Ah, E. coli...is there any limit to your uses?

While E. coli typically makes the news as a food-borne pathogen, that's only one facet of the bacterium. It can be deadly, sure, but it also helps us digest our food; it produces vitamin K for us; benign strains can even protect us from invading pathogens. It's one of the most-studied bacterial species and a "workhorse" for research in microbiology and molecular biology. We use it as a marker of fecal contamination in water, and it can even be used to produce insulin for diabetes patients. So it may come as no surprise that it may one day be a cavity fighter as well:

Imagine being able to protect your children from cavities by taking them, as toddlers, for a painless, nasal vaccination.

George Hajishengallis and fellow U of Louisville researcher Shuang Liang work with modified E. coli in the lab and hope to harness it to control streptococci bacteria that contribute to the development of tooth decay.

Their work could lead to the creation of a vaccine that could be given to children -- perhaps at age 1 -- to protect their teeth against cavities.

Toddlers would be good candidates because "they're more susceptible to develop dental caries (tooth decay) than us (adults)," Hajishengallis said.

Tooth decay is interesting and has been fairly well-studied. Dental plaque builds up as a biofilm in a somewhat sequential manner (as described in in this post), with species of bacteria piling on other species in a complex web of organisms and goo. Though oral streptococci are only one part of this biofilm, they tend to be the ones causing damage, via acids they secrete which harm the teeth. Therefore, if you can eliminate the strep, you could go a long way toward preventing tooth decay.

The idea of a vaccine for tooth decay isn't novel; they've been tried before (typically in an animal model) with varying degrees of success. What's interesting about this is that they're using an engineered protein from E. coli as an adjuvant--a protein that increases the immune response--along with an immunogenic streptococcal protein. What I can't tell for sure, though, is whether they're using an engineered E. coli strain as a vector for both of these (as the researchers did using Salmonella in a previous paper), or if they're just isolating proteins and giving them that way, like a more traditional vaccine (which is how the article makes it sound). Either way, it highlights once again the utility of E. coli for all things biological.