Norovirus and histo-blood group antigens

Weve all heard of that stupid book/diet that tries to tell you what to eat based on your blood type. Of course thats stupid and just a gimmic to get you to buy hundreds of dollars of crap 'supplements' for your blood-type (oh for Petes sake...).

I totally didnt know this before I read this neat Nature review, but there are actually viruses out there that can use the histo-blood group antigens (A, B, O) as their receptors!


Apparently, Type O are the most susceptible to some kinds of norovirus infection, and Type B are the least.

Now, this might be something other kids learned in high school or something, but I dont know jack about blood groups. *shrug* So I was like "WTF! If norovirus uses blood-group antigens as a receptor, how can Type O (lacks A and B) be more susceptible??"

Like I said, this was totally news to me: 'Type O' doesnt mean your red blood cells are 'naked', it just means that there is a standard sugar, 'O'. Some people have an enzyme that makes the standard 'O' a little different with an 'A' modification. Some people have an enzyme that makes a 'B' modification. Some people have both. But if you dont have either, you keep the standard sugar, 'O'. It doesnt mean you lack the sugar entirely.

This makes perfect sense, in retrospect, but its not something I have thought about before!

So, noroviruses like the 'basic' antigens for receptors, not so much the modified ones.

Got it!

But then I was all like "WTF! How can your blood type (glycans on red blood cells) have an impact on a virus that infects your gut??"
News to me: Some people express these antigens on the epithelial cells in their mouths/GI tract. Theyre called 'secretors'.

So even if you are Type O (more susceptible), if you are a non-secretor, you are actually less susceptible!

And this is just super good news for those of you today who are Type B non-secretor. You dont get as many opportunities to poop your guts out as the rest of us. LOL! I dunno how/where/if you can be tested to see if youre a secretor or not, though.

(SUPER AWESOME online textbook that taught me this stuff: 'Essentials of Glycobiology')

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When we learned blood types in high school, I came away thinking type-O meant naked red blood cells too.

Does that mean for the purposes of this virus people with the genotype BO and AO (which we're taught are equivalent to genotypes BB and AA respectively) would also be more susceptible, since half of the sugars on their cells would be the generic O-type that the virus likes?

Abbie, you have a few errors in the above post. The 'O' blood type is, in fact, a "naked" RBC - sort of. The H-antigen (what the ABO group is) on the RBC can be thought of having 2 main glycosylation structure; a "core" structure to which a "side chain" can be added.

People with an 'O' blood type only make the "core" portion, and do not add a "side chain". 'A' blood types add a sugar side-chain onto the core, specifically N-Acetylgalactosamine. 'B' blood types attach a different sugar as the "side chain" - specifically D-galactose.

The genetics that lead to ABO typing is actually a single gene which codes for a protein that adds the side chain. The A/B alleles simply use different sugars as their substrate (I think the primary mutation is in the catalytic domain, but my memory is vague). The O variant is a frame-shift mutant, and people with this mutation don't even express the protein.

As for the viral end of things, that's old news. Many viruses bind to carbohydrate moieties that differ among ABO blood types (influenza being one of them), as do some bacteria. Its though that the ABO system may have evolved either in response to specific pathogens, or alternatively, as a form of non-specific immunity against enveloped viruses (which tend to varry ABO-modified proteins with them when they bud).

Bitchin new banner ERV. Did you make it?

Hey, the banner is up! I enjoyed making the ERV banner almost as much as reading your blog.

By Mind Over Splatter (not verified) on 11 Mar 2010 #permalink

Oh, good, it wasn't just me. Great to finally get to see the banner!

So is this why (the carbohydrates-connection) we are not hungry when we are ill?

My post-doc advisor was a Type B non-secretor, and whenever we played a prank on him (which was often), he'd threaten to contaminate our journal club food with norovirus!

Something you might find interesting: the new, more virulent strain I was talking about in my post has actually lost much of it's specificity towards blood-groups and is affecting them all equally. Which is another reason why it's more dangerous than previous strains :)

1) Now I really wanna home secretor test kit! Or even a lab one, I can make that work.
2) LOVE the banner!

Another thing that you may not have learned in school is that the ABO antigens are glycolipids, not proteins. See here for the structures.

By Albatrossity (not verified) on 12 Mar 2010 #permalink

@14 and @15: I like the blue mask for ERV's character in this and that fact she whacks Matt with a centrifuge though she is not one to ambush (from behind); would have been even better if she'd just mussed his hair (with EtBr or Formalin... maybe that's a little too violent though..)

By not the ervinator (not verified) on 13 Mar 2010 #permalink

Hi Lab Rat, can you point me at the paper that reports "lost much of it's specificity towards blood-groups and is affecting them all equally". Will help me in my job. Thanks Mandy