HIV Elite Controllers
Updated June 20, 2014.
Written or reviewed by a board-certified physician. See About.com's Medical Review Board.
If left untreated, HIV will progress to AIDS; that is generally the rule. However, a small group of HIV-positive people live their whole life without progressing to AIDS -- and do so without the help of HIV medications. These people, once referred to as long term nonprogressors, are today called elite controllers.
Experts have always considered the elite controller's resistance to HIV a mystery. Today, researchers believe the secret to the elite controller is genetic, found on the chromosomes of those fortunate few.
Better yet, two researchers theorize that the secret behind the elite controller may help develop an effective HIV vaccine. Let's learn about elite controllers and how they may be the key.
As a result, researchers have very little idea what sets elite controllers apart from other people living with HIV. However, now research data may tell us why elite controllers are special.
Harvard Medical School researcher Bruce Walker, M.D., along with MIT researcher Arup Chakraborty, Ph.D., believe they have found the genetic difference between the typical HIV-infected person and elite controllers. Their findings come from a series of experiments, including a study of 1,100 elite controllers and 800 people with AIDS.
In the normal immune system, specialized T-cells recognize viruses -- HIV included -- that can do harm to the body. Typically, swarms of these immune system T-cells recognize different attachment points on the virus. Using these attachment points, the T-cells attack and destroy the virus. However, a couple factors make HIV a tough virus to control with only our immune system. First, the T-cell process is too slow to keep up with the replication of HIV. In addition, as HIV replicates, it mutates and changes its genetic structure, which in turn makes it very difficult for the immune system to keep up with the changes. Eventually, the immune system is overwhelmed and loses the fight.
The genetic make-up of the elite controller's immune system is different. Drs. Walker and Chakraborty describe the "killer" T-cells of the elite controller as having unique properties. The T-cells of elite controllers don't need the help of other T-cells to kill HIV. What's more, the elite controller T-cells can kill HIV across a wide range of genetic mutations. These two facts allow the immune system of the elite controller to fight HIV effectively over the long-term, all while maintaining a preserved immune system. All this means elite controllers stay healthy and free of opportunistic infections.
More work is ahead, but many believe this new information about the genetics of elite controllers could mark a turning point in the search for an effective HIV vaccine.
Sources:
Brown, D.; "AIDS Study Focuses on Elite Controllers"; The Washington Post; 17 Aug 2006.
DeNoon, DJ.; "HIV Vaccine Secret Found in Elite Controllers"; WebMD Health News; 7 May 2010.
Markowitz, M.; "HIV Elite Controller Study (MMA-0951); The Rockefeller University; 9 Feb 2011.
Written or reviewed by a board-certified physician. See About.com's Medical Review Board.
If left untreated, HIV will progress to AIDS; that is generally the rule. However, a small group of HIV-positive people live their whole life without progressing to AIDS -- and do so without the help of HIV medications. These people, once referred to as long term nonprogressors, are today called elite controllers.
Experts have always considered the elite controller's resistance to HIV a mystery. Today, researchers believe the secret to the elite controller is genetic, found on the chromosomes of those fortunate few.
Better yet, two researchers theorize that the secret behind the elite controller may help develop an effective HIV vaccine. Let's learn about elite controllers and how they may be the key.
What is an Elite Controller?
Elite controllers are HIV-positive people who maintain an undetectable HIV viral load without the use of HIV medications. With an undetectable viral load, elite controllers typically have a well preserved CD4 count and immune system, meaning their risk of opportunistic infection is very low. Simply put, they stay healthy for a very long time.Out of Sight, Out of Mind
Elite controllers account for about 1 in 300 HIV infected people. Surprisingly little is known about elite controllers, for a few reasons. First, because they stay so healthy, they typically have little contact with the healthcare system, and there's little opportunity for HIV providers or researchers to learn much about them. Second, because of their preserved immune systems and undetectable viral loads, they seldom qualify for HIV clinical trials.As a result, researchers have very little idea what sets elite controllers apart from other people living with HIV. However, now research data may tell us why elite controllers are special.
What Makes Elite Controllers Unique?
Early studies were not successful in finding distinctly common traits and characteristics among elite controllers. Tests typically used to determine immune system health were not helpful in determining why elite controllers are unique. This suggests that the key to elite controllers must be in the human genome -- in the chromosomes and genetic building blocks of the human immune system.Harvard Medical School researcher Bruce Walker, M.D., along with MIT researcher Arup Chakraborty, Ph.D., believe they have found the genetic difference between the typical HIV-infected person and elite controllers. Their findings come from a series of experiments, including a study of 1,100 elite controllers and 800 people with AIDS.
In the normal immune system, specialized T-cells recognize viruses -- HIV included -- that can do harm to the body. Typically, swarms of these immune system T-cells recognize different attachment points on the virus. Using these attachment points, the T-cells attack and destroy the virus. However, a couple factors make HIV a tough virus to control with only our immune system. First, the T-cell process is too slow to keep up with the replication of HIV. In addition, as HIV replicates, it mutates and changes its genetic structure, which in turn makes it very difficult for the immune system to keep up with the changes. Eventually, the immune system is overwhelmed and loses the fight.
The genetic make-up of the elite controller's immune system is different. Drs. Walker and Chakraborty describe the "killer" T-cells of the elite controller as having unique properties. The T-cells of elite controllers don't need the help of other T-cells to kill HIV. What's more, the elite controller T-cells can kill HIV across a wide range of genetic mutations. These two facts allow the immune system of the elite controller to fight HIV effectively over the long-term, all while maintaining a preserved immune system. All this means elite controllers stay healthy and free of opportunistic infections.
What Does all this Mean?
Experts agree that the holy grail of HIV research is the quest for an HIV vaccine. It's generally accepted that an effective HIV vaccine is the best way to stop the HIV epidemic in its tracks. The findings of Walker and Chakraborty may be the break researchers have been looking for. The super T-cells found in elite controllers are found in lesser quantities in the typical HIV-infected patient. Researchers believe if they can "turn on" these few super T-cells with an HIV vaccine, the result would be much like the elite controller -- super T-cells able to control HIV. And once put into action by the vaccine, these super T-cells would replicate more copies, making the immune system even stronger... in theory, of course.More work is ahead, but many believe this new information about the genetics of elite controllers could mark a turning point in the search for an effective HIV vaccine.
Sources:
Brown, D.; "AIDS Study Focuses on Elite Controllers"; The Washington Post; 17 Aug 2006.
DeNoon, DJ.; "HIV Vaccine Secret Found in Elite Controllers"; WebMD Health News; 7 May 2010.
Markowitz, M.; "HIV Elite Controller Study (MMA-0951); The Rockefeller University; 9 Feb 2011.
Source...