June 16, 2009 Scientists have used genetic engineering to tame one of the most deadly food poisoning microbes and turn it into a potential new way of giving patients medicine and vaccines in pills rather than injections.
Colin Pouton and colleagues note that patients by far prefer pills and capsules to the discomfort and inconvenience of injections. But many medicines and vaccines cannot be given by mouth because they would be destroyed by stomach acid without being absorbed into the bloodstream. One promising approach is to use live bacteria, which can survive those harsh conditions and pass easily from the GI tract into the blood.
The scientists describe development of a new strain of Listeria monocytogenes, bacteria that normally cause food poisoning, but which have been genetically engineered to be harmless. Instead of causing disease, the new microbes can be loaded with medicine or vaccine, and deliver that beneficial cargo by "infecting" cells.
After entering cells, the bacteria burst and die, leading to Pouton's term "suicidal strain" for the microbes. The researchers demonstrated that engineered bacteria containing a test protein could successfully penetrate a group of intestinal cells grown in the lab and deliver the protein inside the cells while leaving the cells unharmed. The findings suggest that the approach could potentially work in humans, the researchers say.
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- Kuo et al. A Stably Engineered, Suicidal Strain of Listeria monocytogenes Delivers Protein and/or DNA to Fully Differentiated Intestinal Epithelial Monolayers. Molecular Pharmaceutics, 2009; 090526130050086 DOI: 10.1021/mp800153u
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