Raw cookie dough, which cannot be eaten because raw eggs carry the bacteria salmonella, may soon be safe for consumption thanks to research by UCSB biologists.
Biology Professors David Low, Robert Sinsheimer and Michael Mahan, post-doctoral researcher Douglas Heithoff and research scientist Steven Julio have created a vaccine that defends against multiple salmonella strains.
The research published in the November issue of the biomedical journal Infection and Immunity complements their research on several similar diseases, including a February article in the same journal on a vaccine for a bacterium similar to the one that causes plague.
“This may turn out to be a general theme in how bacteria cause disease,” Heithoff said. “It’s still too early to say that there are bacteria for which this has no applications.”
Most pathenogenic bacteria have multiple strains, and a vaccine for one does not necessarily work for the others.
“The problem with vaccines is that they’re usually designed to protect against a certain strain or group of strains,” Heithoff said. “When you have bacteria that are very diverse, you may not be protected against more than one strain, and salmonella has over 2,500 strains that cause disease.”
The research team used a technology called DNA adenine methylase, or “Dam,” which they discovered in 1999, to inactivate one strain of salmonella and use it as a vaccine. Mice that were injected with the vaccine not only resisted that strain of salmonella, but several other kinds as well.
“The Dam gene basically modifies DNA, and when you disrupt the gene, it can’t cause the disease anymore,” Heithoff said. “In addition to not being able to serve as a disease, we can use it as a vaccine that is without side effects.”
The vaccine was tested using mice in Mahan and Low’s lab and should be available to the public in the next 3-5 years, Mahan said.
Though the research was initially conducted entirely on campus, the scientists founded a company, Remedyne, when their work began to bear fruit.
The precise connection between the vaccine and the protection against multiple strains has not been identified, but Sinsheimer said the researchers could make some inferences.
“There must be some common antigens in the different strains, and these are expressed when the Dam mutation is employed, and then these antigens are able to produce an immune reaction,” he said. “That reaction will work against whatever strains contain those antigens.”
Mahan said he was able to anticipate a connection between vaccines and the modification of certain genes, though he said the high level of protection it allowed surprised him.
This protection will also outdate older, less efficient ways of dealing with salmonella.
“People have talked about irradiating the chickens as a way to get rid of the salmonella and I think that’s a reasonable approach, but I think that our vaccine will make that unnecessary,” Heithoff said.
Researchers are already looking into other uses for the Dam technology, particularly with cancer and E. coli bacteria.
“[Researchers] have used a bacterial strain that’s been genetically modified to prompt the immune system to specifically attack cancer cells,” Julio said.