The Secret To A Universal Blood Type May Rest With Humble Gut Bacteria

Damn that elusive O-negative blood type. NatchaS/Shutterstock

Robin Andrews 22 Aug 2018, 14:46

A team from the University of British Columbia (UBC) caused quite the stir this week at one of the American Chemical Society’s (ACS) annual gatherings in Boston. As spotted by BBC News, it appears that they’ve found an efficient way to use gut bacteria enzymes to change blood types from one to the other.

This ability has been known about for some time. As an example, the very same team announced back in 2015 that enzymes used by Streptococcus pneumoniae could manage this.

The UBC team, however, have seemingly narrowed down the most effective method for achieving this feat to date. In order to understand how it works, though, here’s a quick recap of how blood groups come about.

Blood types come in four main groups: A, B, AB, and O. Bequeathed to you by your inherited genes, they are determined by the presence of proteins named antigens on the surface of your red blood cells.

These antigens come in a variety of forms. Per the UK’s National Health Service (NHS), blood group A features A-type antigens on the red blood cells, along with anti-B antibodies – the handcuffs that pin down and identify threats to the immune system – within the plasma.

Blood group B has the opposite antigen and antidote situation to group A. Those with AB blood have both A and B antigens, but no antibodies in the plasma. Those in blood group O have anti-A and anti-B antibodies in the plasma, but no A or B antigens on their red blood cells.

Each of these types can also be positive or negative for another antigen, known as the Rhesus factor. That means there are eight distinct blood types.

You can’t mix blood types up. If you do so, the various antibodies will recognize their requisite antigens as threats and try to take each other out. That’s why O blood type donations are so important: as their red blood cells contain no A or B antigens, the antibodies of other groups won’t attack them.

O-negative is the most valuable blood type, as its lack of all of these antigens means that it’s safe from the patient’s immune system. It can be given to most people safely.

Sadly, this type is fairly rare. In the US, only 7 percent of people have it. O-positive, at 38 percent, is by far the most common. Although blood type distributions vary across ethnic groups, this is roughly the arrangement you’ll see across the world. That means O-negative blood packs are often in short supply.

Scientists have reasoned that if you could clip away the antigens on red blood cells, then you may be able to turn one person’s incompatible blood type into another that could save someone's life. Enzymes from the gut have been shown to do this in the past, but the UBC team have announced they have identified enzymes that can do this far better than any others.

Instead of looking for such enzymes by going through individual bacterial species one by one, they sampled the collective genome of all of the organisms from the human gut.

Using this genetic soup, they looked for DNA that specifically encoded for enzymes that could chop away sugar compounds that were chemically similar to those antigens. They succeeded, and found an entire family of enzymes that can turn A or B blood types into O 30 times more efficiently than any others.

This as yet un-peer reviewed work still requires plenty more tests to confirm its efficacy. Clinical trials haven’t even been proposed yet, so you shouldn’t expect universal blood packets to be ubiquitous all of a sudden.

It is, however, an undoubtedly promising development.

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