Getting To The Bottom Of The AIDS Pandemic

With approximately 7,000 new HIV infections occurring on a daily basis, the AIDS pandemic is easily the worst pandemic the human race has ever faced. And though anti-retroviral drugs have helped stave off soaring death rates and have led to a better quality of life for many patients infected with HIV, there are many problems that scientists face when dealing with this debilitating disease. Most notably is the ingenuity of the virus itself. Once one becomes infected with the HIV virus, the virus has the ability to insert a copy of its genetic material into the hosts' DNA. What this means is that even though retroviral drugs can help to severely diminish the levels of virus in a patient's bloodstream, the virus itself is still completely concealed within the patient's cells. The virus very simply is always able to make new virus particles, with no worry of ever being destroyed.

But can we target this virus on a genetic level? Though once thought improbable, many researchers now believe that this is the only way to truly eradicate the disease. Recently, some major steps have been taken towards making this pipe dream a reality. In a paper by David DiGiusto et al. (Science Trans Med, DOI: 10.1126/scitranslmed.3000931, 2010), the researchers isolated white blood cell progenitor cells from HIV-infected patients, and added genes to the cells in vitro that are known to make it more difficult for the virus particles to grow. The RNA-based anti-HIV moieties in question are tat/rev shRNA, TAR decoy, and CCR5 ribozyme, but you need not worry about the names of these three genes (if you are interested in the specifics, then I suggest reading the paper in question). What does matter is simple: these genes destroy the activity of the virus by either deactivating it or by acting as decoys during assembly of the virus. Once the cells were transduced with these three genes, they were introduced back into the respective patients, and they were followed up for several years. The results are quite staggering: two years after re-introduction of the progenitor cells, each of the 7 patients still have detectable amounts of the re-introduced cells in their bodies. Once thought impossible, these researchers have now shown that not only is genetic modification of progenitor cells in the human body possible, but also that it's possible to help our bodies defend ourselves from debilitating diseases.

These results are obviously very preliminary, and the next step is to scale up this study to a very large population of patients. But the questions raised by this study are not only promising but thought-provoking. Could this possibly lead to a cure for AIDS? How many other genetic diseases could be treated this way? Or more specifically, how many other genetic diseases are amenable to this type of treatment? Diseases such as cystic fibrosis, multiple sclerosis, and Parkinson's disease spring to mind, along with many others. Though honest-to-goodness cures may not be directly around the corner, one thing's for sure: I'll be following the progress of this study with great enthusiasm.