Evolving a Virus for Gene Therapy (IMAGE) University of California - Berkeley Caption To evolve the virus best suited for gene therapy, more than 100 million engineered adeno-associated viruses (left) are injected into the gel-like center of the eye. Those able to penetrate the many cell layers of the retina are used to shuttle a corrective gene into cells with a defective gene, in particular the light-sensitive photoreceptors and the retinal pigment epithelium cells. To reach these cells, the virus must pass through the retinal ganglion cells and the inner nuclear layer (right). Credit David Schaffer lab, UC Berkeley Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.