When the new donor cells expanded to take their place, the HIV had no place to go and withered away. But none of these things fully explains what happened. One puzzle is that the stem cells used to repopulate the patient’s immune system were HIV resistant — but not HIV proof. The cells lacked the most common doorway, CCR5, that HIV needs to infect cells. But people with long-term HIV infection usually carry HIV capable of using another doorway called CXCR4. And tests showed that the Berlin patient’s blood carried HIV like this.
You will find the original content at this website http://www.medicinenet.com/script/main/art.asp?articlekey=123582