The drugs work, and are getting cheaper by the year: a report released during the conference by the Clinton Foundation, an American global-health charity, put the annual cost of treatment at $200; it used to be $10,000. But once on them, you are on them for life. Stop, and the virus crawls out of cellular hidey-holes that ARVs cannot reach and rapidly reinfects you. This has implications both for patients, whose lives are constrained by the need for constant medication, and taxpayers, who bear most of the cost of this indefinite treatment.
Many of those taxpayers do not live in the rich world but in the worst-afflicted countries. A new estimate by UNAIDS, the United Nations agency charged with combating the disease, suggests that more than half of the cost of treating and preventing AIDS is now borne by these countries, rather than paid for by international agencies (see chart 2). As many of these countries have high economic growth rates, that is only right and proper. But it does mean that they, too, have a strong interest in a cure. And researchers would like to provide them with one.
The road to Berlin
A race is therefore on to work out how to flush the virus from its hiding places and get rid of it completely. Several clues suggest a cure may be possible. But no one knows which route will lead to it.
One of those routes passes through Timothy Brown. Mr Brown, pictured above, is known as the Berlin patient. He was living in that city in 2007 when he underwent radical treatment for leukaemia. This required the destruction of his immune system—the source of the cancer—and its replacement using stem cells transplanted from the bone marrow of a donor, which allowed him to grow a new (but alien) immune system.
Mr Brown did not just have leukaemia. He was also infected with HIV. So his doctor, with his permission, tried an experiment. The doctor searched for and found a donor who had a rare genetic mutation which confers immunity to HIV infection by disabling a protein on cell surfaces to which the virus attaches itself in order to gain entry to a cell.
After the transplant, the virus seemed to disappear from Mr Brown’s body. Traces of viral genes were found recently, but these may have been contamination, and in any case they did not amount to entire, working viruses. There is no disputing, however, that Mr Brown no longer needs drugs to stay healthy, and has not needed them for five years.
No one is suggesting immune-system transplants as a treatment for AIDS. They are far too dangerous and costly. The intriguing point about Mr Brown’s procedure is that it would have been expected to destroy directly only one of the hiding places of the virus: immune-system cells squirrelled away in a quiescent state as the system’s memory. (These allow it to recognise and respond to infections experienced in the past.) Other reservoirs, particularly certain brain cells, would not have been affected directly—and in Mr Brown’s case checking his brain to find out what is going on would be grossly unethical.
Clearly, it is dangerous to draw conclusions from a single example. But if quiescent memory cells are the main source of viral rebound, that would simplify the task of finding a cure. And many groups of researchers are trying to do just that, by waking up the memory cells so that ARVs can get at the virus within them.
by The Economist | Read more:
Photo: Eyevine
