Antineuronal antibodies and infectious pathogens in severe acute pediatric encephalitis.

The pathogenesis of acute encephalitis is divided into either direct infection or by immune-mediated inflammation, but the cause is still unknown. This retrospective study aimed to screen antineuronal antibodies in children with severe acute encephalitis. Thirty-four children (22 boys and 12 girls) underwent assessments such as antineuronal antibodies survey for autoimmune encephalitis and polymerase chain reaction/viral culture and antibody assays for all commonly recognized causes of infectious encephalitis. Sixteen (47.1%) were positive for autoantibodies, including antiglutamic acid decarboxylase antibodies in 16 and voltage-gated potassium channel complex antibodies in 1. Sixteen patients (47.1%) had presumed infectious etiologies, including 6 with influenza, 6 with Mycoplasma pneumoniae, 3 with enterovirus, and 1 with herpes simplex virus. In this study, influenza and Mycoplasma pneumoniae infection are the main presumed causes of severe acute encephalitis in children, although an immune-mediated mechanism may also play a role.

Japanese encephalitis virus non-coding RNA inhibits activation of interferon by blocking nuclear translocation of interferon regulatory factor 3.

Noncoding RNA (ncRNA) plays a critical role in modulating a broad range of diseases. All arthropod-borne flaviviruses produce short fragment ncRNA (sfRNA) collinear with highly conserved regions of the 3'-untranslated region (UTR) in the viral genome. We show that the molar ratio of sfRNA to genomic RNA in Japanese encephalitis virus (JEV) persistently infected cells is greater than that in acutely infected cells, indicating an sfRNA role in establishing persistent infection. Transfecting excess quantities of sfRNA into JEV-infected cells reduced interferon-ß (IFN-ß) promoter activity by 57% and IFN-ß mRNA levels by 52%, compared to mock-transfected cells. Transfection of sfRNA into JEV-infected cells also reduced phosphorylation of interferon regulatory factor-3 (IRF-3), the IFN-ß upstream regulator, and blocked roughly 30% of IRF-3 nuclear localization. Furthermore, JEV-infected sfRNA transfected cells produced 23% less IFN-ß-stimulated apoptosis than mock-transfected groups did. Taken together, these results suggest that sfRNA plays a role against host-cell antiviral responses, prevents cells from undergoing apoptosis, and thus contributes to viral persistence.

Limbic encephalitis in Taiwanese children and adolescence: a single center study.

BACKGROUND: Non-viral limbic encephalitis, which may be paraneoplastic or idiopathic, is increasingly recognized in adults and children. Early identification of potential patients, who have neuronal autoantibodies to intracellular or neuronal surface antigens in order to give appropriate immunotherapy, is key to improving the prognosis. This cross-sectional study describes the clinical manifestation and the serological evidence of the presence of neuronal antibodies in Taiwanese children with limbic encephalitis. METHOD: We enrolled children and adolescents who had been hospitalized due to nonviral limbic encephalitis. Serum samples from these patients were collected to screen antibodies against intracellular antigens [amphiphysin, Ma2, Ri, Yo, Hu and antiglutamic acid decarboxylase (GAD)] and neuronal surface antigens [N-methyl-d-aspartate (NMDA) receptor, γ-amino butyric acid (GABAB) receptor and voltage-gated potassium channel complexes (VGKCs)]. RESULTS: All of the 10 enrolled patients had acute onset of fever and rapid clinical deterioration. They had persistent neuropsychiatric symptoms and 90% developed refractory epilepsy, despite six patients having been treated with methylprednisolone pulse therapy or intravenous immunoglobulin (IVIG) at the acute stage. In the laboratory findings, half of the cases were positive for antibodies with regards to intracellular antigens (amphiphysin or GAD). The general outcomes, assessed by Glasgow Outcome Scale, were similar between patients with and those without the antibodies (Mann-Whitney U test, p = 0.43). One patient, who was positive for antibodies to amphiphysin 10 years after disease onset, still had a significant response to oral prednisolone therapy. At the end of the follow-up period, no cancer or insulin-dependent diabetes mellitus was detected in any of the patients. CONCLUSION: This study provides evidence for a potential association between antibodies and limbic encephalitis. The presence of antibodies, especially antibodies to GAD, may serve as an indicator for immunotherapy.

Antiglutamic acid decarboxylase antibodies in children with encephalitis and status epilepticus.

Encephalitis may present with seizures or status epilepticus, and the etiology is usually presumed. Specific antibodies to ion channels, receptors, and other synaptic proteins were identified during the past decade. However, only a few studies investigated antiglutamic acid decarboxylase antibodies and antibodies to cell membrane ion channels or surface antigens in pediatric encephalitis and status epilepticus. We examined antibodies to glutamic acid decarboxylase and cell membrane ion channels or surface antigens in acute-phase serum from 17 children with encephalitis and status epilepticus. Antiglutamic acid decarboxylase antibody titers were compared with those of control children manifesting therapy-resistant epilepsy. Antiglutamic acid decarboxylase antibody titers were significantly higher in those with encephalitis and status epilepticus than in those with therapy-resistant epilepsy. No patient demonstrated antibodies to cell membrane ion channels or surface antigens. Six children exhibited positive antiglutamic acid decarboxylase antibodies. One child died, three manifested postencephalitic epilepsy with neurologic deficits, and two recovered well. Higher antiglutamic acid decarboxylase antibody titers were evident in the children with encephalitis and status epilepticus. Clinicians should be aware of the potential role of antiglutamic acid decarboxylase antibodies in children with encephalitis and status epilepticus.

Small noncoding RNA modulates Japanese encephalitis virus replication and translation in trans.

BACKGROUND: Sequence and structural elements in the 3'-untranslated region (UTR) of Japanese encephalitis virus (JEV) are known to regulate translation and replication. We previously reported an abundant accumulation of small subgenomic flaviviral RNA (sfRNA) which is collinear with the highly conserved regions of the 3'-UTR in JEV-infected cells. However, function of the sfRNA in JEV life cycle remains unknown. RESULTS: Northern blot and real-time RT-PCR analyses indicated that the sfRNA becomes apparent at the time point at which minus-strand RNA (antigenome) reaches a plateau suggesting a role for sfRNA in the regulation of antigenome synthesis. Transfection of minus-sense sfRNA into JEV-infected cells, in order to counter the effects of plus-sense sfRNA, resulted in higher levels of antigenome suggesting that the presence of the sfRNA inhibits antigenome synthesis. Trans-acting effect of sfRNA on JEV translation was studied using a reporter mRNA containing the luciferase gene fused to partial coding regions of JEV and flanked by the respective JEV UTRs. In vivo and in vitro translation revealed that sfRNA inhibited JEV translation. CONCLUSIONS: Our results indicate that sfRNA modulates viral translation and replication in trans.