Differences in vector-genome processing and illegitimate integration of non-integrating lentiviral vectors.

A variety of mutations in lentiviral vector expression systems have been shown to generate a non-integrating phenotype. We studied a novel 12 base-pair U3-long terminal repeats (LTR) integrase (IN) attachment site deletion (U3-LTR att site) mutant and found similar physical titers to the previously reported IN catalytic core mutant IN/D116N. Both mutations led to a greater than two log reduction in vector integration; with IN/D116N providing lower illegitimate integration frequency, whereas the U3-LTR att site mutant provided a higher level of transgene expression. The improved expression of the U3-LTR att site mutant could not be explained solely based on an observed modest increase in integration frequency. In evaluating processing, we noted significant differences in unintegrated vector forms, with the U3-LTR att site mutant leading to a predominance of 1-LTR circles. The mutations also differed in the manner of illegitimate integration. The U3-LTR att site mutant vector demonstrated IN-mediated integration at the intact U5-LTR att site and non-IN-mediated integration at the mutated U3-LTR att site. Finally, we combined a variety of mutations and modifications and assessed transgene expression and integration frequency to show that combining modifications can improve the potential clinical utility of non-integrating lentiviral vectors.

Characterization of a third generation lentiviral vector pseudotyped with Nipah virus envelope proteins for endothelial cell transduction.

Lentiviruses are becoming progressively more popular as gene therapy vectors due to their ability to integrate into quiescent cells and recent clinical trial successes. Directing these vectors to specific cell types and limiting off-target transduction in vivo remains a challenge. Replacing the viral envelope proteins responsible for cellular binding, or pseudotyping, remains a common method to improve lentiviral targeting. Here, we describe the development of a high titer, third generation lentiviral vector pseudotyped with Nipah virus fusion protein (NiV-F) and attachment protein (NiV-G). Critical to high titers was truncation of the cytoplasmic domains of both NiV-F and NiV-G. As known targets of wild-type Nipah virus, primary endothelial cells are shown to be effectively transduced by the Nipah pseudotype. In contrast, human CD34+ hematopoietic progenitors were not significantly transduced. Additionally, the Nipah pseudotype has increased stability in human serum compared with vesicular stomatitis virus pseudotyped lentivirus. These findings suggest that the use of Nipah virus envelope proteins in third generation lentiviral vectors would be a valuable tool for gene delivery targeted to endothelial cells.

Consenso chileno de manejo de fármacos antiepilépticos en algunos síndromes electro-clínicos y otras epilepsias en niños y adolescentes / Chilean consensus on the use of antiepileptic drugs in electro-clinical syndromes

Por iniciativa de tres instituciones: Liga Chilena contra la Epilepsia (LICHE), Sociedad de Epileptología de Chile (SOCEPCHI) y Sociedad de Psiquiatría y Neurología de la Infancia y Adolescencia (SOPNIA) de Chile, se constituye un comité de trabajo que convoca a un consenso de uso de fármacos antiepilépticos (FAEs) en un grupo de 16 Síndromes electro-clínicos y otras Epilepsias en niños y adolescentes. Cuarenta y dos médicos neuropediatras especialistas en Epilepsias de todas las regiones de Chile, participaron en la discusión y realizaron una propuesta de tratamiento farmacológico para cada cuadro. El comité de trabajo realizó un análisis exhaustivo y discusión de los documentos, para finalmente concluir en una recomendación de tratamiento para cada cuadro. Este consenso es una guía práctica de orientación para ayudar a las decisiones de tratamiento en situaciones clínicas concretas. Su objetivo final es ofrecer una mejor calidad de atención a los niños y adolescentes con epilepsias, a través de decisiones fundadas que contribuyan a disminuir la variabilidad de las decisiones terapéuticas.

Committed by three institutions: Liga Chilena contra la Epilepsia (LICHE), Sociedad de Epileptología de Chile (SOCEPCHI) y Sociedad de Psiquiatría y Neurología de la Infancia y Adolescencia (SOPNIA) de Chile, a 6-member working committee called for a meeting of 42 Chilean pediatric epileptologists from all over the country, with the aim of reaching a consensus on the use of antiepileptic drugs in 16 selected children and adolescents electro-clinical syndromes and epilepsies. These treatment proposals were analyzed and fully discussed by the working committee, ending in an antiepileptic drug treatment recommendation guideline for each condition. This consensus is a practical guideline to be used in specific clinical situations, which aims to support treatment decision making. Its main purpose is to offer the best evidence based treatments to our children and adolescents patients with epilepsy, thus contributing to diminish variability in therapeutic decisions.

Constitutive expression of short hairpin RNA in vivo triggers buildup of mature hairpin molecules.

RNA interference (RNAi) has become the cornerstone technology for studying gene function in mammalian cells. In addition, it is a promising therapeutic treatment for multiple human diseases. Virus-mediated constitutive expression of short hairpin RNA (shRNA) has the potential to provide a permanent source of silencing molecules to tissues, and it is being devised as a strategy for the treatment of liver conditions such as hepatitis B and hepatitis C virus infection. Unintended interaction between silencing molecules and cellular components, leading to toxic effects, has been described in vitro. Despite the enormous interest in using the RNAi technology for in vivo applications, little is known about the safety of constitutively expressing shRNA for multiple weeks. Here we report the effects of in vivo shRNA expression, using helper-dependent adenoviral vectors. We show that gene-specific knockdown is maintained for at least 6 weeks after injection of 1 × 10(11) viral particles. Nonetheless, accumulation of mature shRNA molecules was observed up to weeks 3 and 4, and then declined gradually, suggesting the buildup of mature shRNA molecules induced cell death with concomitant loss of viral DNA and shRNA expression. No evidence of well-characterized innate immunity activation (such as interferon production) or saturation of the exportin-5 pathway was observed. Overall, our data suggest constitutive expression of shRNA results in accumulation of mature shRNA molecules, inducing cellular toxicity at late time points, despite the presence of gene silencing.