Is Anyone Immune to HIV?
BY Trudy Ring
September 07 2012 1:32 PM ET
Even the most careful individuals can find themselves with a positive HIV diagnosis, while others couldn’t get the disease if they tried. Researchers are trying to find out why some people carry a genetic mutation that makes them highly resistant to HIV infection. This mutation, called Delta32, keeps a protein called CCR5 from rising to the surface of the immune system’s T cells. When CCR5 is on the surface of the cell, HIV is able to latch on to it and infect the cell; when it is not, the cell’s “door” is effectively closed to HIV.
Very few people have this genetic variation, which some scientists think has been inherited from ancestors who survived the massive bubonic plague in Europe centuries ago. About 1% of Caucasians have it, and it is even rarer in Native Americans, Asians, and Africans. A 2005 report indicated that 1% of people descended from Northern Europe are virtually immune to AIDS.
Those lucky enough to be resistant must inherit the HIV-shielding genes from both parents, though having only one parent with the mutation still leaves a child better prepared to defend HIV than having none. At least one genetic testing company, 23AndMe.com still does the HIV immunity test (among their battery of tests, not as a stand alone), though many companies that once catered specifically to gay men for the HIV immunity test have closed down.
In the case of Timothy Ray Brown, the so-called Berlin patient cleared of HIV after receiving stem cell transplants to treat his leukemia, there was great difficulty finding a donor who not only had this mutation, but matched other components of Brown’s immune system closely enough that his body would not reject the cells. Researchers are now focusing on the possibility of introducing the rare genetic mutation into a patient’s body, infusing T cells that have been modified so as to have the CCR5 variation.
Under the sponsorship of the National Institutes of Health, researchers at the University of Pennsylvania Perelman School of Medicine in Philadelphia, the Fred Hutchinson Cancer Research Center in Seattle, and other institutions and biomedical companies are conducting research on this process, first to assess its safety, then its effectiveness. The latter will involve stopping study participants’ anti-HIV medications to see if their immune systems continue to suppress the virus.
Joining in such research will be the Timothy Ray Brown Foundation, which Brown has formed in partnership with the World AIDS Institute. “The Timothy Ray Brown Foundation will be solely dedicated to finding a cure for AIDS,” Brown said at the U.N. AIDS conference in July.
Whether Brown has actually been cured of his HIV infection is the subject of some controversy. Some tests have shown tiny traces of HIV in various parts of his body, and there are scientists who say this calls his cure into question. Others say the results could be false positives due to contamination in the laboratory or they note that, in any case, the virus does not appear to be reproducing, meaning he is essentially cured just the same.
At the conference Brown asserted unequivocally that he has been cured. “Despite what you may have read and heard recently in the media, I am cured of the AIDS virus.” He thanked his doctors for the “cutting-edge treatment” he received, adding that he wants to bring similarly groundbreaking therapies to others.
“This foundation will support and invest in cutting-edge therapies and treatments that show promise and have the potential to lead to the end of this disease,” he said. “If it weren’t for my own doctor in Berlin, who took a chance on an alternative therapy, I would not be standing here in front of you as living proof that there is, and could be, a cure for AIDS.”