A caries vaccine is a vaccine to prevent and protect against tooth decay. Streptococcus mutans (S. mutans) has been identified as the major etiological agent of human dental caries. The development of a vaccine for tooth decay has been under investigation since the 1970s. In 1972, a caries vaccine was said to be in animal testing in England, and that it would have begun human testing soon. However, intrinsic difficulties in developing it, coupled with lack of strong economic interests, are the reasons why still no such vaccine is commercially available today. Several types of vaccines are being developed at research centres, with some kind of caries vaccines being considered to diminish or prevent dental caries' impact on young people. Attempts using antibodies Early attempts followed a traditional approach to vaccination where normal S. mutans was introduced to promote a reaction from the immune system, stimulating antibody production. Planet Biotechnology developed a monoclonal antibody against S. mutans, branded CaroRx, produced with transgenic tobacco plants. It is a therapeutic vaccine, applied once every several months. Phase II clinical trials were discontinued in 2016. The International Association for Dental Research and American Association for Dental Research announced a study performed by the Chinese Academy of Sciences which looked at using an inhaled vaccine that uses a protein filament as a delivery vehicle. Trials performed in rats showed an increase in antibody response along with a decrease in the amount of Streptococcus mutans adhering to teeth, leading to significantly fewer cavities observed among the test population. Attempts using replacement therapy On a different line of research, Jeffrey Hillman from the University of Florida developed a genetically modified strain of Streptococcus mutans called BCS3-L1, that is incapable of producing lactic acid – the acid that dissolves tooth enamel – and aggressively replaces native flora. In laboratory tests, rats who were given BCS3-L1 were conferred with a lifetime of protection against S. mutans. BCS3-L1 colonizes the mouth and produces a small amount of a lantibiotic, called MU1140, which allows it to out-compete S. mutans. Hillman suggested that treatment with BCS3-L1 in humans could also provide a lifetime of protection, or, at worst, require occasional re-applications. He stated that the treatment would be available in dentists' offices and "will probably cost less than $100." The product was being developed by Oragenics, but was shelved in 2014, citing regulatory concerns and patent issues. In 2016, Oragenics received