Scientists are attempting to "domesticate the plague", changing the deadly AIDS virus from a killer to a lifesaver. A University of Cambridge team hope to use this radical technique to help heart transplant and Parkinson's Disease patients.
The AIDS virus, HIV, is an unlikely new tool in the fight against disease, according to Prof Andrew Lever who leads the Cambridge group. He described the work yesterday to a session on health and disease at the British Association Festival of Science in Leicester.
"It is the most important and catastrophic disease to have struck humanity in the last 100 years," he said. There are now 40 million infected people worldwide, most of whom live in sub-Saharan Africa. A 15-year-old male in Zimbabwe currently has a 70 per cent chance of dying of AIDS and that country's life expectancy has fallen from 72 to just 45 as a result of the disease.
Yet this dreadful killer has great new potential as a lifesaver when linked to developments in gene therapy, Prof Lever said. It holds such promise because of the virus's exceptional ability to invade cells including non-dividing cells such as brain and muscle, a feat most other viruses can't imitate. "It has come along with a property we didn't have before," he said.
HIV had a unique ability to hide inside these non-dividing cells.
The researchers have developed a way to "domesticate" the virus by removing its core, the genetic code that makes it so dangerous and enables it to replicate itself once it enters a cell. With this genetic code gone, it becomes a harmless "envelope", an empty shell that still retains its superb ability to enter a cell, Prof Lever explained.
This makes the virus an ideal delivery vehicle when employed in gene therapy. Gene therapy is an attempt to cure disease by replacing damaged or missing genes with functioning genes. The viral shell penetrates a cell, bringing with it a working gene that becomes installed in the cell to counteract disease symptoms.
"What is being delivered to the patient doesn't contain any HIV genes at all. It is only a shell," Prof Lever explained. The shell can successfully get into non-dividing cells including brain and muscle tissue, he said, raising the hope that it might open up ways to treat diseases associated with these organs. This is not science fiction, the technique has already been shown to work. Prof Lever's group was the first to use a HIV shell to deliver genes into cells, both in cell cultures and in animal models.
"We have been able to deliver genes to the beating heart of an animal and that is the first time that has been done," he said.
The technique could be used, for example, to treat Parkinson's Disease. In this case the HIV shell would carry replacement genes able to produce the dopamine missing in these patients.
Prof Lever also believes that it might help heart transplant patients, protecting the donor organ against rejection by the recipient's immune system.
Using an HIV shell it might be possible to insert "rejection protection" genes directly into heart muscle cells, giving the donor organ a way to protect itself against immune system attack.