When SARS-CoV-2, the virus that causes COVID-19, first appeared in 2019, docs and scientists started to note a curious affiliation: Sufferers with blood sort A appeared to have an elevated danger of an infection. This was not wholly stunning — blood sort is linked to a bunch of illness states, and 20 years earlier, throughout the SARS epidemic, comparable associations have been seen. However the virus infects our lungs, so what does blood must do with it?
A brand new examine, printed within the journal Blood on June 27, describes a possible mechanism, offering proof that SARS-CoV-2 preferentially binds to the floor proteins related to blood group A. It appears this blood sort would possibly improve the flexibility for the virus to enter a cell.
A person’s blood cells are principally the identical and so they have the identical operate, however they’re lined in proteins that give rise to the totally different blood sorts: A, B, AB, O and the constructive and unfavorable sorts related to Rhesus issue, or Rh. These tiny variations play a task in our danger for sure well being circumstances — together with, for example, how inclined we may be to coronary heart illness or an infection — as a result of the proteins aren’t simply expressed on blood cells however throughout totally different cells within the physique. It was cheap to suppose the chance of an infection by SARS-CoV-2 could possibly be linked to blood sort.
Quite a few research investigated the hyperlink between blood sort and COVID-19 danger, relationship again to the earliest days of the pandemic. In Could 2020, Chinese language researchers explored the affiliation between blood teams and danger of COVID-19 and located that individuals with blood group A have been contaminated greater than wholesome controls, whereas blood group O was decrease. In October 2020, a examine printed in Blood Advances, and one other printed in The New England Journal of Drugs discovered comparable outcomes.
Although the COVID-19 public well being emergency was declared over within the US on Could 11, the virus nonetheless circulates worldwide. In keeping with the World Well being Group, because the begin of the pandemic nearly 7 million individuals have misplaced their lives. About one in three sufferers battle with lengthy COVID, lingering results from the illness that may end up in muscle weak spot or cognitive issues. And lately, a brand new, extremely mutated variant often known as BA.2.86 has scientists on excessive alert.
COVID and spike proteins
The observational research from 2020 offered proof that blood group A was related to COVID-19 an infection whereas blood group O was considerably protecting. Nevertheless, a handful of research steered this would possibly simply be a spurious end result based mostly on the affected person teams studied, and a mechanism that would give rise to this relationship was elusive.
The newest examine offers one, and it is all to do with the spike protein.
To contaminate a cell, SARS-CoV-2 makes use of its spike protein to bind to a protein on the floor of a cell, often known as ACE2. In a lock-and-key situation, the spike protein’s “receptor binding area,” or RBD, acts as a key, recognizing the lock of ACE2. This permits the virus to sneak by way of the cell membrane and start replicating. A wide range of totally different proteins are concerned on this course of, and earlier than unlocking entry by way of the primary lock of ACE2, the virus would possibly strive just a few totally different keyholes. It seems the protein related to blood sort A is simply the fitting measurement to snag the virus.
“This interplay seems to make the blood group A cells extra ‘sticky’ for the spike protein and subsequently the SARS-CoV-2 virus, which in the end enhances its capability to interact ACE2 and infect cells,” says Sean Stowell, affiliate professor of pathology at Harvard Medical College and writer of the brand new examine.
Stowell and his colleagues have been capable of illuminate this mechanism by genetically engineering hamster cells to specific each ACE2 and quite a lot of totally different blood group antigens together with group A and group O. “We engineered cells to specific the identical ranges of ACE2 and subsequently solely differ within the A or O blood group standing,” notes Stowell. The researchers then added a pressure of SARS-CoV-2 — both the unique Wuhan pressure, the delta variant or the omicron variant — and assessed the extent of an infection of the cells.
They discovered that, in all strains, the cells with blood group A proteins confirmed a lot greater ranges of an infection. As well as, the omicron variant confirmed the best selectivity for blood group A people. To substantiate the impact they have been seeing, researchers additionally used one other protein to dam blood group A binding by the virus. When blood group A was blocked, there have been no variations in an infection between the group A and group O blood sorts.
“This direct interplay with blood group A could account for the epidemiological knowledge all through the pandemic demonstrating that blood group A people usually tend to get contaminated with SARS-CoV-2 than blood group O people,” says Stowell.
You have obtained blood sort A. What it is best to know
Three years on from the start of the pandemic, we’re nonetheless studying precisely how SARS-CoV-2 grew to become such a devastating microscopic adversary. Our blood sorts make us barely totally different, however they don’t seem to be the one danger issue.
For those who’re one of many 30% with blood sort A, the outcomes could appear a little bit regarding. “On common, every part else being equal, people who find themselves blood group A could also be 20% extra more likely to turn out to be contaminated than blood group O,” explains Stowell. Nevertheless, he says, it is not attainable to at present assess the chance of an infection, as a result of COVID-19 danger is said to various variables together with age, weight, ACE2 ranges, way of life and different underlying medical circumstances.
Alternatively, it would look like that is constructive information for individuals with blood sort O blood, however it’s necessary to notice this blood group does not make you proof against SARS-CoV-2. You’ll be able to nonetheless be contaminated.
Getting contaminated can also be associated to the bodily actuality of being near an contaminated particular person for lengthy intervals of time. As a result of SARS-CoV-2 travels by way of air, being in well-ventilated areas or outdoor and sporting a masks lowers the chance of an infection. Vaccinating your self in opposition to the virus additionally offers the easiest way to cut back the chance of an infection and, importantly, of extreme problems from the illness, like hospitalization and loss of life. These precautions must be taken no matter your blood group.