TL;DR - A Cure for HIV?

    Scientific American, March 2012 -- "Blocking HIV's Attack," Carl June & Bruce Levine

    In 2009, many headlines were grabbed by a medical story in which a man--the so-called "Berlin Patient"-- was cured of HIV after receiving a bone marrow transplant.  June and Levine explain this case, and why we're still not entirely sure what exactly happened, and elaborate on the work that they and others have done to conceptually follow up on this treatment angle. 
    HIV reproduces by hijacking the body's immune system, invading T cells and using their cellular machinery to make copies.  But some people are lucky enough to be completely resistant to HIV, not showing signs of infection despite repeated exposures.  It turns out that this is because of a genetic mutation that disables the CCR5 protein from being expressed on T cell membranes.  Without this protein, HIV lacks an entry point into the T cells, eliminating its reproductive pathway.  The Berlin Patient was a man who had both HIV and lymphoma, and so was a candidate for a bone marrow transplant.  This involves killing off his existing bone marrow with radiation and then injecting donor bone marrow (which must be a close enough genetic match that the body will accept and use it).  In this case, the bone marrow was selected to be from a donor who also happened to have the rare genetic mutation leading to an absence of CCR5 protein, and this seems to be what led to the elimination (possibly) of HIV from the recipient's system.  This is all tentative, unfortunately, due to the fact that we can't be sure whether the HIV has been eliminated, or is just hiding somewhere we can't find it, that other aspects of the treatment (such as radiation) could have killed off or reduced the HIV, and that this match was such a statistical rarity that a replication is very hard to produce.
    However, it may be possible to artificially cripple the CCR5-coding portion of the genetic code, resulting in gene therapy wherein the patient's own genetic material is extracted, altered, and reintroduced.  This might be a much more efficient, and safer, way of achieving the same sort of results.