THE JOURNAL OF GENE MEDICINE RESEARCH ARTICLE J Gene Med 2009; 11: 382–389. Published online 4 March 2009 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/jgm.1311 Baculovirus is an efficient vector for the transduction of the eye: comparison of baculovirus- and adenovirus-mediated intravitreal vascular endothelial growth factor D gene transfer in the rabbit eye Kati Kinnunen 1,2 Giedrius Kalesnykas 1,2 Anssi J. M¨ ah¨ onen 1,6 Svetlana Laidinen 1,6 Liisa Holma 1 Tommi Heikura 1,6 Kari Airenne 1 Hannu Uusitalo 2,3 Seppo Yl¨ a-Herttuala 1,4,5 * 1 Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute, University of Kuopio, Kuopio, Finland 2 Department of Ophthalmology, University of Kuopio, Kuopio, Finland 3 Department of Ophthalmology, Tampere University Hospital, Tampere, Finland 4 Department of Medicine, University of Kuopio, Kuopio, Finland 5 Gene Therapy Unit, Kuopio University Hospital, Kuopio, Finland 6 Ark Therapeutics Oy, Microkatu 1/S, FI-70210 Kuopio, Finland *Correspondence to: Seppo Yl¨ a-Herttuala, Department of Biotechnology and Molecular Medicine, A.I. Virtanen Institute, University of Kuopio, PO Box 1627, FIN-70211 Kuopio, Finland. E-mail: seppo.ylaherttuala@uku.fi Received: 22 September 2008 Revised: 23 December 2008 Accepted: 15 January 2009 Abstract Background The present study aimed to determine the efficiency and safety of baculovirus-mediated intravitreal gene transfer in rabbit eye and to compare its efficiency with adenovirus. We also studied how an intravitreal injection of vectors producing vascular endothelial growth factor D (VEGF-D) impacts the vasculature of rabbit eye. Methods Baculoviral (BacVEGF-D) or adenoviral VEGF-D (AdVEGF-D) were administered intravitreally into the right eye at different doses (10 8 , 10 9 and 10 10 IU/ml) to 24 animals. Left eyes were injected with control viruses. To determine how long transgene expression lasted, we injected BacVEGF-D or BacLacZ to the vitreous humour of 11 animals and followed them for 4 weeks. Vitreous samples were taken after sacrifice for enzyme-linked immunosorbent assays and eyes were removed and fixed for histological analyses. Results Both baculoviruses and adenoviruses caused efficient expression of VEGF-D in the rabbit eyes. BacVEGF-D caused a dose-dependent vascular leakage and a moderate dilation of the capillaries. The highest effect was seen 6 days after gene transfer and was detectable for 2 weeks. Intravitreal injection of baculovirus caused expression of VEGF-D in the inner retina, photorecetor cells and in retinal pigment epithelium cells, whereas adenovirus-mediated VEGF-D expression was detected in the nerve fiber layer and ganglion cell layer. Baculovirus caused a transient inflammation similar to adenoviruses. Conclusions The study suggests that baculoviruses are efficient vectors for ocular gene transfer, especially if deeper retinal layers need to be transduced. In addition, intravitreal VEGF-D gene transfer caused blood–retina barrier breakdown but not neovessel formation in the rabbit eye. Copyright  2009 John Wiley & Sons, Ltd. Keywords adenovirus; blood–retina barrier; baculovirus; gene transfer; retina; VEGF-D Introduction Ocular angioproliferative diseases, such as diabetic retinopathy and exudative age-related macular degeneration (AMD), are the main causes for blindness Copyright  2009 John Wiley & Sons, Ltd.