1073. Cell Tropism of JC-Virus Derived Viral-Like Particles In Vitro and In Vivo

The goal of the present study was to explore the tropism of Virus-Like Particles (VLP) originating from the human polyoma JC- virus (JCV) in vitro and in vivo. VLP have been known for several years to be a promising alternative to the existing viral and non-viral DNA delivery systems. VLP are self-assembled structures composed only of proteins necessary for capsid formation, DNA packaging and gene delivery. They are replication deficient, exhibit a similar morphology and presumably share the same cell tropism, cellular uptake and intracellular trafficking mechanisms compared to their viral origin. VLP from JCV are being evaluated as a delivery vector for the central nervous system (CNS) because JCV preferentially infects both oligodendrocytes and astrocytes.VLP were produced by expressing VP1 from JCV in insect cells and purified by DEAE Sepharose chromatography. Before DNA packaging the VLP were dissociated into VP1 pentamers by a DTT/ EGTA treatment and contaminating DNA was removed. The purified VP1 pentamers were used for packaging, either EGFP or luciferase expressing DNA. Using VP1-VLP containing plasmid DNA expressing EGFP, we performed transduction assays in a panel of human and rodent brain-derived and non-brain derived cell lines in order to characterize the in vitro tropism and species specificity of VP1-VLP. Both human and rodent cell lines could be transduced. The highest transduction efficiency was observed in TC620 cells, a human oligodendroglioma line. In contrast, with the exception of one human prostate cell line (PC-3), VP1-VLP transduction was not observed in any non-brain-derived human or rodent cell line studied including those from kidney, liver, lung, skeletal muscle, and vascular endothelium. VP1-VLP transduction was also tested in primary brain cells from rats and humans. Transduction activity was detected in both human and rat primary brain cells. Among the brain cells from rats VP1-VLP preferentially transduced oligodendrocytes.To test transduction activity in vivo, VP1-VLP containing a luciferase expression plasmid were injected into the brain of mice. After stereotaxic injection, luciferase expression was measured non-invasively with a bioluminescence imaging system over a time period of 12 weeks. Luciferase expression reached peak levels at week 6 following injection. The level of expression then became relatively stable for another 6 weeks, when the experiment was terminated.In the present study we showed that JCV-derived VP