Scientists from Cornell and Penn, where the experiment was conducted, had identified the eye disease in the dogs and the mutated RPE65 gene responsible. The mutated RPE65 gene causes an estimated 15 percent of LCA cases, with the rest attributed to other mutations.
Efforts are under way to develop gene therapy approaches to combat those other mutations. In the experiment, three Briard puppies had their right eyes treated late last year with a single injection of thousands of copies of the corrective gene in the virus provided by Hauswirth. Their left eyes were untreated as a control. The scientists planned to formally test eye function three months later, when the dogs were 6 months old.
"Well before those tests, the researchers thought the dogs could see because they kept turning their heads to the right to use the eye that had been treated," said Hauswirth, who also holds an appointment in the department of ophthalmology and is affiliated with UF's Genetics Institute and Powell Gene Therapy Center. "But then when the official tests were conducted, I got this very excited phone call, 'Bill, Bill, the dogs can see!'"
The tests showed that the treated eyes responded to light. The dogs also were able to navigate through a maze, even when the lighting was dim. "The dogs bumped into objects on the left side, but would always avoid the objects on the right," Hauswirth said.
Officials from the Foundation Fighting Blindness, which supported the study with grant funds, said the success in reversing blindness in dogs is an important advance. "With this study, gene therapy has overcome a major hurdl
Contact: Victoria White
University of Florida