609. Transduction of the Central Nervous System with the LTR1 Lentiviral Backbone

Abstract

A novel HIV-1-based lentiviral vector has been generated that eliminates 1.7kb of wild-type HIV-1 elements from the vector provirus. This vector, known as LTR1, potentially offers several advantages over current lentiviral technology, such as increased transgene-carrying capacity, resistance to remobilisation in HIV-1 particles and a reduced risk of splicing interactions with host genes. In this study we investigated the persistence and strength of LTR1-derived expression within the central nervous system (CNS). We began by developing LTR1 vectors containing the spleen-focus forming virus (SFFV) promoter driving either green fluorescent protein (GFP) (LTR1-SFFV-GFP), or a bicistronic luciferase-GFP construct (LTR1-SFFV-Luc-GFP). Both LTR1 vector preparations were pseudotyped with the vesicular stomatitis virus glycoprotein (VSV-G) and administered intracranially to newborn outbred CD1 mice. Those that received the LTR1-SFFV-Luc-GFP virus were imaged continually by whole body bioluminescence imaging. From this, we observed long term luciferase expression within the CNS for 32 days post-administration, at which point the mice were sacrificed for further analysis. Mice receiving the LTR1-SFFV-GFP virus were euthanized at day 35 and the brain tissues were collected, sectioned and stained for GFP by free-floating immunohistochemistry, which showed GFP-positive neurons predominately within the cortex and hippocampus. In this research, we demonstrated long-term expression within the CNS, specifically the cortex and the hippocampus, after a single neonatal administration of the LTR1 virus. We have therefore highlighted its potential use as a gene therapy vector for neurological disorders. This, combined with LTR1's potential to incorporate large transgenes, highlights a possible application in gene therapy of channelopathies, which would benefit from viral delivery of the relatively large sodium ion channels.