Bacterium carrying a cloned Bt-gene could help millions infected with roundworms

Intestinal nematodes and roundworms infect more than one billion people worldwide. These parasites lead to malnutrition and developmental problems, especially in children. Unfortunately, resistance to the existing drug treatment is increasing. 

Now a team of researchers has successfully inserted the gene for a naturally-occurring, insecticidal protein called Bt into a harmless bacterium. This could then be incorporated into dairy products, or used as a probiotic to deliver the protein to the intestines of people afflicted with roundworms.

The Bt crystal protein is used in organic insecticidal sprays and has been produced in genetically modified plants as a safe pesticide to kill insects that eat those plants. Bt can also kill some nematodes. In the study, the investigators used the gene for one type of the insecticidal protein, which is naturally produced by the soil bacterium, Bacillus thuringiensis.

The investigators spliced the gene into a plasmid, a short, circular piece of DNA which can replicate independently of the genome in most bacteria. The investigators then inserted the plasmid into Lactococcus lactis, a bacterium that ferments milk to produce yogurt, cheese, and buttermilk.

In the next step, the investigators found that this genetically modified microbe could inhibit the common laboratory roundworm, C. elegans, via the cloned and expressed Bt protein. This method of treating roundworm infections orally with food grade bacteria could be very inexpensive, said Klaenhammer. This would be a huge advantage, because roundworms infect millions of people in impoverished nations.