Cholera molecule helps cocaine addicts kick the habit

The Scientist magazine has a fascinating feature on a new vaccine aimed at weaning cocaine addicts off the drug. The vaccine uses cocaine molecules carried by recombinant cholera toxin B subunit. Cocaine and cholera sound frightening together, but this is harmless in isolation from the natural molecule's toxic A subunit, the magazine explains. Plus, this carrier has been used in a cholera vaccine that has been administered to millions of people without any problems. Also, Americans are so rarely exposed to cholera that the body would "likely mount a new and robust immune response to this protein and the attached cocaine molecule."

The magazine focuses on a vaccine-trial participant, "Joe Clarke," a pseudonym used to protect his identity, and his struggles with cocaine addiction and accompanying troubles with the law and hustle for money to feed the addiction. He tried repeatedly to quit, but always relapsed. The only time he was off the drug was when he was incarcerated for several years. For Joe, there are no FDA-approved treatments for cocaine addiction (as there are with heroin). So, when he enrolled in the vaccine trial last November, this was his last hope.

The way the vaccine works is this: The cocaine/cholera combo enters the bloodstream and triggers plasma cells to produce antibodies to the cocaine molecule as a component of the immunogenic cholera protein. As a result, antibodies take a ride on the cocaine molecules and, since they're too bulky now with antibodies, prevent it from crossing the blood-brain barrier, where it would create a "high." No cocaine in the brain, no dopamine buildup, no reward sensations. This gives the cocaine addict a fighting chance to kick the habit.

- read the feature in The Scientist