infect cells. This protein is called CCR5 and the virus must attach to this protein on the outside of the cell in order to enter and infect the cell. Because of the altered structure of this protein, due to a genetic mutation present in about 1% of Europeans, the virus cannot attach and infect the lymphocyte.
So now, this patient’s blood cells have been replaced with cells that are resistant to HIV infection. The HIV drug Maraviroc (Selzentry) essentially works the same way as this genetic mutation by blocking CCR5 and preventing HIV from infecting cells.
The treatment of the cancer also involved some courses with cancer chemotherapy before the donor cells are administered. The use of these cancer drugs may also have played an important role. Cancer chemotherapy can be toxic to blood cells. However, in this case, it could have possibly been helpful in eliminating cells harboring latent HIV virus, known as the reservoir (See article Why we haven’t cured HIV Infection).
Indeed when the researchers performed special tests to produce virus from the reservoir, no virus was produced; a good sign that the reservoir was eliminated. The transplant required immunosuppressive medicines to keep the patient from having a reaction and rejecting the transplanted blood cells.
So through the very complicated process of treating the London patient’s cancer, a “new” immune system was created by the stem cell transplant that is resistant to HIV, in a patient where it