Delivery of ultraviolet-inactivated ³⁵S-herpesvirus across an osmotically modified blood-brain barrier

The present studies were undertaken to detemine if viral particles can be delivered across the rat blood-brain barrier (BBB). Osmotic BBB modification with intracarotid mannitol (25%) was immediately followed by bolus intracarotid administration of 0.5 ml purified, ultraviolet-inactivated, herpes simplex virus type 1 endogenously labeled with ³⁵S-labeled methionine (2.0 x 10⁶ cpm, approximately 5 x 10⁸ plaque-forming units/ml). After 60 minutes, intravascular virus was cleared by saline perfusion and the animals were sacrificed. A marked increase (fourfold, p ≤ 0.02) in radioactivity was observed in the ipsilateral brain hemisphere when compared to control animals without barrier modification. Administration of intravenous virus immediately after BBB modification displayed no difference in delivery when compared to intracarotid saline-infused controls (without BBB modification) suggesting the importance of a first-pass phenomenon. There were no significant differences in serum concentrations among intracarotid or intravenous groups. These preliminary studies suggest the possibility of delivering viral particles across the BBB with osmotic disruption, which may permit delivery of genetic material in replication-defective viral vectors in the feline model of G(M2)-gangliosidosis.