Japanese Encephalitis Virus Transmitted Via Blood Transfusion, Hong Kong, China

Japanese encephalitis virus (JEV) is a mosquitoborne virus endemic to China and Southeast Asia that causes severe encephalitis in <1% of infected persons. Transmission of JEV via blood transfusion has not been reported. We report transmission of JEV via blood donation products from an asymptomatic viremic donor to 2 immunocompromised recipients. One recipient on high-dose immunosuppressive drugs received JEV-positive packed red blood cells after a double lung transplant; severe encephalitis and a poor clinical outcome resulted. JEV RNA was detected in serum, cerebrospinal fluid, and bronchoalveolar lavage fluid specimens. The second recipient had leukemia and received platelets after undergoing chemotherapy. This patient was asymptomatic; JEV infection was confirmed in this person by IgM seroconversion. This study illustrates that, consistent with other pathogenic flaviviruses, JEV can be transmitted via blood products. Targeted donor screening and pathogen reduction technologies could be used to prevent transfusion-transmitted JEV infection in highly JEV-endemic areas.

Antiepileptic drugs for the primary and secondary prevention of seizures in viral encephalitis

STATEMENT

The mission of the Cochrane Nursing Care Field (CNCF) is to improve health outcomes through increasing the use of the Cochrane Library and supporting Cochrane's role by providing an evidence base for nurses and healthcare professionals who deliver, lead or research nursing care. The CNCF produces Cochrane Corner columns, summaries of recent nursing-care-relevant Cochrane Reviews that are regularly published in collaborating nursing-related journals. Information on the processes CNCF has developed can be accessed at: cncf.cochrane.org/evidence-transfer-program-review-summaries. This is a Cochrane review summary of: Pandey S, Rathore C, Michael D ( 2016 ) Antiepileptic drugs for the primary and secondary prevention of seizures in viral encephalitis. Cochrane Database of Systematic Reviews. Issue 5. CD010247. doi: 10.1002/14651858.CD010247.pub3.

[Detection of West Nile virus in human samples: follow-up studies during the 2015 seasonal period]

INTRODUCTION

West Nile virus, a mosquito-borne viral zoonosis is responsible for human infections in Hungary. Laboratory diagnosis is based on serological tests, however the application of molecular methods has been appreciated.

AIM

The aim of the study was to investigate blood, cerebrospinal-fluid and urine samples of acutely ill patients and to follow-up PCR positive cases to ascertain the length of virus excretion.

METHOD

Clinical specimens were examined by indirect-immunofluorescent, haemagglutination-inhibition, two PCR tests and Sanger-sequencing. Virus isolation in case of two patients was successful.

RESULTS

A follow-up study could be carried out in case of 5 patients. Viral nucleic acid was detectable in urine even for several weeks after symptom onset and viral RNA was present at higher concentration compared with other samples.

CONCLUSIONS

PCR analysis of urine could provide useful epidemiological and diagnostic information. Therefore, it is recommended to collect urine samples in order to supplement the serological diagnosis. Orv Hetil. 2017; 158(20): 791-796.

Estimating the annual burden of tick-borne encephalitis to inform vaccination policy, Slovenia, 2009 to 2013

With an annual incidence between 8 and 15 per 100,000 population in the period from 2009 to 2013, Slovenia has one of the highest notified incidences of tick-borne encephalitis (TBE) in Europe. TBE vaccination coverage remains at about 7.3%. To inform vaccination policy, we used surveillance data from 2009 to 2013 to calculate the overall and age- and sex-specific mean annual TBE incidence. We estimated disability-adjusted life years (DALYs) with 95% uncertainty intervals (UI), using the Burden of Communicable Diseases in Europe approach from the European Centre for Disease Prevention and Control. The mean annual incidence was 11.6 per 100,000 population, peaking in older age groups (50-74 years: 18.5/100,000) while relatively lower among children (5-14 years: 10.2/100,000). We estimated an overall 10.95 DALYs per 100,000 population per year (95% UI: 10.25-11.65). In contrast to the TBE incidence, the disease burden in children aged 5-14 years was higher than in adults aged 50-74 years: 17.31 (95% UI: 14.58-20.08) and 11.58 (95% UI: 10.25-12.91) DALYs per 100,000 stratum-specific population, respectively. In a limited resource setting where prioritisation of TBE vaccination strategies is required, vaccination programmes targeting children may have a higher impact on disease burden.

The role and mechanism of NF-κB in viral encephalitis of children

The aim of this study was to analyze the concentration changes of nuclear factor-κB (NF-κB) and the related inflammatory factors of pre-treatment and post-treatment in children with viral encephalitis, to examine the mechanism of NF-κB in the pathogenesis of child viral encephalitis. Twenty-two children with severe viral encephalitis, 13 children with mild viral encephalitis and 12 normal children, who were treated in our hospital, were randomly selected. Before and after treatment, the concentrations of inflammation-related factors in serum including interleukin (IL)-1, IL-6 and tumor necrosis factor-α (TNF-α) were detected by ELISA and comparative analysis were performed. The expression of NF-κB in peripheral blood and cerebrospinal fluid (CSF) before and after treatment was detected by RT-PCR and western blotting, while the difference of NF-κB expressions between viral encephalitis children and normal children was analyzed. The concentrations of inflammation-related factors in serum of children with viral encephalitis, including IL-1, IL-6 and TNF-α were significantly higher than those of normal children (P<0.01), and after treatment, the concentrations of IL-1, IL-6 and TNF-α were distinctly lower than those of pre-treatment (P<0.01). The concentrations of NF-κB in peripheral blood and CSF of children with viral encephalitis in the mild group and severe group were evidently increased compared to those of pre-treatment, while the degree of increase in the severe group was higher than that in mild group, which was higher than that in the control group (P<0.01). After treatment, the concentrations of serum NF-κB of children in the severe and mild groups were distinctly lower than those of pre-treatment (P<0.01), with statistically significant difference. In conclusion, the NF-κB level in serum and CSF of children with viral encephalitis was positively related to the severity of the disease. The higher the concentration of pre-treatment was, the more serious the disease would be. Our results indicate that NF-κB plays an important role in the occurrence and development of viral encephalitis in children.

Early recognition of encephalitis in acute settings

Encephalitis is a life-threatening condition in which inflammation of the brain tissue occurs. Although it is relatively rare, misdiagnosis or delays in recognition and treatment can have devastating consequences for patients, and there is a high mortality rate. People who survive are often left with neuropsychological impairment. This article describes the pathophysiology of the condition, as well as clinical presentation and treatment, and explains why it can be easily missed. It includes a case study that describes a situation in which the condition was not considered initially as a differential diagnosis, and considers implications for practice.

Complement Components Are Expressed by Infiltrating Macrophages/Activated Microglia Early Following Viral Infection

The individual innate immune components, interleukin-6 and complement component C3, play a role in the development of acute seizures in the Theiler's murine encephalomyelitis virus-induced seizure model. We examined the mRNA expression of various other complement components, cytokines, chemokines, and major histocompatibility complex antigens both within brain and in isolated ramified microglial and infiltrating macrophage/activated microglial cell populations over a time course covering the first 3 days postinfection. We found that complement component C3 showed the greatest increase in expression in brain of all of the complement components assayed and its level of expression was higher in infiltrating macrophages/activated microglia than in ramified microglial cells.

First human case of tick-borne encephalitis virus infection acquired in the Netherlands, July 2016

In July 2016, the first autochthonous case of tick-borne encephalitis was diagnosed in the Netherlands, five days after a report that tick-borne encephalitis virus (TBEV) had been found in Dutch ticks. A person in their 60s without recent travel history suffered from neurological symptoms after a tick bite. TBEV serology was positive and the tick was positive in TBEV qRT-PCR. TBEV infection should be considered in patients with compatible symptoms in the Netherlands.

Criteria to Screen Molecular Tests for the Diagnosis of Herpes Simplex Virus in the Central Nervous System have no Propensity to Harm

Objectives:

Investigators have ruled out herpes simplex virus (HSV) infection without the detection of herpes simplex deoxyribonucleic acid in cerebrospinal fluid (CSF) (i.e., HSV polymerase chain reaction [PCR]) by laboratory (normal CSF white blood cell count and protein) and clinical criteria (age ≥2 years, no history of human immunodeficiency virus or solid-organ transplant). Compared to HSV PCR of all samples, the algorithm saves money in test costs and may decrease exposure to acyclovir by illustrating the low probability that the patient has HSV. Concern exists that algorithm use may cause harm through alteration of empiric acyclovir treatment in patients with true HSV central nervous system infection.

Methods:

All Department of Veterans Affair's patients with a positive HSV PCR of the CSF between 2000 and 2013 were identified and their medical records reviewed to determine the extent and possible impact of omitted HSV PCR testing by the algorithm.

Results:

Of 6357 total results, 101 patients had a positive CSF HSV PCR in the study period. Among the positive CSF HSV PCR results, the algorithm excluded 7 (7%) from PCR testing. Record review indicated these seven patients not tested by the algorithm with a positive CSF HSV PCR were considered by their attending physician not to have active HSV.

Conclusion:

The algorithm to screen HSV tests had no propensity to harm.

Validity of the coding for herpes simplex encephalitis in the Danish National Patient Registry

Background

Large health care databases are a valuable source of infectious disease epidemiology if diagnoses are valid. The aim of this study was to investigate the accuracy of the recorded diagnosis coding of herpes simplex encephalitis (HSE) in the Danish National Patient Registry (DNPR).

Methods

The DNPR was used to identify all hospitalized patients, aged ≥15 years, with a first-time diagnosis of HSE according to the International Classification of Diseases, tenth revision (ICD-10), from 2004 to 2014. To validate the coding of HSE, we collected data from the Danish Microbiology Database, from departments of clinical microbiology, and from patient medical records. Cases were classified as confirmed, probable, or no evidence of HSE. We estimated the positive predictive value (PPV) of the HSE diagnosis coding stratified by diagnosis type, study period, and department type. Furthermore, we estimated the proportion of HSE cases coded with nonspecific ICD-10 codes of viral encephalitis and also the sensitivity of the HSE diagnosis coding.

Results

We were able to validate 398 (94.3%) of the 422 HSE diagnoses identified via the DNPR. Hereof, 202 (50.8%) were classified as confirmed cases and 29 (7.3%) as probable cases providing an overall PPV of 58.0% (95% confidence interval [CI]: 53.0–62.9). For “Encephalitis due to herpes simplex virus” (ICD-10 code B00.4), the PPV was 56.6% (95% CI: 51.1–62.0). Similarly, the PPV for “Meningoencephalitis due to herpes simplex virus” (ICD-10 code B00.4A) was 56.8% (95% CI: 39.5–72.9). “Herpes viral encephalitis” (ICD-10 code G05.1E) had a PPV of 75.9% (95% CI: 56.5–89.7), thereby representing the highest PPV. The estimated sensitivity was 95.5%.

Conclusion

The PPVs of the ICD-10 diagnosis coding for adult HSE in the DNPR were relatively low. Hence, the DNPR should be used with caution when studying patients with encephalitis caused by herpes simplex virus.

Diagnostics and Discovery in Viral Central Nervous System Infections

The range of viruses implicated in central nervous system disease continues to grow with globalization of travel and trade, emergence and reemergence of zoonoses and investments in discovery science. Diagnosis of viral central nervous system infections is challenging in that brain tissue, where the pathogen concentration is likely to be highest, is not readily obtained and sensitive methods for molecular and serological detection of infection are not available in most clinical microbiology laboratories. Here we review these challenges and discuss how they may be addressed using advances in molecular, proteomic and immunological methods.

Inflammatory Biomarkers Associated with Lethal Rift Valley Fever Encephalitis in the Lewis Rat Model

Rift Valley fever (RVF) is an emerging viral disease that causes significant human and veterinary illness in Africa and the Arabian Peninsula. Encephalitis is one of the severe complications arising from RVF virus (RVFV) infection of people, and the pathogenesis of this form of RVF is completely unknown. We use a novel reproducible encephalitic disease model in rats to identify biomarkers of lethal infection. Lewis rats were infected with RVFV strain ZH501 by aerosol exposure, then sacrificed daily to determine the course of infection and evaluation of clinical, virological, and immunological parameters. Weight loss, fever, and clinical signs occurred during the last 1-2 days prior to death. Prior to onset of clinical indications of disease, rats displayed marked granulocytosis and thrombocytopenia. In addition, high levels of inflammatory chemokines (MCP-1, MCS-F, Gro/KC, RANTES, and IL-1β) were detected first in serum (3-5 dpi) followed by brain (5-7 dpi). The results of this study are consistent with clinical data from human RVF patients and validate Lewis rats as an appropriate small animal model for RVF encephalitis. The biomarkers we identified here will be useful in future studies evaluating the efficacy of novel vaccines and therapeutics.

Viral encephalitis complicated by acute retinal necrosis syndrome: A case report

Acute retinal necrosis syndrome (ARN) is a viral infection characterized by focal retinal necrosis. Viral meningitis complicated by ARN is relatively rare. In the present case study, a 44-year-old male presented with fever, headache and mental disorder. After four days, the patient developed blurred vision. The patient was diagnosed with viral encephalitis complicated by bilateral ARN, based on the examination results. After treatment with antivirals and systemic glucocorticoids, the symptoms of the patient improved. Viral encephalitis may be an important risk factor for ARN. For a patient with viral encephalitis who experiences decreased visual acuity or vitreous opacification, the possibility of ARN should be considered.

Avian Bornaviruses in North American Gulls

Avian bornaviruses, recently described members of the family Bornaviridae, have been isolated from captive parrots and passerines as well as wild waterfowl in which they may cause lethal neurologic disease. We report detection of avian bornavirus RNA in the brains of apparently healthy gulls. We tested 439 gull brain samples from 18 states, primarily in the northeastern US, using a reverse-transcriptase PCR assay with primers designed to detect a conserved region of the bornavirus M gene. Nine birds yielded a PCR product of appropriate size. Sequencing of PCR products indicated that the virus was closely related to aquatic bird bornavirus 1 (ABBV-1). Viral RNA was detected in Herring Gulls (Larus argentatus), Ring-billed Gulls (Larus delawarensis), and Laughing Gulls (Leucophaeus atricilla). Eight of the nine positive birds came from the New York/New Jersey area. One positive Herring Gull came from New Hampshire. Histopathologic examination of one well-preserved brain from a Herring Gull from Union County New Jersey, showed a lymphocytic encephalitis similar to that observed in bornavirus-infected parrots and geese. Bornavirus N protein was confirmed in two Herring Gull brains by immunohistochemistry. Thus ABBV-1 can infect gulls and cause encephalitic brain lesions similar to those observed in other birds.

Establishment of a panel of in-house polyclonal antibodies for the diagnosis of enterovirus infections

The aim of this study was to establish a reliable method of virus detection for the diagnosis of critical enterovirus infections such as acute infective encephalitis, encephalomyelitis and myocarditis. Because histopathological and immunohistochemical analyses of paraffin-embedded tissues play an important role in recognizing infectious agents in tissue samples, six in-house polyclonal antibodies raised against three representative enteroviruses using an indirect immunofluorescence assay and immunohistochemistry were examined. This panel of polyclonal antibodies recognized three serotypes of enterovirus. Two of the polyclonal antibodies were raised against denatured virus particles from enterovirus A71, one was raised against the recombinant VP1 protein of coxsackievirus B3, and the other for poliovirus type 1 were raised against denatured virus particles, the recombinant VP1 protein and peptide 2C. Western blot analysis revealed that each of these antibodies recognized the corresponding viral antigen and none cross-reacted with non-enteroviruses within the family Picornaviridae. However, all cross-reacted to some extent with the antigens derived from other serotypes of enterovirus. Indirect immunofluorescence assay and immunohistochemistry revealed that the virus capsid and non-structural proteins were localized in the cytoplasm of affected culture cells, and skeletal muscles and neurons in neonatal mice experimentally-infected with human enterovirus. The antibodies also recognized antigens derived from recent clinical isolates of enterovirus A71, coxsackievirus B3 and poliovirus. In addition, immunohistochemistry revealed that representative antibodies tested showed the same recognition pattern according to each serotype. Thus, the panel of in-house anti-enterovirus polyclonal antibodies described herein will be an important tool for the screening and pathological diagnosis for enterovirus infections, and may be useful for the classification of different enterovirus serotypes, including coxsackieviruses A and B, echoviruses, enterovirus A71 and poliovirus.

Rasmussen's encephalitis: A case report

Rasmussen's encephalitis (RE) is a rare neurological disorder of inflammatory aetiology characterised by encephalitis, intractable seizures, hemiparesis, variable motor deficits, and dementia. It is not commonly considered in the clinical differential diagnosis of a patient with a past history of a stroke-like episode presenting with status epilepticus. It is suspected mainly in children in whom the disease is more common. Here we report a case of an adult man presenting with a common symptom of seizure caused by Rasmussen's encephalitis.

Interleukin 10 modulation of pathogenic Th17 cells during fatal alphavirus encephalomyelitis

Mosquito-borne alphaviruses are important causes of epidemic encephalomyelitis. Neuronal cell death during fatal alphavirus encephalomyelitis is immune-mediated; however, the types of cells involved and their regulation have not been determined. We show that the virus-induced inflammatory response was accompanied by production of the regulatory cytokine IL-10, and in the absence of IL-10, paralytic disease occurred earlier and mice died faster. To determine the reason for accelerated disease in the absence of IL-10, immune responses in the CNS of IL-10(-/-) and wild-type (WT) mice were compared. There were no differences in the amounts of brain inflammation or peak virus replication; however, IL-10(-/-) animals had accelerated and increased infiltration of CD4(+)IL-17A(+) and CD4(+)IL-17A(+)IFNγ(+) cells compared with WT animals. Th17 cells infiltrating the brain demonstrated a pathogenic phenotype with the expression of the transcription factor, Tbet, and the production of granzyme B, IL-22, and GM-CSF, with greater production of GM-CSF in IL-10(-/-) mice. Therefore, in fatal alphavirus encephalomyelitis, pathogenic Th17 cells enter the CNS at the onset of neurologic disease and, in the absence of IL-10, appear earlier, develop into Th1/Th17 cells more often, and have greater production of GM-CSF. This study demonstrates a role for pathogenic Th17 cells in fatal viral encephalitis.

Ischemic Stroke as a Complication of Varicella Zoster Encephalitis: A Case Report With Detailed EEG Discussion

A 72-year-old man with varicella zoster virus (VZV) encephalitis complicated by an ischemic stroke in the right internal capsule, possibly due to secondary small-vessel vasculopathy, is described in this case report. The focus of this article is on the electroencephalogram (EEG) description of varicella zoster encephalitis and secondary vasculopathy because EEG descriptions are scarce in the literature and detailed descriptions are lacking. In this patient's EEG, right temporal theta waves were found in combination with a mild slowing of the background rhythm to 7.5 to 8 Hz in the acute stage with an amplitude asymmetry (right temporal lobe amplitudes were significantly higher compared with the left side). The theta waves were thought to originate from the ischemic lacunar stroke, the slowing of the background rhythm from early encephalitis, and the amplitude asymmetry was presumed to be of physiologic origin. A follow-up EEG 6 days after initiation of treatment with acyclovir showed a normal symmetrical background rhythm of 8 to 8.5 Hz, wherein the theta waves were significantly reduced in abundance, and the amplitude asymmetry was unchanged. In conclusion, the EEG may localize focal abnormalities possibly due to cortical or lacunar ischemia, which could be explained by early small and/or large vessel vasculopathy in patients with suspected VZV encephalitis.

Gliomatosis cerebri mimicking acute viral encephalitis and with malignant transformation of partial lesions: A case report

Gliomatosis cerebri (GC) is a rare glial neoplasm, characterized by extensive diffuse brain infiltration and relative preservation of the underlying architecture. In the present case report, a patient with type 2 GC, which mimicked the clinicoradiological course of acute viral encephalitis, is presented. A 56-year-old male presented with fever, dizziness, headache and numbness in the right extremities three days prior to admission to hospital. The cerebrospinal fluid (CSF) showed mild pleocytosis. Brain magnetic resonance imaging (MRI) revealed hyperintensity on fluid-attenuated inversion recovery images in the left frontal, temporal, insular lobes and in the left thalamus. No signal enhancement was observed following gadolinium administration. The patient was diagnosed with acute viral encephalitis of unknown cause and received a 10-day course of acyclovir, intravenously. At the follow-up three months later, the patient had personality changes and memory deterioration. The results from the follow-up MRI revealed no remarkable changes. At the follow-up six months after presentation, the patient had expressive aphasia and severe headaches. Subsequently, the patient had two tonic-clonic seizure onsets. The results from the MRI showed an increase in lesion size, more edema around the lesion and irregular enhancement in the left frontal lobe. However, the lesions in the left temporal and insular lobes and in the left thalamus were nearly unchanged. Magnetic resonance spectroscopy (MRS) showed elevated choline (Cho)/creatine (Cr) and Cho/N-acetylaspartate (NAA) ratios, as well as decreased NAA/Cr ratios. Surgery was performed and the neuropathological diagnosis of WHO grade III astrocytoma was confirmed. Thus, it is important to pay attention to the differential diagnoses of GC and acute viral encephalitis in patients who have widespread MRI lesions. A brain biopsy is recommended for a diagnosis in this case.

Etanercept reduces neuroinflammation and lethality in mouse model of Japanese encephalitis

BACKGROUND

Japanese encephalitis virus (JEV) is a neurotropic flavivirus that causes Japanese encephalitis (JE), which leads to high fatality rates in human. Tumor necrosis factor alpha (TNF-α) is a key factor that mediates immunopathology in the central nervous system (CNS) during JE. Etanercept is a safe anti-TNF-α drug that has been commonly used in the treatment of various human autoimmune diseases.

METHODS

The effect of etanercept on JE was investigated with a JEV-infected mouse model. Four groups of mice were assigned to receive injections of phosphate-buffered saline, etanercept, JEV, or JEV plus etanercept. Inflammatory responses in mouse brains and mortality of mice were evaluated within 23 days post infection.

RESULTS

The in vitro assay with mouse neuron/glia cultures showed that etanercept treatment reduced the inflammatory response induced by JEV infection. In vivo experiments further demonstrated that administration of etanercept protected mice from JEV-induced lethality. Neuronal damage, glial activation, and secretion of proinflammatory cytokines were found to be markedly decreased in JEV-infected mice that received etanercept treatment. Additionally, etanercept treatment restored the integrity of the blood-brain barrier and reduced viral load in mouse brains.

CONCLUSIONS

Etanercept effectively reduces the inflammation and provides protection against acute encephalitis in a JEV-infected mouse model.

Basics of virology

Viruses are important pathogens of the nervous system. Here we describe the basic properties of viruses and the principles of virus classification, evolution, structure, and replication, with a focus on neurotropic viruses that are important neuropathogens of humans. These properties then provide the background for introductions to pathogenesis of viral diseases of the nervous system, host immune responses to virus infection, and the diagnosis and treatment of virus infections of the nervous system.

Temporal changes of Japanese encephalitits virus in different brain regions of rat

BACKGROUND & OBJECTIVES

Japanese encephalitis virus (JEV) infection results in acute encephalitic illness. The affinity of JEV to different regions of brain and temporal changes in viral load have not been studied. This study was conducted to describe localization of JEV to different regions of the brain at different stages of disease in a rat model of Japanese encephalitis (JE).

METHODS

Twelve days old Wistar rats were inoculated intracerebrally with a dose of 3 x 10⁶ pfu/ml of JEV. After 3, 6, 10 and 20 days post-inoculation, brains were dissected out and different regions of brain (cortex, striatum, thalamus and mid brain) were taken. Motor deficit was assessed by the rota rod and JEV RNA copies were evaluated using real-time PCR assay.

RESULTS

There was a significant increase in motor deficit in rats inoculated with JEV compared to the controls. JEV RNA copies were present in all studied regions of the brain on days 3, 6 and 10 post-inoculation. Maximum number of JEV RNA copies were present in the mid brain on days 3 and 10 post-inoculation. JEV RNA copies were not detected in any of the brain regions on day 20.

INTERPRETATION & CONCLUSIONS

This study reports JEV RNA load in different brain regions of rat with higher affinity of JEV virus to thalamus and mid brain compared to other regions.

Shuanghuanglian injection downregulates nuclear factor-kappa B expression in mice with viral encephalitis

A mouse model of viral encephalitis was induced by intracranial injection of a Coxsackie virus B3 suspension. Quantitative real-time reverse transcription-PCR and western blot assay were applied to detect mRNA and protein expression of intelectin-2 and nuclear factor-kappa B in the viral encephalitis and control groups. Nuclear factor-kappa B and intelectin-2 mRNA and protein expression were significantly increased in mice with viral encephalitis. After intraperitoneal injection of Shuanghuanglian at a dose of 1.5 mg/kg for 5 successive days, intelectin-2 and nuclear factor-kappa B protein and mRNA expression were significantly decreased. To elucidate the relationship between intelectin-2 and nuclear factor-kappa B, mice with viral encephalitis were administered an intracerebral injection of 107 pfu recombinant lentivirus expressing intelectin shRNA. Both protein and mRNA levels of intelectin and nuclear factor-kappa B in brain tissue of mice were significantly decreased. Experimental findings suggest that Shuanghuanglian injection may downregulate nuclear factor-kappa B production via suppression of intelectin production, thus inhibiting inflammation associated with viral encephalitis.

Viral CNS infections: role of glial pattern recognition receptors in neuroinflammation

Viruses are the major causative agents of central nervous system (CNS) infection worldwide. RNA and DNA viruses trigger broad activation of glial cells including microglia and astrocytes, eliciting the release of an array of mediators that can promote innate and adaptive immune responses. Such responses can limit viral replication and dissemination leading to infection resolution. However, a defining feature of viral CNS infection is the rapid onset of severe neuroinflammation and overzealous glial responses are associated with significant neurological damage or even death. The mechanisms by which microglia and astrocytes perceive neurotropic RNA and DNA viruses are only now becoming apparent with the discovery of a variety of cell surface and cytosolic molecules that serve as sensors for viral components. In this review we discuss the role played by members of the Toll-like family of pattern recognition receptors (PRRs) in the inflammatory responses of glial cells to the principle causative agents of viral encephalitis. Importantly, we also describe the evidence for the involvement of a number of newly described intracellular PRRs, including retinoic acid-inducible gene I and DNA-dependent activator of IFN regulatory factors, that are thought to function as intracellular sensors of RNA and DNA viruses, respectively. Finally, we explore the possibility that cross-talk exists between these disparate viral sensors and their signaling pathways, and describe how glial cytosolic and cell surface/endosomal PRRs could act in a cooperative manner to promote the fulminant inflammation associated with acute neurotropic viral infection.

Neurotropic viral infections leading to epilepsy: focus on Theiler's murine encephalomyelitis virus

Neurotropic viruses cause viral encephalitis and are associated with the development of seizures/epilepsy. The first infection-driven animal model for epilepsy, the Theiler's murine encephalomyelitis virus-induced seizure model is described herein. Intracerebral infection of C57BL/6 mice with Theiler's murine encephalomyelitis virus induces acute seizures from which the animals recover. However, once the virus is cleared, a significant portion of the animals that experienced acute seizures later develop epilepsy. Components of the innate immune response to viral infection, including IL-6 and complement component 3, have been implicated in the development of acute seizures. Multiple mechanisms, including neuronal cell destruction and cytokine activation, play a role in the development of acute seizures. Future studies targeting the innate immune response will lead to new therapies for seizures/epilepsy.

Update on rabies

Human rabies is almost invariably fatal, and globally it remains an important public health problem. Our knowledge of rabies pathogenesis has been learned mainly from studies performed in experimental animal models, and a number of unresolved issues remain. In contrast with the neural pathway of spread, there is still no credible evidence that hematogenous spread of rabies virus to the central nervous system plays a significant role in rabies pathogenesis. Although neuronal dysfunction has been thought to explain the neurological disease in rabies, recent evidence indicates that structural changes involving neuronal processes may explain the severe clinical disease and fatal outcome. Endemic dog rabies results in an ongoing risk to humans in many resource-limited and resource-poor countries, whereas rabies in wildlife is important in North America and Europe. In human cases in North America, transmission from bats is most common, but there is usually no history of a bat bite and there may be no history of contact with bats. Physicians may not recognize typical features of rabies in North America and Europe. Laboratory diagnostic evaluation for rabies includes rabies serology plus skin biopsy, cerebrospinal fluid, and saliva specimens for rabies virus antigen and/or RNA detection. Methods of postexposure rabies prophylaxis, including wound cleansing and administration of rabies vaccine and human rabies immune globulin, are highly effective after recognized exposure. Although there have been rare survivors of human rabies, no effective therapy is presently available. Therapeutic coma (midazolam and phenobarbital), ketamine, and antiviral therapies (known as the "Milwaukee protocol") were given to a rabies survivor, but this therapy was likely not directly responsible for the favorable outcome. New therapeutic approaches for human rabies need to be developed. A better understanding of basic mechanisms involved in rabies pathogenesis may be helpful in the development of potential new therapies for the future.

Emerging epidemic viral encephalitides with a special focus on henipaviruses

In the last few decades, there is an increasing emergence and re-emergence of viruses, such as West Nile virus, Enterovirus 71 and henipaviruses that cause epidemic viral encephalitis and other central nervous system (CNS) manifestations. The mortality and morbidity associated with these outbreaks are significant and frequently severe. While aspects of epidemiology, basic virology, etc., may be known, the pathology and pathogenesis are often less so, partly due to a lack of interest among pathologists or because many of these infections are considered "third world" diseases. In the study of epidemic viral encephalitis, the pathologist's role in unravelling the pathology and pathogenesis is critical. The novel henipavirus infection is a good example. The newly created genus Henipavirus within the family Paramyxoviridae consists of two viruses, viz., Hendra virus and Nipah virus. These two viruses emerged in Australia and Asia, respectively, to cause severe encephalitides in humans and animals. Studies show that the pathological features of the acute encephalitis caused by henipaviruses are similar and a unique dual pathogenetic mechanism of vasculitis-induced microinfarction and parenchymal cell infection in the CNS (mainly neurons) and other organs causes severe tissue damage. Both viruses can cause relapsing encephalitis months and years after the acute infection due to a true recurrent infection as evidenced by the presence of virus in infected cells. Future emerging viral encephalitides will no doubt continue to pose considerable challenges to the neuropathologist, and as the West Nile virus outbreak demonstrates, even economically advanced nations are not spared.

Emergence and re-emergence of viral diseases of the central nervous system

Neurologic disease is a major cause of disability in resource-poor countries and a substantial portion of this disease is due to infections of the CNS. A wide variety of emerging and re-emerging viruses contribute to this disease burden. New emerging infections are commonly due to RNA viruses that have expanded their geographic range, spread from animal reservoirs or acquired new neurovirulence properties. Mosquito-borne viruses with expanding ranges include West Nile virus, Japanese encephalitis virus and Chikungunya virus. Zoonotic viruses that have recently crossed into humans to cause neurologic disease include the bat henipaviruses Nipah and Hendra, as well as the primate-derived human immunodeficiency virus. Viruses adapt to new hosts, or to cause more severe disease, by changing their genomes through reassortment (e.g. influenza virus), mutation (essentially all RNA viruses) and recombination (e.g. vaccine strains of poliovirus). Viruses that appear to have recently become more neurovirulent include West Nile virus, enterovirus 71 and possibly Chikungunya virus. In addition to these newer challenges, rabies, polio and measles all remain important causes of neurologic disease despite good vaccines and global efforts toward control. Control of human rabies depends on elimination of rabies in domestic dogs through regular vaccination. Poliovirus eradication is challenged by the ability of the live attenuated vaccine strains to revert to virulence during the prolonged period of gastrointestinal replication. Measles elimination depends on delivery of two doses of live virus vaccine to a high enough proportion of the population to maintain herd immunity for this highly infectious virus.

[What future for ribavirin beyond hepatitis C therapy?]

Most of emerging and re-emerging diseases are due to RNA viruses and available drugs are insufficient. Currently the ribavirin is only licensed for the treatment of chronic hepatitis C infection, whereas this guanosin analogue has a broad-spectrum in vitro activity against many DNA and RNA viruses. It was consequently used as a last resort, in emergency state like avian influenza or in front of new viruses (SARS). The strategies for development of new antiviral drugs are usually based on virus structure and properties. In regard to recent development of chemical vector designed for improving drug bioavailability, use of former drug, like ribavirin, could be reconsidered. For example, complexation of ribavirin with cyclodextrins, cyclic oligosaccharide vectors, can improve its bioavailability in central nervous system and improve encephalitis treatment.

Conduct disorder-A sequelae of viral encephalitis

An 11-year-old girl presented with a behavioural problem of 2 years' duration, which developed following an attack of viral encephalitis. Her behavioural changes had manifested as conduct disorder and were treated with pharmacotherapy as well as behavioural therapy.

Viral encephalitis in England, 1989-1998: what did we miss?

We analyzed hospitalizations in England from April 1, 1989, to March 31, 1998, and identified approximately 700 cases, 46 fatal, from viral encephalitis that occurred during each year; most (60%) were of unknown etiology. Of cases with a diagnosis, the largest proportion was herpes simplex encephalitis. Using normal and Poisson regression, we identified six possible clusters of unknown etiology. Over 75% of hospitalizations are not reported through the routine laboratory and clinical notification systems, resulting in underdiagnosis of viral encephalitis in England. Current surveillance greatly underascertains incidence of the disease and existence of clusters; in general, outbreaks are undetected. Surveillance systems must be adapted to detect major changes in epidemiology so that timely control measures can be implemented.

Immunization with heterologous flaviviruses protective against fatal West Nile encephalitis

Prior immunization of hamsters with three heterologous flaviviruses (Japanese encephalitis virus [JEV] SA14-2-8 vaccine, wild-type St. Louis encephalitis virus [SLEV], and Yellow fever virus [YFV] 17D vaccine) reduces the severity of subsequent West Nile virus (WNV) infection. Groups of adult hamsters were immunized with each of the heterologous flaviviruses; approximately 30 days later, the animals were injected intraperitoneally with a virulent New York strain of WNV. Subsequent levels of viremia, antibody response, and deaths were compared with those in nonimmune (control) hamsters. Immunity to JEV and SLEV was protective against clinical encephalitis and death after challenge with WNV. The antibody response in the sequentially infected hamsters also illustrates the difficulty in making a serologic diagnosis of WNV infection in animals (or humans) with preexisting Flavivirus immunity.

Cervical lymphoid tissue but not the central nervous system supports proliferation of virus-specific T lymphocytes during coronavirus-induced encephalitis in rats

The CD4+ T lymphocyte response in the central nervous system (CNS) and cervical lymph nodes (CLNs) of rats with different susceptibility to coronavirus-induced encephalitis was investigated. The majority of CD4+ T lymphocytes entering the virus-infected CNS in the course of the infection are primed cells that neither proliferate ex vivo nor can be stimulated to proliferation by viral antigens or mitogen in vitro. In contrast, T lymphocytes taken from CLNs of the same animals revealed a strong proliferative response. Restimulation of CLN lymphocytes by viral antigens disclosed a striking difference between the disease-resistant rat strain Brown Norway (BN) and the susceptible Lewis (LEW) strain. Whereas BN lymphocytes responded as early as 5 days post infection, it took more than 11 days until a comparable proliferation was detectable in LEW lymphocytes. From these data we postulate that the majority of T lymphocytes entering the virus-infected brain after sensitisation and expansion in cervical lymph nodes is unresponsive to further proliferation signals and that the kinetics and magnitude of T lymphocyte stimulation in CLNs play an important role in the clinical course of the infection.

Serotonin turnover rate in raphe and cortex of mice infected with Venezuelan equine encephalomyelitis virus

The turnover of serotonin (5HT) was determined in the raphe area and cortex of mice infected with Pixuna, a strain of intermediate virulence of Venezuelan equine encephalomyelitis virus (VEEV). NMRI-mice, 24 days old, were inoculated intracerebrally (ic) with 300 LD50 of the virus. The animals were sacrificed 4, 7, 15, 21, 30, and 60 days postinoculation. 5HT and 5-hydroxyindoleacetic acid (5HIAA) in raphe and cortex were determined by high performance liquid chromatography (HPLC) with electrochemical detection. Turnover rate of 5HT was determined by the administration of pargyline, p-chlorophenylalanine, and probenecid. The content of 5HT or 5HIAA and 5HT/5HIAA ratios were not significantly different in infected compared with control mice. However, a decrease of 5HT turnover rate, determined after pargyline treatment, was observed in the raphe and not in the cortex of infected mice at 4 and 7 days after the inoculation. The turnover rate/(5HT)0 in raphe is decreased in infected mice with signs of illness, suggesting a lower density of 5HT innervation in this brain area. The administration of p-chlorophenylalanine and probenecid showed that the cortex is also affected, but the synthesis is less modified than metabolism or elimination. Cell bodies of 5HT neurons seem to be more susceptible than projections to infection by Pixuna strain of VEEV.