Progress in pathogenic mechanisms of neurotropic viruses crossing blood-brain barrier and invading central nervous system / 中华微生物学和免疫学杂志

Blood-brain barrier is a natural barrier between blood and brain tissue that can protect the brain from invasion by infectious pathogens in blood and maintain the homeostasis of the brain environment. However, neurotropic viruses can escape or disrupt blood-brain barrier and then invade the brain, causing serious complications in the central nervous system such as encephalitis and meningitis, which seriously threaten human life. This paper mainly summarized the research progress in the pathogenic mechanisms of common neurotropic viruses crossing blood-brain barrier and invading the central nervous system.

Atorvastatin ameliorates viral burden and neural stem/ progenitor cell (NSPC) death in an experimental model of Japanese encephalitis

Japanese encephalitis virus, a neurotropic flavivirus, causes sporadic encephalitis with nearly 25% fatal casereports. JEV infects neural stem/progenitor cells (NSPCs) and decreases their proliferation. Statin, a commonlyused class of cholesterol lowering drug, has been shown to possess potent anti-inflammatory and neuroprotective effects in acute brain injury and chronic neurodegenerative conditions. Here, we aimed to check theefficacy of atorvastatin in alleviating the symptoms of Japanese encephalitis (JE). Using BALB/c mouse modelof JEV infection, we observed that atorvastatin effectively reduces viral load in the subventricular zone (SVZ)of infected pups and decreases the resultant cell death. Furthermore, atorvastatin abrogates microglial activation and production of proinflammatory cyto/chemokine production post JEV infection in vivo. It alsoreduced interferon-b response in the neurogenic environs. The neuroprotective role of atorvastatin is againevident from the rescued neurosphere size and decreased cell death in vitro. It has also been observed that uponatorvastatin administration, cell cycle regulatory proteins and cell survival proteins are also restored to theirrespective expression level as observed in uninfected animals. Thus the antiviral, immunomodulatory andneuroprotective roles of atorvastatin reflect in our experimental observations. Therefore, this drug broadens apath for future therapeutic measures against JEV infection.

Ataxias cerebelosas e infecciones virales: caracterización clínica y mecanismos neuropatogénicos / Cerebellar ataxias and viral infections: clinical characterization and neuropathogenic mechanisms

Introducción: La ataxia constituye una alteración en la coordinación de los movimientos, resultado de una disfunción del cerebelo, sus conexiones, así como alteraciones en la médula espinal, nervios periféricos o una combinación de estas condiciones. Las ataxias se clasifican en hereditarias, esporádicas y en adquiridas o secundarias, en las cuales los virus neurotrópicos constituyen los principales causantes. Objetivo: Actualizar los conocimientos relacionados con las ataxias causadas por virus neurotrópicos y los mecanismos neurodegenerativos que pudieran tener relación con la ataxia. Métodos: Se realizó una revisión bibliográfica incluyendo artículos publicados en las principales bases de datos bibliográficas (Web of Sciences, Scopus, SciELO). Se utilizaron las palabras claves: ataxia, virus neurotrópicos, ataxias cerebelosas, ataxias infecciosas, en inglés y español. Análisis e integración de la información: Los virus más conocidos que provocan ataxias infecciosas son el virus de inmunodeficiencia humana, virus del herpes simple, virus del herpes humano tipo 6, virus de la varicela zoster, virus Epstein-Barr, virus del Nilo Occidental, y enterovirus 71, aunque existen otros virus que causan esta afectación. Los mecanismos neuropatogénicos sugeridos son la invasión directa del virus y procesos inmunopatogénicos desencadenados por la infección. Estos virus pueden causar ataxia cerebelosa aguda, ataxia aguda posinfecciosa, síndrome opsoclono-mioclono-atáxico y ataxia por encefalomielitis aguda diseminada. Aunque la mayoría de los reportes de casos informan la evolución satisfactoria de los pacientes, algunos refieren complicaciones neurológicas e incluso la muerte. Conclusiones: Actualmente existe la necesidad de profundizar en el estudio de este tipo de ataxia para favorecer su diagnóstico y tratamiento(AU)

Introduction: Ataxia is an alteration in the coordination of movements caused by a dysfunction of the cerebellum and its connections, as well as alterations in the spinal cord, the peripheral nerves, or a combination of these factors. Ataxias are classified into hereditary, sporadic and acquired or secondary, in which neurotropic viruses are the main causative agents. Objective: Update knowledge about ataxias caused by neurotropic viruses and the neurodegenerative mechanisms which could bear a relationship to ataxia. Methods: A review was conducted of papers published in the main bibliographic databases (Web of Sciences, Scopus, SciELO), using the search terms ataxia, neurotropic virus, cerebellar ataxias, infectious ataxias, in English and in Spanish. Discussion: The best known viruses causing infectious ataxias are the human immunodeficiency virus, herpes simplex virus, human herpesvirus 6, varicella zoster virus, Epstein-Barr virus, Western Nile virus and enterovirus 71, though other viruses may also cause this condition. The neuropathogenic mechanisms suggested are direct invasion of the virus and immunopathogenic processes triggered by the infection. These viruses may cause acute cerebellar ataxia, acute postinfectious ataxia, opsoclonus-myoclonus-ataxia syndrome and ataxia due to acute encephalomyelitis disseminata. Though most case reports describe a satisfactory evolution of patients, some refer to neurological complications and even death. Conclusions: There is a current need to carry out further research about this type of ataxia to improve its diagnosis and treatment(AU)

Comparison of a conventional polymerase chain reaction with real-time polymerase chain reaction for the detection of neurotropic viruses in cerebrospinal fluid samples.

Purpose : To compare a conventional polymerase chain reaction (PCR) and real-time PCR for the detection of neurotropic DNA viruses. Materials and Methods : A total of 147 cerebrospinal fluid (CSF) samples was collected from patients attending a tertiary care hospital in South India for a period from 2005 to 2008. All these samples were tested using a conventional multiplex/uniplex PCR and a real-time multiplex/uniplex PCR. This technique was used to detect a large number of herpes viruses responsible for central nervous system infections, including HSV-1, HSV-2, VZV, CMV and EBV and the polyoma virus JCV. Results : Overall, in the entire set of samples, the real-time PCR yielded 88 (59.9%) positives and conventional PCR had six (4.1%) positives. Conclusion : Our results suggest that the real-time PCR assay was more sensitive compared with the conventional PCR. The advantage of real-time PCR is that it can be performed much faster than conventional PCR. Real-time PCR is less time-consuming, less labour-intensive and also reduces the chance of contamination as there is no post-amplification procedure. In the entire study population, the major viruses detected using real-time PCR were EBV (34%), HSV-2 (10.8%) and VZV (6.8%).