Viruses multiply incredibly quickly once they've infected their victim--so fast that antiviral medications such as Tamiflu are only effective if given during the first few days of an infection. After that, the viral load is just too high for a single drug to fight off. But researchers are working on a treatment for the H1N1 virus (or swine flu) that uses a different approach. Rather than disabling the virus with a drug, they're creating a vaccine that can activate and steer a patient's own immune cells to attack the invader.

Scientists at the Vienna, VA-based Cel-Sci have created a screening platform, called LEAPS (Ligand Epitope Antigen Presentation System) that identifies epitopes--small pieces of a virus that can be used to elicit very specific immune reactions. The DNA segments that make up these epitopes are so short--just eight to 30 amino acids long--that they can be re-created in the lab. Then the Cel-Sci researchers take those segments and attach them to another small molecule--an immune-cell-binding ligand that guides the complex straight to the immune cells in charge of initiating and directing an immune reaction.

The ligand-bound epitope is guided directly to immature dendritic cells, so named for tiny tentacles that reach out in every direction from the main cell body. Dendritic cells are the immune system's conductors, responsible for initiating and guiding the fight against invaders like the influenza virus. Immature dendritic cells are prompted to mature by the presence of these invaders; the mature dendritic cells then activate T cells, which in turn stimulate very specific immunity against the virus.

"It's like a live virus vaccine--and more effective--but without the live virus," says Kenneth Rosenthal, an immunologist at Northeastern Ohio Universities Colleges of Medicine and Pharmacy who has collaborated with the Cel-Sci team.

So far, the company has tested the LEAPS system in mice with herpes and arthritis, and found the approach to be successful in modulating the rodents' immune responses.

"The LEAPS technology allows you to drive an immune response in a desired direction," says Cel-Sci director and CEO Geert Kersten. "It's about modulating an immune response. That's important, because it's also possible to rev up the immune system and have no effect whatsoever."