While poop jokes are all in good fun here in the US (and in other developed parts of the world), diarrhea really isnt all that funny for most of the planet. Dehydration due to diarrhea is the second leading cause of death for babies, worldwide (it was #1 until we started aggressive education/re-hydration efforts). Hundreds of thousands of people die from cholera and enterotoxigenic E. coli (ETEC) infection every year.
Thats not funny
So scientists have been working really hard to create vaccines to cholera and ETEC, and a group of folks have figured out a really cool strategy– genetically modify rice to express part of the cholera toxin. When someone eats the vaccine rice, their immune system gets a cheat-sheet for what the real toxin will look like. Their body starts secreting IgA, antibodies that recognize the toxin, in their mouth/tears/digestive tract/breast milk. If that person is exposed to real cholera, they already have antibodies around to neutralize the toxin, thus are able to prevent or limit the extent of that infection!
BONUS: If the person who gets the vaccine is a breast-feeding mom, these beneficial anti-cholera-toxin IgA antibodies are passed down to their babies via breast milk, thus also protect their babies from cholera!
BONUS BONUS: This plant-based vaccine strategy is also beneficial because it requires no sterile needles, no freezing/refrigeration, and the vaccine would have a ridiculous shelf-life of at least three years.
What have the scientists named this awesome GMO-rice-product?
*gag*… *gaaaag* Oh gross… Christ… LOL! I know its supposed to be ‘muco’ for ‘mucosal immunity’, but all I think is ‘mucus’, and I dont want to eat that… uuuuugh… LOL!
Ignoring the gross name, theyve put a lot of effort into this vaccine– here is just their latest paper, ‘proving’ that the secreted anti-cholera-toxin IgA antibodies are why this vaccine works:
These studies were done in mice. Why did the researchers go back to mice, even though theyve got a non-human primate study under their belt? Well, one of the reasons is that they wanted to establish exactly why their vaccine works. They thought it was because of anti-cholera-toxin IgA being secreted into the intestines, but they wanted to know for sure:
… despite the generally accepted concept that mucosal vaccine induces antigen-specific secretory IgA (SIgA) production, thus providing a first line of specific defense against mucosal infectious diseases, there is no direct evidence that the CTB-specific SIgA production induced by MucoRice-CTB is essential for protection against CT-induced diarrhea.
We use lots of mice in research that are essentially clones of one another. This makes it a little easier to genetically modify them to have certain deficiencies in pathways we want to study. We cant do this with non-human primates. So these folks generated mice that can make IgA, but they cant secrete it. So the mice still have lots of IgA antibodies floating around in their bloodstream, but they never show up in their tears/breast milk/etc.
If you need the antibodies to be secreted for this vaccine to work, then these non-secretor mice will get sick.
If it doesnt really matter whether antibodies are secreted (lets say IgG antibodies can do all the work on their own), then these non-secretor mice will still be protected.
Heres what happened:
The non-secretor mice were not protected against the effects of cholera or E. coli toxin (which has a similar structure to the cholera toxin, the antibodies are cross-reactive), even though they got the vaccine. The mice that could secrete IgA normally were protected. The non-secretor mice still made a ton of anti-cholera IgA, but since it couldnt get out into their intestines, it didnt do them any good.
Secondly, the mice needed to get this vaccine orally to get a really nice IgA response, thus the best protection. When the vaccine was injected instead of eaten, even the normal mice still got sick (though to a lesser degree than the mice who got no vaccine).
Thirdly, immunity against cholera and E. coli toxins lasted at least 6 months, and responded well to boosters (their immune systems remembered what they were seeing– very important). While six months doesnt seem very long to you and me, thats like, a third (or more) of the lifespan of a mouse. And even if it is only 6 months in humans too, this vaccine would be so cheap and easy to store, boosters wouldnt really be that big of an issue– especially in outbreak scenarios (just give a booster to everyone), or even just those of us in the US who want protection when we go overseas for vacations (who gets to go on vacation for over 6 months at a time??).
Very cool research with green vaccines. GMO plants and vaccines might literally save your butt in the near future.