It may be possible to vaccinate people against addictive drugs
THE idea of vaccinating drug addicts against their affliction is an intriguing one. In principle, it should not be too hard. The immune system works, in part, by making antibodies that are specific to particular sorts of hostile molecule. Such antibodies recognise and attach themselves to these molecules, rendering them harmless. Vaccines work by presenting the immune system with novel targets, so that it can learn to react to them if it comes across them again.
The problem is that the molecules antibodies recognise and react to are the big ones, such as proteins, that are characteristic of bacteria, viruses and other infectious agents. Small molecules, such as drugs, go unnoticed. But not for much longer, if Kim Janda of the Scripps Research Institute in San Diego has his way. In a paper just published in theJournal of the American Chemical Society, Dr Janda and his colleagues suggest how a vaccine against methamphetamine, a popular street drug, might be made. If their method works, it would open the possibility of vaccinating people against other drugs, too.
The idea of a methamphetamine vaccine is not new. The problem is getting the immune system to pay attention to a molecule that is such a small target. The way that has been tried in the past is to build the vaccine from several components.
First, there is a large carrier protein that forms a platform for the target. Then there is the target itself, a set of smaller molecules called haptens that are attached to the carrier. These may either be the drug in question or some analogue of it that, for one reason or another, is reckoned to have a better chance of training the immune system. Finally, there is a chemical cocktail called an adjuvant that helps get the immune system to pay attention to the carrier protein and the haptens.