Their discovery, detailed in this week's early online edition of the Proceedings of the National Academy of Sciences, could eventually pave the way for the development of new, more effective treatments for bacterial diseases that kill or sicken millions of people each year, such as pneumonia, strep throat, scarlet fever, rheumatic fever and toxic shock syndrome.

The essential achievement in the UCSD discovery is the team's finding that animal cells, from roundworms to mammals, have a natural defense mechanism to ward off certain kinds of bacteria that secrete toxins in order to form tiny holes in the membranes of the cells they infect. Scientists estimate that such "pore-forming" bacterial toxins account for approximately one-quarter of the known protein "virulence factors" that increase the infection and severity of a bacterial-caused disease.

"For the first time, we have provided a glimpse of how the innate animal immune system reacts to protect itself against a major bacterial virulence system," says Raffi V. Aroian, an associate professor of biology at UCSD who headed the team. "By learning how we can enhance and protect that defense mechanism in human cells, we can help protect people from many kinds of serious bacterial infections."

Pore-forming bacterial toxins are used by bacteria such as Staphylococcus aureus, the most common cause of hospital-acquired infections, which affects some 500,000 patients each year in U.S. hospitals, and Streptococcus pneumoniae, the bacterium responsible for seven million cases of otitis media in children and 500,000 cases of pneumonia in children and adults in the United States each year. The toxins also play a major role in infections from Helicobacter pylori, a bacterium that causes ulcers; Legionella pneumophil
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Contact: Kim McDonald
kmcdonald@ucsd.edu
858-534-7572
University of California - San Diego
12-Jul-2004