The novel vaccine, which has so far been tested only in mice, prompts the body to manufacture an antibody that is attracted to nicotine. The antibodies patrol the bloodstream, soaking up the chemical and preventing it from reaching receptors in the reward centers of the brain, thereby countering the pleasure and addictiveness of smoking.
Nicotine vaccines have been tried before but failed because researchers couldn’t maintain high enough levels of antibody in smokers’ blood to block the drug’s effect. One previous attempt, called NicVax, delivered nicotine encased in a cholera toxin directly to the body in hopes that the immune system would recognize the invader and make antibodies against it. Problem is, nicotine is too small a molecule to trigger the robust immune response needed to inhibit its addictive effects.
So, rather than delivering nicotine itself, or ready-made antibodies against it, researchers led by Dr. Ronald Crystal, chairman of the department of genetic medicine at Weill Cornell Medical College, tried a different method: gene therapy. Crystal and his colleagues’ approach involved using a cold virus to ferry in the genes needed to make the nicotine antibody; the vaccine also contained instructions for infecting the liver, which is a factory for churning out proteins and other compounds. Once the vaccine infected liver cells, they began producing copy after copy of the antibody and releasing them into the bloodstream.