Dissertations / Theses on the topic 'Encephalitis'

This thesis was completed by Della Nicolle for the degree of Doctor of Clinical Psychology at Cardiff University. The thesis is a systematic review and an interpretative phenomenological analysis investigating the impact of anti-NMDAR on cognitive functioning and identity respectively. This thesis was submitted on the 26th May 2017 and is comprised of a thesis abstract followed by three papers. Paper one has been prepared for submission to Archives of Clinical Neuropsychology and paper two for submission to Psychology & Health. Paper one presents a systematic review of current published neuropsychological case studies and series with people with a diagnosis of anti-NMDAR encephalitis. The review was conducted to investigate the emerging cognitive profile for people diagnosed with anti- NMDAR encephalitis. It assessed the quality of these studies using a quality assessment tool created for the purpose of the study. The neuropsychological results were synthesised and the results discussed narratively. A review revealed difficulties with memory, particularly verbal memory, executive functioning and attention/processing speed. Paper two is an interpretative phenomenological analysis of women with a diagnosis of anti-NMDAR encephalitis. The aim of this study was to explore the experience of women diagnosed with anti-NMDAR encephalitis and the phenomenon of identity change. Using a semi-structured interview the women were interviewed about their experience of having the illness, with a focus on impact on identity. These interviews were analysed for themes using the IPA method and four superordinate themes were discussed with direct quotes. Four superordinate themes were revealed ‘Re-finding the ‘normal’ self; ‘A ‘special’ identity’; ‘Evolving from the illness’ and ‘Revised roles. Analysis revealed themes common to many ! 2! severe physical illnesses such as, not feeling oneself and post-traumatic growth. However, themes emerged specific to anti-NMDAR such as feeling abnormal due to the rarity of the disease and its psychiatric symptoms, feeling viewed as special and concerns around fertility and motherhood. Paper three is a Commentary on the former two studies. This paper offers critical appraisal and reflection on the research process, the strengths and limitations of the papers and line of enquiry, as well as implications for further research, clinical practice and personal/professional development, and finally proposals for dissemination. The term ‘patients’ will be used within the systematic review because of its common usage in the target journals, however, it is recognised that its origins are from the medical perspective and other terms that are more person-centred could also be chosen.

N-methyl-D-aspartate receptor (NMDAR) antibody encephalitis is a recently described autoimmune encephalopathy defined by the presence of serum antibodies that bind NMDARs (NMDAR-Abs). NMDAR-Ab encephalitis is a severe, but treatmentresponsive encephalitis with subacute onset. It can be associated with tumours and affects mainly young adults. Patients present with cognitive dysfunction, seizures, psychiatric and sleep disorders and most develop dyskinesias, autonomic instability and reduced consciousness. To explore further the NMDAR-Abs and their potential pathogenicity, a series of in vitro investigations were performed and preliminary attempts at passive transfer of disease. Human embryonic kidney (HEK) cells transfected with the NR1 and NR2B subunits, and live cultured neurons, were used first to detect NMDAR-Ab binding. Immunocytochemistry and ow cytometry demonstrated that binding to transfected HEK cells could be improved when NMDAR were presented in clusters by cotransfection with the postsynaptic density protein PSD-95. The NR1 subunit was identified as the target of NMDAR-Abs, and a novel quantitative assay based on immunoprecipitation of NR1 tagged by fusion with green uorescent protein was developed. Measurement of NMDAR-Ab levels showed that antibody levels corresponded to the clinical disease score within individual patients. Although the purification of full length NR1 was not successful, a secreted N-terminal construct was created and expressed in HEK cells. The binding of NMDAR-Abs was confirmed and this construct will be used for active immunisation in future. To explore pathogenic mechanisms in vitro, the main antibody subclasses were shown to be IgG1 and IgG3. Moreover the patients' autoantibodies, but not healthy control antibodies, were able to activate the complement cascade in vitro in cell lines and primary cultures. Finally, the NMDAR-Abs were shown to bind to primary microglial cultures and to cause morphological changes corresponding to early activation processes after prolonged exposure. The research has developed new assays that could be used for diagnosis and serial studies and revealed new potential mechanisms in NMDAR-Ab encephalitis.

BACKGROUND: The autoimmune encephalitis represents a new category of immune- mediated diseases of the brain that are mediated by antibodies against neurotransmitter receptors, ion channels or neuronal cell-surface proteins. Among the many encephalitis considered idiopathic, there are subtypes that are probably immune-mediated and are pending to be discovered. In the last 11 years, 16 subtypes of idiopathic encephalitis have been found to be immune mediated. The recognition of these disorders is important because despite being potentially lethal, they are curable if promptly recognized and treated. On a more basic level, the study of these diseases has uncovered novel antibody-mediated mechanisms of synaptic dysfunction that lead to changes in memory and behavior, epilepsy, abnormal movements, or decreased level of consciousness. OBJECTIVES: 1) Identify patients with encephalitis of unclear etiology but whose clinical features and initial investigations strongly suggest an antibody-mediated cause; 2) characterize the new autoantibodies associated with these disorders along with the neuronal target antigens, and develop unambiguous diagnostic tests, and 3) determine in animal models how autoantibodies alter the level and function of neuronal synaptic antigens (NMDAR and LGI1) potentially resulting in an impairment of memory and behavior. METHODS: Rat brain sections and primary cultures of dissociated rat hippocampal neurons served to identify patients whose serum and CSF samples contained novel neuronal antibodies. Techniques of tissue immunohistochemistry, neuronal immunocytochemistry and cell-based assays were used to identify the antibodies. Cell- surface neuronal protein immunoprecipitation with patients’ antibodies was used to isolate the target antigen, which was subsequently characterized by mass spectrometry. Cerebroventricular transfer of patients’ antibodies to mice through subcutaneously implanted mini-osmotic pumps was used to determine the pathogenic effect of patients’ antibodies on the corresponding synaptic targets and how these changes altered memory and behavior. An extensive combination of techniques was used for these studies, including quantitative confocal microscopy analysis of the levels of synaptic targets, immunoprecipitation of brain-bound antibodies, immunoblot of precipitated proteins, electrophysiology on acute sections of mice hippocampus, and a comprehensive panel of standard behavioral tests. All studies were conducted with sets of mice at different time points during the antibody infusion (disease phase) and after the infusion was stopped (recovery phase). RESULTS: (1) Two novel autoimmune encephalitis were identified: anti-GABAaR encephalitis and anti-neurexin-3α encephalitis. Anti-GABAaR encephalitis can affect children and adults, associates with prominent seizures and highly suggestive MRI abnormalities, and is treatable with immunotherapy. In some patients the immune response is triggered by the presence of a tumor. Anti-neurexin-3α encephalitis manifests with a less distinctive syndrome, often associates with seizures and is also treatable with immunotherapy. No tumor association has been identified. (2) Immunoprecipitation of the target antigen of anti-GABAaR encephalitis demonstrated that the epitopes are mainly located in the alpha1 and beta3 subunits, and less frequently in the γ2 subunit. Whereas the antibodies against alpha1 and beta3 subunits are disease relevant, the presence of additional antibodies to γ2 does not modify the disease phenotype. Patients’ GABAaR antibodies cause a decrease in the total and synaptic levels of GABAaR clusters, supporting their pathogenicity. (3) Immunoprecipitation of the target antigen of patients with anti-neurexin-3α encephalitis demonstrated that the epitopes are specifically located in neurexin-3α, but not in its postsynaptic ligand LRRTM2. Patients’ antibodies cause a reduction of the total number of synapses as well as the levels of the presynaptic protein Bassoon and the post-synaptic protein Homer1, supporting the pathogenicity of the antibodies. (4) Recombinant expression of the indicated subunits of the GABAaR and neurexin-3α in HEK293 cells can be used as a test to diagnose patients with these autoimmune encephalitis. (5) The infusion of patients’ NMDAR antibodies into the cerebroventricular system of mice, cause memory deficits, anhedonia, and depressive-like behavior. The infused antibodies specifically bind to brain NMDAR resulting in a highly specific reduction of the density of these receptors at synaptic and extrasynaptic levels. The behavioral and molecular effects caused by patients’ antibodies are reversible upon stopping the infusion of antibodies. (6) The administration of ephrin-B2 antagonizes the pathogenic effects of patients’ NMDAR antibodies in all the investigated paradigms, including memory, depressive-like behavior, density of cell-surface and synaptic NMDAR and EphB2, and long-term synaptic plasticity. These findings reveal a strategy beyond immunotherapy to antagonize patients’ antibody effects. (7) The antibodies of patients with anti-LGI1 encephalitis abrogate the binding of the neuronal secreted LGI1 with the presynaptic ADAM23 and with the postsynaptic ADAM22. (8) The infusion of patients’ LGI1 antibodies into the cerebroventricular system of mice cause protracted memory deficits, together with a decrease of presynaptic Kv1.1 potassium channels and post- synaptic AMPAR. These structural effects associate with impairment of synaptic plasticity and increase of neuronal excitability, which are in line with the models of genetic depletion of LGI1. CONCLUSIONS: (1) Anti-GABAaR and anti-neurexin-3α encephalitis are two new forms of antibody-mediated encephalitis for which there is evidence of antibody-mediated pathogenicity. These findings support the concept that among the many types of encephalitis of unclear etiology, there are some that are immune mediated but are still pending to characterize. (2) Direct neuronal antigen precipitation using patients’ antibodies is an excellent strategy to isolate and characterize disease-relevant antigens, and subsequently develop diagnostic screening tests. (3) My studies have contributed to develop two animal models of antibody-mediated symptoms (NMDAR, LGI1) and uncover the underlying antibody-mediated changes in synaptic function and plasticity. Both models fulfill the Witebsky’s criteria for antibody-mediated disease, and provide the basis for modeling other antibody-mediated neurological disorders.
INTRODUCCIÓN: La encefalitis autoimmune representa una nueva categoria de enfermedades immunomediadas del cerebro que estan mediadas por anticuerpos dirigidos contra receptores sinápticos, canales iónicos o proteinas neuronales de superfície. De entre todas las encefalitis consideradas idiopaticas, hay un subgrupo, probablemente immunomedidos, pendientes de ser identificadas. En los ultimos 11 años, 16 subtipos de encefalitis idiopaticas han sido identificadas como immunomediadas. La identificación de estas enfermedades es importante porque, aunque son potencialmente letales, son curables si se identifican rapid de nuevas en amente y se tratan. El estudio de estas enfermedades ha permitido el descubrimiento de nuevos mecanismos de alteración de la sinapsi medidados por anticuerpos que dan lugar a alteraciones de comportamiento y de memoria, epilepsia, movimientos anormales, o bajo nivel de consciencia. OBJETIVOS: 1) Identificar pacientes con encefalitis de etiologia desconocida, pero con caracteristicas clinicas y paraclinicas que sugieren una causa immunomedidada; 2) Caracterizar nuevos autoanticuerpos asociados a estos trastornos asi como las dianas antigenicas, y desarrollar pruebas diagnosticas inequivocas, y 3) determinar en modelos animales como los autoanticuerpos alteran el nivel y funcion de de los antigenos neuronales sinápticos (NMDAR y LGI1). MÉTODOS: Se usaron secciones de cerebro de rata y cultivos primarios de neuronas hipocampales de rata para la identificación de nuevos anticuerpos contra proteinas neuronales en muestras de suero y liquido cefaloraquideo (LCR) de pacientes. Para la detección de los anticuerpos se usó immunohistoquimica, immunocitoquimica de neuronas y en células HEK293 transfectadas. El aislamiento de nuevos antigeno diana se hizo mediante la immunoprecipitacion de proteinas de superficie neuronal con anticuerpos de los pacientes, y posterior caracterización por espectometria de masas. Para determinar el efecto patogenico de los anticuerpos de los pacientes, durante 14 dias los ratones fueron expuestos de manera cerebroventricular a los anticuerpos mediante la implantación subcutanea de bombas osmoticas, y posteriormente se analizó el efecto sobre las dianas antigenicas asi como alteraciones de comportamiento y memoria. Para ello, se usaron tecnicas de microscopia confocal cuantitativa de los niveles de antigenos sinápticos, immunoprecipitación de los anticuerpos unidos al tejido cerebral, immunoblot de las proteinas precipitadas, electrofisiologia en secciones de cerebro de raton, y una bateria de pruebas de comportamiento estandarizadas. Todos los estudios se realizaron en dias determinados de exposición a los anticuerpos (fase de la enfermedad), asi como después de la infusión (fase de recuperación). RESULTADOS: (1) Se identificaron dos nuevas encefalitis autoimmunes: encefalitis anti-GABAaR y encefalitis anti-neurexin-3α. La encefalitis anti-GABAaR puede afectar niños y adultos, esta asociada con crisis epilepticas y anormalidades en la resonancia magnetica del cerebro, y es tratable con immunoterapia. En algunos pacientes la respuesta immune se desencadena por la presencia de un tumor. La encefalitis anti-neurexin-3α manifiesta con un sindrome menos distintivo, a menudo se asocia con crisis epilepticas y tambien es tratable con immunoterapia. No se ha identificado asociacion tumoral. (2) La diana antigenica de los anticuerpos de la encefalitis anti-GABAaR se encuentra principalmente en las subunidades alfa1 y β3, y menos frecuentemente en la subunidad γ2. Mientras que las subunidades alfa1 y β3 son relevantes para la enfermedad, la presencia de anticuerpos adicionales contra γ2 no modifica el fenotipo de la enfermedad. Los anticuerpos anti-GABAaR producen una disminución de los niveles de GABAaR totales y sinapticos, apoyando su patogenicidad. (3) La immunoprecipitación de la diana antigenica de pacientes con encefalitis anti-neurexin-3α demostró que los epitopos estan localizados en la subunidad 3alfa, y no en su ligando postsinaptico LRRTM2. Estos autoanticuerpos causan una reducción del numero total de sinapsis asi como de la proteina presinaptica Bassoon, y de la postsinaptica Homer1, apoyando su patogenicidad. (4) La expresion recombinante de las subunidades antigenicas en celulas HEK293, pueden ser usadas como prueba diagnostica para identificar pacientes con estas encefalitis autoimmunes. (5) La infusión de anticuerpos NMDAR en el sistema cerebroventricular de ratones causa problemas de memoria, anhedonia, y comportamientos depresivos. Los anticuerpos infusionados se unen especificamente a los receptores NMDA del cerebro y provocan la disminución de la densidad de dichos receptores a nivel sinaptico y extrasinaptico. Estos efectos son reversibles despues de la suspension de la infusion de anticuerpos. (6) La administracion de ephrin-B2 antagoniza el efecto patogenico de los anticuerpos contra NMDAR de los pacientes, incluyendo los efectos de memoria, depresion, densidad de receptores NMDA y EphB2, y plasticidad sinaptica a largo plazo, pudiendo ser usado como estrategia terapeutica. (7) Los anticuerpos de los pacientes con encefalitis anti-LGI1 impiden la unión entre la proteina neuronal secretada LGI1 y la proteina presinaptica ADAM23 y la postsinaptica ADAM22. (8) La infusión de anticuerpos de los pacientes contra LGI1 en el sistema cerebroventricular de los ratones causa problemas de memoria, asi como disminución de los niveles de canales de potasio Kv1.1 presinapticos y de receptores AMPA postsinapticos. Estos efectos se asocian a una alteración de la plasticidad sinaptica e incremento de excitabilidad neuronal, de manera similar a los modelos de depleción genetica de LGI1. CONCLUSIONES: (1) Las encefalitis Anti-GABAaR y anti-neurexin-3α encephalitis son dos nuevas formas de encefalitis mediadas por anticuerpos. Hay evidencia que sostiene que estos anticuerpos son patogenicos, apoyando el concepto de que hay encefalitis sin caracterizar dentro de las muchas formas de encefalitis de causa desconocida. (2) La precipitación del antigeno neuronal es una estrategia excelente para aislar y caracterizar antigenos relevantes para la enfermedad, y poder desarrollar pruebas de detección. (3) Estos estudios han contribuido a desarrollar dos modelos animales de infusión de anticuerpos de encefalitis autoimmunes (NMDAR, LGI1) y a descubrir los cambios subyacentes mediados por anticuerpos en la función sináptica y la plasticidad. Los dos modelos cumplen con los criterios de Witebsky para enfermedades immunomediadas, y proporcionan la base para modelar otros trastornos neurológicos mediados por anticuerpos.

ABSTRACT Eastern Equine Encephalitis virus (EEEV) is an alphavirus with high pathogenicity in both humans and horses. Florida continues to have the highest occurrence of human cases in the USA, with four fatalities recorded in 2010. Unlike other states, Florida supports year-round EEEV transmission. This research uses Geographic Information Science (GIS) to examine spatial patterns of documented sentinel seroconversions and horse cases in order to understand the relationships between habitat and transmission intensity of EEEV in Florida. Sentinel sites were categorized as enzootic, periodically enzootic, and negative based on the amount of chicken seroconversions to EEEV. Sentinel sites were analyzed based on land classification data d using the Kruskal-Wallis test to determine which habitats were associated with disease transmission. Cluster analyses were performed for the horse cases using density-based spatial clustering of applications with noise (DBSCAN). Ecological associations of EEEV were examined using compositional analysis and Euclidean distance analysis to determine if the proportion or proximity of certain habitats played a role in transmission. The research in these studies provides evidence of ecological associations for EEEV transmission in Florida that hasn't been previously analyzed. Furthermore, these studies provide the groundwork for better understanding of why there is a disproportionate number of horse and human cases of EEEV in Florida than in any other state.

Concomitant with the Spanish influenza and extending to the 1920s encephalitis lethargica (EL), also termed von Economo's disease or sleepy sickness, occurred in epidemic proportion. A previous epidemic of encephalitis lethargica also appeared at the time of 1889 influenza pandemic. Certain clinical and pathological features of encephalitis lethargica of 1916-1920 strongly suggested a viral aetiology and subsequently it was suggested that influenza virus was the responsible pathogen (Ravenholt & Foege, 1982). Sensitive molecular techniques are now available which can be applied both to fresh tissue and old formalin fixed and paraffin blocked sections using RT-PCR. Recent genetic analyses of haemagglutinin (HA) and neuraminidase (NA) genes of 1918 influenza virus have failed to identify virulence motifs (Taubenberger et al., 1997 & 1999; Reid et al., 1999,2000 & 2002). These methods were applied to eight brain samples from patients who died of encephalitis lethargica in 1916-1920 for the presence of influenza genes. The sections of brain from eight archival, unique cases of EL had been neuropathologically reviewed and the diagnosis confirmed prior to analysis using established reverse transcription-polymerase chain reaction (RT-PCR). Although our genetic study detected ß-actin genes in the archived brains, we found no evidence of influenza genes. An animal model of influenza neuropathogenesis was established for investigations of the localisation of influenza genes in brain tissue using in situ hybridisation (ISH). Influenza gene sequences were detected in ependymal cells, choroid plexus, hippocampal neurons, periventricular regions of the lateral ventricle and cerebral aqueduct, and cells of the raphe nucleus. A persistent influenza infection in the brains of infected mice is reported. Therefore short influenza sequences could, in theory and based on a simple longevity comparison of man and mouse, be detected in brain tissues of infected subjects for a period of 1.9 -6.7 years after its initial exposure to influenza infection.

Introduction Acute viral encephalitis is a severe form of brain inflammation due to sporadic infection, typically with herpes simplex virus, or epidemic/pandemic infections. Epidemiological data are particularly important for pandemic viruses. Although new reporting approaches are often considered, no real-time clinical data collection tool has been developed. These data are dependent on diagnosis of individual cases. However, the aspects of management that result in delays and missed diagnoses are not clear and it is not known if interventions can improve sample collection and diagnosis. Whilst the importance of cytokines and associated mediators is increasingly recognised, signatures associated with specific aetiologies have not been established. Also, it is not known whether these mediators correlate with clinical severity and outcome, or their impact on blood-brain barrier permeability. Methods I undertook a national surveillance study through neurology networks, and investigated alternative notification approaches. I undertook a multicentre cross-sectional study of clinical investigation, studied viral load and assessed the impact of a lumbar puncture pack. I used bead array to assess mediator profiles and assessed the albumin ratio and viral load, in samples from a Health Protection Agency study. I examined profiles with respect to aetiology, disease severity and outcome and compared this with histopathology tissue and a blood-brain barrier model. Results In the context of a pandemic influenza virus, existing mechanisms identified limited cases, and a smartphone application was developed to collect real-time data. Delays in lumbar puncture and sub-optimal sample collection were identified, in association with a lower viral load. A lumbar puncture pack improved sample collection. Mediator profiles differed between those with an infectious versus immune-mediated aetiology, and those of unknown aetiology best reflected infectious; particularly myeloperoxidase, in part relating to neutrophils in cerebrospinal fluid and parenchyma. The interleukin1 antagonists, IL1RA and IL10, were associated with coma and outcome; and IL10 with reduced blood-brain barrier permeability. Adhesion molecules may counteract this, in both clinical samples and the model. Conclusions Current limitations of detection may be augmented with novel real-time technologies. Diagnosis is limited by delayed and sub-optimal sample collection, which can be improved with a simple pack. Mediators profiles may assist in the distinction of infectious from immune-mediated encephalitis, and cytokines that act against IL1 correlated with clinical severity and outcome. This may be more closely associated with outcome than viral load, although this may reflect sample timing. These findings should direct future research to develop approaches for improved diagnostics and adjunctive therapies.

Autoimmune neurological syndromes have become increasingly recognised over the last decade. Early immune suppressive treatment of autoimmune encephalitis can improve outcomes1. However, symptomatic management of autoimmune encephalitis, particularly anti-NMDAR encephalitis is not well described in the literature. In children presenting with an acute encephalopathy the differentials for management are based on early clinical features and investigation modalities such as electroencephalography (EEG) and magnetic resonance imaging (MRI). Autoimmune encephalitis often presents with movement disorders accompanying other clinical features2. Some of these syndromes such as anti-NMDAR encephalitis and autoimmune basal ganglia encephalitis were recognised entities at the start of my PhD tenure, while others like autoimmune relapse after Herpes encephalitis with movement disorders were not well understood, although thought to be immune mediated. At the start of my PhD, certain EEG and MRI features were proposed to be indicative of particular syndromes such as extreme delta brush in anti-NMDAR encephalitis, periodic discharges in Herpes simplex encephalitis (HSE) and bilateral basal ganglia changes in autoimmune basal ganglia encephalitis3. Hypotheses • The description of discriminatory movement disorder phenomenology, EEG features on early EEG and MRI brain patterns can help early recognition and treatment of autoimmune encephalitis in children. • Symptomatic management of anti-NMDAR encephalitis utilises polypharmacy and pleiotropic effects of various medications. • Herpes encephalitis relapse with movement disorder is autoimmune.

Japanese encephalitis virus (JEV), a member of the family flaviviridae, is one of the most important pathogens of the developing countries, causing high mortality and morbidity amongst children. The present study is aimed at the development of a DNA vaccine for Japanese Encephalitis (JE). As a first step towards developing a DNA vaccine for JE, an eukaryotic expression plasmid encoding the envelope (E) glycoprotein of Japanese Encephalitis Virus (pCMXENV) was constructed. This plasmid expresses the E protein intracellularly, when transfected into Vero cells in culture. Several independent immunization and intracerebral (i.e.) JEV challenge experiments were carried out and the results indicate that 51% and 59% of the mice are protected from lethal i.e. JEV challenge, when immunized with pCMXENV via intramuscular (i.m.) and intranasal (i.n.) routes respectively. JEV-specific antibodies were not detected in pCMXENV-immunized mice either before or after challenge. JEV-specific T cells were observed in mice immunized with pCMXENV, which increased significantly after JEV challenge indicating the presence of vaccination-induced memory T cells. Enhanced production of interferon-y (EFN-y) and complete absence of interleukin-4 (IL-4) in splenocytes of pCMXENV-immunized mice on restimulation with JEV antigens in vitro indicated that the protection is likely to be mediated by T helper (Th) lymphocytes of the Thl sub type. These results demonstrated that immunization with a plasmid DNA expressing intracellular form of JEV E protein confers significant protection against i.e. JEV challenge even in the absence of detectable antiviral antibodies. We then examined the potency of JEV DNA vaccines as well as that of the inactivated mouse brain derived BIKEN vaccine in the i.e. challenge model. The results indicate that all the mice immunized with BIKEN JE vaccine were protected against i.e. JEV challenge while 50% protection was observed in case of mice immunized with pJME or pJNSl and 38% protection was observed in pCMXENV-immunized mice. Immunization with both pJME and pJNSl resulted in 66% protection. These results indicate that the BIKEN JE vaccine confers better protection against i.e. JEV challenge than DNA vaccines. The fact that the BIKEN vaccine conferred better protection against i.e. JEV challenge than DNA vaccines indicated that the i.e. JEV challenge model can be exploited further to examine the potency of different DNA vaccine constructs. Towards this goal, we constructed plasmids that encode secretory or nonsecretory forms of JEV E protein and examined their potency in the i.e. JEV challenge model. Our results indicate that i.m. immunization of mice with plasmid encoding secretory form of JEV E protein confers higher level (75%-80%) protection than those encoding nonsecretory forms. Cytokine analysis of splenocytes isolated from DNA immunized mice after stimulation in vitro with JEV revealed that immunization with plasmid encoding secretory form of JEV E protein induces both Thl and Th2 responses while those encoding nonsecretory forms induce only Thl type of response. Thus, synthesis of secretory form of JEV E protein results in an altered immune response leading better protection against i.e. JEV challenge. Based on our studies, we propose that both cellular and humoral immune responses play a key role in protective immunity against i.e. JEV challenge and DNA vaccines that can induce higher levels of neutralizing antibodies will be as efficient as the BIKEN vaccine in conferring protection against i.e. JEV challenge.

Japanese encephalitis virus (JEV), a member of the family flaviviridae, is one of the most important pathogens of the developing countries, causing high mortality and morbidity amongst children. The present study is aimed at the development of a DNA vaccine for Japanese Encephalitis (JE). As a first step towards developing a DNA vaccine for JE, an eukaryotic expression plasmid encoding the envelope (E) glycoprotein of Japanese Encephalitis Virus (pCMXENV) was constructed. This plasmid expresses the E protein intracellularly, when transfected into Vero cells in culture. Several independent immunization and intracerebral (i.e.) JEV challenge experiments were carried out and the results indicate that 51% and 59% of the mice are protected from lethal i.e. JEV challenge, when immunized with pCMXENV via intramuscular (i.m.) and intranasal (i.n.) routes respectively. JEV-specific antibodies were not detected in pCMXENV-immunized mice either before or after challenge. JEV-specific T cells were observed in mice immunized with pCMXENV, which increased significantly after JEV challenge indicating the presence of vaccination-induced memory T cells. Enhanced production of interferon-y (EFN-y) and complete absence of interleukin-4 (IL-4) in splenocytes of pCMXENV-immunized mice on restimulation with JEV antigens in vitro indicated that the protection is likely to be mediated by T helper (Th) lymphocytes of the Thl sub type. These results demonstrated that immunization with a plasmid DNA expressing intracellular form of JEV E protein confers significant protection against i.e. JEV challenge even in the absence of detectable antiviral antibodies. We then examined the potency of JEV DNA vaccines as well as that of the inactivated mouse brain derived BIKEN vaccine in the i.e. challenge model. The results indicate that all the mice immunized with BIKEN JE vaccine were protected against i.e. JEV challenge while 50% protection was observed in case of mice immunized with pJME or pJNSl and 38% protection was observed in pCMXENV-immunized mice. Immunization with both pJME and pJNSl resulted in 66% protection. These results indicate that the BIKEN JE vaccine confers better protection against i.e. JEV challenge than DNA vaccines. The fact that the BIKEN vaccine conferred better protection against i.e. JEV challenge than DNA vaccines indicated that the i.e. JEV challenge model can be exploited further to examine the potency of different DNA vaccine constructs. Towards this goal, we constructed plasmids that encode secretory or nonsecretory forms of JEV E protein and examined their potency in the i.e. JEV challenge model. Our results indicate that i.m. immunization of mice with plasmid encoding secretory form of JEV E protein confers higher level (75%-80%) protection than those encoding nonsecretory forms. Cytokine analysis of splenocytes isolated from DNA immunized mice after stimulation in vitro with JEV revealed that immunization with plasmid encoding secretory form of JEV E protein induces both Thl and Th2 responses while those encoding nonsecretory forms induce only Thl type of response. Thus, synthesis of secretory form of JEV E protein results in an altered immune response leading better protection against i.e. JEV challenge. Based on our studies, we propose that both cellular and humoral immune responses play a key role in protective immunity against i.e. JEV challenge and DNA vaccines that can induce higher levels of neutralizing antibodies will be as efficient as the BIKEN vaccine in conferring protection against i.e. JEV challenge.

Japanese encephalitis virus (JEV) is the most important cause of epidemic encephalitis worldwide but its origin is unknown. Epidemics of encephalitis suggestive of Japanese encephalitis (JE) were described in Japan from the 1870s onwards. Four genotypes of JEV have been characterised and representatives of each genotype have been fully sequenced. Based on limited information, a single isolate from Malaysia, the Muar strain, is thought to represent a putative fifth genotype. I have determined the complete nucleotide and amino acid sequence of the Muar strain and compared it with other fully sequenced JEV genomes. Muar was the least similar, with nucleotide divergence ranging from 20.2 to 21.2% and amino acid divergence ranging from 8.5 to 9.9%. Phylogenetic analysis of the Muar strain revealed that it does represent a distinct fifth genotype of JEV. I elucidated the Muar signature amino acids in the envelope (E) protein, including E327 Glutamine on the exposed lateral surface of the putative receptor binding domain of the E protein, which distinguishes the Muar strain from the other four genotypes. Evolutionary analysis of full-length JEV genomes revealed that the mean (range) evolutionary rate is 4.35 x 10-4 (3.4906 X 10-4 to 5.303 x 10-4) nucleotides substitutions per site per year and suggests JEV originated from its ancestral virus in the mid 1500s. It is postulated to have originated in the Indonesia-Malaysia region and evolved there into different genotypes, which then spread across Asia. No strong evidence for positive selection was found between JEV strains of the five genotypes and the E gene has generally been subjected to strong purifying selection. The ability of intravenous immunoglobulins (IVIGs) which sometimes are used as supportive treatment for JEV infection to protect against strains of JEV representing the five major genotypes was assessed. Neutralization assays showed IVIGs appear cross-reactive across the five JEV genotypes with effective but lower titers for the Muar strain as well as representatives from genotype IV. Whether there are other strains from genotype V, and what happened to them remains unknown.

Spatial and temporal components play a critical role in explaining variability across geographic regions and time, and are necessary components to space-time epidemiological research. Until recent years, most spatial epidemiological studies have used simple space-time analyses, but the continuous advancements in statistical modeling software and geographic information systems have made more complex spatial analyses readily available. However, methods may be problematic and several ongoing statistical weaknesses have been documented, including failing to account for three significant correlative factors - spatial, temporal, and spatiotemporal autocorrelations. Using Eastern Equine Encephalitis (EEE) human incidence data, this Master's thesis aimed to answer the research question, is there a northeastern shift in human EEE incidence within the United States, by identifying a statistical model that adjusts for spatial, temporal, and spatiotemporal autocorrelations. This thesis introduced the spatial autoregressive distributed lag (SADL) model, a model that adjusts for spatial, temporal, and spatiotemporal autocorrelations. However, results demonstrated that EEE is too rare an event for the SADL model to be appropriate, and a non-autocorrelation model was used as the final model. Results showed that EEE incidence is significantly increasing over time for all infected regions of the United States, with a significant difference of 1.4 cases/10 million between 1964 and 2015. Results did not demonstrate a northeastern shift in EEE incidence as the northeastern US had the highest expected incidence across the entire study period (1964-1967: 2.9/10 million; 2012-2015: 6.8/10 million), but results did demonstrate that the northeastern US had the quickest increasing risk for EEE as compared to other infected regions of the US with an increase in expected incidence of 3.9/10 million between 1964 and 2015.

Contexte Malgré le développement des connaissances physiopathologiques et la généralisation des techniques de biologie moléculaire, l'étiologie des encéphalites reste inconnue dans la majorité des cas. Leur incidence, le pronostic des patients à moyen et court terme et la persistance et la gravité des séquelles sont inconnus. Les objectifs de ce projet étaient d'améliorer les connaissances sur l'étiologie des encéphalites en France et dedécrire les patients hospitalisés en France pour encéphalites en terme cliniques, biologiques, démographiques, épidémiologiques et pronostiques Matériel et méthode Les patients de plus de 28 jours répondant à la définition de cas étaient inclus au cours de l'année 2007. Une exploration des étiologies possibles était effectuée selon une stratégie pré-définie. Des informations épidémiologiques, cliniques, paracliniques et biologiques étaient recueillies à l'aide de questionnaires standardisés à l'admission, 5 jours après et à la sortie de l'hôpital. Cette étude était réalisée selon la règlementation en vigueur. Le devenir à long terme des patients a été évalué au cours de l'année 2010 à l'aide de questionnaires standardisés. Les données recueillies concernaient les symptômes persistants, la reprise des activités de loisirs, la reprise du travail ou de la scolarité et la qualité de vie. Le déclin cognitif était évalué auprès de la famille des patients à l'aide du test QIDECO. La mesure principale de l'issue de l'encéphalite était le Glasgow outcome scale (GOS). Résultats 253 patients atteints d'encéphalites aiguës ont été inclus. Un agent étiologique a été identifié pour 131 (52%) d'entre eux. Les agents étiologiques les plus fréquemment identifiés étaient le virus Herpes simplex (HSV, n=55), le virus Varicella Zoster (VZV, n=20), Mycobacterium tuberculosis (n=20) et Listeria monocytogenes (n=13). Vingt-six patients (10%) sont décédés durant l'hospitalisation. En 2010, 176 patients ont pu être inclus et évalués. L'issue de l'encéphalite était favorable pour 61% des patients et défavorable pour 39%. Parmi les patients qui travaillaient avant l'encéphalite, 24% n'avaient pas repris le travail au moment de l'évaluation. Les patients qui avaient présenté une encéphalite herpétique en 2007, avaient un GOS étaient moins bon que les autres patients. Discussion Notre travail a permis une amélioration significative de la proportion d'encéphalites pour lesquelles un diagnostic étiologique est établi. Nous avons montré que les bactéries occupent une place non négligeable dans les causes de ce syndrome, et sont responsables de la majorité des décès survenant durant la phase aigue des encéphalites. A long terme, une proportion importante de patients présente des séquelles significatives ce qui témoigne de la transformation de l'encéphalite en maladie neurologique et neuropsychologique chronique une fois l'épisode infectieux aigu résolu. La fréquence importante des séquelles d'encéphalite herpétique relativise le succès obtenu en terme de létalité avec la généralisation de l'aciclovir. Conclusion Notre travail permet de définir des recommandations utilisables en routine pour le diagnostic étiologique des encéphalites, et le suivi à long terme des patients qui devrait être généralisé. Les encéphalites herpétiques doivent faire l'objet de recherche physiopathologique pour expliciter lagravité résiduelle de la maladie en dépit d'un traitement spécifique, et proposer une meilleureprévention et une meilleure prise en charge des séquelles
Abstract Background Despite a better knowledge about pathophysiological mechanisms and the generalisation of molecular biological Tools, the aetiology of encephalitis is still undetermined in most cases. Their incidence, the short-term and long-term prognosis of the disease and the persistence of sequelae are unknown. The objectives of this work were to improve the knowledge about the aetiology of encephalitis in France and to describe the patients hospitalized in France with encephalitis according to clinical, biological, demographic, epidemiological and outcome data. Methods Patients aged 28 days or more, who fitted the case definition, were enrolled in 2007. The investigation of aetiological diagnosis was carried out according to a previously defined diagnosis strategy. Epidemiological, clinical and biological data were collected using standardised questionnaires on admission, on day 5 of hospitalisation and on discharge. The study was carried out in accordance with French regulations. The long-term outcome of patients was assessed in 2010. Data collected encompassed persisting symptoms, resuming leisure activities, return to wok or resuming education and quality of life. Cognitive decline was assessed with patients' relatives using IQCODE. The main outcome measure was the Glasgow outcome scale (GOS). Results 253 patients presenting with acute encephalitis were included. A causative agent was identified for 131 (52%) of them. Most frequent causative agents were Herpes simplex virus (HSV, n=55), Varicella Zoster virus (VZV, n=20), Mycobacterium tuberculosis (n=20) and Listeria monocytogenes (n=13). Twenty-six patients (10%), died during hospitalisation. In 2010, 176 patients could be included and assessed. The outcome of encephalitis was favourable for 61% of patients and 39% had a poor outcome. Among patient employed before onset of encephalitis, 24% had not returned to work at the time of evaluation. Patients who presented with herpes encephalitis in 2007 had a lower score on GOS than other patients. Discussion Our study resulted in a important improvement of the proportion of encephalitis with a causative agent identified. We demonstrated that bacteria play a significant role as causes of encephalitis, and are responsible for most death occurring during the acute stage of encephalitis. An important proportion of patients presented long-term sequelae, illustrating the evolution of encephalitis from an acute infectious disease toward a chronic neurological disease. The high frequency of sequelae following herpes encephalitis is a shadow on the success of aciclovir. Conclusion Considering our results, we can propose recommendation for the everyday management of encephalitis patients, both to achieve aetiological diagnosis and a long-term follow-up that should be extended to all encephalitis patients. Herpes encephalitis should be more studied on pathophysiological aspects to explicate the severity of the disease despite the existence of a specific treatment, and to propose better prevention and management of sequelae

Bipycнi енцефаліти (ВЕ) займають важливе місце у структурі нейроінфекцій у дітей. Одними з найтяжчих різновидів є герпетичні енцефаліти. До застосування специфічного лікування летальність при них складала 55-76 %, при проведенні терапії ацикловіром – 28 %. Маємо досвід лікування 72 дітей, віком від 5 міс. до 15 років, хворих на енцефаліти різної етіології. Вони знаходилися у відділенні анестезіології та інтенсивної терапії Сумської міської дитячої клінічної лікарні за період із 1995 по 2008 рік; з них дітей старше 3 років – 26 (36,1 %). При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/14370

Ticks are blood-sucking parasites that are an inconvenience for both humans and animals. The tick by itself is normally harmless unless they attack in excessive numbers. The harm from ticks stems from them being excellent vectors for other parasites, in the form of bacteria and virus that via the ticks are provided a bridge to move across the blood streams of different animals, including humans. One of the most pathogenic tick-borne disease for humans is caused by a flavivirus, the tick-borne encephalitis virus (TBEV). Each year approximately 10 000 individuals on the Eurasian continent develop neurological disease, in the form of meningitis, encephalitis, myelitis and radiculitis, following a bite by a TBEV infected tick. To evaluate the risk of TBEV infection after a tick-bite, we have developed a study to investigate ticks that have bitten humans and to follow up the tick-bitten humans to investigate if they get infected, and if they develop symptoms, and further trace the virus back to the tick that is infected with TBEV. Ticks, blood samples, and questionnaires were collected in collaboration with 34 primary health care centers in Sweden and on the Åland Islands during 2008 and 2009. Several demographical and biological factors were investigated regarding the interaction between ticks and humans. The main finding was that men removed the ticks later than women, and that both older men and older women removed the ticks later than younger individuals. This could in part explain why older individuals in general, and men in particular, are at greater risk of acquiring tick-borne encephalitis (TBE). Furthermore, the prevalence of TBEV in ticks that have bitten humans were investigated, in order to correlate the copy number of TBEV in the tick and the tick feeding-time to the risk of developing symptomatic and asymptomatic infection. This entailed the development of new methodology for tick analysis and TBEV real-time PCR. The result showed a very low risk of TBEV infection in the studied areas, only 5 of 2167 investigated ticks contained TBEV. Three of the individuals bitten by TBEV infected ticks were vaccinated and did not develop symptoms of TBEV infection. One unvaccinated individual got bitten by a tick containing 1800 virus copies, with a feeding-time of 12-24h, and interestingly showed no signs of infection. Another unvaccinated individual got bitten by a tick containing 7.7 million virus copies, with a feedingtime of >60h. This individual developed symptoms consistent with a 1st phase of TBE, including fever and headache, but did not develop the 2nd neurological phase of TBEV infection. Despite only  finding 5 ticks infected with TBEV, a correlation between the virus load in the tick and the tick feeding-time was observed. In 2 other individuals, TBEV antibody seroconversion was detected during the 3 month study period, one without symptoms, while the other experienced symptoms consistent with the 1st phase of TBE. These observations support the hypothesis that a higher virus amount in the tick and a longer feeding time increases the risk of TBEV infection. To further examine TBEV in ticks that have bitten humans and find factors that may predict the risk of human infection and development of TBE, we characterized several TBEV strains genetically. Including TBEV strains isolated from ticks that have bitten human, from questing field-collected ticks, and TBEV strains isolated from patients with TBE. In one of the ticks detached from a human after >60h of feeding, there was a heterogeneous population of TBEV quasispecies with varying poly(A) length in the 3’ untranslated region of the genome was observed. These variations might have implications for differences in virulence between TBEV strains, and the heterogeneous quasispecies population observed could be the virus adapting from replication in tick cells to mammalian cells. We also investigated the response to TBEV vaccination in relation to 14 health-related factors in a population of older individuals on the Åland Islands. Blood samples, questionnaires, and vaccination records were collected from 533 individuals. Three different serological assays to characterize antibody response to TBEV vaccination were used. The main finding was that the number of vaccine doses in relation to age was the most important factor determining successful vaccination. The response to each vaccination dose declined linearly with age, and as much as 47%  of individuals 50 years or older that had taken 3 vaccine doses were seronegative, compared to 23% that had taken 4 doses and 6% with 5 doses. Comparison between the serological assays revealed that the cutoffs determining the balance between sensitivity and specificity differed, but not the overall accuracy. Taken together, these results contribute to a better understanding of the TBEV epidemiology and can provide tools in the prevention of TBE.

This thesis explores the importance of IFN in SFV encephalitis. A quantitative PCR assay for IFN-β and IFN-α transcripts and a quantitative IFN bioassay were developed to determine differences in IFN expression under different infection conditions. Mouse models and primary cell lines were used to establish the importance of PKR for IFN=β expression during SFV infection and to determine whether SFV nsP2 has a role in modulating IFN responses. In the absence of PKR, at early times post-infection, cultured cells reproducibly produced significantly lower levels of IFN-β transcripts. Reduced levels of functional IFN were also demonstrated by bioassay. Previous data has shown that PKR is not required for IFN-β induction. The sensitivity of the qPCR assay has allowed the demonstration that PKR, although not critical for IFN induction, is involved in IFN-β induction and is particularly important at early time points post infection. SFV-nsP2 has been postulated to be involved in IFN interference. Comparing SFV4 to SFV4-nsP2-RDR (a mutant virus with a single amino acid change within the nuclear localisation signal of nsP2, which prevents its translocation into the nucleus) demonstrated that relative to the number of infected cells, the SFV4nsP2-RDR mutant induced over ten –fold more IFN-β transcripts than the wildtype SFV4 strain; this upregulation was specific to IFN-β. The IFN bioassay results supported this data; SFV4-nsP2-RDR induced higher functional IFN levels in comparison to wt SFV4. Both viruses grew to similar titres and at similar rates. In the mutant and wt infections both NF-κB and IRF-3 translocated into the nucleus; however, preliminary EMSA data has suggested that the amount of NF-κB and IRF-3 translocated into the nucleus; however preliminary EMSA data has suggested that the amount of NF-κB bound to the IFN-β promoter is reduced during a wt infection. This suggests a possible mechanism for the differential IFN expression and represents the first IFN evasion mechanism described for an alphavirus.

The flavivirus genus is of major concern for world morbidity and mortality and includes viruses causing both encephalitic as well as hemorrhagic diseases. The incidence of Tick-borne encephalitis is increasing in many European countries and several reports have emphasized the expansion of the main vector, Ixodes ricinus. The pattern of vector distribution is also changing in Sweden, which makes it important to set up solid and successful strategies for detection and genetic characterization of novel Swedish TBEV strains. In this study we have generated strategies for detection of broad types of tick-borne flaviviruses in pools of I. ricinus sampled in Sweden. The positive collection on the island of Torö was used to generate a sequence of a complete TBEV genome straight from the arthropod reservoir. This cloned virus was used to construct a self-replicating DNA based sub-genomic TBEV replicon capable of expressing reporter genes. The replicon was used to study the effect of TBEV on neurite outgrowth, which revealed that the MTase domain of NS5 block the formation of the Scribble/Rac1/βPIX protein complex, impairing neurite outgrowth in neuronal growth factor induced PC12 cells. We also demonstrate that TBEV replication is affected by two PDZ binding motifs within NS5 and reveal putative PDZ binding proteins. These interactions might affect cellular pathways and might have a role in flavivirus replication. We also characterize the variable 3´ non-coding region (V3’-NCR) by in silico studies on TBEV. Analysis brings new evidence that V3’-NCR region carries an enhancer element important for different replication/translation dynamics during the viral lifecycle in mammalian and tick cells. We also propose a temperature-sensitive trans-acting riboswitch mechanism; altering the secondary RNA structures of a closed form at lower temperatures and a form open for translation at higher temperatures. This mechanism may explain the low TBEV level observed in sampled ticks.

At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Manuscript.

Thesis advisor: Kenneth C. Williams
Individuals infected with Human Immunodeficiency Virus (HIV) are susceptible to pathological abnormalities due to the infiltration of virus into different anatomical compartments. Monocytes are a heterogeneous population that undergoes changes in phenotype with HIV infection. It is hypothesized that changes in monocyte subsets observed through the course of infection will correlate with the development of SIV-Encephalitis (SIVE). 14 CD8+ T cell depleted rhesus macaques were infected with SIVmac251 and changes in 3 monocyte subsets, defined by their CD14 and CD16 surface expression as CD14+CD16-, CD14+CD16+, and CD14-CD16+, were tracked through the course of disease. The CD14+CD16- subset increased in the absolute number of cells and decreased in percentage of the total monocyte population. The CD14+CD16+ and CD14-CD16+ subsets increased in both absolute number and percentage. These changes have a biphasic dynamic that occurs during early infection and is pronounced in encephalitic animals. Several markers showed differential expression with infection and between subsets. Mac387, an early monocyte-macrophage marker, demonstrated a considerable decrease in expression. Concomitant with this change, CD68, CD163, CD44v6, CCR2, and CD64 increased expression in the total monocyte population, with the magnitude of these changes occurring in a subset-specific manner. In conclusion, monocyte subsets undergo changes with SIV infection that correspond to the development of encephalitis, highlighting the contribution of monocytes in neuroAIDS
Thesis (MS) — Boston College, 2010
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Biology

This document describes an evaluation of acute (meningitis)-encephalitis syndrome (AES/AMES) surveillance established in India, Bangladesh and China. The key objectives of the project included 1) building on existing networks for syndromic surveillance and laboratory confirmation, 2) establishing laboratory-based surveillance for vaccine-preventable causes of encephalitis and meningitis, 3) enhancing capacity to use data to guide disease control and prevention programs, and 4) improving capacity to recognize new or emerging diseases. The syndromes encompass several diseases, including Japanese encephalitis (JE), pneumococcal meningitis, Haemophilus influenzae type b (Hib), and meningococcal meningitis. The purpose of the evaluation is to assess the extent to which the key objectives were met in the three project countries, compare and contrast the experiences among the countries, document the strengths and weaknesses, and make recommendations. The indicators used in the evaluation include feasibility of integration, availability of country protocols, appropriate training, data quality, sensitivity, specificity, positive predictive value, negative predictive value, representativeness, timeliness, integration with AFP surveillance, simplicity and efficiency, acceptability, usefulness, flexibility, stability, and sustainability. The criteria and standards are based on WHO recommendations. Data sources include AES/AMES epidemiologic and laboratory data sets, trip reports, country reports, field observations, and published bulletins. All countries made substantial progress in a relatively short period of time using the infrastructure and technical tools of existing surveillance and laboratory networks for acute flaccid paralysis. After one year, India and Bangladesh collects and maintains high quality epidemiologic data, exceeds targets for timeliness of reporting, and has quality-assured capacity for laboratory confirmation of Japanese encephalitis (JE) virus infection. India now has regional laboratory capacity for reference testing on virology and bacteriology. After two years of operations, China has population-based surveillance data for JE that meets targets for timeliness. Several levels have well-established capacity for laboratory confirmation of JE virus infection. The national level has the technical ability to provide proficiency testing for virology and to provide reference testing for bacteriology. In all countries, challenges in building capacity for basic bacteriology, quality control and quality assurance for all laboratory testing, and management of laboratory data.

Japanese encephalitis (JE) is a major cause of childhood mortality and morbidity in Asia and for which there is no treatment. In addition to direct viral cytopathology, a poorly regulated inflammatory response is postulated to contribute to the pathogenesis, possibly through bystander death of uninfected neurons; but there have been few studies examining this. We used a validated macaque model of JE to characterize the inflammatory response and cytopathic effects of JE virus (JEV) in the brain. There was strong perivascular infiltration of leukocytes, particularly T cells, with endothelial cell activation, vascular damage and leakage of serum across the blood brain barrier (888). Adjacent parenchyma exhibited macrophage rich infiltrates, with astrocyte and microglia activation. JEV antigen was seen mostly in neurons, but there was no correlation between intensity of viral infection and degree of inflammatory response. Apoptotic cell death was seen in both infected and non-infected neurons. Interferon (IFN)-a, which is a microglial activator, was also expressed by both. Tumour necrosis factor-a (which can induce neuronal apoptosis), inducible nitric oxide synthase and nitrotyrosine (involved in nitric oxide production) was expressed by microglial cells, astrocytes and to some extent macrophages. The same cells expressed matrix metalloproteinase (MMP)-2 whilst MMP-9 was expressed by neurons; both MMPs cause BBB disruption. The results are consistent with JEV inducing neuronal apoptotic death and release of cytokines such as IFN-a; these are postulated to initiate microglial activation, and release of pro-inflammatory and apoptotic mediators with subsequent apoptotic death of both infected and uninfected bystander neurons. Activation of astrocytes, microglial and endothelial cells likely contributes to inflammatory cell recruitment and BBB breakdown. These results provide strong evidence that neuronal apoptotic death and activation of microglial cells and astrocytes play a crucial role in the pathogensis of JE, and suggest new paths for targeted therapies.

Background: There are a large number of viruses spread by mosquitoes, many of which cause debilitating, often fatal, neurological disease such as acute encephalitis. In this study we have used two different neurotropic viruses: Semliki Forest virus (SFV), and West Nile virus (WNV), both of which can cause severe panencephalitis in the mouse. The influx of leukocytes into the infected tissues is mediated by chemokines and is believed to be important for virus clearance. To date, we have only limited insights into the precise nature of chemokine involvement, and an improved understanding of these important axes provides a new target for the development of novel therapies. Hypothesis: Based on previous studies investigating the role of chemokines during neuroinflammation it was hypothesised that chemokines and other cytokines are highly upregulated during viral encephalitis, and the blockade of selected chemokine receptors would lead to altered disease outcome. It was also hypothesised that chemokine receptors would present plausible targets for the treatment of viral encephalitis. Results: To test these hypotheses, the chemokine expression pattern and the kinetics of chemokine mediated leukocyte recruitment during viral encephalitis were analysed in unprecedented detail by TaqMan low density array, and flow cytometry, respectively, and key chemokine receptor were identified as therapeutic targets. Both SFV and WNV exhibited a similar pattern of chemokine upregulation, although WNV induced significantly higher fold expression. The key chemokines upregulated were CCL2, 3, 5, 7, CXCL9 and CXCL10. The upregulation of chemokines coincided with leukocyte influx into the CNS. After identifying the key chemokines upregulated during viral encephalitis, next a selected panel of chemokine receptor antagonists was utilized to evaluate the hierarchy and relative importance of distinct chemokine receptors for CNS leukocyte influx, viral clearance, neuropathogenesis and host survival. We identified the CXCR3 axis as being the key instigator of CNS inflammation in response to alphavirus infection, placing it at the top of a hierarchal cascade that is followed by CCR2 and CCR5. Critically, inhibition of both CXCR3 and CCR2 simultaneously, significantly improved host survival to otherwise lethal encephalitis. Conclusion: These data suggest that chemokine receptors represent plausible therapeutic targets for viral encephalitis.

Japanese Encephalitis (JE) is the most common form of viral encephalitis in the world, caused by the Japanese Encephalitis virus (JEV), it is responsible for around 10,000 deaths a year whilst many more are left with long term neurological sequelae and disability. This work sought to use small-scale development techniques alongside high-throughput methodologies to explore and develop selected processing techniques. Formaldehyde inactivation of JEV was characterised and optimised through the use of Design of Experiments screening techniques where temperature, time and formaldehyde concentration were found to be key factors in antigen loss. Glycine and to a lesser extent sorbitol were found to have positive effects as stabilisers during inactivation at different stages of the process. Four anion exchange resins were screened at micro-scale, with the help of an ELISA method evaluated for high-throughput screening, for their potential to replace sucrose gradient purification as the principle purification step of the process. Although Q Sepharose FF was eventually chosen for scale-up studies, the transition of method and recovery rates from batch bind micro-plate studies to 1 mL column scale proved difficult. Yet it was observed that pre-treatment of feed with formaldehyde and glycine could increase JEV antigen recovery rates in flow-through mode chromatography, thought to be due to enhanced stability of the virus particles.

Vector-borne diseases are an increasing global threat to humans due to climate changes, elevating the risk of infections transmitted by mosquitos, ticks, and other arthropod vectors. Ixodes ricinus, a common tick in Europe, transmits dangerous tick-borne pathogens to humans. Tick-borne encephalitis (TBE) is a vector-borne disease caused by TBE virus (TBEV). Climate change has contributed to increased tick abundance and incidence of tick-borne diseases, and between 10,000 and 15,000 human TBE cases are reported annually in Europe and Asia. TBEV shows a patchy geographical distribution pattern where each patch represents a natural focus. In nature, TBEV is maintained within the tick-rodent enzootic cycle. Co-feeding is the main route for TBEV transmission from infected to uninfected ticks and for maintenance within the natural foci. The increasing number of TBE cases in Scandinavia highlights the importance of characterizing additional TBEV sequences and of identifying novel natural foci, and in this work we sequenced and phylogenetically characterized four TBEV strains: Saringe-2009 (from a blood-fed nymph), JP-296 (from a questing adult male), JP-554 (from a questing adult male), and Mandal-2009 (from a pool of questing nymphs, n = 10). Mandal-2009 represents a TBEV genome from a natural focus in southern Norway. Saringe-2009 is from a natural endemic focus in northern Stockholm, Sweden, and JP-296 and JP-554 originate from a natural focus “Torö” in southern Stockholm. In addition, we have studied the effect of different biotic and abiotic factors on population dynamics of I. ricinus in southern Stockholm and observed significant spatiotemporal variations in tick activity patterns. Seasonal synchrony of immature stages and total tick abundance are important factors for the probability of horizontal transmission of TBEV among co-feeding ticks. We found that the probability of co-occurrence of larvae, nymphs, and female adults was highest during early summer whereas increasing vegetation height and increasing amounts of forest and open water around the study sites had a significant negative effect on co-occurrence of larvae, nymphs, and female adults. The proximal part of the 3 ́non-coding region (3 ́NCR) of TBEV contains an internal poly(A) tract, and genomic analysis of Saringe-2009 revealed variability in the poly(A) tract indicating the existence of different variants within the TBEV pool of Saringe-2009. Like other RNA viruses, TBEV exists as swarms of unique variants called quasispecies. Because Saringe-2009 came from an engorged nymph that had been feeding on blood for >60 h, we propose that Saringe-2009 represents a putative shift in the TBEV pool when the virus switches from ectothermic/tick to endothermic/mammalian environments. We investigated the role of poly(A) tract variability in replication and virulence of TBEV by generating two infectious clones of the TBEV strain Toro-2003, one with a short/wild-type (A)3C(A)6 poly(A) tract and one with a long (A)3C(A)38 poly(A) tract. The infectious clone with the long poly(A) tract showed poor replication in cell culture but was more virulent in C57BL/6 mice than the wild-type clone. RNA folding predictions of the TBEV genomes suggested that insertion of a long poly(A) tract abolishes a stem loop structure at the beginning of the 3 ́NCR. Next generation sequencing (NGS) analysis of the TBEV genomes after passaging in cell culture and/or mouse brain revealed molecular determinants and quasispecies structure that might contribute to the observed differences in virulence. Our findings suggest that the long poly(A) tract imparts instability to the TBEV genome resulting in higher quasispecies diversity that in turn contributes to TBEV virulence. Phylogenetic analysis of Saringe-2009, JP-296, JP-554, and Mandal-2009 predicted a strong evolutionary relationship among the four strains. They clustered with Toro-2003, the first TBEV strain from Torö, demonstrating a Scandinavian clade. Except for the proximal part of the 3 ́NCR, TBEV is highly conserved in its genomic structure. Genomic analysis revealed that Mandal-2009 contains a truncated 3 ́NCR similar to the highly virulent strain Hypr, whereas JP-296 and JP-554 have a genomic organization identical to Toro-2003, the prototypic TBEV strain from the same natural focus. NGS revealed significantly higher quasispecies diversity for JP-296 and JP-554 compared to Mandal-2009. In addition, single nucleotide polymerphism (SNP) analysis showed that 40% of the SNPs were common between quasispecies populations of JP-296 and JP-554, indicating the persistence and maintenance of TBEV quasispecies within the natural focus. Taken together, these findings indicate the importance of environmental factors for the occurrence pattern of the different life-stages of the tick vector, which are important for the persistence of TBEV in nature. Our findings also show that the selection pressure exerted by specific host also affects the population structure of the TBEV quasispecies. In addition, our results further demonstrate that the evolution of quasispecies has effect on TBEV virulence in mice.
Vektorburna sjukdomar är ett växande globalt hot mot både människor och djur. De pågående klimatförändringarna kan leda till förhöjda risker för infektioner överförda av myggor, fästingar och andra leddjursvektorer. Ixodes ricinus är en vanlig fästing i Europa som överför fästingburna patogener som är farliga för människor. Fästingburen encefalit (TBE) är en vektorburen sjukdom som orsakas av TBE-virus (TBEV). De pågående klimatförändringarna har bidragit till en ökning både av vektorn och sjukdomsfrekvensen. Mellan 10 000 och 15 000 mänskliga TBE-fall rapporteras årligen i Europa och Asien. Den geografiska fördelningen av TBEV visar ett ojämnt fördelningsmönster där viruset är koncentrerat till vissa fokusområden. TBEV återfinns i naturen i en livscykel där viruset hela tiden överförs mellan fästingar och däggdjur. Spridningen sker dels från en infekterad fästing till ett ryggradsdjur när fästingen äter på värddjuret. Spridning mellan fästingar sker troligen främst genom så kallad “co-feeding”, det vill säga att flera fästingar suger blod samtidigt från samma värddjur. Viruset kan då passera från en infekterad fästing, genom värddjuret till oinfekterade fästingar. Virus kan identifieras och studeras med genetiska metoder. Det ökande antalet TBE-fall i Skandinavien styrker vikten av att hitta och karakterisera ytterligare TBEV-stammar och identifiera nya naturliga fokusområden. Vi har sekvenserat och fylogenetiskt beskrivit fyra TBEV-stammar: Saringe-2009 (blodfylld nymf), JP-296 (födosökande vuxen hane), JP-554 (födosökande vuxen hane) och Mandal-2009 (födosökande nymfer, n = 10). Mandal-2009 är ett TBEV från ett naturligt fokusområde i södra Norge. Saringe-2009 kommer från ett naturligt fokusområde i norra Stockholms län, Sverige. JP-296 och JP-554 härstammar från Torö som är ett naturligt fokusområde i södra Stockholms län, Sverige. Förutom den genetiska sekvenseringen av TBEV har vi också studerat effekten av olika biotiska och abiotiska faktorer på populationsdynamik av I. ricinus i södra Stockholm och observerade variation i fästingsaktivitetsmönster både temporalt och spatialt. Förekomstmönster av fästinglarver, nymfer och vuxna honor, och det totala antalet fästingar är viktiga faktorer för sannolikheten för horisontell överföring av TBEV mellan fästingar. Vi fann att sannolikheten för synkron förekomst av larver, nymfer och honor var högst under försommaren. Vegetationshöjd, mängden skog och mängd öppet vatten runt undersökningsområden hade signifikanta negativa effekter på sannolikheten för att larver, nymfer och honor skulle förekomma samtidigt. Den variabla delen av den icke-kodande 3 ́regionen (3'NCR) av TBEV-genomet innehåller ofta en intern poly(A)-sekvens. Liksom andra RNA-virus, förekommer TBEV som så kallade ”quasispecies” vilka definieras som grupper av olika genetiska varianter av virus. Genom analysen av TBEV-stam Saringe-2009 avslöjades variation i poly(A)-sekvensen vilket indikerar förekomst av ”quasispecies”. Eftersom Saringe-2009 kom från en blodfylld nymf som hade sugit blod i > 60 timmar, föreslår vi att Saringe-2009 visar en förändring i ”quasispecies”-poolen när viruset överförs från exoterm fästingmiljö till endoterm däggdjursmiljö. Vi undersökte poly(A)-ekvensens variabilitet och dess roll vid replikering och för virulens hos TBEV, genom att skapa två infektiösa kloner av Torö-2003 stammen; en med en kort/vild-typ (A)3C(A)6 poly(A)-sekkvens, och en med en lång (A)3C(A)38 poly(A)-sekvens. Den infektiösa klonen med lång poly(A)-sekvens replikerade sämre än vildtypklonen i cellkultur, men (A)3C(A)38 poly(A) var mer virulent i C57BL/6-möss än (A)3C(A)6 poly(A). Datasimulering av TBEV-genomets sekundär-RNA-struktur visade att de längre poly(A)-sekvenserna påverkar veckningen av en specifik sekundärstruktur (SL14) i början av 3 ́NCR. Djupsekvenseringsanalys av TBEV-gnomen avslöjade skillnader för specifika gener och ”quasispecies”-strukturen efter passering i cellkultur och/eller mushjärna. Dessa förändringar föreslås bidra till de observerade skillnaderna i virulens. Våra resultat indikerar att den långa poly(A)-sekvensen ger instabilitet i TBEV-genomet, vilket resulterar i ökad mångfald av ”quasispecies”-populationen som i sin tur kan bidra till TBEV-virulens. Fylogenetisk analys av Saringe-2009, JP-296, JP-554 och Mandal-2009 visade på ett nära släktskap mellan de fyra skandinaviska TBEV-stammarna. De nya stammarna formerade ett kluster med en tidigare TBEV-stam identifierad på Torö (Toro-2003), vilket skapade ett skandinaviskt klad. Genetisk analys visade att Mandal-2009 innehåller en trunkerad 3 ́NCR som liknar den högvirulenta stammen HYPR. JP-296 och JP-554 hade däremot samma genetiska struktur som den längre Torö-2003 stammen från samma fokusområde. Djupsekvensering visade höge mångfald av ”quasispecies”-populationen för JP-296 och JP- 554 jämfört med Mandal-2009. Analys av enkel nukleotid polymorfism (SNP) visade att 40 % av alla SNP var gemensamma mellan ”quasispecies”-populationen för JP-296 och JP-554. Detta indikerar att TBEV-”quasispecies”-strukturen kan vara konserverad för närbesläktade virus vilken kan leda till att den bevaras inom specifika fokusområden. Sammantaget så visar dessa studier att miljöfaktorer påverkar förekomsten av fästingvektorn och dess olika livsstadier, vilket är en bakomliggande faktor för utbredning av TBEV i naturliga fokusområden. Det visar även på att värdmiljön påverkar strukturen för ”quasispecies”-populationen. Dessutom visar våra studier att evolution och utveckling av ”quasispecies”-strukturen kan påverka virulensen för TBEV i möss.

Acute Encephalitis Syndrome (AES) is a group of clinical symptoms and signs, used by the World Health Organisation (WHO) and clinicians, to screen for acute encephalitis. Viruses are the most important cause of AES worldwide. Japanese encephalitis virus (JEV), which causes Japanese encephalitis (JE), accounts for approximately one-quarter of AES cases in Nepal. In the absence of definite treatments for JE and many other viral enecpahlitides, improvements in supportive management are vital. In my thesis, the predictors of bad outcome (neurological sequelae or death) among patients with AES and JE were investigated. The relationships between weight-for-age (WFA), hydration status, intravenous fluids and outcome were studied. In addition, a preliminary randomised double blind placebo controlled trial of intravenous immunoglobulin (IVIG), as a novel adjunctive treatment for JE, was conducted. Prolonged fever duration was identified to be a significant predictor of bad outcome in both AES and JE patients. Prolonged fever, low Glasgow coma score (GCS) and focal neurological deficit at hospital admission were significantly associated with bad outcome in AES patients. AES patients with focal neurological deficit were significantly more likely to have a final diagnosis of JE. JE patients presented with a significantly lower body weight and higher respiratory rate. They also presented with a trend for higher urea and potassium levels compared to other AES patients. These findings led me to investigate further whether children with JE were more likely to suffer from dehydration during acute illness. When children are grouped into different weight categories by WFA (Z score), low WFA can indicate dehydration or malnutrition. I found a significant association between frequency of bad outcome and low WFA among both AES and JE patients at hospital admission. To help distinguish dehydration and malnutrition in low WFA children, I then studied additional indicators of malnutrition and dehydration status, including midupper arm circumference, blood lactate levels and fluid status at admission and during hospital stay. I found AES patients suffering a bad outcome had significantly higher admission serum lactate levels, drunk a lower volume of oral fluids, and were more likely to be prescribed a restricted regimen of intravenous fluids. These results suggest AES patients with bad outcome were more likely to be dehydrated. The implications of my findings are that earlier hospital admission during the course of the illness and better in hospital administration of adequate and appropriate fluids may improve outcome among AES and JE patients. Since the majority of families self-refer to hospitals, provision of this simple message into the community, could help improve the lives of people living in high risk areas for JE, like Nepal. Improvement in the treatment of JE is necessary to improve the outcome of the disease in Nepal. Intravenous immunoglobulin, which contains anti-JE virus neutralising antibodies and has anti-inflammatory properties, may be a useful adjunctive treatment. In a preliminary Phase II study, I showed IVIG could be safely administered to JE patients, without any significant increase in drug related adverse events. JE patients treated with IVIG exhibited higher levels of neutralising antibodies and higher IL-4 and IL-6 cytokine levels compared with placebo (saline) treated patients. Although, there was no difference in clinical outcome, the data from this small pilot study suggests IVIG may be an appealing adjunctive treatment option for a phase III trial in the future.

Das Frühsommer-Meningoezephalitis-Virus (FSMEV) ist eines der wichtigsten vektorübertragenen Viren in Europa und Asien. Die häufigste Übertragung erfolgt durch den Stich einer infizierten Zecke, gelegentlich werden FSME Infektionen auch durch den Genuss von Rohmilchprodukten infizierter Tiere verursacht. Die Pathogenese von Caco-2 Monolayer Epithelzellen zeigten nach Infektion mit FSMEV morphologische Änderungen mit signifikanter Vakuolisierung. Ultrastrukturanalysen zeigten eine Ausdehnung des rauen ER und das Auftreten FSMEV haltiger Kavernen. Monolayer von Caco-2 Zellen bildeten eine Barriere mit stabilem transepithelialem elektrischem Widerstand (TEER). Auch traten Viren im basolateralen Medium auf, die über einen Tanscystose pathway (PW) aufgenommen wurden. Der Zelleintritt von FSMEV konnte durch verschiedene Inhibitoren wirksam blockiert werden, was darauf hinweist, dass Aktinfilamente und Mikrotubuli wichtig für die PI3K-abhängige Endozytose sind. Die experimentelle Flüssigkeitsaufnahme zeigte erhöhte intrazelluläre Ansammlungen von FITC-Dextran haltigen Vesikeln und die Co-Lokalisation von FSME-Viren mit frühem Endosom Antigen-1 und mit sorting nexin-5. Was auf die Makropinozytose als Transportmechanismus hinweist. Während der Infektion wurden weitere Hinweise für die Virustranslokation über den parazellulären Weg gefunden. Das konnte den FSMEV Pathomechanismus in humanen Intestinalepithelzellen über Nahrungsmittel näher aufklären. Die Untersuchung der zwei UPR „signaling PWs“ während der FSMEV Infektion in VeroE6 Zellen zeigte, dass die Menge von „heat shock protein“ 72 im Verlauf der FSMEV Infektion ansteigt, und eine FSMEV Infektion den „IRE1- und den ATF6 PW“ aktiviert. Auch die Hemmung des „IRE1 PW“ wirkt auf die FSMEV Infektion, was darauf hinweist, dass eine FSMEV Infektion die beiden „UPR signaling PWs“ aktiviert. Diese Hemmung der FSMEV Replikation durch UPR Inhibitoren könnte ein neuer Ansatz für spezifische Therapien gegen FSME sein.
Tick-borne encephalitis virus (TBEV) is one of the most important vector-borne viruses in Europe and Asia. The transmission mainly occurs by the bite of an infected tick. Consuming of rough milk products from infected livestock animals also occasionally cause TBE cases. Human intestinal Caco-2 cells were used to investigate the pathogenesis caused by TBEV. During TBEV infection Caco-2 monolayers showed morphological changes with significant vacuolization. Ultrastructural analysis revealed dilatation of the rough endoplasmic reticulum and further enlargement to TBEV containing caverns. Caco-2 monolayers showed an intact epithelial barrier with stable transepithelial electrical resistance (TER). Concomitantly, viruses were detected in the basolateral medium, taken up via a transcytosis pathway. TBEV cell entry was efficiently blocked with different inhibitors, suggesting that actin filaments and microtubules are important for PI3K-dependent endocytosis. Moreover, experimental fluid uptake assay showed increased intracellular accumulation of FITC-dextran containing vesicles and co-localization of TBEV with early endosome antigen-1 and with sorting nexin-5 could confirm macropinocytosis as trafficking mechanism. In the late phase of infection, further evidence was found for translocation of virus via the paracellular pathway. Thus, TBEV pathomechanisms in human intestinal epithelial cells and its transmission via the alimentary route were enlightened. In addition, I investigated the effects of the two unfolded protein response (UPR) signaling pathways upon TBEV infection in Vero E6 cells. I showed that the amount of heat shock protein 72 increased in the course of TBEV infection. I then confirmed that TBEV infection activates the IRE1 pathway and ATF6 pathway. These findings provide the first evidence that TBEV infection activates the two UPR signaling pathways. Moreover, inhibition of UPR may provide a novel therapeutic strategy against TBE.

Le danio zébré est un modèle bien établi pour étudier la biologie du développement des vertébrés. Ses larves transparentes sont favorables à des approches de microscopie non invasive, qui permettent de réaliser des observations à l’échelle d’un individu entier à des niveaux de résolution cellulaire et subcellulaire. Ces atouts font du danio zébré un excellent modèle pour étudier les infections virales in vivo. Au cours de mon projet, j’ai etudié l’entrée et la colonisation du système nerveux central (SNC) par le virus Sindbis (SINV) dans le modèle danio zébré. Mon projet présentait plusieurs axes: 1) développer un modèle d’infection du virus Sindbis chez le danio zébré, 2) caractériser l’invasion du SNC par le virus par des techniques d’imagerie à haute résolution, 3) définir la voie d’entrée du virus dans le SNC, 4) évaluer la dynamique de la réponse immunitaire innée par l’étude de la réponse interféron. Le suivi de la propagation du virus a été rendu possible par l’utilisation d’un ARN viral recombinant exprimant la protéine fluorescente verte ‘GFP’. L’utilisation de cette construction m’a permis de caractériser la progression de SINV chez le danio zébré et d’identifier les organes/tissus cibles que sont le vitellus, le foie, le cœur et enfin, le cerveau. Les données rassemblées jusqu'à présent m’ont aussi permis d’identifier le mécanisme par lequel SINV se propage vers le cerveau: le virus se propage par un transport axonal du system nerveux périphérique vers le SNC. Dans le cadre de la réponse immunitaire au niveau cellulaire, j’ai pu observer le rôle joué par les leucocytes, en particulier les neutrophiles, comme cellules productrices d'interféron
The zebrafish (Danio rerio) is an important model organism, particularly for studies of development and more recently host pathogen interactions. As opposed to other vertebrate model organisms, its optical clarity and ease of genetic manipulations allow to visualize highly dynamic cellular processes in vivo at the whole organism scale. These assets make the zebrafish a perfect model for the study of viral infections in vivo, such as those caused by neurotropic viruses. The aim of this project has been to gain insights in some of the interactions that determine encephalitis, by characterizing the neurotropic Sindbis virus (SINV). This Thesis project has consisted therefore in: 1) the development of a SINV infection model in zebrafish larvae, 2) the characterization of SINV neuroinvasion upon its inoculation in the bloodstream, thanks to the use of high resolution microscopy, 3) the study of SINV mechanism of entry in the CNS, 4) the characterization of the innate immune response, both at the whole organism and organ specific level. Thanks to the use of a SINV recombinant strain, engineered to express the green fluorescent protein “GFP” in infected cells upon viral replication, we have been able to follow the onset and the progression of the infection. We have suggested infection of peripheral neurons and subsequent axonal transport to the CNS as SINV entry mechanism. At the cellular level, we have identified neutrophils as the main IFN producing cells

Master of Science
Department of Diagnostic Medicine/Pathobiology
Natalia Cernicchiaro
Japanese encephalitis virus (JEV) is a virus of the Flavivirus genus that may result in encephalitis in vertebrate hosts. This vector-borne zoonosis occurs in Eastern and Southeastern Asia and an intentional or inadvertent introduction into the United States (US) would lead to important public health and economic consequences. The objective of this study was to gather, appraise, and synthesize primary research literature to identify and quantify vector and host competence for JEV, using a systematic review-metaanalysis (SR-MA) approach. After defining the research question, we performed a search in selected electronic databases. The title and abstract of the identified articles were screened for relevance using a defined set of exclusion and inclusion criteria, and relevant articles were subjected to a risk of bias assessment followed by data extraction. Random-effects subgroup meta-analysis models were fitted by species (mosquito or vertebrate host species) to estimate pooled summary measures as well as to compute the variance between studies. Meta-regression models were fitted to assess the association between different predictors and the outcomes of interest and to identify sources of heterogeneity among studies. Data were extracted from 171 peer-reviewed articles. Most studies were observational (59.06%) and reported vector competence (60.2%). The outcome measures reported pertained to transmission efficiency, host preference, and vector susceptibility to infection within vector competence; and susceptibility to infection within host competence. All outcome measures (JEV proportion of infection in vectors and hosts from observational studies; and JEV infection, dissemination, and transmission rates in vectors from experimental studies) had high heterogeneity. Mosquito species, diagnostic method, country, and capture method represented important sources of heterogeneity associated with the proportion of JEV infection in vectors; host species and region were considered sources of heterogeneity associated with the proportion of JEV infection in hosts; and diagnostic and mosquito capture methods were deemed important contributors of heterogeneity for the minimum infection rate (MIR) outcome. Mosquito species and administration route represented the main sources of heterogeneity associated with JEV infection rate in vectors. Quantitative estimates resulting from this SR-MA will be inputted into risk assessment models to evaluate risks associated with the introduction of JEV in the US.

Immune mechanisms are thought to be involved in the pathological disease process in a number of childhood epileptic syndromes and encephalitis. Of particular interest is the occurrence of autoantibodies to essential neuronal proteins, for example the N-methyl-D-aspartate receptor (NMDAR), in the blood and spinal fluid in some of these patients. The aims of this study were: to examine the sera of newly diagnosed paediatric epilepsy patients for specific neuronal autoantibodies, correlate to epilepsy phenotype and disease outcomes; to investigate the pathogenicity and epileptogenicity of central nervous system autoantibodies (CNS) in vivo; and to test new therapies in vitro and in vivo based on the potential pathogenic mechanisms. In 290 paediatric patients with new-onset epilepsy and seizures tested for CNS autoantibodies, 11.4% were positive (33/290 versus 8/112 in controls; p=0.01, Fisher's exact test). Previously unreported contactin-2 antibody positive and contactin-associated-protein 2 (CASPR2) antibody positive epilepsy patients were described. Patients with 'focal epilepsy of unknown cause' were more likely to be antibody positive. To test the pathogenicity and epileptogenicity of these antibodies, a novel in vivo telemetry system was used to continuously record electroencephalogram (EEG) in mice injected into the cerebral lateral ventricle with NMDAR antibody (NMDAR-Ab) positive immunoglobulin (IgG). Although no spontaneous seizures were seen, mice challenged with the pro-convulsant pentylenetetrazole (PTZ) had increased seizure susceptibility, and more epileptiform "spikes" in the EEG after PTZ compared to healthy control (HC) IgG injected mice. Seizure susceptibility strongly correlated with binding intensity of NMDAR-Ab IgG analysed in post-mortem tissue. Given the hypothesis this epileptogenic effect was mediated by NMDAR-Abs internalising cell surface NMDARs, and to try and rescue this deficit, a neurosteroid, pregnenolone sulphate (PregS) known to increase NMDAR cell surface expression, was therapeutically used. This approach worked in vitro, and although in vivo effects were not yet established, treatment with neurosteroids may be beneficial for autoantibody mediated neurological disease.