223. Delivery of HSV Based Vectors for Correction of CNS Pathology in Mucopolysaccharodosis Type vii (MPS vii)

Current gene therapy strategies targeting the CNS involve multiple and cumbersome modes of delivery. In the current study we used a neuroattenuated Herpes simplex -1 (HSV-1/1716-LAT-hGUSB) containing beta glucuronidase (GUSB) driven by the latency associated transcript (LAT) promoter and lacking the ICP 34.5 gene. We analyzed the sites of expression of the transgene activity as well as the latent viral vector after delivering the recombinant vector into the cerebrospinal fluid by injection of 3 105 PFU/10 l into the cisterna magna of C3H HeOuJ mice (4 weeks old). Our study showed that there is significant expression of the transgene after 4 weeks post-injection in mice injected with the 1716-LAT-hGUSB recombinant virus compared to control mice injected with the 1716 parental strain virus. The expression of the transgene declined after 4 weeks, but was still seen until 8 weeks post injection. Our results also showed a unique pattern of distribution of the transgene and the vector. Transgene activity was localized in the spinal cord, brainstem, and midbrain whereas the mRNA expression of the virus/vector was confined predominantly to the cerebral cortex. In addition to analyzing the transgene pattern at the mRNA level we also quantitate the amount of GUSB activity. Our results showed that there was a significant increase in the amount of protein produced in the different parts of the brain in the animals injected with BB2 compared with control HSV-1 virus. In addition to the intrathecal route two other peripheral routes of inoculation were tried, intraocular and intranasal. Neither of these routes showed any expression of the transgene or the protein. One possible reason for the failure of expression by these two routes is because 1716 virus cannot effectively spread/establish latency in the CNS when inoculated peripherally. In conclusion we have developed a comparatively noninvasive mode of delivery of recombinant virus into the CNS which could eventually be used for correction of CNS pathology in MPS vii mice.