The spectrum of herpes simplex encephalitis in children

Predictors of Neurological Disability at Hospital Discharge for Acyclovir-treated Pediatric Herpes Simplex Virus Encephalitis

BACKGROUND

Herpes simplex virus encephalitis (HSE) is a rare but serious neurological infection that causes neurological dysfunction. Research is lacking on the clinical predictors of neurological outcomes and the optimal duration of therapy for pediatric HSE patients. In this study of pediatric HSE patients, we identified factors predicting neurological disability at hospital discharge and examined associations of acyclovir therapy duration with neurological outcomes.

METHODS

This was a retrospective cohort study on 37 children diagnosed with HSE confirmed by polymerase chain reaction at age 1 month to 16 years from 2015 to 2021 in Ho Chi Minh City's Children's Hospital No. 2, Vietnam. For the acyclovir duration analysis, we examined 22 children with negative polymerase chain reaction on day 14 of treatment. Poisson regression was used to obtain the risk ratio and 95% confidence interval.

RESULTS

The study population consisted of 73% males, with a median age of 14 months (interquartile range: 9-35). Coma at acyclovir treatment, hypotension and the need for mechanical ventilation ≥48 hours significantly predicted neurological disability in the bivariate analysis. There were no significant associations between acyclovir duration (14 vs. 21 days) and neurological outcomes, adjusting for age at diagnosis and pediatric Glasgow Coma Scale score at acyclovir initiation.

CONCLUSION

We identified significant predictors of neurological disability unaffected by postacyclovir treatment factors. Among patients with negative HSE polymerase chain reaction on day 14, 14 days of acyclovir treatment may be as effective as 21 days. Additional studies on the effects of acyclovir duration are needed.

Radiological Features of Herpetic Encephalitis in Children

BACKGROUND

Nonspecific clinical manifestations and unclear radiological features may delay treatment initiation in pediatric patients with Herpes simplex encephalitis (HSE). The aim of this study is to analyze the clinical and radiological features of the disease.

METHODS

Clinical, laboratory, and magnetic resonance imaging (MRI) data were obtained retrospectively from a group of 37 hospitalized pediatric patients older than two months and with a polymerase chain reaction-confirmed HSE diagnosis. Clinical severity (i.e., mechanical ventilatory support) and outcome at discharge (i.e., pediatric modified Rankin Scale [ped-mRS]) were also assessed.

RESULTS

Median age was 14 months (interquartile range: 10-36). All patients survived, 15 (41%) had complete recovery (i.e., ped-mRS = 0), and 10 (27%) had significant residual disability at discharge (i.e., ped-mRS ≥3). Brain MRI was obtained in 31 patients. T2-hyperintense lesions were usually bilateral (28, 90%) and multifocal (30, 97%). Hemorrhage and mass effect were observed in 13 (42%) and 15 (48%) patients, respectively. Parenchymal lesions involved the temporal lobes (94%), insula (90%), parietal lobes (84%), and frontal lobes (61%). Occipital lesions were rare. In multivariable binary logistic regression models the presence of altered consciousness was associated with mechanical ventilation (odds ratio [OR] = 8.2, Nagelkerke R2 = 0.22), whereas the involvement of the occipital lobes (OR = 7.8) and the administration of vasopressors (OR = 12.1) were independent predictors of poor outcome (Nagelkerke R2 = 0.41).

CONCLUSIONS

Brain MRI is useful for diagnosis and outcome assessment in pediatric HSE. Radiological patterns with common frontotemporal involvement overlap adults, but multifocal and parietal lobe abnormalities are observed as well.

Herpes simplex (HSV-1) encephalitis in an infant: a case report study

Introduction and importance

The herpes simplex virus (HSV) is the most common cause of acute sporadic encephalitis, a severe and often fatal disease in humans. It is associated with high mortality and morbidity rates in untreated patients.

Case presentation

An 11-month-old child was admitted to the hospital presenting with acute fever and seizures characterized by staring episodes and spastic movements affecting the left side of the body. Diagnostic workup revealed abnormal T2 flair hyperintense foci in bi-temporoparietal lobes and right thalamus, and bilateral otomastoiditis were detected. A positive result for HSV-1 was obtained through HSV type 1/2 polymerase chain reaction (PCR) testing, leading to a diagnosis of herpes encephalitis.

Clinical discussion

While acyclovir has proven to be an effective therapeutic option, mortality and neurological sequelae continue to be reported in a notable fraction of patients. HSV encephalitis is mainly caused by two strains of the herpes simplex virus: HSV-1, more frequently observed in children and adults, and HSV-2, commonly seen in neonates and those with compromised immune systems. MRI scans often reveal that the brain lesions are localized to certain areas, although temporal involvement may not always be evident. The symptoms of herpetic encephalitis can greatly vary, making early diagnosis and treatment vital for improving patient outcomes.

Conclusion

This case report highlights the clinical presentation, diagnostic challenges, and treatment strategies for HSV-1 encephalitis and underscores the importance of early recognition and prompt initiation of antiviral therapy in suspected cases of HSV-1 encephalitis.

Neuroinfectious Diseases in Children: Pathophysiology, Outcomes, and Global Challenges

Pathogens with affinity for the central nervous system (CNS) in children are diverse in their mechanisms of infecting and attacking the brain. Infections can reach the CNS via hematogenous routes, transneurally thereby avoiding the blood-brain barrier, and across mucosal or skin surfaces. Once transmission occurs, pathogens can wreak havoc both by direct action on host cells and via an intricate interplay between the protective and pathologic actions of the host's immune system. Pathogen prevalence varies depending on region, and susceptibility differs based on epidemiologic factors such as age, immune status, and genetics. In addition, some infectious diseases are monophasic, whereas others may lie dormant for years, thereby causing a dynamic effect on outcomes. Outcomes in survivors are highly variable for each particular pathogen and depend on the vaccination and immune status of the patient as well as the speed by which the patient receives evidence-based treatments. Given pathogens cause communicable diseases that can cause morbidity and mortality on a population level when spread, the burden is often the greatest and the outcomes the worst in low-resource settings. Here we will focus on the most common infections with a propensity to affect a child's brain, the pathologic mechanisms by which they do so, and what is known about the developmental outcomes in children who are affected by these infections.

Microbes and Mental Illness: Past, Present, and Future

A review of the association between microbes and mental illness is performed, including the history, relevant definitions, infectious agents associated with mental illnesses, complex interactive infections, total load theory, pathophysiology, psychoimmunology, psychoneuroimmunology, clinical presentations, early-life infections, clinical assessment, and treatment. Perspectives on the etiology of mental illness have evolved from demonic possession toward multisystem biologically based models that include gene expression, environmental triggers, immune mediators, and infectious diseases. Microbes are associated with a number of mental disorders, including autism, schizophrenia, bipolar disorder, depressive disorders, and anxiety disorders, as well as suicidality and aggressive or violent behaviors. Specific microbes that have been associated or potentially associated with at least one of these conditions include Aspergillus, Babesia, Bartonella, Borna disease virus, Borrelia burgdorferi (Lyme disease), Candida, Chlamydia, coronaviruses (e.g., SARS-CoV-2), Cryptococcus neoformans, cytomegalovirus, enteroviruses, Epstein-Barr virus, hepatitis C, herpes simplex virus, human endogenous retroviruses, human immunodeficiency virus, human herpesvirus-6 (HHV-6), human T-cell lymphotropic virus type 1, influenza viruses, measles virus, Mycoplasma, Plasmodium, rubella virus, Group A Streptococcus (PANDAS), Taenia solium, Toxoplasma gondii, Treponema pallidum (syphilis), Trypanosoma, and West Nile virus. Recognition of the microbe and mental illness association with the development of greater interdisciplinary research, education, and treatment options may prevent and reduce mental illness morbidity, disability, and mortality.

Expression and mechanisms of interferon-stimulated genes in viral infection of the central nervous system (CNS) and neurological diseases

Interferons (IFNs) bind to cell surface receptors and activate the expression of interferon-stimulated genes (ISGs) through intracellular signaling cascades. ISGs and their expression products have various biological functions, such as antiviral and immunomodulatory effects, and are essential effector molecules for IFN function. ISGs limit the invasion and replication of the virus in a cell-specific and region-specific manner in the central nervous system (CNS). In addition to participating in natural immunity against viral infections, studies have shown that ISGs are essential in the pathogenesis of CNS disorders such as neuroinflammation and neurodegenerative diseases. The aim of this review is to present a macroscopic overview of the characteristics of ISGs that restrict viral neural invasion and the expression of the ISGs underlying viral infection of CNS cells. Furthermore, we elucidate the characteristics of ISGs expression in neurological inflammation, neuropsychiatric disorders such as depression as well as neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). Finally, we summarize several ISGs (ISG15, IFIT2, IFITM3) that have been studied more in recent years for their antiviral infection in the CNS and their research progress in neurological diseases.

TLR3 controls constitutive IFN-β antiviral immunity in human fibroblasts and cortical neurons

Human herpes simplex virus 1 (HSV-1) encephalitis can be caused by inborn errors of the TLR3 pathway, resulting in impairment of CNS cell-intrinsic antiviral immunity. Deficiencies of the TLR3 pathway impair cell-intrinsic immunity to vesicular stomatitis virus (VSV) and HSV-1 in fibroblasts, and to HSV-1 in cortical but not trigeminal neurons. The underlying molecular mechanism is thought to involve impaired IFN-α/β induction by the TLR3 recognition of dsRNA viral intermediates or by-products. However, we show here that human TLR3 controls constitutive levels of IFNB mRNA and secreted bioactive IFN-β protein, and thereby also controls constitutive mRNA levels for IFN-stimulated genes (ISGs) in fibroblasts. Tlr3-/- mouse embryonic fibroblasts also have lower basal ISG levels. Moreover, human TLR3 controls basal levels of IFN-β secretion and ISG mRNA in induced pluripotent stem cell-derived cortical neurons. Consistently, TLR3-deficient human fibroblasts and cortical neurons are vulnerable not only to both VSV and HSV-1, but also to several other families of viruses. The mechanism by which TLR3 restricts viral growth in human fibroblasts and cortical neurons in vitro and, by inference, by which the human CNS prevents infection by HSV-1 in vivo, is therefore based on the control of early viral infection by basal IFN-β immunity.

Encephalitis in Previously Healthy Children

Encephalitis is defined as altered mental status for more than 24 hours accompanied by 2 or more findings concerning for inflammation of the brain parenchyma: fever, seizures or other focal neurologic disorders, cerebrospinal fluid pleocytosis, and abnormal neuroimaging and electroencephalographic findings. Herpes simplex virus causes the most severe form of virus-induced encephalitis; the early administration of acyclovir can improve the prognosis of this disease. The rising interest in autoimmune causes of encephalitis, most notably anti-N-methyl-d-aspartate receptor, should prompt the clinician to consider immunomodulatory treatments, which may improve outcomes. A broad testing panel may be necessary to detect the etiologic agent; a few published pediatric cases suggest that infectious and autoimmune causes may occur concurrently in the same patient with encephalitis. More than 40% of children diagnosed as having encephalitis will not return to their previous level of neurologic function after resolution of their disease, although outcomes are highly variable depending on the etiologic agent.

Management and results of epilepsy surgery associated with acyclovir prophylaxis in four pediatric patients with drug-resistant epilepsy due to herpetic encephalitis and review of the literature

PURPOSE

Herpes simplex virus encephalitis (HSE) is the most common cause of sporadic viral encephalitis in children and is responsible for epilepsy in approximately half of patients. In addition to medical treatment, epilepsy surgery may be offered to drug-resistant patients but carries a high risk of relapse of herpetic encephalitis. We are reporting our series of patients operated on between 2000 and 2019 with the systematic administration of acyclovir (ACV).

RESULTS

Four pediatric patients aged 4.5-12.8 years with drug-resistant epilepsy post-HSE underwent a tailored focal resection following invasive recordings (three patients) and a complete callosotomy (one patient). The total number of the surgical procedures for the four patients was eight, and a systematic administration of ACV as a prophylactic treatment of herpetic encephalitis relapse was done at each step. No patients had a relapse and the ACV was well-tolerated in all the cases. Following surgery two patients are seizure free, the patient who underwent callosotomy is Engel 3 and the fourth patient, in whom a large epileptic zone has contraindicated a second surgery, is Engel 4.

CONCLUSIONS

Our series demonstrated the dramatic efficacy of systematic ACV prophylaxis during all cranial surgeries. Moreover, our results on epilepsy, together with those of the literature, encourage more consideration regarding epilepsy surgery in this specific etiology. All types of surgical procedures (curative or palliative) can be offered to the patients, but in the case of focal surgery, due to the poor anatomical limits, invasive recordings are highly recommended.

Immunomodulatory Strategies in Herpes Simplex Virus Encephalitis

Herpes simplex virus 1 (HSV-1) can be responsible for life-threatening HSV encephalitis (HSE). The mortality rate of patients with HSE who do not receive antiviral treatment is 70%, with most survivors suffering from permanent neurological sequelae. The use of intravenous acyclovir together with improved diagnostic technologies such as PCR and magnetic resonance imaging has resulted in a reduction in the mortality rate to close to 20%. However, 70% of surviving patients still do not recover complete neurological functions. Thus, there is an urgent need to develop more effective treatments for a better clinical outcome. It is well recognized that cerebral damage resulting from HSE is caused by viral replication together with an overzealous inflammatory response. Both of these processes constitute potential targets for the development of innovative therapies against HSE. In this review, we discuss recent progress in therapy that may be used to ameliorate the outcome of patients with HSE, with a particular emphasis on immunomodulatory agents. Ideally, the administration of adjunctive immunomodulatory drugs should be initiated during the rise of the inflammatory response, and its duration should be limited in time to reduce undesired effects. This critical time frame should be optimized by the identification of reliable biomarkers of inflammation.

Herpes simplex encephalitis in adult patients with MASP-2 deficiency

We report here two cases of Herpes simplex virus encephalitis (HSE) in adult patients with very rare, previously uncharacterized, non synonymous heterozygous G634R and R203W substitution in mannan-binding lectin serine protease 2 (MASP2), a gene encoding a key protease of the lectin pathway of the complement system. None of the 2 patients had variants in genes involved in the TLR3-interferon signaling pathway. Both MASP2 variants induced functional defects in vitro, including a reduced (R203W) or abolished (G634R) protein secretion, a lost capability to cleave MASP-2 precursor into its active form (G634R) and an in vivo reduced antiviral activity (G634R). In a murine model of HSE, animals deficient in mannose binding lectins (MBL, the main pattern recognition molecule associated with MASP-2) had a decreased survival rate and an increased brain burden of HSV-1 compared to WT C57BL/6J mice. Altogether, these data suggest that MASP-2 deficiency can increase susceptibility to adult HSE.

Human herpes virus type 1 (HSV-1) infects a large number of individuals during their life, with manifestations usually limited to mild and self-limiting inflammation of the oral mucosa (cold sore). However, HSV-1 can cause a very severe disease of the brain called Herpes simplex encephalitis (HSE) in 1 out of 250’000–500’000 individuals per year. The reasons why HSV-1 can cause such a devastating disease in a very limited number of individuals are unknown. Increasing evidence suggests that susceptibility to HSE in children can results from genetic variations in the immune system, in particular in a viral detection pathway called the Toll-like receptor 3 (TLR3)–interferon (IFN) axis. Fewer data are available to explain HSE in adult patients. Here, we describe two adult patients with HSE who carry mutations in a gene called mannan-binding lectin serine protease 2 (MASP2), which is part of an immune pathway different from the TLR3-IFN axis, called the lectin pathway of the complement system. We demonstrate that MASP2 mutations induce functional defects in immune defense against HSV-1 that prevent viral replication. Mice deficient in the lectin pathway have higher mortality compared to wild-type mice after HSV-1 infection. Altogether, our study suggests that susceptibility to HSE in adults relies of immune deficiencies that are different from those causing HSE in children.

Acute and chronic viral infections

A large number of viruses belonging to various families are able to cause central nervous system (CNS) infections and contribute significantly to burden of disease in humans globally. Most viral CNS infections are benign and self-limiting, and most remain undiagnosed. However, some viruses can cause severe inflammation, leading to morbidity and mortality, and result in severe long-term residual damage and neurologic dysfunction in patients. The potential of viruses to cause CNS inflammation greatly varies depending on host factors, such as age, sex, and genetic background, as well as viral factors. Despite the need for protection against viral invasion and replication, the extent of the immune response in the CNS is carefully regulated to prevent excessive inflammation and tissue destruction leading to irretrievable loss of neurons. Direct cytopathology is for many virus infections a major cause of neurologic symptoms; however, the antiviral immune response can in some instances contribute substantially to pathology. This chapter highlights a selection of clinically important neurotropic viruses that infect the CNS and cause neurologic diseases such as meningitis, encephalitis, and myelitis in humans, with a focus on neuropathologic findings.

Functional failure of TLR3 and its signaling components contribute to herpes simplex encephalitis

Herpes simplex encephalitis (HSE) is a severe neurological disease in children and adults caused by herpes simplex virus. This review discusses recent findings on the role of Toll-like receptor 3 (TLR3) deficiencies in the HSE development. Critical checkpoints in the TLR3 signaling that contribute to innate response are discussed, including the importance of TLR3 ligand recognition site and transportation in the cell. We also indicate unresolved issues in the TLR3 functioning that might lead to thorough understanding of immunity during HSE. Such a knowledge base will lead to discovery and design of a rationale therapeutic and preventive approach against HSE.

Herpes simplex encephalitis with thalamic, brainstem and cerebellar involvement

Herpes simplex virus encephalitis is a common and treatable cause of acute encephalitis in all age groups. Certain radiological features such as temporal parenchymal involvement facilitate the diagnosis. The use of herpes simplex virus polymerase chain reaction has expanded the clinical and imaging spectrum. We report the case of a young patient who presented with a movement disorder and predominant involvement of thalami, brainstem and cerebellum on magnetic resonance imaging, and was diagnosed with herpes simplex virus encephalitis. Differentiation from Japanese encephalitis may be difficult in these patients, especially in endemic areas, and may necessitate the use of relevant investigations in all patients.

What factors determine the need for lumbar puncture in patients with fever and headache?

INTRODUCTION

We performed this study to find clinical features and laboratory parameters that could facilitate the process of selecting patients who should receive lumbar punctures from among those who present with headache and fever.

METHODS

We selected patients aged ≥ 16 years who presented to and received lumbar puncture in the emergency department of Kangwon National University Hospital, South Korea, between 2011 and 2013. Patients who received lumbar punctures were divided into two groups - those who were diagnosed with viral meningitis and those who were not. We compared the clinical features and laboratory data between the two groups. Key indices were then used to develop a scoring system to diagnose viral meningitis in patients and identify those who should receive lumbar punctures.

RESULTS

Among the patients who were included in the study, 42 had viral meningitis and 96 did not. The variables of C-reactive protein level ≤ 1.291 mg/dL, neck stiffness and vomiting were assigned 3 points, 2 points and 1 point, respectively, in the scoring system. Overall scores ≥ 4 yielded a positive likelihood ratio of 7.79 (sensitivity 0.600, specificity 0.923), while negative likelihood ratio decreased to less than 0.1 (0.072) for overall scores < 3.

CONCLUSION

Using the proposed scoring system, we were able to determine the likelihood of viral meningitis in patients presenting with fever and headache, and to successfully identify those who should receive lumbar punctures.

Human TBK1: A Gatekeeper of Neuroinflammation

The importance of TANK binding kinase-1 (TBK1), a multimeric kinase that modulates inflammation and autophagy, in human health has been highlighted for the first time by the recent discoveries of mutations in TBK1 that underlie amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), normal tension glaucoma (NTG) or childhood herpes simplex encephalitis (HSE). Gain-of-function of TBK1 are associated with NTG, whereas loss-of-function mutations result in ALS/FTD or in HSE. In light of these new findings, we review the role of TBK1 in these seemingly unrelated, yet allelic diseases, and discuss the role of TBK1 in neuroinflammatory diseases. This discovery has the potential to significantly increase our understanding of the molecular basis of these poorly understood diseases.

Acute opercular syndrome in 4-year-old boy

Acute opercular syndrome is a rare described syndrome caused by a sudden damage of the cerebral cortex and subcortical white matter, located around the insula. A rare cause of this syndrome can be an infectious agent, particularly herpes simplex virus. Quick diagnosis and immediate initiation of treatment significantly reduce the risk of neurological consequences and mortality. We present a case of encephalitis of unknown etiology and severe course, with the symptoms of acute opercular syndrome in 4-year-old boy.

Anaplastic astrocytoma mimicking herpes simplex encephalitis in 13-year old girl

Astrocytoma is the most common childhood brain tumor. Anaplastic astrocytoma (AA) are high grade gliomas (HGG), found very rarely in pediatric patients. AA mainly results from a dedifferentiation of a low grade astrocytoma. Clinical features of supra-tentorial tumors vary according to their anatomic location, biologic aggressiveness and age of the patient. They can be either completely asymptomatic or present with signs of raised intracranial pressure, seizures (about 40% of cases), behavior changes, speech disorders, declining school performance, or hemiparesis. There have been published adult cases of brain tumor misdiagnosed as viral encephalitis. Due to variety of clinical presentations, diagnosis of AA can be challenging. Here we report a case of a 13 year old girl who presented with clinical features suggestive of viral encephalitis, such as fever, headache, dizziness, and first seizure with postictal sleep and prolonged drowsiness. However, her brain MRI findings were consistent with long standing mass effect from the underlying intracranial contents and that coupled with her history of unusual taste led to further investigations and the diagnosis of the AA. In retrospect, this presentation could have been a temporal epileptic aura. High grade astrocytomas are particularly difficult to treat with a two-year survival rates range from 10% to 30%. The treatment is multimodal with gross total surgical resection of the tumor, followed by radiotherapy with or without nitrosourea-containing chemotherapy regimen. Recent promising results seen with the use of temozolamide in adults has not been yet demonstrated in the pediatric patients. The extent of tumor resection remains the most significant indicator of survival and early recognition of this tumor is essential. This case report emphasizes the fact that mass lesions in the temporal lobe, including high-grade astrocytoma, should be considered in the differential diagnosis of suspected herpes simplex encephalitis, especially those not responding to therapy. Remodeling of the calvarium adjacent to an intracranial lesion suggests a long standing process.

[Post-herpes simplex encephalitis chorea: Viral replication or immunological mechanism?]

INTRODUCTION

Herpes simplex encephalitis is a severe neurological condition, whose outcome is improved if treated early with acyclovir. Post-herpes simplex encephalitis with acute chorea has rarely been reported.

CASE REPORT

We report on two observations of children presenting with post-herpes simplex encephalitis with acute chorea, related to two different pathophysiological mechanisms. The first one is an 11-month-old girl developing relapsing herpes simplex encephalitis with chorea due to resumption of viral replication. The second one is a 2-year-old boy with relapsing post-herpes simplex encephalitis acute chorea caused by an immunoinflammatory mechanism. We discuss the different neurological presentations of herpetic relapses, notably those presenting with movement disorders, as well as their clinical, paraclinical, physiopathological, and therapeutic aspects.

CONCLUSION

Post-herpes simplex encephalitis with acute chorea may involve two mechanisms: resumption of viral replication or an immunoinflammatory mechanism. Treatment of post-herpes simplex encephalitis with acute chorea depends on the underlying mechanism, while prevention is based on antiviral treatment of herpes simplex encephalitis with acyclovir at the dose of 20mg/kg/8h for 21 days.

Fifteen minute consultation: managing neonatal and childhood herpes encephalitis

Herpes simplex encephalitis (HSE) is the most common single cause of viral encephalitis in infants and children. Treated or untreated, it can be associated with considerable morbidity and mortality, and its presentation is usually insidious and non-specific. Prompt and careful investigation is important in order to establish the diagnosis so that treatment can be optimised. We address some common questions arising when diagnosing and treating presumed HSE throughout childhood.

The anterior commissure is a pathway for contralateral spread of herpes simplex virus type 1 after olfactory tract infection

Herpes simplex encephalitis (HSE), targeting the limbic system, is the most common cause of viral encephalitis in the Western world. Two pathways for viral entry to the central nervous system (CNS) in HSE have been suggested: either via the trigeminal nerve or via the olfactory tract. This question remains unsettled, and studies of viral spread between the two brain hemispheres are scarce. Here, we investigated the olfactory infection as a model of infection and tropism of herpes simplex virus 1 (HSV-1), the causative agent of HSE, in the CNS of rats. Rats were instilled with HSV-1 in the right nostril and sacrificed 1-6 days post-infection, and tissues were analysed for viral spread using immunohistochemistry and quantitative PCR (qPCR). After nasal instillation, HSV-1 infected mitral cells of the olfactory bulb (OB) on the right side only, followed by limbic encephalitis. As a novel finding, the anterior commissure (AC) conveyed a rapid transmission of virus between the right and the left OB, acting as a shortcut also between the olfactory cortices. The neuronal cell population that conveyed the viral infection via the AC was positive for the water channel protein aquaporin 9 (AQP9) by immunohistochemistry. Quantification of AQP9 in cerebrospinal fluid samples of HSE patients showed increment as compared to controls. We conclude that the olfactory route and the AC are important for the spread of HSV-1 within the olfactory/limbic system of rats and furthermore, we suggest that AQP9 is involved in viral tropism and pathogenesis of HSE.

TLR3 deficiency in herpes simplex encephalitis: high allelic heterogeneity and recurrence risk

OBJECTIVE

To determine the proportion of children with herpes simplex encephalitis (HSE) displaying TLR3 deficiency, the extent of TLR3 allelic heterogeneity, and the specific clinical features of TLR3 deficiency.

METHODS

We determined the sequence of all exons of TLR3 in 110 of the 120 patients with HSE enrolled in our study who do not carry any of the previously described HSE-predisposing mutations of TLR3 pathway genes (TLR3, UNC93B1, TRIF, TRAF3, and TBK1). All the new mutant TLR3 alleles detected were characterized experimentally in-depth to establish the causal relationship between the genotype and phenotype.

RESULTS

In addition to the 3 previously reported TLR3-deficient patients from the same cohort, 6 other children or young adults with HSE carry 1 of 5 unique or extremely rare (minor allele frequency <0.001) missense TLR3 alleles. Two alleles (M374T, D592N) heterozygous in 3 patients are not deleterious in vitro. The other 3 are deleterious via different mechanisms: G743D+R811I and L360P heterozygous in 2 patients are loss-of-function due to low levels of expression and lack of cleavage, respectively, and R867Q homozygous in 1 patient is hypomorphic. The 3 patients' fibroblasts display impaired TLR3 responses and enhanced herpes simplex virus 1 susceptibility. Overall, TLR3 deficiency is therefore found in 6 (5%) of the 120 patients studied. There is high allelic heterogeneity, with 3 forms of autosomal dominant partial defect by negative dominance or haploinsufficiency, and 2 forms of autosomal recessive defect with complete or partial deficiency. Finally, 4 (66%) of the 6 TLR3-deficient patients had at least 1 late relapse of HSE, whereas relapse occurred in only 12 (10%) of the total cohort of 120 patients.

CONCLUSIONS

Childhood-onset HSE is due to TLR3 deficiency in a traceable fraction of patients, in particular the ones with HSE recurrence. Mutations in TLR3 and TLR3 pathway genes should be searched and experimentally studied in children with HSE, and patients with proven TLR3 deficiency should be followed carefully.

Akathisia in association with herpes simplex encephalitis relapse and opercular syndrome in children

We report a 2-year-old boy with herpes simplex virus type 1 encephalitis (HSE) and opercular syndrome who presented with clinical relapse characterized by chorea-like involuntary movements that suggest akathisia. The patient initially presented with multiple focal seizures that cause epilepsia partialis continua, polymerase chain reaction (PCR) for herpes simplex virus type 1 was positive. He developed hypersalivation, speech and swallowing difficulties within 30days. Based on these findings the patient was diagnosed as having opercular syndrome due to HSE. He developed akathisia on 44th day of admission as a relapse and he was successfully treated with propranolol. Opercular syndrome might be seen HSE in children and it may cause neurological suquela. Akathisia might be seen after encephalitic process as a symptom of relapse, however diagnosis of akathisia is difficult in young children. It should be noted that because propranolol effective for these involuntary movements. It can be add additional choice of treatment in these patients.

Proteomics in immunity and herpes simplex encephalitis

The genetic theory of infectious diseases has proposed that susceptibility to life-threatening infectious diseases in childhood, occurring in the course of primary infection, results mostly from individually rare but collectively diverse single-gene variants. Recent evidence of an ever-expanding spectrum of genes involved in susceptibility to infectious disease indicates that the paradigm has important implications for diagnosis and treatment. One such pathology is childhood herpes simplex encephalitis, which shows a pattern of rare but diverse disease-disposing genetic variants. The present report shows how proteomics can help to understand susceptibility to childhood herpes simplex encephalitis and other viral infections, suggests that proteomics may have a particularly important role to play, emphasizes that variation over the population is a critical issue for proteomics and notes some new challenges for proteomics and related bioinformatics tools in the context of rare but diverse genetic defects.

Toll-like receptors' pathway disturbances are associated with increased susceptibility to infections in humans

Toll-like receptors (TLRs) sense microbial products and play an important role in innate immunity. Currently, 11 members of TLRs have been identified in humans, with important function in host defense in early steps of the inflammatory response. TLRs are present in the plasma membrane (TLR1, TLR2, TLR4, TLR5, TLR6) and endosome (TLR3, TLR7, TLR8, TLR9) of leukocytes. TLRs and IL-1R are a family of receptors related to the innate immune response that contain an intracellular domain known as the Toll-IL-1R (TIR) domain that recruits the TIR-containing cytosolic adapters MyD88, TRIF, TIRAP and TRAM. The classical pathway results in the activation of both nuclear factor κB and MAPKs via the IRAK complex, with two active kinases (IRAK-1 and IRAK-4) and two non-catalytic subunits (IRAK-2 and IRAK-3/M). The classical pro-inflammatory TLR signaling pathway leads to the synthesis of inflammatory cytokines and chemokines, such as IL-1β, IL-6, IL-8, IL-12 and TNF-α. In humans, genetic defects have been identified that impair signaling of the TLR pathway and this may result in recurrent pyogenic infections, as well as virus and fungi infections. In this review, we discuss the main mechanisms of microbial recognition and the defects involving TLRs.

Children often present with infantile spasms after herpetic encephalitis

PURPOSE

To determine what epilepsy types occur after herpetic encephalitis and what are the determinant factors for subsequent infantile spasms.

METHODS

We analyzed retrospectively the clinical history of 22 patients, referred to Necker and Saint Vincent de Paul Hospitals (Paris) through the French pediatric epilepsy network from March 1986 to April 2010 and who developed epilepsy some months after herpetic encephalitis. We focused on seizure semiology with video-electroencephalography (EEG) recording, and on neuroradiology and epilepsy follow-up.

KEY FINDINGS

Fourteen patients developed pharmacoresistant spasms, and eight developed focal epilepsy, but none had both. The patients who developed spasms were more frequently younger than 30 months at age of onset of epilepsy and had herpetic encephalitis earlier (mean 10.6 months of age) than those who developed focal epilepsy (mean 59.7 and 39.6 months, respectively). Epilepsy follow-up was similar in both groups (8.5 and 11 years, respectively). We found 26 affected cerebral areas; none alone was related to the development of epileptic spasms.

SIGNIFICANCE

Risk factors to develop epileptic spasms were to have had herpetic encephalitis early (mean 10 months); to be significantly younger at onset of epilepsy (mean 22.1 months); and to have cerebral lesions involving the insula, the hippocampus, and the temporal pole.

The proteome of Toll-like receptor 3-stimulated human immortalized fibroblasts: implications for susceptibility to herpes simplex virus encephalitis

BACKGROUND

Inborn errors in Toll-like receptor 3 (TLR3)-IFN type I and III pathways have been implicated in susceptibility to herpes simplex virus encephalitis (HSE) in children, but most patients studied do not carry mutations in any of the genes presently associated with HSE susceptibility. Moreover, many patients do not display any TLR3-IFN-related fibroblastic phenotype.

OBJECTIVE

To study other signaling pathways downstream of TLR3 and/or other independent pathways that may contribute to HSE susceptibility.

METHODS

We used the stable isotope labeling of amino acids in cell culture proteomics methodology to measure changes in the human immortalized fibroblast proteome after TLR3 activation.

RESULTS

Cells from healthy controls were compared with cells from a patient with a known genetic etiology of HSE (UNC-93B-/-) and also to cells from an HSE patient with an unknown gene defect. Consistent with known variation in susceptibility of individuals to viral infections, substantial variation in the response level of different healthy controls was observed, but common functional networks could be identified, including upregulation of superoxide dismutase 2. The 2 patients with HSE studied show clear differences in functional response networks when compared with healthy controls and also when compared with each other.

CONCLUSIONS

The present study delineates a number of novel proteins, TLR3-related pathways, and cellular phenotypes that may help elucidate the genetic basis of childhood HSE. Furthermore, our results reveal superoxide dismutase 2 as a potential therapeutic target for amelioration of the neurologic sequelae caused by HSE.

Mendelian predisposition to herpes simplex encephalitis

Herpes simplex encephalitis (HSE) is the most common sporadic viral encephalitis in the Western world. The pathogenesis of HSE, which affects a small minority of HSV-1-infected individuals, has long remained elusive. Mendelian defects in the TLR3-interferon (IFN) and IFN-responsive pathways were recently shown to predispose to HSE, at least in some children. Autosomal recessive STAT-1 deficiency and X-linked NEMO deficiency were found in children with both mycobacterial disease and HSE. Autosomal recessive UNC-93B deficiency and autosomal dominant TLR3 deficiency were then described in children with isolated HSE. These discoveries provided proof-of-principle that HSE may result from a novel group of single-gene inborn errors of interferon (IFN)-mediated immunity. The TLR3-UNC-93B-dependent production of IFN-α/β and IFN-λ is essential to confer protective immunity to HSV-1 in the central nervous system during the course of primary infection in childhood.

Primary immunodeficiencies of pattern recognition receptors

Primary immunodeficiencies (PIDs) are severe defects in the capacity of the host to mount a proper immune response, and are characterized by an increased susceptibility to infections. Although classical immunodeficiencies have been characterized based on broad defects in cell populations (e.g. T/B cells or polymorphonuclear leukocytes) or humoral factors (e.g. antibodies or complement), specific immune defects based on well-defined molecular targets have been described more recently. Among these, genetic defects in pattern recognition receptors (PRRs), leading to impaired recognition of invading pathogens by the innate immune system, play an important role in specific defects against human pathogens. Defects have been described in three of the major families of PRRs: the Toll-like receptors, the C-type lectin receptors and the nucleotide-binding domain leucine-rich repeat-containing receptors. By contrast, no defects in the intracellular viral receptors of the RigI helicase family have been described to date. Defects in the PRRs show a broad variation in severity, have a narrow specificity for certain classes of pathogens, and often decrease in severity with age; these characteristics distinguish them from other forms of PIDs. Their discovery has led to important insights into the pathophysiology of infections, and may offer potential novel therapeutic targets for immunotherapy.

Encephalitis with thalamic and basal ganglia abnormalities: etiologies, neuroimaging, and potential role of respiratory viruses

BACKGROUND

Encephalitis is a severe neurological syndrome with devastating consequences. Despite extensive testing, the etiology often remains unknown. Involvement of the thalamus or basal ganglia (T/BG) occurs in a subset of patients with encephalitis and may be an important etiological clue. In order to improve diagnosis of T/BG patients, we reviewed this subgroup within the California Encephalitis Project (CEP).

METHODS

Data from T/BG cases enrolled in CEP were retrospectively reviewed. Cases were stratified by age and grouped by etiological classification: infectious, postinfectious, and noninfectious. Neuroimaging reports were examined and compared between etiologies.

RESULTS

T/BG neuroimaging abnormalities were reported in 6% of 3236 CEP cases. An etiology was found in 76%: 37% infectious, 16% postinfectious, and 23% noninfectious. The most frequently identified infectious agents were respiratory viruses, accounting for 31%, predominantly in children. Other infections more common in the T/BG group included Creutzfeldt-Jakob disease, arbovirus, and Mycobacterium tuberculosis. Infectious and postinfectious cases had higher median cerebrospinal fluid white blood cell count than noninfectious etiologies. Notably, T/BG neuroimaging characteristics were associated with distinct etiologies. In particular, symmetric hemorrhagic abnormalities involving the thalamus were most frequently found within the respiratory virus group.

CONCLUSIONS

T/BG involvement in patients with suspected encephalitis was associated with specific etiologies. In addition to agents with established predilection for the T/BG such as M. tuberculosis and arboviruses, a surprisingly high number of cases were associated with respiratory viruses, especially in children. Neuroimaging abnormalities in such patients can aid clinicians in narrowing the etiological scope and in guiding testing.

Suboptimal management of central nervous system infections in children: a multi-centre retrospective study

OBJECTIVE

We aimed to audit the regional management of central nervous system (CNS) infection in children.

METHODS

The study was undertaken in five district general hospitals and one tertiary paediatric hospital in the Mersey region of the UK. Children admitted to hospital with a suspected CNS infection over a three month period were identified. Children were aged between 4 weeks and 16 years old. Details were recorded from the case notes and electronic records. We measured the appropriateness of management pathways as outlined by national and local guidelines.

RESULTS

Sixty-five children were identified with a median age of 6 months (range 1 month to 15 years). Ten had a CNS infection: 4 aseptic meningitis, 3 purulent meningitis, 3 encephalitis [2 with herpes simplex virus (HSV) type 1]. A lumbar puncture (LP) was attempted in 50 (77%) cases but only 43 had cerebrospinal fluid (CSF) available for analysis. Of these 24 (57%) had a complete standard set of tests performed. Fifty eight (89%) received a third generation cephalosporin. Seventeen (26%) also received aciclovir with no obvious indication in 9 (53%). Only 11 (65%) of those receiving aciclovir had CSF herpes virus PCR. Seventeen had cranial imaging and it was the first management step in 14. Treatment lengths of both antibiotics and aciclovir were highly variable: one child with HSV encephalitis was only treated with aciclovir for 7 days.

CONCLUSIONS

The clinical management of children with suspected CNS infections across the Mersey region is heterogeneous and often sub-optimal, particularly for the investigation and treatment of viral encephalitis. National guidelines for the management of viral encephalitis are needed.

Poor neurological sequelae of herpes simplex virus encephalitis in an infant despite adequate antiviral and adjunct corticosteroid therapy

A 2-month-old infant presented to our emergency department with fever, altered consciousness, and focal seizures of acute onset. He had vesicular skin lesions over the right preauricular region. CT brain showed a large hypodense lesion involving the left temporo-parietal region, left basal ganglia and left thalamus. MRI brain revealed bilateral multifocal corticomedullary lesions suggestive of encephalitis. CSF-PCR was positive for herpes simplex virus (HSV) type I. He was treated with standard dose intravenous acyclovir for 15 days along with a trial of pulse methylprednisolone, but was readmitted within a week with features of an early relapse. The infant survived but developed significant neurological sequelae. Although treatment of HSV is available, the neurological outcome is guarded even with adequate antiviral therapy. Adjunct corticosteroid therapy did not appear to attenuate the neurological sequelae.

Heterozygous TBK1 mutations impair TLR3 immunity and underlie herpes simplex encephalitis of childhood

Two unrelated children with HSE carry distinct heterozygous mutations in the gene encoding TANK-binding kinase 1.

Childhood herpes simplex virus-1 (HSV-1) encephalitis (HSE) may result from single-gene inborn errors of TLR3 immunity. TLR3-dependent induction of IFN-α/β or IFN-λ is crucial for protective immunity against primary HSV-1 infection in the central nervous system (CNS). We describe here two unrelated children with HSE carrying different heterozygous mutations (D50A and G159A) in TBK1, the gene encoding TANK-binding kinase 1, a kinase at the crossroads of multiple IFN-inducing signaling pathways. Both mutant TBK1 alleles are loss-of-function but through different mechanisms: protein instability (D50A) or a loss of kinase activity (G159A). Both are also associated with an autosomal-dominant (AD) trait but by different mechanisms: haplotype insufficiency (D50A) or negative dominance (G159A). A defect in polyinosinic-polycytidylic acid–induced TLR3 responses can be detected in fibroblasts heterozygous for G159A but not for D50A TBK1. Nevertheless, viral replication and cell death rates caused by two TLR3-dependent viruses (HSV-1 and vesicular stomatitis virus) were high in fibroblasts from both patients, and particularly so in G159A TBK1 fibroblasts. These phenotypes were rescued equally well by IFN-α2b. Moreover, the IFN responses to the TLR3-independent agonists and viruses tested were maintained in both patients’ peripheral blood mononuclear cells and fibroblasts. The narrow, partial cellular phenotype thus accounts for the clinical phenotype of these patients being limited to HSE. These data identify AD partial TBK1 deficiency as a new genetic etiology of childhood HSE, indicating that TBK1 is essential for the TLR3- and IFN-dependent control of HSV-1 in the CNS.

Protective activity of the ethanol extract of Cynanchum paniculatum (BUNGE) Kitagawa on treating herpes simplex encephalitis

To date there has been no valid treatment for herpes simplex encephalitis (HSV). This study explores the protective activity of ethanol extract of Cynanchum paniculatum (bunge) kitagawa for treatment of HSV. Cell models and animal models were established and divided into 4 groups: normal group, virus group, cynanchum paniculatum group and Dexamethasone group. Flow cytometry was employed to detect apoptosis of cell model and TUNEL assay was chosen to detect apoptosis of animal tissues. The survival time of the animal models was observed. ELISA was used to measure TNF-alpha expression and the Greiss method to measure Nitric Oxide (NO) expression in the mouse brain. As a result, it was found that extract of Cynanchum paniculatum can improve the survival rate of HSV-infected mice. The extract could prevent apoptosis in the neuron cell model and reduce apoptosis rate in brain tissue after HSV infection. With the extract intervention, TNF-alpha and NO levels in brain tissue were significantly decreased in the animal model. In conclusion, the extract of Cynanchum paniculatum can prevent HSV-inducing impairment in the cell and animal model of HSE.

Genetic variation in Toll-like receptors and disease susceptibility

Toll-like receptors (TLRs) are key initiators of the innate immune response and promote adaptive immunity. Much has been learned about the role of TLRs in human immunity from studies linking TLR genetic variation with disease. First, monogenic disorders associated with complete deficiency in certain TLR pathways, such as MyD88-IRAK4 or TLR3-Unc93b-TRIF-TRAF3, have demonstrated the specific roles of these pathways in host defense against pyogenic bacteria and herpesviruses, respectively. Second, common polymorphisms in genes encoding several TLRs and associated genes have been associated with both infectious and autoimmune diseases. The study of genetic variation in TLRs in various populations combined with information on infection has demonstrated complex interaction between genetic variation in TLRs and environmental factors. This interaction explains the differences in the effect of TLR polymorphisms on susceptibility to infection and autoimmune disease in various populations.

Herpes simplex serious neurological disease in young children: incidence and long-term outcome

OBJECTIVE

To determine the contribution of herpes simplex virus (HSV) to serious neurological disease.

SETTING AND PATIENTS

A 3-year prospective survey of children aged 2-23 months in Britain and Ireland.

RESULTS

19 children had HSV central nervous system (CNS) infection; 13 aged 2-11 months had focal neuroimaging abnormalities and 11 long-term neurological sequelae. Of six aged 12-35 months, one had abnormal neuroimaging and three long-term neurological sequelae. 17 of the 19 had serious neurological disease. HSV CNS infection accounted for 23% of serious neurological disease in children aged 2-11 months and 4.5% in older children.

CONCLUSIONS

The incidence of HSV-induced serious neurological disease in the UK was estimated at 1 in 64 000/year in younger children and 1 in 230 000 in older children. HSV CNS infection has clinical effects ranging from frank encephalitis to severe illness with fever and convulsions to milder disease lacking encephalopathy.

Herpes simplex encephalitis in children with autosomal recessive and dominant TRIF deficiency

Herpes simplex encephalitis (HSE) is the most common sporadic viral encephalitis of childhood. Autosomal recessive (AR) UNC-93B and TLR3 deficiencies and autosomal dominant (AD) TLR3 and TRAF3 deficiencies underlie HSE in some children. We report here unrelated HSE children with AR or AD TRIF deficiency. The AR form of the disease was found to be due to a homozygous nonsense mutation that resulted in a complete absence of the TRIF protein. Both the TLR3- and the TRIF-dependent TLR4 signaling pathways were abolished. The AD form of disease was found to be due to a heterozygous missense mutation, resulting in a dysfunctional protein. In this form of the disease, the TLR3 signaling pathway was impaired, whereas the TRIF-dependent TLR4 pathway was unaffected. Both patients, however, showed reduced capacity to respond to stimulation of the DExD/H-box helicases pathway. To date, the TRIF-deficient patients with HSE described herein have suffered from no other infections. Moreover, as observed in patients with other genetic etiologies of HSE, clinical penetrance was found to be incomplete, as some HSV-1-infected TRIF-deficient relatives have not developed HSE. Our results provide what we believe to be the first description of human TRIF deficiency and a new genetic etiology for HSE. They suggest that the TRIF-dependent TLR4 and DExD/H-box helicase pathways are largely redundant in host defense. They further demonstrate the importance of TRIF for the TLR3-dependent production of antiviral IFNs in the CNS during primary infection with HSV-1 in childhood.

Management of suspected viral encephalitis in children - Association of British Neurologists and British Paediatric Allergy, Immunology and Infection Group national guidelines

In the 1980s the outcome of patients with herpes simplex encephalitis was shown to be dramatically improved with aciclovir treatment. Delays in starting treatment, particularly beyond 48 h after hospital admission, are associated with a worse prognosis. Several comprehensive reviews of the investigation and management of encephalitis have been published. However, their impact on day-to-day clinical practice appears to be limited. The emergency management of meningitis in children and adults was revolutionised by the introduction of a simple algorithm as part of management guidelines. In February 2008 a group of clinicians met in Liverpool to begin the development process for clinical care guidelines based around a similar simple algorithm, supported by an evidence base, whose implementation is hoped would improve the management of patients with suspected encephalitis.

Transient asymptomatic white matter lesions following Epstein-Barr virus encephalitis

We present the case of a patient with Epstein-Barr virus (EBV) encephalitis who developed abnormal white matter lesions during the chronic phases of the infection. A 2-year-old-boy was admitted for a 2 day history of decreased activity with ataxic gait. The results of the physical examination were unremarkable except for generalized lethargy and enlarged tonsils with exudates. Brain magnetic resonance imaging (MRI) at admission showed multiple high signal intensities in both basal ganglia and thalami. The result of EBV polymerase chain reaction (PCR) of the cerebral spinal fluid was positive, and a serological test showed acute EBV infection. The patient was diagnosed with EBV encephalitis and recovered fully without any residual neurologic complications. Subsequently, follow-up MRI at 5 weeks revealed extensive periventricular white matter lesions. Since the patient remained clinically stable and asymptomatic during the follow-up period, no additional studies were performed and no additional treatments were provided. At the 1-year follow-up, cranial MRI showed complete disappearance of the abnormal high signal intensities previously seen in the white matter. The patient continued to remain healthy with no focal neurologic deficits on examination. This is the first case of asymptomatic self-limited white matter lesions seen in serial MRI studies in a Korean boy with EBV encephalitis.

Herpes simplex virus encephalitis in a patient with complete TLR3 deficiency: TLR3 is otherwise redundant in protective immunity

A new autosomal recessive form of complete TLR3 deficiency reveals that human TLR3 is nonredundant in immunity against herpes simplex virus 1 in the central nervous system (CNS) but redundant in host defense against viruses outside the CNS.

Autosomal dominant TLR3 deficiency has been identified as a genetic etiology of childhood herpes simplex virus 1 (HSV-1) encephalitis (HSE). This defect is partial, as it results in impaired, but not abolished induction of IFN-β and -λ in fibroblasts in response to TLR3 stimulation. The apparently normal resistance of these patients to other infections, viral illnesses in particular, may thus result from residual TLR3 responses. We report here an autosomal recessive form of complete TLR3 deficiency in a young man who developed HSE in childhood but remained normally resistant to other infections. This patient is compound heterozygous for two loss-of-function TLR3 alleles, resulting in an absence of response to TLR3 activation by polyinosinic-polycytidylic acid (poly(I:C)) and related agonists in his fibroblasts. Moreover, upon infection of the patient’s fibroblasts with HSV-1, the impairment of IFN-β and -λ production resulted in high levels of viral replication and cell death. In contrast, the patient’s peripheral blood mononuclear cells responded normally to poly(I:C) and to all viruses tested, including HSV-1. Consistently, various TLR3-deficient leukocytes from the patient, including CD14⁺ and/or CD16⁺ monocytes, plasmacytoid dendritic cells, and in vitro derived monocyte-derived macrophages, responded normally to both poly(I:C) and HSV-1, with the induction of antiviral IFN production. These findings identify a new genetic etiology for childhood HSE, indicating that TLR3-mediated immunity is essential for protective immunity to HSV-1 in the central nervous system (CNS) during primary infection in childhood, in at least some patients. They also indicate that human TLR3 is largely redundant for responses to double-stranded RNA and HSV-1 in various leukocytes, probably accounting for the redundancy of TLR3 for host defense against viruses, including HSV-1, outside the CNS.

Inducing-Apoptotic Activity of the Ethanol Extract of Duchesnea Indica Focke on Treatment of Herpes Simplex Encephalitis

This study explores the inducing-apoptotic activity of the ethanol extract of Duchesnea indica Focke on treatment of herpes simplex encephalitis. Cell models were employed and divided into 4 groups: normal group, virus group, Duchesnea indica group and dexamethasone group. Cytopathic effect examination was employed to detect apoptosis of PC-12 and BV-2 cells. ELISA was used to measure TNF-α and IL-1β, and Greiss method to measure NO secretion. Flow cytometry assay for caspase-3 expressions was performed. As a result, the ethanol extract of Duchesnea indica could protect the neuron cell model from impairment by virus. In the cell model of microglia stimulated by herpes simplex virus (HSV), with the ethanol extract intervention, TNF-α, IL-1β and NO levels were significantly decreased and cell death of BV-2 cells were markedly increased. The expression level of caspase-3 was notably elevated after the extract intervention. In conclusion, the ethanol extract of Duchesnea indica can reduce HSV-induced inflammatory injury on neuron due to the induction of microglia apoptosis.

Defects of pattern recognition: primary immunodeficiencies of the innate immune system

Genetic defects leading to impaired recognition of invading pathogens by the innate immune system, and hence to increased susceptibility to specific classes of microorganisms have been recently recognized. To date, defects have been described in three of the major families of pattern recognition receptors (PRRs): the Toll-like receptors (TLRs), the C-type lectin receptors (CLRs), and the nucleotide binding domain leucine-rich repeat containing receptors (NLRs). By contrast, defects in the viral receptors RigI helicases have not been found. PRR defects vary greatly in severity, display a narrow susceptibility profile towards specific pathogens, and when severe in infancy and childhood, often decrease in severity thereafter. Their discovery leads to crucial insight in the pathophysiology of infections, and offer therapeutic targets for future immunotherapy.

Early ''relapse'' after herpetic encephalitis: extensive white matter lesions in an infant with interferon production deficit

Acute secondary neurological deterioration after herpes simplex encephalitis has been reported. An immune-mediated process is thought to be responsible for some cases. The authors report the case of an infant who presented with fever, irritability, and orofacial involuntary movements, 15 days after herpes encephalitis onset. Polymerase chain reaction for herpes simplex virus was negative, and the magnetic resonance imaging revealed extensive white matter lesions. Chorea appeared only 11 days later. Raised immunoglobulin G index with oligoclonal bands and spreading of white matter lesions corroborated an immune-mediated etiology. An interferon production deficit was also detected. This case alerts that this form of ''relapse'' appears earlier than previously reported. A high level of suspicion is needed in the presence of atypical neurological deterioration and early white matter lesions should be considered as a warning sign. This case is also relevant because it associates, for the first time, an immune-mediated ''relapse'' to an interferon production deficit.

Age-dependent Mendelian predisposition to herpes simplex virus type 1 encephalitis in childhood

OBJECTIVE

To test the hypothesis that predisposition to childhood herpes simplex virus (HSV) type 1 encephalitis (HSE) may be determined in part by human genetic factors.

STUDY DESIGN

A genetic epidemiologic survey of childhood HSE (onset at age 3 months to 15 years) over a 20-year period (1985-2004) was conducted throughout France (comprising 29 university hospital neuropediatric centers). A total of 85 children fulfilled the diagnostic criteria for inclusion. Family and personal histories were obtained by face-to-face interview for 51 patients.

RESULTS

No familial cases of HSE were identified in our survey; however, a high proportion (20%) of the children interviewed had a relevant family history: parental consanguinity (12% of patients), early-onset herpetic keratitis in a first-degree relative (6%), or both (2%). The narrow window of high susceptibility to HSE before age 3 years (62% of patients) further indicates that predisposition to HSE is tightly age-dependent.

CONCLUSIONS

This survey suggests that childhood HSE, although sporadic, may result from Mendelian predisposition (from autosomal recessive susceptibility in particular), at least in some children. There likely is incomplete penetrance, however, which may reflect, at least in part, the impact of age at the time of HSV-1 infection.