Portuguese scientists develop vaccine for dental caries
Researchers at the Portuguese Biomedical Science Institute of the University of Porto believe that they have discovered a vaccine that will prevent one of the most common health complaints worldwide: dental caries. The vaccine has been successfully tested with lab rats. Dental caries is one of the most prevalent infectious diseases in humans. Indeed, it is among the most expensive diseases in the world due to its prevalence. A group of related oral bacteria, known as the mutans streptococci, is the primary etiological agent of human caries. Within this group, Streptococcus sobrinus and Streptococcus mutans are the species most commonly isolated from humans. Streptococcus sobrinus produces a virulence-associated immunomodulatory protein (VIP), which suppresses the host-specific immune response to the bug. The researchers thought that specific VIP immunisation might result in protection against the responsible microbe, and so tested the hypothesis using S. sobrinus-infected rats. The rat caries model has been extensively used for delineating immune protection for this disease as it develops in very similar ways as to human caries. All rats involved in the Porto research were given a cariogenic diet with sugar in the drinking water. Then, all the rats were infected orally with S. sobrinus. Some of the animals were repeatedly immunised intranasally with the vaccine. At the end of the trial, the extent of enamel caries lesions in the first, second, and third molar teeth of all rats (caries score) was microscopically evaluated and the S. sobrinus infection levels were assessed. The differences in enamel caries scores between the immunised group and the control group showed a 50 per cent reduction in caries lesions. The researchers also evaluated S. sobrinus colonisation in the oral cavities of the rats. This showed that VIP-immunised groups exhibited a significant reduction in S. sobrinus levels, while the sham-immunised group maintained high levels of bacteria throughout the study. The potential benefits are considerable: painful and expensive fillings could soon be a thing of the past. The benefits for those who cannot afford dentistry, including many poor people in rich countries and most of the population of developing countries, would be enormous. The discovery has been patented in Portugal, and the researchers have applied for an international patent. The following phase of the research will comprise the development, still in rodents, of a 'preventive' vaccine. So far, results have been obtained through a 'therapeutic' vaccine. The final goal of the scientists is to succeed in pre-immunisation, that is, before the infection occurs. The Portuguese team is now seeking financing for trials with primates and later, in human beings. The team believes that the human vaccine could be on the market at the beginning of the next decade.
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