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Type A Blood Converted To Universal Donor Blood With Help From Bacterial Enzyme

An anonymous reader quotes a report from Science Magazine: For a transfusion to be successful, the patient and donor blood types must be compatible. Now, researchers analyzing bacteria in the human gut have discovered that microbes there produce two enzymes that can convert the common type A into a more universally accepted type. If the process pans out, blood specialists suggest it could revolutionize blood donation and transfusion. To up the supply of universal blood, scientists have tried transforming the second most common blood, type A, by removing its “A-defining” antigens. But they’ve met with limited success, as the known enzymes that can strip the red blood cell of the offending sugars aren’t efficient enough to do the job economically.

After 4 years of trying to improve on those enzymes, a team led by Stephen Withers, a chemical biologist at the University of British Columbia (UBC) in Vancouver, Canada, decided to look for a better one among human gut bacteria. Some of these microbes latch onto the gut wall, where they “eat” the sugar-protein combos called mucins that line it. Mucins’ sugars are similar to the type-defining ones on red blood cells. So UBC postdoc Peter Rahfeld collected a human stool sample and isolated its DNA, which in theory would include genes that encode the bacterial enzymes that digest mucins. Chopping this DNA up and loading different pieces into copies of the commonly used lab bacterium Escherichia coli, the researchers monitored whether any of the microbes subsequently produced proteins with the ability to remove A-defining sugars. At first, they didn’t see anything promising. But when they tested two of the resulting enzymes at once — adding them to substances that would glow if the sugars were removed — the sugars came right off. The enzymes also worked their magic in human blood. Tiny amounts added to a unit of type A blood could get rid of the offending sugars, they found. The findings have been reported today in the journal Nature Microbiology.


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