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.

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, photoreceptor 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.