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D.A. White, W.W. Hauswirth, A.S. Lewin; ERG Analysis of the Effect of Subretinal Allele-Independent Ribozyme Injections on the Visual Responses of Wild-Type and P23H Mutant Rats . Invest. Ophthalmol. Vis. Sci. 2003;44(13):2332.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Our initial efforts at treating a rat model of Autosomal Dominant Retinitis Pigmentosa (ADRP) utilized ribozymes designed to specifically cleave the mutant opsin transcript responsible for the P23H form of the disease; however, over one hundred different opsin mutations have been found to be associated with ADRP. In an attempt to avoid the problem of having to develop a different ribozyme for each disease-causing mutation, we have designed allele-independent ribozymes that target sequences conserved among wild-type and mutant forms of the disease-causing transcript. Methods: Two allele-independent ribozymes were cloned into rAAV packaging vectors under the control of a mouse opsin promoter. These vectors were packaged as recombinant AAV and injected subretinally into the right eyes of both wild-type rats and rats containing a P23H transgene. ERG analysis was performed at regular intervals to determine the effects of these ribozymes on the visual responses of the animals by comparing the ribozyme-injected right eyes with control, uninjected left eyes. Results: Subretinal injection of P23H rats with recombinant AAV expressing these allele-independent ribozymes did not alter the course of retinal degeneration based on ERG amplitudes. Similarly, the ribozymes show no effect on the ERG response of wild-type animals. Conclusions: Delivery of our allele-independent ribozymes to wild-type retinas did not cause a reduction of rhodopsin synthesis that was great enough to be deletorious to the visual response, as measured by ERG. Allele-independent ribozymes injected into P23H mutant retinas do not by themselves rescue retinal degeneration. Future studies will focus on determining the amount of rhodopsin message reduction achieved by these ribozymes, as well as on combining these ribozyme treatments with the delivery of ribozyme-resistant opsin replacement genes.
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