After a decade of unsuccessful attempts to introduce therapeutic genes into human cells, it was reported in 2001 that US researchers were using viruses as tiny innoculation vehicles for delivering genes directly. Scientists combined pieces from two of the world's deadliest microbes, the ebola virus and the HIV virus, to make a hybrid virus. The goal was to make a virus with ebola's unusual talent for attaching to lung cells and the AIDS virus's exceptional ability to persist in the body, then use that new virus to deliver curative genes lacking in sufferers with the lung disease cystic fibrosis. The "deadly" parts of both viruses were removed. The hybrid virus was being tested on in vitro lung cells of mice and humans in a "biosafety level 3" containment module because the US Federal Drug Authority (FDA) ordered a halt to all human clinical studies after a young gene therapy patient died.
In 2001, it was reported that adeno-associated virus carrying FHIT, a gene which causes damaged and pre-cancerous cells to self-destruct, prevented the mice from developing cancer.
Adeno-associated viruses, which do not cause disease in humans, are safer and more effective vectors or carriers for gene therapy.
A hybrid HIV virus might combine with wild HIV to create an entirely new kind of contagious virus.