(AFP) - Ebola and HIV, two of the most terrifying viruses known to Man, are being harnessed to fight a killer lung disease.

In a remarkable tale of poachers-turned-gamekeepers, Ebola and the human immunodeficiency virus (HIV) that causes AIDS are being called upon along with the flu virus to help treat people with cystic fibrosis.

Scientists hope to cure inherited lung diseases with gene therapy, in which a gene is tucked inside a harmless virus. Like the Trojan Horse, the virus would infect the lung cells, delivering a good gene to replace the flawed gene that causes the ailment.

The problem, though, is finding a Trojan Horse smart enough to penetrate the thick wall of the lungs, which in the case of cystic fibrosis are covered by a mucus barrier.

This is where Ebola and the flu virus, both notorious for attacking the lungs, come in, the monthly journal Nature Biotechnology reports in its March issue.

A team led by James Wilson from the Institute for Human Gene Therapy at the University of Philadelphia Health System, stripped the lung-binding proteins from the Ebola and flu virus.

They then inserted these proteins into the coating of a lentivirus, a disabled virus based on HIV, which would be the vehicle for the therapeutic gene.

The new lentivirus proved a success in delivering its secret weapon to lung cells in a test tube as well as small samples of trachea tissue, and also penetrated the lungs of lab mice.

The Wilson team stressed that additional testing on primates had to be carried before this "pseudotyped" lentivirus could be put to any human trials, notably to see whether it caused any backlash from the immune system or whether the HIV components of the virus mutated.

Gene therapy is highly experimental and somewhat controversial, as researchers are discovering there are few diseases that are pinned to a single gene and can thus be reversed without complications.

One big success in gene therapy was reported last year, when French researchers stunningly restored the immune system of several "bubble" babies who would otherwise have been condemned to spend their lives in sterile plastic tents to ward off infection.

Ebola is a ferociously virulent disease that causes death by severe haemorrhaging. The latest outbreak, in Uganda, killed 173 people before it was officially declared over on Tuesday.