The latest big discovery in the war on HIV centers around the memory T-cells, the “veterans” of the immune system’s armed forces. Yuntao Wu, one of the authors of the study and a professor at Mason’s National Center for Biodefense and Infectious Diseases, calls it a big breakthrough.
HIV works by hijacking T-cells. Helper T-cell numbers then plummet, and the body is left vulnerable to disease. It’s noted that nobody has ever died of HIV or AIDS. Rather, HIV and AIDS leave the body incapable of defending against so much as a common cold.
Now, not all helper T-cells are the same. You effectively have experienced cells and virgin cells. The experienced cells are called memory helper T-cells, and HIV actually tends to target these ones, shunning the virgin cells.
HIV is able to kill most of a body’s memory cells, according to Weifeng Wang, PhD Biosciences, pointing out that the future of the HIV fight may well be in the difference between a memory and naive T-cell on the molecular level.
Though the two appear similar, we can see some differences between the two. Memory cells tend to be more mobile, carrying much more momentum. This is what seems to attract the HIV virus, making the memory cell more vulnerable, according to Harvard Medical School Dana-Farber Cancer Institute research fellow Wang.
A memory cell’s movement, called “treadmilling,” is comparable to a waterfall on the moving edge. The cell’s bone, the cytoskeleton, acts like a muscle, pushing the cell to migrate. HIV travels to the center of this cell, the nucleus, which requires crossing the cytoskeleton, like a thief sneaking through a brick wall.
According to Wu, the HIV virus appears to use the treadmilling process against the cell, using a receptor to attach to the cell like “ringing the doorbell,” using the treadmilling process to work its way to the center. The virgin cell’s cytoskeleton is quite different from a veteran cell’s cytoskeleton, resulting in the HIV having a harder time attaching itself to the cell and using the treadmilling process to work its way inward.
The HIV virus has the ability to mutate within the body, which is why the immune system has such a hard time fighting it. Like a criminal who can change his face every time a wanted poster goes up, your T-cells wind up looking for a HIV virus that looks very different from the one infecting your body right now.
Wang has spent much of his career as well as six years in medical school researching for his doctoral thesis looking at why, precisely, HIV chooses to attack memory cells, and this discovery is the fruit of that labor, but few answers in science are simple and linear, and many more questions remain. The next step, suggests Wu, is to look at what the virus is feeding on, what it needs to survive. Wu compares a memory T-cell to a house and the virus to an invader, and suggests looking into what the house contains that the virus needs. As a thief might break into your home for your television, what is the HIV virus breaking into the memory cells for?
One seen as an instant, immutable death sentence, patients suffering from HIV today have a much greater range of options, and thanks to researchers like Wang and Wu, they should have even more in the near future.