subacute sclerosing panencephalitis is a progressive neurodegenerative disorder caused by a latent and mutant measles virus which is extremely rare in developed countries. The lack of effective treatments leads to the research of other anti-inflammatory and neuroprotective treatments.

Case

Here we present a case of a 17-year-old patient affected by subacute sclerosing panencephalitis who manifest a dramatic improvement in neurological and general clinical conditions, as well as an arrest in the progression of demyelinating process in the central nervous system, after the beginning of a high ratio ketogenic diet.

Conclusions

Given its anti-inflammatory, antioxidant and metabolic effects, we believe that ketogenic diet utilisation could be a rational approach, can be considered a safe add-on therapy, carrying on with only a minimal risk of adverse effects or interactions.

Measles Sclerosing Subacute PanEncephalitis (SSPE), an intriguing and ever-present disease: Data, assumptions and new perspectives

BACKGROUND

Subacute sclerosing panencephalitis (SSPE) is a rare, non-treatable and fatal neurological complication of measles, still present due to the return of the epidemic linked to the loosening of vaccination policies. Its mechanism remains unexplained.

OBJECTIVE

The main objective was to investigate explanatory variables relating to the risk of developing SSPE and its pathophysiology.

METHODS

Literature analysis was focused on different varieties of SSPE: perinatal forms, short-incubation forms similar to acute measles inclusion body encephalitis (MIBE), rapidly evolving forms, forms occurring in the immunosuppressed, adult forms, and family forms. In addition, several studies on the parameters of innate immunity and interferon responses of patients were analyzed.

RESULTS

Two main data were highlighted: a relationship between the so-called fulminant forms and the prescription of corticosteroids was established. In familial SSPE, two groups were individualized according to the duration of the latency period, prompting an analysis of patient exomes.

CONCLUSION

Treatment with corticosteroids should be banned. Knowledge of the genes involved and epigenetics should be useful for understanding the pathophysiology of SSPE and other late-onset neurological infections with RNA viruses.

Resurgence of Subacute Sclerosing Panencephalitis: Case Series and Global Epidemiological Trends

Resurgence of subacute sclerosing panencephalitis (SSPE)—case series and global epidemiological trends. We noted a recent increase in cases of SSPE admitted in our institute, even though they had received measles vaccination. We did a detailed study of our cases and compared with global epidemiological trends of SSPE in preimmunization and era of developed immunity. Out of total 23 cases of SSPE, 12 presented in the year 2017 alone, reflecting a steep rise in incidence. Sixteen patients had received measles vaccine and never had prior measles infection. Mean age of onset was 8.2 years and average time of progression to advanced stage of disease was 65 days. Global data showed similar trends, that is, earlier age of onset with a faster rate of progression in the postvaccination era as compared with prevaccine era. Possible mechanisms to account for this trend include an early wild measles infection in the critical age of 6 to 9 months, before vaccination. There is a changing epidemiological trend of SSPE in terms of lower age of onset and faster rate of progression, also reflected in global data. There is a need for multicenter studies to verify the findings and explore possible measures like lowering the age of measles vaccination to halt this alarming trend.

A Rare Case of Subacute Sclerosing Panencephalitis Presenting As Generalized Seizure

Subacute sclerosing panencephalitis (SSPE) is a late complication of childhood measles. It is characterized by a progressive decline in cognitive and motor functions, seizures, and eventually death. Although a combination of intrathecal interferon alpha (IFN-α) and daily oral isoprinosine has been reported to have a good outcome, there is no cure for this condition.  We present a case of a 16-year-old male with SSPE who presented with progressive weakness, frequent loss of postural control, multiple episodes of generalized tonic-clonic seizures, and urinary incontinence. On exploration of his history, he had measles at the age of two months. Investigation showed increased serum measles antibody titer, high amplitude spikes in electroencephalogram (EEG), and high fluid-attenuated inversion recovery (FLAIR) signals on MRI of the brain consistent with probable SSPE. He was managed symptomatically until his condition got worse and he eventually passed away.

Adult-onset subacute sclerosing panencephalitis

Subacute sclerosing panencephalitis (SSPE) is a lethal slow viral disease of the central nervous system caused by a defective measles virus. The onset is mostly in childhood, manifesting clinically as decline in academic performance, behavioural changes, motor dysfunction and myoclonus. Adult-onset SSPE is rare and can present as rapidly progressive dementia. We present a young man of Indian origin with adult-onset SSPE with rapidly progressive dementia but no localising neurological signs. The diagnostic clues were parieto-occipital white matter changes on MR brain scan and history of childhood fever with rash. High titres of antimeasles antibody in cerebrospinal fluid confirmed the diagnosis. The long latency from primary measles virus infection to symptom onset can be misleading in adults. SSPE should be considered in adults with dementia, especially in tropical countries where vaccination coverage is suboptimal.

Seizures as onset symptoms and rapid course in preschool children with subacute sclerosing panencephalitis

BACKGROUND

The clinical features and outcomes of subacute sclerosing panencephalitis (SSPE) in younger children are different from those of adults, leading easily to misdiagnosis during the early stage. So far, there are limited data related to SSPE in preschool children.

METHODS

In order to summarize the clinical data and evolution of SSPE in preschool children and to expand the phenotypes of SSPE, the medical charts of preschool patients diagnosed with SSPE were retrospectively reviewed and analyzed; the clinical outcomes of the enrolled cases were evaluated and followed up.

RESULTS

Overall, we included three cases in the study. Their onset age was 5 years and 2 months, 4 years and 3 months, and 4 years and 2 months, respectively. All patients presented drop attacks or jerks as the onset symptom, and one patient had concurrent gait disturbance. Atypical periodic complexes on electroencephalography (EEG) were recorded in all patients. The brain magnetic resonance imaging (MRI) findings of two cases showed demyelinating lesions predominantly on the white matter. The neurological conditions of all cases deteriorated rapidly. Two children died at 21 months and 6 months after onset, respectively. The other case progressively developed vegetative status and akinetic mutism within 4 months.

CONCLUSIONS

In younger children, the characteristic features of SSPE may be seizures and gait instability as onset manifestations, atypical periodic complexes on EEG, and rapid worsening of neurological conditions.

Innate Immune Sensing of Viruses and Its Consequences for the Central Nervous System

Viral infections remain a global public health concern and cause a severe societal and economic burden. At the organismal level, the innate immune system is essential for the detection of viruses and constitutes the first line of defense. Viral components are sensed by host pattern recognition receptors (PRRs). PRRs can be further classified based on their localization into Toll-like receptors (TLRs), C-type lectin receptors (CLR), retinoic acid-inducible gene-I (RIG-I)-like receptors (RLRs), NOD-like receptors (NLRs) and cytosolic DNA sensors (CDS). TLR and RLR signaling results in production of type I interferons (IFNα and -β) and pro-inflammatory cytokines in a cell-specific manner, whereas NLR signaling leads to the production of interleukin-1 family proteins. On the other hand, CLRs are capable of sensing glycans present in viral pathogens, which can induce phagocytic, endocytic, antimicrobial, and pro- inflammatory responses. Peripheral immune sensing of viruses and the ensuing cytokine response can significantly affect the central nervous system (CNS). But viruses can also directly enter the CNS via a multitude of routes, such as the nasal epithelium, along nerve fibers connecting to the periphery and as cargo of infiltrating infected cells passing through the blood brain barrier, triggering innate immune sensing and cytokine responses directly in the CNS. Here, we review mechanisms of viral immune sensing and currently recognized consequences for the CNS of innate immune responses to viruses.

Advances in Antiviral Therapy for Subacute Sclerosing Panencephalitis

Subacute sclerosing panencephalitis (SSPE) is a late-onset, intractable, and fatal viral disease caused by persistent infection of the central nervous system by a mutant strain of the measles virus. Ribavirin intracerebroventricular therapy has already been administered to several SSPE patients in Japan based on fundamental and clinical research findings from our group, with positive therapeutic effects reported in some patients. However, the efficacy of this treatment approach has not been unequivocally established. Hence, development of more effective therapeutic methods using new antiviral agents is urgently needed. This review describes the current status of SSPE treatment and research, highlighting promising approaches to the development of more effective therapeutic methods.

Atypical adult-onset subacute sclerosing panencephalitis

Although subacute sclerosing panencephalitis is almost exclusively a childhood disease, it can occur in adults as well. We present an atypical case of adult-onset subacute sclerosing panencephalitis. The disease was characterized by prolonged insidious course followed by accelerated and aggressive phase, atypical EEG findings, and absence of myoclonic jerks. The diagnostic and treatment-related pitfalls are discussed.

Adult-Onset Subacute Sclerosing Panencephalitis With a 30-Year Latent Period

Subacute sclerosing panencephalitis (SSPE) is a rare progressive neuroinfectious disease due to a late complication of the measles virus. The hallmark clinical features of this disease include behavioral changes, myoclonus, dementia, visual disturbances, and pyramidal and extrapyramidal signs. The presence of characteristic high-amplitude periodic complexes on electroencephalography and raised antibody titers against measles in the cerebrospinal fluid help solidify the diagnosis. We present a case of a 40-year-old patient with SSPE who initially developed ophthalmologic manifestations 30 years after the primary measles infection. This case highlights both typical and atypical features of SSPE and provides a diagnostic framework for evaluating cases that fall outside of the standard scope of this disease.

Viral encephalitis: a practical review on diagnostic approach and treatment

OBJECTIVES

To review the diagnostic criteria for encephalitis and encephalopathy of presumed infectious etiology, as well as the diagnostic workup for viral encephalitis and its treatment approaches. The authors also intended to summarize relevant information on specific viruses frequently found in Brazil.

SOURCE OF DATA

Literature search on Pubmed/MEDLINE using the following keywords: "viral", "encephalitis", "child", or "adolescents", filtering for articles on humans and in English.

SUMMARY OF DATA

Viral encephalitis is the most common cause of encephalitis and is responsible for high rates of morbidity, permanent neurologic sequelae, and according to the virus, may have high mortality rates. The most common etiologies are herpesviruses 1 and 2 (HSV-1 and HSV-2), non-polio enterovirus, and arboviruses (in Brazil, dengue, Zika, and chikungunya). Other relevant etiologies are seasonal influenza, cytomegalovirus (CMV), Epstein-Barr virus (EBV), human herpesvirus 6 (HHV-6), and the re-emergent measles.

CONCLUSION

Clinical data, laboratory results, and neuroimaging findings support the diagnosis of encephalitis and the specific viral etiology. To increase the likelihood of etiologic confirmation, it is important to know the best approach to collecting samples and to choose the best identification technique for each virus. The differential diagnosis of viral encephalitis includes other infections and immune-mediated inflammatory central nervous system disorders.

Childhood neurodegeneration associated with a specific UBTF variant: a new case report and review of the literature

BACKGROUND

A new monogenic neurodegenerative disease affecting ribosomal metabolism has recently been identified in association with a monoallelic UBTF putative gain of function variant (NM_001076683.1:c.628G>A, hg19). Phenotype is consistent among these probands with progressive motor, cognitive, and behavioural regression in early to middle childhood.

CASE PRESENTATION

We report on a child with this monoallelic UBTF variant who presented with progressive disease including regression, episodes of subacute deterioration during febrile illnesses and a remarkable EEG pattern with a transient pattern of semi-periodic slow waves.

CONCLUSIONS

This case further supports the phenotype-genotype correlation of neurodegeneration associated with UBTF c.628G>A. Moreover, it brings new insights into the clinical features and EEG that could possibly serve as diagnostic markers of this otherwise nonspecific phenotype.

Clinical approach to neurodegenerative disorders in childhood: an updated overview

Neurodegenerative disorders include a group of severe diseases that share a core including a gradual loss of previously acquired motor, sensory and cognitive functions. In pediatric age, the main diagnostic issues are the discrimination between the loss of previously acquired competencies and the lack of achievement of specific developmental milestones. An ideal classification of these disorders could be based on the combination of genetic, clinical and neuroimaging features. Diagnostic workup should be organized with a special attention to the few diseases with an available and effective therapeutic treatment. The present paper reports a proposal of classification that is based on the prominently involved structure and summarizes the hallmarks for clinical approach and therapeutic management.

High risk of subacute sclerosing panencephalitis following measles outbreaks in Georgia

OBJECTIVE

To describe cases and estimate subacute sclerosing panencephalitis (SSPE) risk following large-sale measles outbreaks in Georgia. A rare, fatal late complication of measles, SSPE is often overlooked in assessments focused on the acute illness. Georgia had 8377 and 11,495 reported measles cases during the 2004-2005 and 2013-2015 outbreaks, respectively, but SSPE burden has not been assessed.

METHODS

SSPE cases diagnosed during 2008-2017 were identified from hospitalization registries in major neurological departments likely to admit SSPE patients. Information on reported measles cases and deaths was obtained from the national measles surveillance system and published reports. The risk of SSPE (number of measles cases per one SSPE case) was calculated for cases associated with the 2004-2005 outbreak. Crude estimates were adjusted to account for potential under-reporting of measles, using 50%, 25% and 10% estimates of completeness of reporting.

RESULTS

Sixteen SSPE cases diagnosed during 2008-2017 were identified. Eleven (92%) of 12 SSPE cases with a known history of measles had infection at ≤2 years and one (8%) at 3 years of age. Crude estimate of SSPE risk for the 2004-2005 outbreak was 1:1396. Adjusted estimates were 1:2792, 1:1:5584 and 1:13 960, assuming 50%, 25% and 10% completeness of reporting measles cases, respectively.

CONCLUSIONS

The review demonstrated substantial risk of SSPE in Georgia, supporting recent data suggesting that risk of SSPE following measles infection is higher than previously thought. To prevent SSPE in Georgia, very high timely immunization coverage for measles should be achieved among children, and immunity gap among adults should be closed.

Measles Encephalitis: Towards New Therapeutics

Measles remains a major cause of morbidity and mortality worldwide among vaccine preventable diseases. Recent decline in vaccination coverage resulted in re-emergence of measles outbreaks. Measles virus (MeV) infection causes an acute systemic disease, associated in certain cases with central nervous system (CNS) infection leading to lethal neurological disease. Early following MeV infection some patients develop acute post-infectious measles encephalitis (APME), which is not associated with direct infection of the brain. MeV can also infect the CNS and cause sub-acute sclerosing panencephalitis (SSPE) in immunocompetent people or measles inclusion-body encephalitis (MIBE) in immunocompromised patients. To date, cellular and molecular mechanisms governing CNS invasion are still poorly understood. Moreover, the known MeV entry receptors are not expressed in the CNS and how MeV enters and spreads in the brain is not fully understood. Different antiviral treatments have been tested and validated in vitro, ex vivo and in vivo, mainly in small animal models. Most treatments have high efficacy at preventing infection but their effectiveness after CNS manifestations remains to be evaluated. This review describes MeV neural infection and current most advanced therapeutic approaches potentially applicable to treat MeV CNS infection.

[Panencephalitis in children in modern conditions: clinical, etiological and mri-aspects]

AIM

To characterize the clinical picture, infectious etiology and MRI results of panencephalitis (PANE) in children, depending on the duration of the disease.

MATERIAL AND METHODS

Children (n=32) with PANE at the age from 3 months up to 17 years were examined for a group of actual viral and bacterial infections. The inclusion criterion was a diffuse lesion of white matter hemispheres on MRI. MRI of the brain and spinal cord, CSF study (pleocytosis, oligoclonal IgG, the main myelin protein (MBP) were performed. The follow-up was 5-10 years. The complex therapy included etiotropic (antiviral) and pathogenetic agents, with priority given to cytoflavin as a drug with a multimodal effect.

RESULTS

In 84.4% of cases, PANE in children are recorded under the age of 3 years and in 71.9% of cases, are associated with congenital infections with the prevalence of herpes viruses, especially cytomegalovirus (37,8%) and herpes type 6 (21.9%). In 78.3% of cases, PANE have chronic gradual development more often with a delay in the formation of motor and speech/prespeech skills, and manifested with pyramidal, cerebellar and other symptoms in the future. PANE is accompanied by a lesion of the white matter of the hemispheres in ¹/₂ cases with periventricular localization, less often in infratentorial structures (46.9%) and spinal cord (21.9%). With the duration of symptoms up to 3 months (n=22) PANE are characterized by inflammatory-demyelinating changes, signs of mass effect, contrast+, pleocytosis in CSF and the increase in MBP (average 4.2±0.8 ng/ml), and, with the duration of more than 3 months, by degenerative-sclerosing changes (n=10) and CSF oligoclonal IgG in 90% of cases.

CONCLUSION

In almost ²/₃ of cases, PANE are associated with congenital infections, accompanied by extensive symmetrical foci of demyelination in the CNS, and their clinical and laboratory parameters and outcomes depend on the start of treatment, with the positive dynamics in 75% of cases.

Elevated quinolinic acid levels in cerebrospinal fluid in subacute sclerosing panencephalitis

Subacute sclerosing panencephalitis (SSPE) is a rare neurodegenerative disorder caused by a persistent infection with aberrant measles virus. Indoleamine-2, 3-dioxygenase (IDO) initiates the increased production of kynurenine pathway (KP) metabolites quinolinic acid (QUIN), which has an excitotoxic effect for neurons. We measured serum IDO activity and cerebrospinal fluid (CSF) levels of QUIN. The CSF QUIN levels were significantly higher in SSPE patients than in controls, and increased according as neurological disability in a patient studied. Elevation of CSF QUIN and progression of SSPE indicate a pathological role of KP metabolism in the inflammatory neurodestruction.

Subacute sclerosing panencephalitis: clinical phenotype, epidemiology, and preventive interventions

Subacute sclerosing panencephalitis (SSPE) is a preventable condition reported in 6.5 to 11 per 100 000 cases of measles, and highest in children who contracted measles infection when they were less than 5 years of age. Children residing in areas with poor vaccination coverage and high prevalence of human immunodeficiency virus are at increased risk of developing SSPE. SSPE is life-threatening in most affected children. This report documents current data relating to the clinical phenotype, epidemiology, and understanding of SSPE, inclusive of preventive interventions. While improvements in disease progression with immunomodulation may occur, overall there is no cure. Most therapies focus on supportive needs. Seizures and abnormal movements may respond to carbamazepine. Many countries advocate policies to enhance vaccination coverage. Effective preventive health care programmes, assurance of parental perceptions, and crisis support for unprecedented events obstructing effective primary health care are needed. Until measles is eradicated worldwide, children in all regions remain at risk. WHAT THIS PAPER ADDS: Measles contracted under 5 years of age has highest risk of developing subacute sclerosing panencephalitis (SSPE). Children with, or exposed to, human immunodeficiency virus infection, who contract measles may be at increased risk of SSPE.

Immune-Mediated Control of a Dormant Neurotropic RNA Virus Infection

Genomic material from many neurotropic RNA viruses (e.g., measles virus [MV], West Nile virus [WNV], Sindbis virus [SV], rabies virus [RV], and influenza A virus [IAV]) remains detectable in the mouse brain parenchyma long after resolution of the acute infection. The presence of these RNAs in the absence of overt central nervous system (CNS) disease has led to the suggestion that they are viral remnants, with little or no potential to reactivate. Here we show that MV RNA remains detectable in permissive mouse neurons long after challenge with MV and, moreover, that immunosuppression can cause RNA and protein synthesis to rebound, triggering neuropathogenesis months after acute viral control. Robust recrudescence of viral transcription and protein synthesis occurs after experimental depletion of cells of the adaptive immune response and is associated with a loss of T resident memory (T_rm) lymphocytes within the brain. The disease associated with loss of immune control is distinct from that seen during the acute infection: immune cell-depleted, long-term-infected mice display severe gait and motor problems, in contrast to the wasting and lethal disease that occur during acute infection of immunodeficient hosts. These results illuminate the potential consequences of noncytolytic, immune-mediated viral control in the CNS and demonstrate that what were once considered "resolved" RNA viral infections may, in fact, induce diseases later in life that are distinct from those caused by acute infection.IMPORTANCE Viral infections of neurons are often not cytopathic; thus, once-infected neurons survive, and viral RNAs can be detected long after apparent viral control. These RNAs are generally considered viral fossils, unlikely to contribute to central nervous system (CNS) disease. Using a mouse model of measles virus (MV) neuronal infection, we show that MV RNA is maintained in the CNS of infected mice long after acute control and in the absence of overt disease. Viral replication is suppressed by the adaptive immune response; when these immune cells are depleted, viral protein synthesis recurs, inducing a CNS disease that is distinct from that observed during acute infection. The studies presented here provide the basis for understanding how persistent RNA infections in the CNS are controlled by the host immune response, as well as the pathogenic consequences of noncytolytic viral control.

Inosine Pranobex: A Key Player in the Game Against a Wide Range of Viral Infections and Non-Infectious Diseases

Inosine pranobex (IP), commonly known as inosine acedoben dimepranol, isoprinosine and methisoprinol, has been proven to positively impact the host’s immune system, by enhancing T-cell lymphocyte proliferation and activity of natural killer cells, increasing levels of pro-inflammatory cytokines, and thereby restoring deficient responses in immunosuppressed patients. At the same time, it has been shown that it can affect viral RNA levels and hence inhibit growth of several viruses. Due to its immunomodulatory and antiviral properties, and its safety profile, it has been widely used since 1971 against viral infections and diseases, among which subacute sclerosis panencephalitis, herpes simplex virus, human papilloma virus, human immunodeficiency virus, influenza and acute respiratory infections, cytomegalovirus and Epstein–Barr virus infections. Following an analysis of almost five decades of scientific literature since its original approval, we here summarize in vivo and in vitro studies manifesting the means in which IP impacts the host’s immune system. We also provide a synopsis of therapeutic trials in the majority of which IP was found to have a beneficial effect. Lastly, positive results from limited studies, suggesting the putative future use of IP in new therapeutic indications are briefly described. In order to support use of IP against viral infections apart from those already approved, and to establish its use in clinical practice, further well-designed and executed trials are warranted.

Funding: Ewopharma International.

Type I Interferon Receptor Signaling Drives Selective Permissiveness of Astrocytes and Microglia to Measles Virus during Brain Infection

Fatal neurological syndromes can occur after measles virus (MeV) infection of the brain. The mechanisms controlling MeV spread within the central nervous system (CNS) remain poorly understood. We analyzed the role of type I interferon (IFN-I) receptor (IFNAR) signaling in the control of MeV infection in a murine model of brain infection. Using organotypic brain cultures (OBC) from wild-type and IFNAR-knockout (IFNARKO) transgenic mice ubiquitously expressing the human SLAM (CD150) receptor, the heterogeneity of the permissiveness of different CNS cell types to MeV infection was characterized. In the absence of IFNAR signaling, MeV propagated significantly better in explant slices. In OBC from IFNAR-competent mice, while astrocytes and microglia were infected on the day of explant preparation, they became refractory to infection with time, in contrast to neurons and oligodendrocytes, which remained permissive to infection. This selective loss of permissiveness to MeV infection was not observed in IFNARKO mouse OBC. Accordingly, the development of astrogliosis related to the OBC procedure was exacerbated in the presence of IFNAR signaling. In the hippocampus, this astrogliosis was characterized by a change in the astrocyte phenotype and by an increase of IFN-I transcripts. A proteome analysis showed the upregulation of 84 out of 111 secreted proteins. In the absence of IFNAR, only 27 secreted proteins were upregulated, and none of these were associated with antiviral activities. Our results highlight the essential role of the IFN-I response in astrogliosis and in the permissiveness of astrocytes and microglia that could control MeV propagation throughout the CNS.IMPORTANCE Measles virus (MeV) can infect the central nervous system (CNS), with dramatic consequences. The mechanisms controlling MeV invasion of the CNS remain ill-defined since most previous data were obtained from postmortem analysis. Here, we highlight for the first time the crucial role of the type I interferon (IFN-I) response not only in the control of CNS invasion but also in the early permissiveness of glial cells to measles virus infection.