14 Treatments for HIV/AIDS (Part 2)
Posted on March 11th, 2010 in Global Focus HIV/AIDS, Treatment
5. Bone marrow transplant and gene therapyIn November 2008, a pair of German doctors made headlines by announcing they had cured a man of HIV infection by giving him a bone marrow transplant. The transplant – given as a treatment for leukemia – used cells from a donor with a rare genetic mutation known as Delta 32 that confers resistance to HIV infection. Twenty months after the procedure researchers reported they could find no trace of HIV in the recipient’s bone marrow, blood and other organ tissues.
Other experts have said that more tests are required to verify this cure claim, though it is not the first of its kind. Of more than thirty HIV positive patients given bone marrow transplantation prior to 1996, two appeared to have been cured of their infection based on molecular testing and post-mortem biopsy samples.
Even assuming it can be effective, bone marrow transplantation is too dangerous and costly for widespread use as a cure. Many patients die as a result of chemotherapy or reactions to the transplant, which is usually a last resort in treating life-threatening diseases. As Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, put it:
“It’s very nice, and it’s not even surprising. But it’s just off the table of practicality.”
Nevertheless the German transplant does raise hope for related approaches. If scientists can find another way – such as gene therapy – to confer the same sort of protection against HIV as Delta 32 provides, then they may be able to stop the virus replicating. Research in this area is in its very early stages; it may be many years before a useful treatment is found, if at all.
6. Activating resting immune cells
Many researchers believe the best hope for eradicating HIV infection lies in combining antiretroviral treatment with drugs that flush HIV from its hiding places. The idea is to force resting CD4 cells to become active, whereupon they will start producing new HIV particles. The activated cells should soon die or be destroyed by the immune system, and the antiretroviral medication should mop up the released HIV.
Early attempts to employ this technique used interleukin-2 (also known as IL-2 or by the brand name Proleukin). This chemical messenger tells the body to create more CD4 cells and to activate resting cells. Researchers who gave interleukin-2 together with antiretroviral treatment discovered they could no longer find any infected resting CD4 cells. But interleukin-2 failed to clear all of the HIV; as soon as the patients stopped taking antiretroviral drugs the virus came back again.
There is a problem with creating a massive number of active CD4 cells: despite the antiretroviral drugs, HIV may manage to infect a few of these cells and replicate, thus keeping the infection alive. Scientists are now investigating chemicals that don’t activate all resting CD4 cells, but only the tiny minority that are infected with HIV.
One such chemical is valproic acid, a drug already used to treat epilepsy and other conditions. In 2005 a group of researchers led by David Margolis caused a sensation when they reported that valproic acid, combined with antiretroviral treatment, had greatly reduced the number of HIV-infected resting CD4 cells in three of four patients. They concluded that:
“This finding, though not definitive, suggests that new approaches will allow the cure of HIV in the future.”
Sadly, it seems such optimism was premature; more recent studies suggest that valproic acid has no long term benefits.4 5 In fact it’s quite possible that all related approaches are flawed because the virus has other hiding places besides resting CD4 cells. There is a lot about HIV that remains unknown.
7. Spontaneous healing
Occasionally there are reports of HIV seeming to vanish for no obvious reason. One especially sensational story broke on 13th November 2005, when two British newspapers reported that a 25-year old Scot, Andrew Stimpson, had become the first person to be cured of HIV infection.
In interviews with the two papers, Stimpson said he first suspected he might have HIV in 2002, after several weeks of feeling tired and feverish. Knowing his partner had been HIV positive for a number of years, Stimpson visited the Victoria Sexual Health Clinic in London for an HIV antibody test in May. The result was negative, but he was encouraged to return for further tests, as HIV antibodies often do not appear in the blood until several weeks or even months after initial infection.
In August 2002, Stimpson returned for three more HIV antibody tests. His first, taken on the 15th, was “indeterminate” (i.e. neither definitely positive nor negative), but the following two (taken on 20th and 23rd August) both found him to be HIV antibody positive. However, a viral load test showed the amount of virus in his blood was low, so he was not prescribed antiretroviral therapy. He made a personal choice to start taking multivitamin and mineral tablets and other dietary supplements.
For fourteen months Stimpson remained surprisingly healthy, so much so that, in October 2003, his doctor offered him a repeat test for HIV antibodies. Remarkably, the test came back negative. Two more, carried out in December 2003 and March 2004, also gave negative results.
Andrew Stimpson tried to launch a legal case against the Chelsea and Westminster NHS Trust (CWT) which had tested him, assuming his results had been mixed up with those of another client. The blood samples associated with his original positive diagnosis and his subsequent negative results were retested, and the DNA from the samples compared to his. All the samples were found to belong to Stimpson, and retesting produced the same “positive then negative” antibody results. According to Stimpson:
“After the repeat tests my doctor came into the room saying, ‘You’ve cured yourself! This is unbelievable.’”
Andrew Stimpson’s story became an overnight media sensation. But a statement from the CWT cast doubt on the cure claims:
“It is probable that there was never any evidence of Mr Stimpson having the HIV virus but rather that there was transient evidence of an antibody response to the virus present in his bloodstream when he had the initial tests… The antibody testing is exquisitely sensitive and the smallest measure can be recorded which is probably what happened in this case.”
A spokesperson for the CWT later said they had not categorically stated that Andrew Stimpson’s case was an example of a false positive test result, but that it was one of a number of scenarios that needed to be considered.88 The media quickly accepted the “false positive” explanation, and by the end of the month the story had ceased to be of interest to them.
The only news since then dates from June 2006, when the Guardian newspaper reported that Stimpson was still working with doctors, but that because of medical confidentiality, very little more was known about the case. However, Anna Maria Geretti, a clinical virologist at the Royal Free Hospital, was willing to speculate:
“These follow-up tests are very complicated. They could take over six months. But personally, I’m sceptical that they will find a cure from this case.”
The most likely explanation remains the occurrence of a highly unusual false positive antibody test result. This may happen if the test detects a non-HIV antibody (i.e. a similar antibody produced against a different virus) or, theoretically, because there are somehow HIV antibodies present without an actual HIV infection. Occasionally a false positive may be the result of a faulty test, though a second backup test would normally eliminate this possibility.
Although receiving three false positive results would be exceedingly unusual, some scientists believe it is more plausible than a spontaneous cure. In any case it’s extremely unlikely that, as some newspapers suggested, the multivitamins and dietary supplements that Andrew Stimpson took would have had any effect on his “seroreversion” (the process of going from HIV antibody positive to HIV antibody negative). Millions of people living with HIV take multivitamins and minerals; while such supplements may help to maintain good general health, there is no evidence that they can eliminate HIV infection.
Related posts:
- 14 Treatments for HIV/AIDS (Part 4)
- 14 Treatments for HIV/AIDS (Part 3)
- 14 Treatments for HIV/AIDS (Part 1)
- PROLOG : MENELUSURI JEJAK KESEMBUHAN
- Health Insurance, To Protect Your Unpredictable Cost
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