I've Built Up an Immunity- The Science of Venom Resistance
“You say the key is in one of these holes?” Kai asked, pointing to the openings at the edges of the runes.”
“Aye,” said the witch with the wicked smile. “You must use your wits to remove the key, lest you feel the vipers’ venom seep into your veins.”
“Listen, I love the alliteration. But this seems a little… I don’t know. Simple? Just reach in and grab it. I feel like there should be more to it than that.”
The witch scowled. Of course the so-called hero had to be the dunce of the group. “The point is to not get bitten. Ergo, don’t stick your hand in the hole. You must first deduce which is—Hey!”
Kai proceeded to shove his hands into the nearest hole. He pulled out his hand with a viper stuck into his palm. “Nope. Not this one.” He shoved his hand into the next hole. A snake hissed before sinking its teeth into his wrist. “Nope.”
“W-what are you doing?! You’re going to die before you find the key!”
“Nope, nope, nope… Aha! That feels like some metal!”
The witch gaped. “You have got to be the stupidest hero I’ve ever had go through my challenges.”
Kai grinned and held up the key with his swelling hands. “I built up an immunity to viper venom years ago. Did it on a dare, but it’s come in handy more than once.”
“Again, my statement still stands.”
Hello all of you lovely people! I have some housekeeping things before we continue:
Quick update for my readers who may not follow me in other corners of the internet; I’ve been taking a break after finishing my PhD and moving out of Utah! I’ve been house sitting, but recently found an apartment where I can set up my science communication shop. The only problem is that the apartment has not had internet until veeeeeery recently… which has made uploading this post impossible until today. Hence why there’s really no images in this blog post!
I know that there’s been little action on the blog this year. Please know that the lack of activity on this blog is not that this blog is dead, it’s just PhD (and chaotic post-grad school) life!
Also, due to the lack of internet while writing this post, I’m going to be citing my 6+ years of immunology training more than I’m citing papers. I may come back and add them later, as I prefer to provide citation for my claims, but this is one of those “trust me, I’m an academic doctor” moments.
Onward!
During my final months of my PhD, as I was drowning in thesis writing and editing, I fell in love with the animated series, The Apothecary Diaries. It’s a story set in fictional ancient China that follows a young woman specializing in medicine and, of course, poison. There’s a shocking amount of real-world science integral to the show’s plot, and it made this science communicator/blogger so, so happy. One of the most pivotal plot points is that the main character, Mao Mao, has exposed herself to so many poisons that she’s now become immune to many of them.
Now, I originally was going to write up a blog post covering this, as this is a trait that shows up in fantasy quite often, and in real world folklore. Exposing oneself to toxins in tiny amounts to develop resistance is called mithridatism, named after the king who reportedly ingested small doses of poisons to protect himself from assassinations. Think Wesley and the Iocane powder from The Princess Bride. As fantastical as it may seem, someone exposing themselves to venoms to become immune (called “self-immunization”) has a fair bit of real-world science in my field of study!
Imagine my shock, however, when I am scouring the internet during my thesis writing brakes and came across multiple Spring 2025 articles describing how an American man had become “immune to snake venom” through self-immunization. It’s not a headline you expect to see in the real world.
What Happened with the Man and The Snakes?
While many news sites have covered this story, this article has been my favorite that I’ve found so far. It not only covers the very basic science that’s behind this phenomenon, but it also has a fantastic little glossary at the bottom for reference.
Long story short, this man decided to inject snake venom into his body (whether via bites or injections, I’m not sure, but it was probably a combination of the two). Now his body produces antibodies that can neutralize many snake venoms.
He allowed scientists in San Francisco to test the antibodies circulating in his blood. The scientists wanted to see if the man produced any antibodies that could neutralize more than one snake venom, which could help make antivenoms more effective and potent. In fact, they wanted to see if his antibodies could protect against an entire class of snake venom (which, as we’ll discuss later, would be an amazing biological feat).
The Disclaimer
PLEASE do not, do not, do not, do not, do not, do not, do not, do not, do not, do not, do not, do not, do not, do not, do not, do not, DO NOT self-immunize to snake venom. Or any poison. This is dumb. Even the man who gained this “venom immunity” has even admitted that this was a bad idea.
As stated in my zombie rant back in my Virus Part 3, being bitten by any animal is considered a really really really bad idea. Please don’t do this on purpose just because some rich guy managed to survive this horrifyingly bad hobby.
How We Get Antibodies Nowadays
I work with antibodies from all sorts of animals (Or I did before I graduated from my PhD this summer). We use antibodies from goats, rats, and mice. I know some labs use antibodies from horses. These antibodies are used in countless experiments; they can be used to label cells, to block molecules from binding, to locate molecules, to activate cells, to even recognize other antibodies, and so much more.
The reason why we use animals is because it’s extremely illegal and unethical to inject people with venom.
Anyhow, back to the biology! Producing snake venom neutralizing antibodies will sound a lot like what vaccines do.
That’s because it is. This biology is what we’re “hijacking” when we’re given vaccines. The difference is that a vaccine is meant to be annoying, but extremely safe and extremely non-lethal, while the virus (or in this case, venom), is meant to be lethal.
The components of venom kick off an immune response the second they get under your skin. The molecules in venom can be recognized by T-cells, which in turn activate B-cells. The B-cells will then start producing antibodies that target and ideally neutralize that molecule.
Simple, right? Step 1, step 2, step 3.
Except this explanation leaves out the more complicated parts of this response, one of which being that there isn’t one molecule to choose from within venom. Snakes produce up to 70 unique protein toxins (deadly molecules), and that’s not accounting for the variation of these complicated molecules between snakes within the same species.
Let’s do some back of the envelope calculations, which may hurt some of my fellow immunologists, as this is a massive oversimplification of what happens. We can estimate that your body may be trying to make up to 70 antibodies per snake venom, assuming the body makes 1 antibody per venom component (this is the biological equivalent of the “assume a perfect sphere” from physics problems). And that’s not considering that each snake’s venom has slight molecular variations in them, adding to the variation of antibodies you can create. AND it doesn’t take into that some produced antibodies are more effective than others.
(Again, this is meant to illustrate how much diversity there is, not be the most accurate calculations! No one quote me on these numbers!)
This is all assuming the host doesn’t die before the antibodies can be produced. Remember, antibodies are only produced in the body during the second exposure, not the first. This is why vaccines are effective preventative care, tricking your body into making effective antibodies before your first real encounter with a disease. This is also why we produce anti-venom antibodies in other animals and not humans.
So to have a human with effective antibodies against so many snake venoms is incredibly impressive!
Venom in Humans?
Fundamentally, the same process occurs where your body recognizes the venom particles as foreign enemies, your T-cells go and activate B-cells, which then produce antibodies to said particles, and voilà! You have your anti-venom antibodies!
Is this the way to go? NO.
I’m looking at the provided immunization records of the self-immunized man provided in the aforementioned paper, and oh goodness, he immunized himself to cobras, taipans, rattlesnakes, mambas, and water cobras. And if I’m reading the graph right, he self-immunized (aka “let them bite him”) at least 700 times, if not 800.
Sidenote: I used to work with a snake venom component called “convulxin.” This is a molecule that doesn’t target your nerves, it makes your blood clot. It’s not the main component of snake venoms, but it is one that I know intimately. So, when I hear those numbers, I hear that he tried to die from a stroke at least 700 times.
But back to the science paper!
It turns out that 700 injections results in antibodies that can block components from multiple venoms! This is the new and exciting portion of the paper, as antibodies effectively blocking more than one venom is unheard of (as I understand it). They call these antibodies “broad reactivity” or “broadly neutralizing.” What’s exciting is that the scientists were able to mix two of these broadly neutralizing antibodies along with a small-molecule inhibitor into a cocktail that was able to effectively protect mice against 19 different snake venoms.
It wasn’t perfect, as not all the mice survived the injections after receiving the cocktail, but the survival rate was much, much higher than the mice that recieved no cocktail injections (which had a survival rate of nearly 0% for many of the injections, aka “they all died from venom”).
Funny enough, in every piece of fiction that I’ve run across the “poison/venom” immunity trope, the characters always state (or heavily implies) that they’ve been microdosing for over a decade. With Apothecary Diaries’ Mao Mao, she probably puts the IRL self-immunized man to shame with how many snake bites she’s exposed herself too. Therefore, it’s absolutely plausible for these characters to be safely immune to not just their venom of choice, but to even venoms they’ve never encountered, as hinted in the paper.
Takeaways?
There are many takeaways from this:
1) Never “self-immunize” against snakes. Leave that to the funny fictional characters. 2) We love vaccines, as they help us make protective antibodies without putting our lives at risk. 3) A fictional character continuously exposing themselves to (and surviving) a wide variety of venoms would allow them to make effective neutralizing antibodies to the venom. The “I built up an immunity” is a realistic, though not advisable, character trait. 4) Scientists are working on antivenoms that can be used for patients immediately without having to identify the snake after the bite, removing the guesswork in patient treatment and improving patient care.
I know there may be readers who will want to give credit to the snake bite man and point out that he has provided crucial samples. And to that I say: scientists should never look a gift horse in the mouth. This is maybe a research chance of a lifetime.
That said, I still would tell my readers to never be the “gift horse” in these kinds of scientific breakthroughs. Anyhow, that’s all I have! Perhaps we will dive into more “Apothecary Diaries” inspired posts, as 90% of what that anime/manga covers is scientifically accurate… and then there’s the 10% that relies on fudging the science. Let me know if you’d be interested in a mini blog post series like that!