"For 70 years the only adjuvants being used were aluminum salts," said Stephen Trent, associate professor of biology in the College of Natural Sciences. "They worked, but we didn't fully understand why, and there were limitations. Then four years ago the first biological adjuvant was approved by the Food and Drug Administration. I think what we're doing is a step forward from that. It's going to allow us to design vaccines in a much more intentional way."

Adjuvants were discovered in the early years of commercial vaccine production, when it was noticed that batches of vaccine that were accidentally contaminated often seemed to be more effective than those that were pure.

"They're called the 'dirty little secret' of immunology," said Trent. "If the vials were dirty, they elicited a better immune response."

What researchers eventually realized was that they could produce a one-two punch by intentionally adding their own dirt (adjuvant) to the mix. The main ingredient of the vaccine, which was a killed or inactivated version of the bacteria or virus that the vaccine was meant to protect against, did what it was supposed to do. It "taught" the body's immune system to recognize it and produce antibodies in response to it.