Researchers at the University of Texas' Southwestern Medical Center have discovered a protein that is vital to the immune system's ability to fight off viral infections. They say their findings may lead to new therapies aimed at preventing and treating viral diseases such as the flu, hepatitis, West Nile virus, and SARS.

Dr. Zhijian "James" Chen unexpectedly found the protein in the membrane of an organelle called the mitochondrion.

Says Chen, "This is the first mitochondrial protein known to be involved in immune defense against any microbial infection. This discovery puts mitochondria on the map in terms of immunity, and it opens up a new avenue of research in immunology."

The study will appear in the Sept. 9 issue of the journal Cell.