The team successfully simulated a mutation process that diversifies the proteins, or antibodies, responsible for immunity a phenomenon known as somatic hypermutation. This process enables the body to fight off a wide range of diseases.

Their findings are detailed in the July 3 issue of the journal Nature.

"When performing laboratory or in vitro experiments you always hope to get results that are close to the real thing," said John Petruska, one of the paper's authors and a professor of molecular biology in USC's College of Letters, Arts & Sciences. "In this case, it is fascinating to discover that the somatic hypermutation process in vitro is nearly identical to that in a natural environment."

"This is the first step in building an in vitro system that would completely mimic the body's immune response," Petruska added.

One of the first tactics the immune system uses to fight off foreign molecules is the production of protective antibody proteins, which are unique in their unlimited ability to diversify.

As one's immune response intensifies, antibodies undergo mutations that enable them to attack foreign molecules more forcefully, said Phuong Pham, the paper's lead author and a USC molecular biology postdoctoral researcher.

That process is known as somatic hypermutation.

Those more powerful antibodies allow the immune system to respond quickly and effectively to pathogens, particularly those from previous infections. In other words, the antibodies are much like soldiers sent to fight an enemy they've encountered in the past.

People whose immune systems lack the ability to create these strengthened antibodies may suffer from recurring bacterial and viral infections and do not respond to vaccinations.

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Contact: Gia Scafidi
scafidi@usc.edu
213-740-9335
University of Southern California
30-Jun-2003