Site Where AIDS Virus Attaches to Some Cells Found
Researchers at the California Institute of Technology and the University of Alabama at Birmingham have identified a specific site where the AIDS virus attaches to the surface of some human cells, it was reported today.
The scientists have also shown that a synthetic protein fragment that mimics the attachment site can act as a decoy to prevent the AIDS virus from infecting human cells in laboratory experiments.
The new findings, reported in today’s issue of the journal Science, are part of a broader effort by many laboratories around the world to combat the AIDS virus by blocking its ability to infect human cells.
This effort is expected to lead to a better understanding of the AIDS virus on a molecular level and has been touted by some researchers as a possible approach to AIDS therapy. But there is no evidence to date that more effective treatments for people already infected with the AIDS virus will result from the binding-site blocking experiments.
Receptor Protein Studied
The quickly expanding research field has focused on the interaction between the AIDS virus and a receptor protein on the surface of some human cells, such as the white blood cells known as T4 lymphocytes. The receptor protein is known as CD4.
The new findings localize the attachment site of the virus on the CD4 protein to a loop of 17 amino acids out of the total of 168 amino acids that make up the CD4 protein. The researchers contend that a small protein fragment can be used to block this specific attachment site.
A key problem with the binding-site blocking approach to AIDS therapy is that the deadly virus is able to infect some human cells that do not contain the CD4 protein, for example some brain cells and apparently immature bone marrow cells. In addition, the AIDS virus can infect T4 lymphocytes and other white blood cells through surface proteins unrelated to CD4, said Dr. Jay A. Levy of the UC Medical Center, San Francisco.
The authors of the Science paper include Stephen B.H. Kent, Bradford A. Jameson and Leroy E. Hood of the California Institute of Technology, Beatrice H. Hahn and George M. Shaw of the University of Alabama and Patricia E. Rao of ORTHO Pharmaceuticals in Raritan, N. J.
