Congenitally acquired persistent lymphocytic choriomeningitis viral infection reduces neuronal progenitor pools in the adult hippocampus and subventricular zone.

Lymphocytic choriomeningitis virus (LCMV) can be transmitted through congenital infection, leading to persistent infection of numerous organ systems including the central nervous system (CNS). Adult mice persistently infected with LCMV (LCMV-cgPi mice) exhibit learning deficits, such as poor performance in spatial discrimination tests. Given that deficits in spatial learning have been linked to defects in adult neurogenesis, we investigated the impact of congenital LCMV infection on generation of neuroblasts from neural progenitor cells within neurogenic zones of adult mice. In LCMV-cgPi mice, QPCR and immunohistochemistry detected presence of LCMV glycoprotein-coding RNA and nucleoprotein in the hippocampal dentate gyrus and subventricular zone (SVZ), sites of neurogenesis that harbor populations of neuroblasts. Numbers of neuroblasts were reduced in LCMV-cgPi mice, as determined by IHC quantification, and analysis of BrdU incorporation by flow cytometry revealed lower numbers of BrdU-labeled neuroblasts. Additionally, TUNEL assays performed in situ showed increased numbers of apoptotic cells in the two neurogenic regions. Next, neurosphere cultures were infected in vitro with LCMV and differentiated to create a population of cells that consisted of both transit amplifying cells and neuroblasts. Immunocytochemical and TUNEL assays revealed increased numbers of TUNEL-positive cells that express nestin, suggesting that the drop in numbers of neuroblasts was due to a combination of impaired proliferation and apoptosis of progenitor cells. LCMV-cgPi mice exhibited transcriptional up-regulation several cytokines and chemokines, including gamma-interferon inducible chemokines CXCL9 and CXCL10. Chronic up-regulation of these chemokines can facilitate a pro-inflammatory niche that may contribute to defects in neurogenesis.

Microglia and a functional type I IFN pathway are required to counter HSV-1-driven brain lateral ventricle enlargement and encephalitis.

HSV-1 is the leading cause of sporadic viral encephalitis, with mortality rates approaching 30% despite treatment with the antiviral drug of choice, acyclovir. Permanent neurologic deficits are common in patients that survive, but the mechanism leading to this pathology is poorly understood, impeding clinical advancements in treatment to reduce CNS morbidity. Using magnetic resonance imaging and type I IFN receptor-deficient mouse chimeras, we demonstrate HSV-1 gains access to the murine brain stem and subsequently brain ependymal cells, leading to enlargement of the cerebral lateral ventricle and infection of the brain parenchyma. A similar enlargement in the lateral ventricles is found in a subpopulation of herpes simplex encephalitic patients. Associated with encephalitis is an increase in CXCL1 and CXCL10 levels in the cerebral spinal fluid, TNF-α expression in the ependymal region, and the influx of neutrophils of encephalitic mouse brains. Reduction in lateral ventricle enlargement using anti-secretory factor peptide 16 reduces mortality significantly in HSV-1-infected mice without any effect on expression of inflammatory mediators, infiltration of leukocytes, or changes in viral titer. Microglial cells but not infiltrating leukocytes or other resident glial cells or neurons are the principal source of resistance in the CNS during the first 5 d postinfection through a Toll/IL-1R domain-containing adapter inducing IFN-ß-dependent, type I IFN pathway. Our results implicate lateral ventricle enlargement as a major cause of mortality in mice and speculate such an event transpires in a subpopulation of human HSV encephalitic patients.

Clinical and neuroimaging profile of HIV-1 encephalopathy in infancy and childhood in a sub-Saharan African country.

BACKGROUND: Neurological dysfunction in AIDS is common, occurring in as many as eighty percent of children. Thus, it is important to recognize the central nervous system imaging appearance of HIV, in particular those of HIV encephalopathy, as this is an AIDS defining illness and with distinct neuro-imaging features essential for early diagnosis and timely therapeutic intervention AIM: To identify the clinical features in HIV-1 infection of the central nervous system and their associated neuroradiological correlates. METHODS: Retrospective review of the records of all children with HIV-1 encephalopathy identified among children with neurological and developmental problems and who were on follow up at a child development and neurology clinic in an African city. RESULTS: A total of 22 children (10 male and 12 female) with HIV-1 encephalopathy were identified among 2382 children with various forms of neurological and developmental problems and who were on follow up at a child development and neurology clinic for a little bit over eight years period. All the children acquired the infection vertically. The age range of these children was between 10 months to 14 years. The median age was 5.6 years. The mean duration of symptom was 3.2 years. Global delay or regression in development along with signs of pyramidal tract involvement and seizures were the commonest clinical signs observed in these children. Neuro-behavioral problems were commonly observed among preschool and school aged children. In older children and preadolescents focal seizures with or with out neurologic deficit and neuroradiological findings were common. Nonhemorrhagic stroke was rare and occurred in one child and another child had cortical blindness. Three children had no neurological deficit. Rapid progression of the disease carried grave prognosis. Opportunistic infections and tumors of the central nervous system were also uncommon among these children. Brain volume loss with dilatation of the lateral ventricle, bilateral symmetrical or asymmetrical calcification of the basal ganglia and periventricular involvement of the white matter were the commonest neuro-radiological findings observed in these children. CONCLUSION: Atrophy of the brain with dilatation of the lateral ventricles and calcification of the basal ganglia and peri-ventricular involvement of the white matter were the commonest neuro-radiological findings in children with HIV-1 encephalopathy. Similarly global delay or regression in development along with pyramidal tract signs and seizures were the commonest neurological findings. Behavioral problems were common in preschool and school aged children. Focal seizures were common in older children and preadolescents. Rapid progression of the disease carried grave prognosis.

Multivariate tensor-based morphometry on surfaces: application to mapping ventricular abnormalities in HIV/AIDS.

Here we developed a new method, called multivariate tensor-based surface morphometry (TBM), and applied it to study lateral ventricular surface differences associated with HIV/AIDS. Using concepts from differential geometry and the theory of differential forms, we created mathematical structures known as holomorphic one-forms, to obtain an efficient and accurate conformal parameterization of the lateral ventricular surfaces in the brain. The new meshing approach also provides a natural way to register anatomical surfaces across subjects, and improves on prior methods as it handles surfaces that branch and join at complex 3D junctions. To analyze anatomical differences, we computed new statistics from the Riemannian surface metrics-these retain multivariate information on local surface geometry. We applied this framework to analyze lateral ventricular surface morphometry in 3D MRI data from 11 subjects with HIV/AIDS and 8 healthy controls. Our method detected a 3D profile of surface abnormalities even in this small sample. Multivariate statistics on the local tensors gave better effect sizes for detecting group differences, relative to other TBM-based methods including analysis of the Jacobian determinant, the largest and smallest eigenvalues of the surface metric, and the pair of eigenvalues of the Jacobian matrix. The resulting analysis pipeline may improve the power of surface-based morphometry studies of the brain.

Reprogramming of neonatal SVZ progenitors by islet-1 and neurogenin-2.

The subventricular zone (SVZ) lining the lateral walls of the lateral ventricles is one of the major neurogenic areas in the postnatal brain. Precursor cells in the SVZ migrate via the rostral migratory stream to the olfactory bulb where they differentiate into neurons. Cell replacement strategies utilizing the recruitment of these endogenous progenitors and their progeny to different areas of the brain hold great promise for the future, but much research is needed in order to understand the sequence of molecular signals necessary to induce proliferation, migration and site-specific differentiation of these cells. In this study we show that the SVZ cells can be redirected from their normal migration route and directed towards other brain regions when they are infected with retroviruses encoding the developmentally important transcription factors Islet-1 and Neurogenin-2. After co-transduction with these transcription factors, transduced cells could be detected in several areas of the brain. When located in the striatum, the reprogrammed cells displayed neuroblast-like morphology. Once removed from the striatal parenchyma and allowed to further differentiation in vitro they developed into beta-III-tubulin positive neurons.

Lentiviral vectors mediate efficient and stable gene transfer in adult neural stem cells in vivo.

Modulation of adult neurogenesis may offer new therapeutic strategies for various brain disorders. In the adult mammalian brain the subventricular zone (SVZ) of the lateral ventricle is a region of continuous neurogenesis. Lentiviral vectors stably integrate into dividing and nondividing cells, in contrast to retroviral vectors, which integrate only into dividing cells. We compared their potential for gene transfer into both quiescent and slowly dividing stem cells as well as into more rapidly dividing progenitor cells. In contrast to retroviral vectors, stereotactic injection of lentiviral vectors into the SVZ of adult mice resulted in efficient and long-term marker gene expression in cells with characteristics of both immature type B cells and migrating precursor cells. After migration along the rostral migratory stream and differentiation, the number of enhanced green fluorescent protein (eGFP)-expressing granular and periglomerular interneurons increased over time in the ipsilateral olfactory bulb. Moreover, the number of eGFP-labeled neuronal progenitor cells in the SVZ increased over time. By intraventricular injection of lentiviral vectors we could restrict gene transfer to ependymal cells and type B astroglial-like stem cells. In conclusion, lentiviral vectors surpass retroviral vectors in efficient long-term in vivo marking of subventricular zone stem cells for basic research and therapeutic applications.

Outcome of bovine herpesvirus 4 infection following direct viral injection in the lateral ventricle of the mouse brain.

A recombinant bovine herpesvirus 4 (BoHV-4EGFPDeltaTK), obtained by the insertion of an EGFP gene into the TK locus of DN 599 BoHV-4 strain, was injected into the lateral ventricle of the brain of mice and a clinical score was evaluated for 90 days. Although BoHV-4 was not neuro-pathogenic, BoHV-4EGFPDeltaTK transduction capability was analyzed. EGFP expression was localized in close proximity to the border of the ventricles and EGFP-positive cells were found to co-localize with ependymal cells. Although most of the cells had a polarized morphology, they were not neurons. EGFP-positive cells were seen to spread in tangentially oriented rows within the rostral migratory stream (RMS). Co-localization of EGFP signal with anti-GFAP antibody showed that they were glial cells. EGFP-positive cells were observed until 31 days post-injection and then disappeared completely. Virus isolation was possible at an early post-injection time (3 days), but then virus titer was below the detection limits at later times. Viral DNA, however, could be detected until 21 days post-injection. Thus, in this report we showed that (i) BoHV-4EGFPDeltaTK did not replicate in the mouse brain, (ii) is not pathogenic and (iii) gene transfer can be obtained in long-lived cells belonging to the RMS after BoHV-4EGFPDeltaTK injection within the lateral ventricle.

Diffuse encephaloventriculitis and substantial leukoencephalopathy after intraventricular administration of recombinant adenovirus.

OBJECTIVES: The use of recombinant adenovirus as a vehicle for gene transfer into ependymal cells is a potential therapeutic tool for the treatment of various neural disorders. However, gene transfer into the ependymal cells of the ventricular wall is associated with high-level expression of the transferred gene, which declines rapidly. The purpose of this study is to understand the cause of this early decline in gene expression. METHODS: Different doses of adenovirus-expressing beta-galactosidase (Ad-beta-gal) were injected into the lateral brain ventricle of C57BL/6 mice, and the brains were observed histologically and with magnetic resonance (MR) imaging for a month. RESULTS: Inoculation of the lateral ventricle with more than 1 x 10(8) viral particles (2.6 x 10(6) pfu) resulted in a rapid decline of beta -gal expression. MR imaging indicated gradual ventriculomegaly and histological analysis showed the loss of the ependymal cells from the ventricular wall, lymphocytes infiltration near the wall, degeneration of myelinated fibers and apoptosis in the external capsule. Reactive astrocytes proliferated in the external capsule 17 days following inoculation. To avoid this irreversible brain atrophy, the inoculated adenovirus should be reduced to less than 1 x 10(7) particles (2.6 x 10(5) pfu) in mice. DISCUSSION: Our results indicate the presence of a unique and diffuse immune response of the brain; therefore, the clinical use of recombinant virus for intraventricular gene transfer must be carefully evaluated.