July 21, 2010
Last week, U.S. government scientists announced their discovery of three antibodies in a man's cells, including one that neutralizes 91 percent of HIV strains. At the age of 60, this man, known in scientific circles as Donor 45, became one of the most important participants in HIV research. Donor 45 is Black, gay and has been living with HIV for 20 years. What makes him special in the field of HIV is not his gender or race or sexual orientation or age. He has a rare ability to produce antibodies that block HIV from invading his cells.
As a clinical trial participant, Donor 45's identity remains a mystery and the antibodies that he produces are under wraps. Most HIV-positive people like Donor 45 are what scientists call "elite controllers." These men and women, also known as "long-term survivors" or "non-progressors," naturally maintain viral loads, the amount of HIV virus present in their blood, at levels so low that the virus can't be detected. Somehow their bodies stop HIV from replicating. They remain healthy with undetectable loads for long periods of time without taking prescription drugs. About one to four percent of HIV-infected people are said to be in this group.
Scientists hope to better understand why elite controllers' bodies produce antibodies that other HIV-infected people's bodies do not. Uncovering this mystery offers another step toward what researchers call a "functional cure," defined as a life free from symptoms, where the disease does not progress and prolonged antiretroviral treatment is unnecessary. Donor 45 is of particular interest to vaccine researchers because, unlike his fellow elites, his viral load remains high whereas their viral load is typically low. Yet, even with a high viral load Donor 45's immune system is stable, a fact which offers a building block to developing an HIV vaccine, says Anthony Fauci, M.D., director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health. "If we're ever going to get a cure for HIV," Dr. Fauci says, "we're going to have to have a patient whose immune function has some degree of integrity." Donor 45's does.
But the contributions of Donor 45 and other clinical-trial participants don't come without risk. A study presented at the XVIII International AIDS Conference by Lindsey R. Baden, M.D., of Brigham and Women's Hospital and Harvard Medical School in Boston, found that the test results of nearly half of the trial volunteers she surveyed yielded false-positive results. This means that many trial participants who subsequently got screened for HIV tested HIV-positive -- only to discover later that their HIV-positive results were wrong; they were in fact HIV-negative. Besides the traumatic emotional impact an HIV diagnosis can have, this vaccine-induced seropositivity/reactivity may cause the person who receives an HIV-positive result to have difficulties obtaining insurance or donating blood and organs -- not to mention encounter problems with employment, military service and or immigration.
However, it isn't the test that's faulty. The diagnostic test works as it should by detecting HIV antibodies. The problem occurs because the vaccine prototype is designed to fool the body into thinking that it has those antibodies. The VISP test picks up on the change and returns a positive test result. The HIV-positive test result is correct, yet the person is HIV-negative.
The solution seems simple: Getting retested using viral load or p24 antigen tests will show if the original antibody test was wrong. However, this is where things get complicated, since patients have to have both the health literacy and presence of mind following a traumatic diagnosis to ask for additional testing or depend on their health professional to request tests for them. This may be unlikely, particularly for volunteers with low education, or without the financial means to pay for more tests, the insurance to cover them or health practitioners open to performing them.
However, Donor 45's results suggest that the potential benefits of volunteering for HIV trials may outweigh these and other risks. His participation unlocks a door allowing scientists to ask: Why does his body produce antibodies to HIV, and how can this information be used to get everyone else's body to do the same? While uncovering these answers could take 10 or so years, they become of special importance as we reach the 30th anniversary of the first reported AIDS case in 2011.
But if Donor 45 is a superhero of the disease, HIV is its Lex Luther. The virus is smart. It hides from the immune system in lymph nodes and lymphocytes, mutating the cells that should be fighting it off and turning them into deadly helpers. Its identity is hard to isolate and fight because unlike the flu or small pox, the HIV virus is unstable and its identity changes as it spreads. This makes developing a vaccine particularly difficult. How do scientists hit a target good at hiding and even better at changing its appearance? Is there a weapon strong or smart enough? The hope is that one day the antibodies developed from donors like 45 and elite controllers can give us the answers.
Volunteers in vaccine trials (see Can I get HIV from a vaccine clinical trial?) help researchers take a crucial step forward in the long journey to HIV-vaccine development. The greater the number of volunteers, the more likely that elite controllers like Donor 45 will be found. Medicines work best when they are tested on people most like those who will ultimately take them. Almost 50 percent of AIDS diagnoses and 45 percent of new HIV infections in the United States occur among African Americans. So Black participation is essential in clinical trials, and we stand the most to gain.
Trial volunteerism offers an "opportunity for leadership in the Black community," says Katharine Kripke, M.D., assistant director in the vaccine research program at the National Institute of Allergy and Infectious Diseases Division of AIDS. She notes that while African Americans are disproportionately affected by HIV, we are the least likely to volunteer to participate in research. In one U.S. HIV-vaccine efficacy study, only 10 percent of male participants were Black, even though Black men are eight times more likely to be infected than White men. "What does this mean for our likelihood for finding a vaccine and knowing that it's going to work for the community that most needs it?" she asks. Unless greater numbers of Black people don't participate in clinical trials, "we are not going to have a vaccine," she states.
A viable vaccine is years away, and even when one is developed, elite-controllers, long-term survivors and other HIV-positive people won't be cured. However, Black people can play a key role in facilitating a functional cure, as has Donor 45, furthering the possibility of long-term health for the HIV-positive and another step toward ending HIV and AIDS.
New York City resident Ramon Johnson is the gay lifestyle guide at About.com, part of the New York Times Company.
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