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A pair of human intestinal microbiome enzymes can convert type A red blood cells to O-type red blood cells. These enzymes could, with subsequent development, contribute to the manufacture of a universal blood that could be transfused at a minimum. any patient, even if his blood group is unknown.
Type A red blood cells have carbohydrates with an N-acetyl galactosamine (GalNAc) at the ends, and people with other blood groups have an immune reaction to this group, so that type A blood can not not be used universally. Type O red blood cells do not have GalNAc or galactose type B blood. This type of blood can therefore be used in all patients. Previously identified enzymes can convert type A blood to type O, but large amounts are needed.
Stephen G. Withers and colleagues at the University of British Columbia have identified new, more efficient enzymes by performing metagenomic analyzes of bacteria in human faeces (Nat. Microbiol. 2019, DOI: 10.1038 / s41564-019-0469-7). They transferred the DNA of non-culturable bacteria to Escherichia coli and tracked for microbes that could convert type A to type O.
The most efficient E. coli has produced several microbiome enzymes. Individually, these enzymes could not convert. Using the enzymes in various combinations, the researchers found a couple that performed the desired reaction with great efficiency. A galNAc deacetylase converts the acetamide group of the carbohydrate into an amine, forming an intermediate of galactosamine. The second enzyme eliminates galactosamine, giving type O antigen. Both enzymes come from the intestinal bacteria Flavonifractor plautii.
The enzymes are effective and work in whole blood, without additional isolation stages, at physiological pH, says Dana Devine, chief scientist at Canadian Blood Services, who did not participate in the work. "Of course, the jury is not aware until certain studies show that Group O red blood cells prepared with this enzyme cocktail function properly after transfusion and do not cause unexpected reactions in recipients", she warned.
That's next. Withers says his team is in discussions with Canadian Blood Services and other agencies to conduct safety tests.
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