Cure for HIV?
July 15, 2007
Once again we are hearing about efforts to eradicate HIV, at least in some people. These efforts are being made, not by marginal actors, but by some of the country's top doctors, such as Anthony Fauci, M.D., longtime director of many HIV research efforts at the National Institutes of Health. On May 24th the Bloomberg report (Bloomberg.com) headlined the issue this way:
A summary of scientists' efforts exploring the possibility of eradication can be found here.
So what happened?
Well, for many years scientists have understood that after HIV gets into someone's body, it starts infecting lots of T helper cells. These cells are also sometimes called CD4+ T cells. T helper cells are the cells that recognize that the body has been invaded by some enemy germ. If these kinds of cells are significantly reduced, the body is unable to recognize many illnesses. As a result, people with HIV can get sick with many serious illnesses.
Once HIV gets into someone's body, HIV begins inserting instructions into these T helper cells on how to make more HIV. These instructions are known as "provirus." They are kind of the brain of HIV and it is these instructions that transform the T helper cell into a factory that can make HIV.
Soon after an HIV-positive person begins taking HIV medications, known as antiretrovirals, the number of these factories is dramatically reduced. But, unfortunately the medicines we have today do not actually eliminate all of the provirus.
In fact, if you checked the cells of people with HIV who are taking antiretroviral medicines, you'd see that although these medications have eliminated most of the HIV from their bloodstream, some cells with these instructions on how to manufacture HIV still remain. Scientists don't yet understand why these cells containing instructions remain while most of the virus has been eliminated. The cells that have provirus but are not producing HIV are known as "latently infected cells." They are "latent" because they have the ability to spring into action at any time.
Scientists have at least two different theories that might explain why the HIV in someone's body does not disappear altogether with the use of antiretrovirals.
The first theory makes researchers pessimistic about getting rid of HIV and curing someone infected with it.
As I mentioned, provirus does not make virus until the cell containing it is "activated." All this means is that the cell remains quiet until it finds evidence of a germ which it recognizes as an enemy. This causes the T cell to produce proteins that get the immune system ready to fight. When the T cell begins to manufacture these proteins, it also starts making HIV.
No one knows exactly HOW long it takes before all latently infected cells in someone's body are activated. For this reason, most scientists, doctors and activists have been skeptical about finding a cure for HIV. Finding a cure would require getting rid of all cells which contain provirus. Unfortunately, the HIV medications we currently use do not get rid of these latently infected cells.
The second theory suggests that with more powerful drugs we might eliminate all HIV from the body.
In fact, we are in an exciting period in the development of HIV medicine. We actually have new drugs such as integrase inhibitors and entry inhibitors which are in the pipeline that are much more powerful than the antiretroviral drugs we have right now.
This leads us to a hopeful possibility. What if we could eliminate virtually all infected cells with the help of these brand new HIV medications that are more powerful than ever before? What if the new drugs work so well that the immune system is able to get rid of the few infected cells that are left? This is the operating theory behind radiation treatments for cancer.
How can we find out which theory is correct?
First we would use these powerful new HIV medications and see if they can successfully shut down all HIV replication completely and if the body then clears HIV infection.
Then, after testing to make sure no virus or provirus can be found, we would stop using the powerful drugs and wait and see if the virus comes back.
Sounds interesting, doesn't it? This extraordinary experiment is actually taking place right now.
Why try this now?
First, because it was recently discovered that latently infected cells, containing provirus, DO get eliminated from the body. It is not clear why or how, but the data shows that the body does in fact get rid of these latently infected cells (provirus).
Dr. Fauci at the National Institutes of Health, whom I mentioned above found that in seven HIV-positive people who used strong antivirals within four months of being infected with HIV saw a reduction in the amount of provirus by 50% every 4.6 months. If these results hold up, the scientists estimate that 7.7 years of antiviral therapy could possibly eliminate HIV.
The experiment is underway. Patients will be given the powerful new antivirals. These drugs will, hopefully, shut down replication altogether for one year. Then these patients will be taken off the medication -- assuming no virus can be found -- to see if the virus comes back.
This is an experiment which needs to be done, and it's fine to hope for good results. However, there are good reasons to think it will not work, and we should not raise our expectations too high. Perhaps it will work in a few unusual people, such as people who not only were diagnosed with HIV soon after they were infected, but those who also almost immediately went to a doctor and got HIV medication.
Clearly we are far away from understanding how this could work for the majority of people with HIV. Perhaps it will work for a limited period of time in some people, giving them a vacation from HIV medications. Perhaps it will succeed completely and we can look forward to a cure.
The world will be waiting to hear the results.
David Scondras is the founder of Search For A Cure. He developed the nationally-recognized HIV treatment series, Reasons for Hope. All articles in the series are reviewed by expert HIV doctors and scientists as well as an HIV positive and negative focus group to ensure both accuracy and understandability.
This article has been reviewed by Alfred DeMaria, Jr., M.D. Chief Medical Officer, State Epidemiologist; Director, Bureau of Communicable Disease Control State Laboratory Institute and Dr. Cal Cohen of Community Research Initiative of New England.
Any errors are entirely those of Search For A Cure, not our reviewers.
This article was provided by Search for a Cure.