In December of 2010, the AWord posted an article which outlined the discovery of a group of doctors in Berlin who believed they had cured HIV in Timothy Ray Brown, click here to read. As Brown has gained more attention over the past year, here is a more in-depth look into what could be considered Brown’s unique medical phenomenon.
Recently, a new ray of hope has been cast on the fight against HIV/AIDS. Specifically, this ray is Timothy Ray Brown, otherwise known as the “Berlin Patient.” The 45 year old man tested HIV positive for over a decade and now tests HIV negative(1), much to the astonishment of the scientific community and AIDS researchers. The story of the Berlin Patient is the first ever observed case of a person completely reverting back to an HIV negative status after confirmed seroconversion. Furthermore, he apparently no longer needs to take any anti-HIV medication(1). It should be pointed out early in the discussion as a sort of disclaimer, however, that Timothy was under specific circumstances and you might say he is enjoying a certain simple twist of fate. Bearing this in mind, the event still has significant implications on our knowledge of exactly what we may be capable of when it comes to fighting HIV. Timothy Brown’s instance has introduced the word “cure” into the vocabulary of AIDS specialists(1).
After living with HIV for some time, Timothy developed Leukemia(4). At the time he was living in Berlin (hence the nickname “The Berlin Patient”) and he received a bone marrow stem cell transplant to replenish some of his white blood cell supply. His donor happened to be a member of the 1-2.5% of Caucasians who are inherently immune to some types of HIV(4). Over the course of his treatment, the donor’s white blood cells populated his body and began to replace his own white blood cells which were not immune. It may be inferred that once there were no more host cells for HIV to target (Timothy’s own white blood cells) the virus eventually died off. This is because, just like any other virus, HIV cannot survive on its own without incorporating itself into a host.
Dr. Paul Volberding was quick to point out, however, that the stem cell transplant procedure itself can be fatal and that the case of the Berlin Patient cannot be generalized(1), at least not yet. At the very least, it serves as a new lead for researchers. Put in the scope of HIV medical development, this case opens all kinds of new doors and raises new questions, the overall one being how to recreate the genetic mutation (sometimes called the delta 32 mutation) that has been shown to create effective immunity to some forms of HIV.
HIV targets a specific type of white blood cell called the CD4+ cell. In order to enter the host white blood cell, HIV must attach itself to a CD4 receptor as well as one of two co-receptors: either the CCR5 co-receptor or the CXCR4 co-receptor(3). Without going into extensive detail on the science, CCR5 and CXCR4 receptors can be thought of as flags that stick out of the cell that HIV searches for in the host’s body. Once HIV locates the flags, it can enter the cell and attack. The 1-2.5% of Caucasians who present immunity to HIV apparently have a mutated form of CCR5 and HIV no longer recognizes it as one of the two flags (3). Therefore, if the type of HIV inside a person’s body specializes on CCR5 receptors, the virus will be unable to enter the individual’s white blood cells. However, it should be noted that the CCR5 mutation only protects against types of HIV that enter the cell via this co-receptor. HIV that enters a cell via the CXCR4 co-receptor will not be hindered by this rare genetic mutation. By targeting the gene that codes for CCR5, researchers may be able to reproduce the same mutation in people who are not immune.
As mentioned at the beginning of this article, it is important to remember that Timothy Brown’s circumstances are completely rare and unique. However, I think it’s safe to say and so far it seems like some new doors have opened, at least in the way of research, and this discovery should be celebrated as yet another stride in understanding the inner workings of HIV.
Note from the editor: When reading anything about Brown’s case, it must be mentioned that whether or not Brown has been officially “cured” of HIV is still a highly debated issue. Also, to put things into perspective, through Brown’s elaborate medical procedure, which led to his eventual cure, Brown himself wanted people to know that “…this is something he wouldn’t wish upon his worst enemy”, as mentioned in last month’s issue of POZ magazine(5).
This article was written by Volunteer Blog Writer Cory Waller. Cory has a B.Sc. in Biochemeistry from the University of Calgary. This is Cory's second article for The AWord, his first article was The low down on rapid testing.
Sources:
1. 2011, International Business Times, http://www.ibtimes.com/articles/146949/20110517/timothy-ray-brown-berlin-patient-hiv-cure-video.htm
2. March 1995, Microbiological Reviews (pp. 63 – 93), Bour S, Geleziunas R, Wainberg MA, The Human Immunodeficiency Virus Type 1 (HIV-1) CD4 Receptor and Its Central Role in Promotion of HIV-1 Infection, http://mmbr.asm.org/cgi/reprint/59/1/63
3. 2011, Understanding Genetics, Kimmel R, http://www.thetech.org/genetics/news.php?id=13
4. 2011, AIDS Committee of Guelph, Caldwell BJ, http://www.aidsguelph.org/the-berlin-patient-receptors-and-zinc-fingers-new-hiv-research-field-is-energized
5. June 2011, POZ Magazine, Regan Hofmann, Patient No More, http://www.poz.com/articles/Timothy_Brown_HIV_2615_20349.shtml
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