Scientists Develop New Virus to Restore Sight

Amy Taylor June 14, 2013

Tweet

A new therapy, which takes just about 15 minutes, successfully restored the sight of study participants with a rare inherited disease that causes complete blindness in adulthood. Unlike other treatments, it’s easy, effective and non-invasive.

The therapy, which was developed by the researchers at University of California, Berkeley, involved injecting a virus paired with a normal gene into the liquid vitreous humour of an eye with the dysfunctional gene. The newly engineered virus, called adeno-associated virus (AAV), carried the normal gene to the hard-to-reach areas in the eye, especially the photoreceptor cells, in a non-invasive way – something that conventional treatments haven’t done before. The new therapy, which took 14 years of research, lasts for only up to 15 minutes and the patient can go home on the same day.

Engineered Virus that Could Restore Sight

Previous studies have used a different type of virus which is injected directly into the retina of the eye. But according to David Schaffer, professor of chemical and biomolecular engineering and director of the Berkeley Stem Cell Centre at the University, sticking a needle through the retina is a risky surgical procedure. But doctors had no choice because one of the gene delivery viruses can travel all the way to the back of the eye and reach the photoreceptors – the light-sensitive cells that need therapeutic gene.

The therapy can be used to treat varying diseases, from inherited defects like retinitis pigmentosa to degenerative diseases such as macular degeneration.

Schaffer and his colleagues are now working with physicians to identify patients who are most likely to benefit from the new treatment.

AAV is a common but benign respiratory virus that is used to incorporate functional gene into their chromosomes to form a protein that a defective gene could not do. However, the new therapy is not applicable to all kinds of eye diseases because there is always a possibility of retinal detachment, which aggravates the condition. The AAV virus is the only engineered virus that can penetrate through the foveae cell – a very small, dimple-like structure which has the eye’s sharpest vision and the location of most colour perception.

Schaffer predicts that the new virus will not just restore dysfunctional genes but may also knock out genes or stop the processes that are actively killing the retinal cells, which normally takes place in macular degeneration.

The study was published in the journal Science Translational Medicine.

Source of this article:

Directed evolution of novel adeno-associated viruses for therapeutic gene delivery