To treat the boys, the Great Ormond Street team took the stem cells that give rise to immune cells from the two boys bone marrow. Then they used a modified form of a retrovirus found in gibbons to add a normal copy of the faulty gene to the stem cells. The virus has altered spikes on its surface which may mean it binds better to stem cells and transfers the gene to them more efficiently, team leader Adrian Thrasher told New Scientist. The engineered stem cells were then returned to the boys bodies. Rhys Evans is now back at home, with normal T cell levels, seven months after treatment. The second child, treated just three months ago, continues to improve at home. The Great Ormond Street researchers say they are planning to treat another four boys over the next two years.
http://www.newscientist.com/news/news.jsp?id=ns99992124
