Epstein-Barr Virus encephalitis associated hemophagocytic lymphohistiocytosis in childhood-onset systemic lupus erythematosus: a case-based review.

BACKGROUND: Hemophagocytic lymphohistiocytosis (HLH) is characterized by immune dysregulation that results in an uncontrolled hyperinflammatory state. HLH is classified into two main categories: primary (familial) HLH and secondary (acquired) HLH. Secondary HLH can result from various underlying, including infection-associated hemophagocytic syndrome (IAHS) and macrophage activation syndrome (MAS) associated with rheumatologic disorders, among others. Epstein-Barr virus (EBV) often causes IAHS, but central nervous system (CNS) involvement is rare among systemic lupus erythematosus (SLE) patients. We report a case of EBV encephalitis associated with HLH in a patient with childhood-onset SLE. CASE PRESENTATION: A 12-year-old girl had received a diagnosis of SLE 2 months before presentation. After a period of inactive disease on treatment, fever and seizures, with altered mental status and hallucinations, developed over several weeks. A complete blood cell count (CBC) revealed pancytopenia, accompanied by elevated levels of inflammatory markers: 86 mm/hr erythrocyte sedimentation rate, 8.9 mg/dl c-reactive protein, and 3,966 ng/mL of ferritin. The differential diagnosis included active neuropsychiatric SLE, CNS infection and neurological manifestations in secondary HLH, which could have represented either IAHS or MAS. Meropenem and acyclovir were initially administered for clinical acute encephalitis, followed by pulse methylprednisolone; however, the fever persisted, and another CBC revealed progressive cytopenia. A bone marrow study showed hypocellularity and active hemophagocytic activity, and intravenous immunoglobulin was additionally given due to the diagnosis of HLH. Cerebrospinal fluid (CSF) analysis showed 60/mm3 white blood cells (N 55%, L 45%), 141 mg/dL glucose (0.7 blood-CSF glucose ratio), < 4 mg/dL protein; results of Gram stain and bacterial culture were negative. The viral encephalitis panel from the CSF confirmed EBV infection. Bone marrow immunohistochemistry examination revealed increasing levels of CD8 + T-cell and equivocal positive results for EBV-encoded RNA in situ hybridization; therefore, HLH potentially associated with EBV was diagnosed. After treatment with IVIg, cyclosporin A, and prednisolone, the patient's symptoms gradually improved and she was eventually able to return to school. CONCLUSIONS: Our case highlights the importance of a thorough differential diagnosis, including EBV encephalitis associated with HLH, in patients with childhood SLE, particularly in cases of clinical deterioration occurs after initial treatment.

MAVS signaling shapes microglia responses to neurotropic virus infection.

Viral encephalitis is characterized by a series of immunological reactions that can control virus infection in the brain, but dysregulated responses may cause excessive inflammation and brain damage. Microglia are brain-resident myeloid cells that are specialized in surveilling the local CNS environment and in case of viral brain infection they contribute to the control of the infection and to restriction of viral dissemination. Here, we report that after exposure to neurotropic vesicular stomatitis virus (VSV), murine in vitro microglia cultures showed rapid upregulation of a broad range of pro-inflammatory and antiviral genes, which were stably expressed over the entire 8 h infection period. Additionally, a set of immunomodulatory genes was upregulated between 6 and 8 h post infection. In microglia cultures, the induction of several immune response pathways including cytokine responses was dependent on mitochondrial antiviral-signaling protein (MAVS). Consequently, in Mavs-deficient microglia the control of virus propagation failed as indicated by augmented virus titers and the accumulation of viral transcripts. Thus, in the analyzed in vitro system, MAVS signaling is critically required to achieve full microglia activation and to mediate profound antiviral effects. In Mavs-deficient mice, intranasal VSV instillation caused higher disease severity than in WT mice and virus dissemination was noticed beyond the olfactory bulb. Virus spread to inner regions of the olfactory bulb, i.e., the granular cell layer, correlated with the recruitment of highly inflammatory non-microglia myeloid cells into the olfactory bulb in Mavs-/- mice. Furthermore, increased cytokine levels were detected in the nasal cavity, the olfactory bulb and in other brain regions. Thus, microglial MAVS signaling is critically needed for virus sensing, full microglia activation, and for orchestration of protective immunity in the virus-infected CNS.

Dynamic findings of brain magnetic resonance imaging in a haploidentical hematopoietic stem cell transplantation recipient with cytomegalovirus ventriculoencephalitis: a case report and systematic review.

Our case demonstrated unique cytomegalovirus (CMV) encephalitis post-haploidentical donor hematopoietic stem cell transplantation (HID-HSCT), with early findings on diffusion-weighted brain magnetic resonance imaging (MRI) in the absence of any neurologic symptoms. A 54-year-old Chinese man with acute lymphoblastic leukemia (Philadelphia chromosome-negative) underwent HID-HSCT. After HSCT, the patient developed CMV viremia and severe acute graft-versus-host disease. Recurrence of CMV viremia was observed. On day 129, brain MRI was performed to determine the cause for the intermittent fever. Diffusion-weighted imaging (DWI) revealed several bright spots in the cortex of the frontal lobes and anterior angle of the left lateral ventricle. Subsequently, he developed transplant-associated thrombotic microangiopathy, posterior reversible encephalopathy syndrome, and enlargement of lesions alongside the ventricular wall on a brain MRI series. Metagenomic next-generation sequencing (NGS) of the cerebrospinal fluid (CSF) led to the final diagnosis of CMV encephalitis. Although ganciclovir combined with foscarnet was administered, the patient's consciousness deteriorated, followed by respiratory failure. The patient died on day 198. Additionally, we performed a systematic review to comprehensively analyze this disease. Regarding treatment, immunological therapies, including virus-specific T cells from a third donor and CMV-cytotoxic T lymphocytes, may be more effective. This case report and systematic review underscores the complexities of managing CMV ventriculoencephalitis in HSCT recipients and emphasizes the importance of early diagnosis by brain MRI and CSF polymerase chain reaction or NGS and ongoing research in improving outcomes.

SIV-specific antibodies protect against inflammasome-driven encephalitis in untreated macaques.

Viral encephalitis is a growing public health threat with limited diagnostic and treatment options. Simian immunodeficiency virus (SIV)-infected macaques are an established model for human immunodeficiency virus (HIV), and approximately 60% of untreated pigtail macaques rapidly progress to characteristic SIV encephalitis (SIVE). The immune responses of SIV-infected macaques are investigated in plasma, cerebrospinal fluid (CSF), and brain tissue to determine correlates with SIVE pathology. Macaques with SIVE show myeloid-dominant brain lesions with inflammasome activation in infected and bystander cells, as assessed by interleukin (IL)-1ß, IL-18, and apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC), and elevations in monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1α, and tumor necrosis factor alpha (TNF-α). SIV-specific immunoglobulin (Ig)G in plasma and CSF is predictive of SIVE as early as 21 days post-inoculation; animals with SIVE continue to show negligible seroconversion 3 months after infection. This dichotomy in immune responses, wherein some macaques fail to initiate robust IgG responses and subsequently develop SIVE, provides insight into the pathogenesis and heterogeneous outcomes in viral encephalitis.

[Relationship of cerebrospinal fluid and serum levels of SIL-2R, eNOS, and CD93 with the progression and prognosis of viral encephalitis in children]. / ç— æ¯’æ€§è„‘ç‚Žæ‚£å„¿è„‘è„Šæ¶²å’Œè¡€æ¸ ä¸­SIL-2R、eNOS、CD93æ°´å¹³ä¸Žç–¾ç— è¿›å±•åŠé¢„åŽçš„å ³ç³».

OBJECTIVES: To investigate the relationship of cerebrospinal fluid and serum levels of soluble interleukin-2 receptor (SIL-2R), endothelial nitric oxide synthase (eNOS), and cluster of differentiation 93 (CD93) with the progression and prognosis of viral encephalitis (VE) in children. METHODS: Prospectively, 102 children with VE admitted from January 2021 to January 2024 were selected as the VE group. The patients were divided into a mild subgroup (64 patients) and a severe subgroup (38 patients) according to disease progression. The patients were also divided into a good prognosis subgroup (29 patients) and a poor prognosis subgroup (73 patients) according to prognosis. A control group of 102 children with central nervous system diseases who were examined and found not to have VE during the same period was selected. The factors contributing to the poor prognosis of children with VE and the predictive value of SIL-2R, eNOS, and CD93 in cerebrospinal fluid and serum for the poor prognosis of children with VE were evaluated. RESULTS: Cerebrospinal fluid and serum SIL-2R, eNOS, and CD93 levels were significantly increased in the VE group, severe subgroup, and poor prognosis subgroup (P<0.05). Multivariate logistic regression analysis showed that high SIL-2R, eNOS, and CD93 levels in cerebrospinal fluid and serum were risk factors for poor prognosis in children with VE (P<0.05). Receiver operating characteristic curve analysis showed that the combination of cerebrospinal fluid SIL-2R, eNOS, and CD93 was superior to these individual indicators in prediction of poor prognosis in children with VE (P<0.05). Similarly, the combination of serum SIL-2R, eNOS, and CD93 was superior to these individual indicators in prediction of poor prognosis in children with VE (P<0.05). CONCLUSIONS: The cerebrospinal fluid and serum levels of SIL-2R, eNOS, and CD93 are significantly elevated in children with VE, and they are associated with VE progression and prognosis.

Torque teno virus (TTV) Infection in Patients with Encephalitis.

Torque teno virus (TTV) is a ssDNA orphan virus belonging to the Anelloviridae family, but some recent studies suggested its possible involvement in central nervous system (CNS) pathology. We analyzed serum and cerebrospinal fluid samples (CSF) from 109 patients with encephalitis for TTV infection using serological and molecular testing, virus quantitative measurement, and next-generation sequencing-based (NGS) phylogenetic analysis. TTV noncoding region (UTR) and/or open reading frame 1 (ORF-1) sequences were detected in serum of 86 (79%) patients and in nine (8%) patients in CSF. Five of the latter patients were coinfected with various entero- and herpesviruses. Anti-TTV-IgG were detected in 80 (73.4%) sera and in two (1.8%) CSF samples, while anti-TTV-IgM were present in three (2.8%) sera and in none of the CSFs. Phylogenic analysis of CSF-derived TTV ORF-1 sequences revealed the presence of three unique variants in one patient. TTV was quantified in five CSF-serum pairs: in two patients viral loads were similar, and in three serum TTV loads were approximately one log higher. Our results suggest at least an occasional replication of TTV in CNS. However, whether TTV could be the cause of encephalitis requires further studies.

The emergence of parvovirus B19 as a pathogen in acute encephalitis syndrome.

Despite scarcity of data, in recent years, human parvovirus B19 (PVB19) has been emerging as an important pathogen in acute encephalitis syndrome (AES). But, PVB19 virus is mostly looked for only after the exclusion of other common pathogens implicated in AES. Hence, this study was conducted to correlate clinical, radiological, and sequencing data to establish the crucial role of PVB19 in AES. Cerebrospinal fluid and/or serum samples were collected from AES patients as per WHO criteria and tested by ELISA, real-time PCR and bacterial culture sensitivity for various pathogens. PVB19 positive samples were subjected to sequencing. PVB19 attributed to 5% of total AES cases in the present study with fatalities in two of eight cases. Two isolates of PVB19 belonged to Genotype 1 A whereas one belonged to Genotype 3B. On multivariate analysis of predictive symptoms of PVB19 AES cases, blurring of vision (odds ratio [OR] 20.67; p = 0.001) was found to be significant independent predictor of PVB19 AES. Six of eight patients (two encephalitis specific and four nonspecific) had abnormal radiological findings. Hence, being an emerging viral pathogen, PVB19 should be included in the diagnostic algorithm of AES for prompt diagnosis and definitive management to prevent undesired neurological sequelae.

Clinical features and prognostic model for viral encephalitis after allogeneic haematopoietic stem cell transplantation.

The objective of this study was to identify independent prognostic factors of viral encephalitis (VE) after allogeneic haematopoietic stem cell transplantation (allo-HSCT) and establish a prognostic model to identify post-transplant VE patients with a greater likelihood of mortality. Among 5380 patients in our centre from 2014 to 2022, 211 patients who developed VE after allo-HSCT were reviewed in this retrospective study. Prognostic factors were selected, and a prognostic model was constructed using Cox regression analysis. The model was subsequently validated and estimated using the area under the receiver operating characteristic curve (AUC), a calibration plot and decision curve analysis (DCA). Glasgow Coma Scale score <9, lesions >3 lobes on magnetic resonance imaging and severe thrombocytopenia were identified as independent prognostic risk factors for VE patients who underwent allo-HSCT. The prognostic model GTM (GTM is an abbreviation for a model composed of three risk factors: GCS score <9, severe thrombocytopenia [platelet count <20 000 per microliter], and lesions >3 lobes on MRI) was established according to the regression coefficients. The validated internal AUC was 0.862 (95% confidence interval [CI], 0.773-0.950), and the external AUC was 0.815 (95% CI, 0.708-0.922), indicating strong discriminatory ability. Furthermore, we constructed calibration plots that demonstrated good consistency between the predicted outcomes and the observed outcomes. DCA exhibited high accuracy in this system, leading to potential benefits for patients.

Transcriptomic analysis unveils bona fide molecular signatures of microglia under conditions of homeostasis and viral encephalitis.

Microglia serve as a front-line defense against neuroinvasive viral infection, however, determination of their actual transcriptional profiles under conditions of health and disease is challenging. Here, we used various experimental approaches to delineate the transcriptional landscape of microglia during viral infection. Intriguingly, multiple activation genes were found to be artificially induced in sorted microglia and we demonstrated that shear stress encountered during cell sorting was one of the key inducers. Post-hoc analysis revealed that publicly available large-scale single-cell RNA sequencing datasets were significantly tainted by aberrant signatures that are associated with cell sorting. By exploiting the ribosomal tagging approach, we developed a strategy to enrich microglia-specific transcripts by comparing immunoprecipitated RNA with total RNA. Such enriched transcripts were instrumental in defining bona fide signatures of microglia under conditions of health and virus infection. These unified microglial signatures may serve as a benchmark to retrospectively assess ex vivo artefacts from available atlases. Leveraging the microglial translatome, we found enrichment of genes implicated in T-cell activation and cytokine production during the course of VSV infection. These data linked microglia with T-cell re-stimulation and further underscored that microglia are involved in shaping antiviral T-cell responses in the brain. Collectively, our study defines the transcriptional landscape of microglia under steady state and during viral encephalitis and highlights cellular interactions between microglia and T cells that contribute to the control of virus dissemination.

[Dengue encephalitis in Argentina]. / Encefalitis por dengue en Argentina.

Dengue virus is an endemic virus in Argentina that, although it was initially considered to be non-neurotropic, it is currently recognized to be neuroinvasive; thus conditioning a prevalence of neurological manifestations of up to 15% among patients. Even being considered severe symptoms, there is underdiagnoses of dengue encephalitis due to its varied clinical presentation. Neurological manifestations of dengue encephalitis can range from fever and headache to altered levels of consciousness and seizures. Although the cerebrospinal fluid may be normal in up to a third of cases, it usually presents increased protein concentration and pleocytosis. Regarding neuroimaging methods, the findings are usually varied and nonspecific, and can even be normal in up to 40-50% of cases. We present three cases of dengue encephalitis diagnosed in a university hospital in Buenos Aires, Argentina, where the clinical presentation varied from temporal-spatial disorientation to refractory convulsive status with different presentations in the cerebrospinal fluid but all with positive PCR for dengue in it and with normal neuroimaging.

El virus dengue es un virus endémico en Argentina que, si bien inicialmente se consideró que no era neurotrópico, actualmente se reconoce que tiene neuroinvasión, condicionando así una prevalencia de manifestaciones neurológicas de hasta el 15% entre los enfermos. Aun siendo considerados síntomas de gravedad, existe subdiagnóstico de encefalitis por dengue debido a su variada forma de presentación clínica. Las manifestaciones neurológicas de la encefalitis por dengue pueden abarcar desde fiebre y cefalea hasta alteraciones del nivel de conciencia y convulsiones. Si bien el líquido cefalorraquídeo (LCR) puede hallarse normal en hasta un tercio de los casos, lo habitual es que presente aumento de concentración de proteínas y pleocitosis. En cuanto a los métodos de neuroimagen, los hallazgos suelen ser variados e inespecíficos, e incluso pueden ser normales hasta en 40-50% de los casos. Se presentan 3 casos de encefalitis por dengue diagnosticados en un hospital universitario de Buenos Aires, Argentina, en donde la presentación clínica varió desde desorientación témporo-espacial hasta estatus convulsivo refractario con diferentes presentaciones en el LCR pero todos con PCR positivo para dengue y con neuroimágenes sin alteraciones.

Characteristics and outcome of influenza-associated encephalopathy/encephalitis among children in China.

BACKGROUND: Influenza-Associated Encephalopathy/Encephalitis (IAE) is characterized by high incidence and poor prognosis. The aim of this study is to describe the clinical features and outcomes of IAE in pediatric patients. METHODS: We performed a retrospective review of hospitalized cases of laboratory-confirmed influenza infection between January 2018 and December 2021. Demographic, clinical, imaging, treatment and outcome data were collected. Statistical analysis was performed using SPSS software. RESULTS: Of 446 children hospitalized with influenza, 71 cases were identified with a diagnosis of IAE. The median age was 3 years and 46 (64.8 %) were younger than 5 years. Only one patient was vaccinated for seasonal influenza. 46 (64.8 %) patients had abnormal electroencephalogram examination and 47 (66.2 %) had abnormal brain MRI or CT findings. 68 (95.8 %) patients were treated with oseltamivir/peramivir. 12 (16.9 %) patients suffered mortality. Non-survivors were more likely to have lower Glasgow coma score (median 7), longer duration of fever (median 3 days), with underlying medical conditions (P = 0.006), and complications including sepsis (P = 0.003), shock (P < 0.001), respiratory failure (P = 0.006), acute renal failure (P = 0.001), myocardial damage (P < 0.001), coagulation disorders (P = 0.03), electrolyte disturbance (P = 0.001) and hyperlactacidemia (P = 0.003). Non-survivors had higher percentages of corticosteroids (P = 0.003) and immunoglobulin (P = 0.003) treatments compared to survivors. CONCLUSIONS: Children with IAE have a high mortality rate. Lower Glasgow coma score, longer duration of fever, with underlying medical conditions and complications pose a great risk to poor prognosis. Influenza vaccination is recommended to all eligible children.

SARS-CoV-2 brainstem encephalitis in human inherited DBR1 deficiency.

Inherited deficiency of the RNA lariat-debranching enzyme 1 (DBR1) is a rare etiology of brainstem viral encephalitis. The cellular basis of disease and the range of viral predisposition are unclear. We report inherited DBR1 deficiency in a 14-year-old boy who suffered from isolated SARS-CoV-2 brainstem encephalitis. The patient is homozygous for a previously reported hypomorphic and pathogenic DBR1 variant (I120T). Consistently, DBR1 I120T/I120T fibroblasts from affected individuals from this and another unrelated kindred have similarly low levels of DBR1 protein and high levels of RNA lariats. DBR1 I120T/I120T human pluripotent stem cell (hPSC)-derived hindbrain neurons are highly susceptible to SARS-CoV-2 infection. Exogenous WT DBR1 expression in DBR1 I120T/I120T fibroblasts and hindbrain neurons rescued the RNA lariat accumulation phenotype. Moreover, expression of exogenous RNA lariats, mimicking DBR1 deficiency, increased the susceptibility of WT hindbrain neurons to SARS-CoV-2 infection. Inborn errors of DBR1 impair hindbrain neuron-intrinsic antiviral immunity, predisposing to viral infections of the brainstem, including that by SARS-CoV-2.

Coronavirus disease-19 encephalitis as a differential diagnosis of a cyclosporine related posterior leukoencephalopathy syndrome: A case report.

INTRODUCTION: Posterior leukoencephalopathy syndrome (PRES) is a rare neurological disease possibly associated with the use of calcineurin inhibitors like cyclosporine A (CSA). Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) responsible for the outbreak of coronavirus disease 19 (COVID-19) can cause neurological manifestations. We described a case of CSA-related PRES whose diagnosis was difficult due to a concurrent infection with SARS-CoV-2. OBSERVATION: The 16-year-old patient was known to have corticosteroid-resistant nephrotic syndrome secondary to minimal change disease. CSA was introduced, and on the fifth day of treatment, the patient presented with seizures followed by fever. Biological and magnetic resonance imaging data were in favor of SARS-CoV-2 encephalitis. Relief of immunosuppression by discontinuation of CSA was decided and the patient was put on anticonvulsants. After being declared cured of COVID-19, which was without other clinical signs, the CSA was reintroduced but the patient presented with seizures the next day. This allowed the physicians to rectify the diagnosis and relate the seizures to a CSA-related PRES. CONCLUSION: Infection with SARS-CoV-2 could be a differential diagnosis of a PRES related to calcineurin inhibitors.

Emerging shadows: HHV-8-associated encephalitis unveiled in a solid organ transplant recipient.

Human herpesviruses (HHVs) cause a wide variety of central nervous system (CNS) infections including meningitis and encephalitis. While HHV-8 is not typically associated with neurological diseases, several studies have indicated a relationship, such as secondary central nervous system (CNS) metastases and a few isolated cases of HHV-8 encephalitis in acquired immunodeficiency syndrome (HIV). However, it has not been previously linked to encephalitis in solid organ transplantation (SOT). This case presents the first-ever instance of HHV-8 encephalitis in a SOT recipient. Our case highlights the association of HHV-8-related diseases, such as post-transplant Kaposi's Sarcoma (KS), with encephalitis. The patient was diagnosed with KS before developing neurological symptoms and received a prompt clinical response through intravenous foscarnet and ganciclovir treatment for 14 days. It is important to note that HHV-8 is a rare cause of encephalitis, and diagnosis requires a high index of suspicion in the appropriate clinical context, allowing for the use of antiviral therapy. This case also underscores the importance of considering the possibility of HHV-8-related diseases in SOT recipients, as they are at risk of developing such infections.

Guillain-Barré Syndrome and Encephalitis Following a Cytomegalovirus Infection in an Immunocompetent Adult: A Case Report.

BACKGROUND Cytomegalovirus (CMV) is a common herpesvirus that often causes asymptomatic or mild infections. In immunocompromised patients, CMV can lead to severe complications, including Guillain-Barre syndrome (GBS) and encephalitis. While these conditions have been described in the immunocompetent population, simultaneous presentation of CMV-associated GBS and encephalitis in such individuals has not been previously reported. CASE REPORT We present a case of a 58-year-old woman with poorly controlled diabetes who developed concurrent GBS and encephalitis following a CMV infection. The patient experienced bilateral ascending paraparesis 1 week after self-limited gastrointestinal symptoms. Despite initial treatment with plasma exchange therapy, her condition deteriorated with altered mental status and generalized tonic-clonic seizures, necessitating orotracheal intubation. Laboratory analysis revealed the presence of CMV in her cerebrospinal fluid. After treatment with further sessions of plasma exchange therapy and ganciclovir, her muscular strength in the extremities improved. However, she developed acute lung edema and failed extubation, leading to cardiorespiratory arrest with neurological sequelae. Palliative care was institutionalized, and she died 2 weeks later due to pneumonia. CONCLUSIONS This case highlights an unusual clinical presentation of overlapping CMV-associated GBS and encephalitis in an immunocompetent individual, with diabetes as the only identified risk factor. It underscores the importance of considering CMV as a potential etiological factor in such complex cases and the need for prompt diagnosis to improve patient outcomes. Further research is warranted to explore the underlying mechanisms and implications of this rare overlapping neurological manifestation.

Orchestration of antiviral responses within the infected central nervous system.

Many newly emerging and re-emerging viruses have neuroinvasive potential, underscoring viral encephalitis as a global research priority. Upon entry of the virus into the CNS, severe neurological life-threatening conditions may manifest that are associated with high morbidity and mortality. The currently available therapeutic arsenal against viral encephalitis is rather limited, emphasizing the need to better understand the conditions of local antiviral immunity within the infected CNS. In this review, we discuss new insights into the pathophysiology of viral encephalitis, with a focus on myeloid cells and CD8+ T cells, which critically contribute to protection against viral CNS infection. By illuminating the prerequisites of myeloid and T cell activation, discussing new discoveries regarding their transcriptional signatures, and dissecting the mechanisms of their recruitment to sites of viral replication within the CNS, we aim to further delineate the complexity of antiviral responses within the infected CNS. Moreover, we summarize the current knowledge in the field of virus infection and neurodegeneration and discuss the potential links of some neurotropic viruses with certain pathological hallmarks observed in neurodegeneration.

Risk factors and long-term outcomes for human herpesvirus 6 encephalitis in the early period after allogeneic stem cell transplantation.

Human herpesvirus 6 (HHV6) encephalitis is a rare but life-threatening complication for patients undergoing allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, reports on susceptibility factors and clinical outcomes are limited. We enrolled HHV6 encephalitis patients following allo-HSCT between 2018 and 2022, then conducted a 1:4 nested case-control cohort study to evaluate risk factors and long-term outcomes. Among 1350 patients, 20 (1.48%) developed HHV6 encephalitis, with a median onset time of 25.5 days after HSCT. Patient age<30 (odds ratio [OR], 3.24, P = 0.016) and NK cell count<115/ul at 21 days (OR, 6.07, P = 0.018) were identified as independent risk factors in multivariate analysis. Moreover, the HHV6 encephalitis group was significantly associated with higher incidence of grade II-IV graft-versus-host disease (aGVHD) (hazard ratio [HR], 5.52, P < 0.001) and transplant-associated microangiopathy (HR,9.86, P < 0.001), and demonstrated a significantly higher non-relapse mortality (NRM) (HR, 5.28, P = 0.004) and a lower overall survival (HR, 4.34, P = 0.001) or progression-free survival (HR, 3.94, P = 0.001) compared to control group. In conclusion, patients <30 years old or with delayed NK cell recovery are more susceptible to HHV6 encephalitis after allo-HSCT, and patients with HHV6 encephalitis after transplantation have poorer clinical outcomes.

The lipopeptide Pam3CSK4 inhibits Rift Valley fever virus infection and protects from encephalitis.

Rift Valley fever virus (RVFV) is an encephalitic bunyavirus that can infect neurons in the brain. There are no approved therapeutics that can protect from RVFV encephalitis. Innate immunity, the first line of defense against infection, canonically antagonizes viruses through interferon signaling. We found that interferons did not efficiently protect primary cortical neurons from RVFV, unlike other cell types. To identify alternative neuronal antiviral pathways, we screened innate immune ligands and discovered that the TLR2 ligand Pam3CSK4 inhibited RVFV infection, and other bunyaviruses. Mechanistically, we found that Pam3CSK4 blocks viral fusion, independent of TLR2. In a mouse model of RVFV encephalitis, Pam3CSK4 treatment protected animals from infection and mortality. Overall, Pam3CSK4 is a bunyavirus fusion inhibitor active in primary neurons and the brain, representing a new approach toward the development of treatments for encephalitic bunyavirus infections.

[Epidemiological characteristic of viral encephalitis in children and adolescents in Henan Province, 2012-2023].

Objective: To understand the epidemiological characteristics and spatiotemporal distribution of viral encephalitis in children and adolescents in Henan Province from 2012 to 2023. Methods: The information about viral encephalitis cases from October 1, 2012 to July 26, 2023 were collected from Zhengzhou Children's Hospital (National Children's Regional Medical Center),Henan Provincial Children's Hospital for the analyses on temporal distribution the cases, the severe illness rate, age distribution, pathogen type and imaging findings of the cases. Results: A total of 6 276 cases of viral encephalitis were included in this study after excluding cases with incomplete information. The cases mainly originated from Zhengzhou (38.96%), followed by Zhoukou (9.93%), Xuchang (8.68%), Zhumadian (7.90%) and Pingdingshan (7.39%). The cases in boys accounted for 62.13% and the cases in girls accounted for 37.87%. Most cases (72.45%) occurred in age group 7-13 years. The overall rate of severe illness cases was 4.51% from 2012 to 2023. There were significant differences in severe illness cases among different areas and years (χ2=5.33,P=0.021; χ2=48.14,P<0.001). Enteroviruses were mainly detected (31.57%), in which Coxsackie virus was predominant (58.37%). Imaging findings showed that cerebral hemisphere damage was most common in children and adolescents with viral encephalitis (54.93%). Conclusions: From 2012 to 2023, more cases of viral encephalitis occurred in boys in Henan. Children and adolescents aged 7-13 years were the main affected group. The prevention of enteroviruses infection, especially Coxsackie virus, needs to be strengthened. Special attention should be paid to the prevention of cerebral hemisphere damage after viral encephalitis diagnosis.