Baculovirus Is an Efficient Vector for Intravitreal Gene Transfer in the Rabbit Eye

Abstract

Abstract: : Purpose: Several viruses have been studied for vectors in gene therapy. The most studied vectors include adeno–associated viruses, retroviruses and adenoviruses. Baculovirus is less frequently studied virus in gene therapy, especially in ocular tissues, although it is a promising vector because it does not cause human diseases and it has a capacity to carry large inserts. The aim of this study was to find out the efficiency and safety of baculovirus in intravitreal gene transfer in rabbit eye. Also we wanted to determine which tissues in the eye respond to an intravitreal injection of vascular endothelial growth factor D (Vegf–D). Methods: There were 9 rabbits participating this study divided to three groups. Baculo–vegf–D 10¹⁰vp/ml 0,1ml (BacVegf–D) was injected intravitreally to the right eye of three animals under the microscope. To compare different viruses as a vector, another three animals were injected intravitreally with adenovirus expressing vegf–D (AdVegf–D) to the right eye with same dose. Three animals were injected with Baculo–gfp (BacGFP) and they served as a control group. All the animals were injected with saline to the left eye. Animals were photographed preoperatively and postoperatively at day 5. They were killed at day 6, eyes were removed and histologically analysed. Results: Baculovirus showed to be efficient and safe vector for gene transfer. There was dilatation, tortuosity and leakage of retinal veins in postoperative fundus photographs compared the preoperative pictures in BacVegf–D eyes. In histologic analysis, average capillary area and perimeter were increased in the BacVegf–D eyes compared the saline injected eyes or the BacGFP eyes. Vegf–D was expressed in the ganglion cell layer of retina, papilla and corneal endothelium. Also the control eyes showed pretty high endogenous vegf–D expression in the ganglion cell layer and papilla. RAM–11 staining showed only slight inflammation in the BacVegf–D eyes. With the same dose, adenovirus showed no significantly increased gene expression in transfected eyes compared the control eyes. Conclusions: This study showed that vegf–D was expressed in the retina, the papilla and the anterior segments. Baculovirus is efficient and safe virus in transferring genes to the eye. With the same dose it appeared to be more efficient than adenovirus. Baculovirus is a promising vector for intravitreal gene transfer in ocular tissues.

Keywords: growth factors/growth factor receptors • gene transfer/gene therapy • neovascularization