Generation and Characteristics of Transgenic Rabbit Model of Retinal Degeneration

Abstract

Purpose: : To generate a rabbit that expresses a mutant rhodopsin gene, and to characterize the progressive retinal degeneration using RT-PCR, electroretinography (ERG), and histology.

Methods: : The bacterial artificial chromosome (BAC) that contains a rhodopsin gene was identified in a NZW rabbit BAC library. The Pro347Leu mutation of the rhodopsin gene was introduced into the BACs, and these BACs were microinjected into fertilized rabbit eggs. The eggs were then transplanted into 17 recipient rabbits. Transgene-positive animals were identified by Southern blot and PCR analysis. The expression level of the transgene in the retinal tissue was measured by real-time RT-PCR. Scotopic and photopic ERGs elicited by different stimulus intensities were recorded. Paraffin retinal sections were stained with hematoxylin and eosin.

Results: : Ten transgene-positive founders were identified, and transgene-positive F1 animals were obtained from 6 of the 10 founders. The expression level of the transgene ranged from 7-51% for the six transgenic lines. ERGs indicated a progressive retinal dysfunction with increasing age in which the rod function was more impaired than the cone function. The ERG abnormality was most severe in the line with the highest transgene expression. Retinal histology demonstrated a progressive loss of photoreceptors and a shortening of the outer segments.

Conclusions: : To the best of our knowledge, this is the first transgenic rabbit model of retinal degeneration. The speed of retinal degeneration was dependant on the expression level of the transgene. Because the rabbits have large eyes and are easy to handle, these animals will be a useful model to stud the pathophysiology and treatment of retinal degeneration.

Keywords: transgenics/knock-outs • retinal degenerations: hereditary • electrophysiology: non-clinical