A1: Microbes in the news Modified Salmonella targets tumors


This article explains how genetically modified Salmonella targets tumor cells and makes the immune system aggressive towards cancer cells. There’s no arguing that cancer is very aggressive and sticks around because the immune system is unable to recognize these foreign invaders. This article explains how scientist have modified Salmonella bacteria to generate an immune response against human colon cancer cells which have been implanted in mice. The results have been favorable because some of the tumors have shrunk and it has also prevented metastasizing. Scientist modified Salmonella typhimurium so that it secretes the protein FlaB from another bacterium called Vibrio. The experiment was carried out by injecting the Salmonella into 20 mice that had human colon cancers and noticed that after three days the mice had cleared most of the bacteria but the tumorous tissue in their colons was full of Salmonella. A few days later the tumors were then undetectable in 11 out of the 20 mice.

 Connections: We have discussed in class some of the ways that the idea to use bacteria to fight diseases have been around for a while. Salmonella is usually associate with being “bad’, different types of the salmonella bacteria can cause illnesses in humans. Salmonella thrives in environments with no oxygen and tumors also gave no oxygen so it has a lot of dead cells the bacteria can feed on. We have also been discussing bacterial structures; a protein in the Vibrio flagellum (a tail used for swimming) caused a strong response from immune cells (FlaB). The Salmonella was then altered so that it would secrete the protein.   I found that very interesting because they took something from the Vibrio bacterium and altered the Salmonellas function to secrete this protein to fight cancer.

Critical analysis: I really enjoyed this article, it was short and easy to comprehend. I know salmonella is a bacterium found in the intestines of humans and animals. But I also know it can be bad if live salmonella bacteria enter the body which can cause illness.   I always thought of Salmonella as being this bad thing that we careful of. I found it very fascinating that Salmonella was modified to targets cancers cells and the results were great based on the mice.

Questions: Would modified Salmonella that secretes FlaB work on all types of cancers? How advanced can the cancer be? What modifications to it are necessary so that it safe for humans and can be used as anticancer therapy? Will it work on other types of cancer?


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