TOOTHACHE and fillings could soon be a thing of the past. On both sides of the Atlantic, scientists are developing vaccines aimed at eliminating dental caries, one of the most common infectious diseases.
The vaccines target the bacterium Streptococcus mutans, which damages teeth by secreting large amounts of lactic acid that erodes tooth enamel. The bug also makes a sticky substance that helps it cling to tooth surfaces, forming a furry layer called plaque.
Martin Taubman, Daniel Smith and their team at the Forsyth Institute in Boston are developing a vaccine against S. mutans that they hope can be given to children aged 18 months to 3 years. "We found that's the best time to immunise," says Taubman. If toddlers fight off the bacteria before they have fully colonised the mouth, he says, the vaccine could give lifelong protection.
Rather than attack S. mutans directly, the vaccine targets the enzyme that makes the goo it uses to stick to teeth. Deprived of this anchor, the bugs should easily be swept away when people brush their teeth.
When adults were given an oral version of the vaccine, they produced antibodies to the bacteria, Taubman found. And rats given the vaccine as a nasal spray secreted bacteria-fighting antibodies in their saliva, where it is needed to eradicate the bugs.
Julian Ma and colleagues at Guy's Hospital in London are developing a different kind of vaccine, consisting of highly purified antibodies that attack the bugs directly. Because the vaccine doesn't induce an immune response, it might not provide such long-term protection and so may have to be given every year or so. But this "passive" approach has safety advantages, because it reduces the risk of unwanted immune reactions. The vaccine is now in clinical trials.
Both groups say it may be 5 to 7 years before a caries vaccine is available. Part of the delay comes from the difficulty in funding clinical trials. Companies that make dental products, says Ma, "are not used to dealing with the idea of vaccines," while drugs companies don't see caries as a major problem.
Author: Sylvia Pagan Westphal, Boston
More at: Infection and Immunity (vol 69, p 4767)
New Scientist issue: 15 September 2001
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