People infected with the Human Immunodeficiency virus (HIV) can survive an average of 10 years. People appear fine for a number of years and then suddenly they start having serious health problems (Acquired Immunodeficiency Syndrome; AIDS). Eric Verdin, MD, at the University of California San Francisco, and Georges Herbein, MD, PhD, at the Picower Institute for Medical Research and other investigators report in a recent article in Nature (September, 10, 1998) that they may have determined how HIV causes infected people to suddenly make a turn for the worse.
Scientists have known for a long time that the HIV virus infects CD4 cells (Helper T cells). These CD4 cells are the white blood cells that help other white blood cells (B cells) make antibodies. CD4 cells also help CD8 cells (killer T cells) kill virus infected cells. Without CD8 cells, people get very sick when infected by viruses. When HIV-infected people suddenly get worse, their CD4 and CD8 cell numbers go way down in the blood stream. They are more likely to develop severe viral infections. They also have trouble with bacterial, fungal, and parasitic infections.
The mystery of all this is that the HIV virus does not infect CD8 cells. Why do these uninfected CD8 cells die? It is known that the HIV virus can change while it resides in a person. Other researchers have shown that most people are initially infected with one type HIV virus that does not attach to CD8 cells. However, with time, the HIV virus mutates and another type of the virus becomes more numerous. This new type of HIV can attach to a protein on the surface of the CD8 cell called CXCR4. If another white blood cell called a macrophage is also around, an interesting thing happens. The CD8 cells suddenly start commiting suicide. This cell suicide response is called apoptosis or programmed cell death. If ways could be found to block HIV binding to the CXCR4 protein on CD8 cells, then people with this infection might live longer and healthier lives.
For more information go to:
A review of the research at the ScienceDaily
Press release from University
of California San Francisco
Want to know more about the HIV virus? Then go to the CDC's
National AIDS Clearinghouse
Take Care and Think Microbiologically!
Go To Page: 1
