Dr. Catharine Bosio — The Weird and Deadly Francisella Tularensis Bacterium

Monday, November 18, 2019

Our houses, workplaces, and even the air we breathe are teeming with microbes, some of which can cause severe illness. Dr. Catharine Bosio is an immunologist studying how airborne pathogens infect and alter cells in the lungs. Her work focuses in particular on a bacterium called Francisella tularensis, which causes a life-threatening disease called tularemia and has the unique ability to change how energy-producing mitochondria function in immune cells. Dr. Bosio's experiments with these deadly bacteria could lead to more effective ways to diagnose and treat tularemia and other infectious diseases.  

Catharine Bosio, Ph.D., is a Senior Investigator in the Immunity to Pulmonary Pathogens Section at the NIH's National Institute of Allergy and Infectious Diseases (NIAID). Learn more about Dr. Bosio and her research at https://irp.nih.gov/pi/catharine-bosio

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Transcript

>> We're at the Rocky Mountain Labs in Hamilton, Montana. It's part of the National Institutes of Health. And my section is the Immunity to Pulmonary Pathogens Section, where we primarily study Francisella tularensis, which is a causative agent for tularemia, a really nasty infection that nobody wants to get.

>> What do you do for fun around Hamilton, Montana?

>> I enjoy, you know, being outdoors, hiking. I run quite a bit. Not as much as I'd like to. But that, and I have a senior in high school, so I spend a lot of time with him. He's a soccer player. So, I get roped into managing soccer teams often. So, that's, but, yeah, I mean, Hamilton is a great place if you like to ski, hike, camp, you know, things like that, so, we try to get out there as much as we can, but not as often as we'd like.

>> Yeah, and you've got great coffee shops.

>> We do have great coffee shops. The coffee, I don't want to shout out to anybody, because I don't want to get in trouble.

>> Oh, yeah, for promoting something.

>> Right, exactly. See, government mind at work.

>> Yep, all coffee shops are equal.

>> All coffee shops are equal in Hamilton. They're all awesome. Go to any one of them, it will be great.

>> But I have been going to one repeatedly.

>> There you go.

>> I haven't gone to them all yet.

>> Yeah, very good. Very good. We have, for such a small town, we have a lot to offer, which is pretty cool. So, we have a wonderful community here. And it's--we're very, very, very lucky that, you know, we're surrounded by such a supportive city and a supportive county. And the lab, you know, tries to find ways to, you know, give back and educate. And, you know, it's a nice balance, I think, you know, and so there are some things that you miss, you know, and there's more opportunity sometimes for kids in bigger cities and, you know, things like that. But on the other hand, you know, I know all of my son's teachers. I am 10 minutes away from the school. So, that makes a difference, you know? And I'm not so sure, you know, for him, that he maybe wouldn't have had those opportunities if we were in a bigger place. So, it's kind of, you know, you have to weigh it.

>> Yeah, there's always trade‑offs. But it seems like there's a lot of benefits to living in a place like this.

>> If you're, if you're an outdoors person, this is a really wonderful place to be. And I think the other side of it too is that, again, you're drawing back into working in containment. That can be a fairly intense place. I mean, you saw the amount of preparation that we have to do before we go in, you know, there's very specific SOPs, standard operating procedures, that you have to follow. I mean, you have to be, even sometimes when you don't realize it, aware all of the time. Being able to execute that type of work, and then come out to, you know, this wonderful environment is just, it's a blessing. I mean, it's just, it's so, I've worked in containment all over the country. This is the best. This is the best. So, it's like, I'm not sorry for that at all.

>> I think you said something about that you liked working in containment. What is, what do you like about that?

>> I think for me personally, on a really basic level, I like the organization of it. I like the predictability, and, you know, the planning part of it. It just suits me as an individual. But then as I mentioned before, and I'll tell you a little bit about the bug that we work with, because of the things that I study, working with a truly virulent pathogen, it's just, there's no substitute for it at the end of the day. And it doesn't mean that, you know, working with attenuated strains, or surrogate strains doesn't reveal important things. Of course they do, you know? And yes, there's many things that are very helpful about doing that, that type of work. But having access, and really being able to work with, you know, the fully virulent nasty organism, there's just so much insight that we gain, and really understanding, you know, how it manipulates the immune response, and how it can cause disease in the host, and allows us, I think, in my feeling, to really go after how do we resolve these problems, which you can't always do with an attenuated strain because oftentimes, you know, that interacts with the host a little bit differently, or, you know, it won't, you know, necessarily kill the host, you know, and that can be a problem if you're studying something that will kill you. Anyway, so, the bug that I wound up working on is quite unusual, but it's, I think an interesting way to pose it is sort of think about what we see in popular culture now. So, you know, we've all seen those movies of, you know, this deadly pathogen, and et cetera, et cetera, and it's like, oh, well, this could happen. And so if I started out saying, you know, what if there was a microorganism – I'm not going to say if it's a bacteria or virus, just microorganism – that if you got exposed to 10 or a few of those, there's a 60 to 80% chance you're going to die in about a week? And it doesn't matter if you drink it or you breathe it in or you rub your eye or you have a, you know, you brushed up against something and cut your arm and, you know, is like a scrape if you get in there, and that, for the first part of that week, you didn't even know you were sick, that the organism multiplied en masse before you even felt ill. And by the time you felt ill, the chances of treating you are almost zero. Okay? All right? That sounds like something made up maybe for a TV movie or whatever.

>> A very evil little bug.

>> Yeah, right? That is essentially the organism that I work on. All of those things are true. It's called Francisella tularensis. It was discovered in the early 1900s. It was actually a very, very important infectious organism in terms of settling the west. They found it first in Tulare County, which is where it was first identified.

>> What state is that?

>> California.

>> Okay.

>> And it was, it was a plague‑like illness in ground squirrels. But what happened is that it was making an economic impact because it was so easily disseminated to people. So, people were getting pretty sick. It's also, a lot of people call it rabbit fever because rabbits are an easily infected host in the environment, and people have often, you know, close contact with rabbits. And so at that time, also, rabbits were an important food source. And so you had even more people getting exposed that way. And because the infectious dose is so low that a lot of people getting very, very sick, and a lot of people that were succumbing to infection. And so that was true out here as well. You know, we had serious problems with tularemia in Western Montana. And so one of the first bugs that they studied in addition to Rickettsia was Francisella tularensis.

>> Here at Rocky Mountain Labs?

>> Here at Rocky Mountain Labs, yeah, back in the, back in the 40s and 50s. And so what, unfortunately what people soon realized with this organism, and it's also quite promiscuous. So, this bacterium will infect just about anything. It will--even amoeba. You can find it in amoeba. That's one way that they think it might be spread in water. So, you can find it in reptiles. You can find it in a variety of mammals. It certainly infects people. We're considered more of a dead-end host. The one caveat is that it's not easily transmissible.

>> Between people?

>> Right, exactly, which is quite interesting. There's never been a documented case of someone that has pneumonic tularemia that they first got exposed in the lung, spreading that to another individual. But part of that, as it turns out, is likely how it manipulates the immune response, okay? So, like pneumonic plague blocked us. When people hear about that, a cough, and it spread. That's a lot of information that goes on with that, which enables a bacteria to be easily transmitted. With Francisella, they'll tell you that's not necessarily the case. So, unfortunately, because of all these features, easily transmissible, easily cultured in the lab, so it's not, we don't, for some pathogens, you have to grow it like in a cell line, or something like that, in order to keep it going. Viruses are that way. You just can't grow them in broth. For bacteria, that's often not the case. And that's true for Francisella as well. We can grow it on the agar plates. And we can grow it in broth. It doesn't take long to grow. A few days is all that you need. We work on--we utilize a virulent isolate that a lot of people work on in labs that study Francisella. But it came from a person that was infected a long time ago. So, but the threat is real, you know, and that's, you know, frankly something that's important to understand. But the other element, and it is a small public health threat in the United States. As I mentioned before, there are more cases of tularemia, which is the disease manifestation, than there are of plague in the United States every year. So, we have roughly around, somewhere between two and three hundred cases of tularemia. The last couple of years have been really bad in the Rocky Mountain Front. So, we've seen a lot of cases in New Mexico and Colorado. And some of that might be due to just the ecology. So, it's often transmitted by tick.

>> Oh.

>> That's where a lot of people get exposed to it out in the environment, or their pets got sick, and then they get it from their pets, or they pick up a rabbit carcass. Don't do that. Not with your bare hands, anyway. And so, yeah, it's been, it's been, the last two years have been exceptional in the number of cases that they've had. So, it's not huge. It's not, you know, this is not TB. This is not HIV, right? It's not a huge public health threat. But it is a consistent one. And there's a, you know, always the potential as a threat agent. But what's really unique about this pathogen, and what we particularly find fascinating about it, is its power to manipulate the immune response. So, mostly when they think that they have a bacterial infection, you think, and I know you've talked with Olivia, and think about Salmonella, and that causes a lot of inflammation. You're not happy. Your GI tract is not happy. Bad things are happening. Right? Lots and lots and lots of inflammation. And that's how it drives the infectious process. With Francisella, I do not know of another pathogen that is as good at evading and suppressing the immune response as this particular microorganism.

>> And that's why you don't really know you have it until it's kind of too late?

>> That's right. That's right. So, they've taken radiographs of people that are known to have a pulmonary infection. They know that that's the route that they were infected. Now, and I should preface all of this with at the very end of the disease, there's all kinds of inflammation. But by then, it's too late. And they bring them into the hospital, they do the x‑ray and radiograph. And there's, you know, normally you would expect to see someone that had a fulminant lung infection, you know, there's inflammation, there's, you know, stuff going on there. It doesn't look good. That's not really the case that we see with Francisella. So, it has found a way to infect things like macrophages and dendritic cells. So, it is an intercellular pathogen. Get into the cytosol of those cells, which is even more remarkable. So, if you think of things like tuberculosis, or, you know, there's a couple of other pathogens that people work on here, like Coxiella burnetii – it causes Q fever – those live within a membrane in a cell. So, it's called a vacuole, right? And that's a way for them to sort of protect themselves from all the stuff in the cell that's supposed to say, hey, you don't belong here. Beat it. Francisella doesn't do that. It actually replicates in the cytosol. So, it is potentially exposed to all of those little defense networks that live in the inside of your cells that are supposed to say, that's not me, you know, you should leave now, I'm going to kill you.

>> And they just blend in?

>> Yeah, that's right. And so first they are able to evade the immune response. And there's a number of ways that it does that. And that's part of what my lab studies. And then it's very, very good at suppressing the inflammatory response in ways that are unique in contrast to other pathogens. And so the primary objective of my lab is to identify those mechanisms. How does it evade being detected? How does it suppress the inflammatory response? And then how does that then manipulate the, you know, potential ongoing immune response? The other kind of unfortunate thing about this organism is that most people, you know, if you get exposed to bacterium X, you're going to develop an immune response to bacterium X. And if you get exposed to that pathogen again, you're probably going to be okay because you have a memory immune response. You have adapted. So, you remember that organism and your body says, okay, yeah, I saw that before, we're going to defend it and you won't get sick again. Right? With Francisella, that's not the case. So, with Francisella, you can be infected. Let's say you're a small population of people that recover. Or you did successfully get treated with antibiotics. Two things can happen. So, another way to think about this particular pathogen is that it causes an acute infection, but a chronic disease.

>> Oh, really?

>> Yeah. So, they have cases of people, even from here, a long time ago, that, you know, seemed to resolve the infection. And then six months later, had a recrudescence, which is quite unusual. So, it has to be hiding somewhere. But the other element of it is that you are not fully immune. So, if you become infected, you resolve the infection, you know, a couple of years later, you're out hunting rabbits, didn't learn your lesson the first time, you know, you get exposed again, you can get sick all over again. Now, oftentimes, this may not be as severe, but you still get pretty sick. That's also quite unusual for a pathogen where there's not a lot of strain variability. So, it's not like influenza where the things that decorate the surface change. Right? So, that's why we have to have a new flu vaccine every year. This is--they don't shift like that. And so it is very, very good at manipulating the immune system. And even though we've known about this pathogen for almost 100 years, we know almost nothing about how it does that. And so that's what my lab work is on. And that really comes from my past experience in working with lots of different organisms, but really focusing on the immune response. So, the other element that we sort of tackled is lots of people, when they study microorganisms, they study the proteins, right? And there's a good reason for that. Proteins do a lot of stuff, first of all. But they're also, you know, you have a gene that encodes for the protein. So, if you want to understand how that protein works, you can knock that gene out, or you can make a recombinant organism that expresses that gene. You can make lots of, you know, the protein, et cetera, et cetera. When I started, there were other labs that were working on that. And having a background in mycobacterium, I was like, well, you know, lipids might be important. So, with mycobacteria, it turns out that lipids are really important. Right? It has a big waxy thick coat on it. And they can manipulate the immune response in different ways. So, I was like, well, why don't we look at the lipids that are associated with Francisella? Which, at the time, was a bit of an undertaking. So, I am not a biochemist. I am an infectious disease immunologist. Getting the expertise to learn how to isolate lipids from bacteria was quite a challenge. But we had, Pam Small was, at the time, a special volunteer at the lab, and she had worked on a mycobacterium, so she--mycobacterium lipids. She actually identified an important toxin from, I'm trying to remember the exact species, it's a mycolate. Anyway, so, she was here, and kind of got it started. And as it turns out, the lipids are incredibly important with this organism. They're very weird. They are unlike any other lipids that we find with other, with other bacterial species. But they are pretty good at suppressing the immune response. And so where we've taken that is we're trying to understand how that works with the microorganism. But because they're so good at impairing inflammation, we're trying to use that as a therapeutic strategy for other infectious disease processes. So, for example, when you get a virus infection, almost, you know, every virus infection out there that's acute, one of the problems is you have unconstrained inflammation. And that causes a lot of the disease manifestations that you see in people. And so we had the idea of like, well, maybe these lipids would be good at kind of dampening down that viral inflammation, but not so much that, you know, now the virus can just replicate, you know, and cause more problems. And so collaborating with Sonja Best’s lab upstairs, we were able to use our lipid in a synthetic version that we had generated to show that it has the potential to be a gold mine of novel therapeutics that we could use for any number of disease processes. We also started studying the capsule that's associated with those organisms as bacteria goes. It's kind of a weird capsule, because, of course, everybody looks at Francisella. It's like, that's something that we say in the lab. Like, it's weird. Well, it's Francisella. Of course it's weird. And that, that really, working with that particular sugar or carbohydrate is what really kicked off our interest in metabolism, because we were able to show just that capsular material, separate from the organism, again, doesn't stimulate an immune response. Potently suppressed inflammatory responses. And the way that it did that was manipulating the metabolism of the host cell. It's pretty incredible that just a fairly simple carbohydrate could do that. And so it turns out that that one is pretty important for the disease process of the bacterium. And that's where Forest was mentioning before is like that led us into trying to understand how does the organism and its parts not only manipulate cellular metabolism, but specifically manipulate things like the mitochondria, right? So, the mitochondria is like the powerhouse of the cell. It's where you get all the energy that's produced, mostly through the mitochondria in an efficient manner. And the thing that's also associated with that process is that typically that's sort of where your cells are every day. Right? They're using the mitochondria and they're making the ATP and things are great. When you have a microorganism come in, something like Salmonella, and that interacts with your macrophage, what happens is that you have a shift in cellular metabolism. So, the mitochondria aren't the ones that are making ATP anymore. It's a different chemical process called glycolysis. Okay? Ends up it's not really as efficient, but it's fast. Okay? And a number of years ago now, there were a few groups that were able to show that that shift from sort of mitochondrial‑generated ATP to glycolytic generation of ATP turns out to be really, really, really important for inducing inflammation. Okay? And the long story of, you know, complex metabolites and the circles with the arrows that we all are like, oh, chemistry, oh. I should have paid better attention in my biochemistry class, for sure. And what Francisella does, it gets in there and it prevents that shift. So, it likes to manipulate. What we're finding is that it manipulates the mitochondria to basically, even though the bacterium are replicating very quickly in the cytosol, you know, and they're not detected by the host cell, it's just telling the mitochondria, you just do what you need to do, you know, we're actually going to help you, mitochondria, we're going to make more of you and bigger, you know, mitochondria. So, really you can see that scenario by not letting it go into that state that's necessary for inflammation, it kind of just keeps the cell on an even keel while it's utilizing all the nutrients and replicating very quickly until there's nothing left. And then you get necrosis and it spreads onto the next cell. So, by understanding that--we were talking about antibiotics, right? So, most antibiotics are targeting the pathogen, right? That's how they work, you know, they target the cell wall, or they target a ribosome, you know, it's some internal component. Well, bacteria are really good at saying, no, not today. You know, right? They're like, no. And that's where they talk about Frank and they talk about antibiotic resistance, whether it's with MRSA or, you know, he now works with Klebsiella quite a bit. Our strategy is, well, maybe we can manipulate the host cell. Right? Because the host cell is not going to mutate. And the bacteria aren't expecting that. So, if we can identify these processes that the bacterium absolutely requires in order to successfully infect and replicate and then spread to another cell, if we can disrupt that at the host cell level, we probably are going to limit bacterial replication. And as it turns out, we're correct. So, that's one of the things that Forest is also working on is that he is testing a collection of drugs. And as I said, they're already FDA‑approved. They're safe in people for their effectiveness at limiting tularemia infections. And some of it is like that would be great if we had new drugs to use. But the other side of it too is the proof of principle that this idea of we can, in a controlled way, manipulate host cell metabolism as a mechanism to inhibit infectious disease is just, it's great.

>> Yeah.

>> It's great. Right? And they're like, I don't have to make a new drug. I've got a drug already. And I already know it's safe in people. So, you know, that works out. So, that's sort of the strategy that we've taken in the lab is that we're really interested in understanding this bug, that because it's so virulent, it's sort of unlocking a lot of cellular secrets that we probably wouldn't have been able to understand or identify if we had been working on another organism.

>> What aspect of the host cell are you changing with these compounds that's disrupting bacteria?

>> So, as it turns out for Francisella, what's really important is that it wants to keep the mitochondria functioning. And it also wants to not let glycolysis happen. And so it turns out that some of these drugs will sort of gently break the mitochondrial, you know, the electron transport chain, so it can't function quite as well. And also uplifting glycolysis. So, what we've done is we've done, as Forest said, we've artificially shifted the cell and said, you're not going to use mitochondria. You're going to use more glycolysis. And the bug just has a really hard time with that. It just, like, it doesn't know what to do. It dies. That's what it does. So, it's like, and so we're trying to figure out specifically why that happens. Like, what metabolites are around, you know, and what, you know, how is the microorganism dying in that environment? But that's how, in a general sense, that's how those drugs work that seem to be successful so far.

>> You said there's a few hundred people a year in the U.S. who get infected. And you said people generally don't know they have it until it's too late. So, do those infections, 60% to 80%, result in death?

>> It can, yeah, without intervention. I mean, there are folks that, especially if they're in an area where it's known to be endemic, and when they go to the hospital, you know, and they take a history from the person, it's like, well, there's a pretty good chance you probably have tularemia, so we're just going to treat you with antibiotic right away rather than waiting to specifically diagnose, you know, what's going on there. So, I think that that's one thing that helps quite a bit.

>> So, they might start to have a little bit of symptoms and go to the hospital.

>> Well, so, here's, this is the deal, right, is that, you know, the symptoms of early disease are like any other infection you might have: flu‑like illness, you know, you're tired, you have malaise, you know, achy, fever, so most people don't run off to the ER, you know, for the first day or two that they have that. And so by the time people come to the hospital, they can be pretty sick. And that's the challenge. I mean, that's the challenge of any infectious disease, you know, if you, if someone winds up at the hospital at a point where, let's say, for example, they're septic, which means now you have organisms in your blood, now it's a bad scenario to be in. It's really difficult to effectively treat that. Just because of the number of pathogens there and trying to utilize the antibiotic. And, you know, there's just a number of complications that can happen. And so, you know, in some other places where you might, where people are aware of tularemia, it's endemic there, the hospital is going to know what to do a little bit faster and get you on the right antibiotic too. So, for example, if you came in and they treated you with, if you had tularemia, they treated you with Penicillin, you're not going to do well. Penicillin is not an effective drug against this pathogen. So, that also can complicate things, if you're in an area where they're not familiar with the disease.

>> And, yeah, I think, maybe you said it was 60 to 80% of people will die without treatment.

>> Right.

>> But since there are treatments, 60 to 80% of people aren't dying from this.

>> That's right. That's right. That's right. And so that's, as long as those antibiotics remain effective, yeah, we can usually go in and save people. But, again, they'll get infected again. There's no long‑term immunity against this particular pathogen. So, and that's another mistake people make. They think that once they've had it that they're fine and they might repeat the behavior that wound up getting them infected in the first place. Not so good. So, that's the other challenge that we have with this particular pathogen.

>> Are there any issues with antibiotic resistance with‑‑

>> As far as I know, I don't think there has been a documented sort of wild‑type strain that was found to be antibiotic‑resistant yet. Some of that has to do with there's not that many cases. So, they're not routinely exposed to the things, right? That's how antibiotic resistance happens. The more that the bacterium are exposed to that drug, depending on its target, the higher the chance that they'll find a way to mutate, to sort of deal with that particular insult. So, part of it is that because there's been fewer cases, the organisms that are out there don't get exposed to the drugs that work on a routine basis. But if that were ever to change, that would be a problem, that would be a problem.

>> And you said it doesn't really transfer from people too much, so once they're treated with antibiotics, it's probably not going to mutate and go and infect something else.

>> Right, right, right, exactly, exactly. That is one of the few blessings of this organism is that it's not easily transmissible that we know of from person to person.

>> Otherwise, it would be a horror movie.

>> See, that's the only thing that's keeping us up at night. Yeah.

>> So, I guess it potentially, theoretically, it could mutate out there and become a horror movie.

>> It could. It could.

>> Yeah, so could a lot of things.

>> So could a lot of things. That's right. That's right. We're lucky that we understand as much as we do about this organism so we can study it before that happens, so we won't be surprised.

>> If someone doesn't get treated, what are the symptoms of the late stage of infection?

>> So, they, they'll end up, well, people dying of tularemia, is that no matter what route you get it, it's a systemic disease. So, even if you breathe it in, it's not like something like influenza that just stays in the upper respiratory tract in the lung and then causes lots of inflammation. It will disseminate throughout the body. And once it gets into organs, like, for example, the liver, and it starts to really replicate there at the end stage of the disease, you have quite a bit of inflammation and necrosis. And so you really are dying of multiorgan failure. So, your liver is toast. It's necrotic. It's, you know, non‑functional anymore. You will eventually wind up having significant inflammation in the lungs. But by that point, you're usually, you know, bedridden, you're not walking around coughing on people, you know, and it will, it will infect just about every organ in the body. I think the consensus is that if someone wanted to say what the cause of death was it’s liver failure. But, you know, it's a systemic septic infection.

>> Sure. If it's not the liver, something else will probably fail next.

>> Yeah, I mean, just because at the very end of the disease, you do have widespread inflammation. So, you know, it's like other cases of sepsis they'd find with things like E. Coli and things like that. So, yeah, it's not a pleasant way to go, I'd say, I would say.

>> So, while you're in the Immunity to Pulmonary Pathogens Section, so this is considered a pulmonary pathogen, like mainly in the lungs?

>> Yeah. So, that, so, most people in the field consider that pneumonic tularemia, so that which is inhaled, and that's where the disease starts to be the most dangerous form of the disease. And part of that is because it really takes advantage of that lung environment. So, the lung does not like having inflammation, right? That's incompatible with breathing, right? Think about it. Asthma, lots of inflammation. Not good. Constriction. It's bad. You know, influenza, inflammation, bad. You know, the lung doesn't like this. And this particular organism we've discussed, you know, is very good at evading and suppressing until it really likes that pulmonary compartment, but it's already dampened down for having an ongoing immune response. And so we spend a lot of time trying to understand that interaction of the organism in the pulmonary compartment, in addition to what happens in the periphery. But, for example, there's another element in my lab where we're trying to look at the adaptive response or memory immunity of this organism, which turns out to be far more complicated than we first anticipated. And we're looking at cells that are involved in trying to protect against this organism. And it turns out that the pulmonary compartment, where cells are, whether they're in the tissue or they're circulating through, ends up being really important for how well you can deal with the pulmonary infection with Francisella. And so, in that way, we're really lucky because we're then able to compare like how does Francisella compare to other pathogens that might be a lung infection? So, like I said, we had attenuated mycobacterium, so we use BCG, we have to start comparing it to things like pertussis, because that's another bacterial infection. It's actually clearing, so it's, in some ways, similar. So, we can gain also a better picture of how is lung immunity changed in these different infections, and what's the same? So, that's what our interest is.

>> Adaptive immunity is not really working with these bacteria. I don't know if it's‑‑

>> Not so much.

>> Yeah. And I think, I'm not sure, because I'm not a scientist, is it antibodies that the body uses? Like when you get a viral infection, I believe you generate antibodies that recognize it. Is that the same for bacteria, or is it a different kind of process?

>> It can be.

>> Oh, okay.

>> For this particular organism, I'm sure that at some level, antibodies play a role. But they're not the dominant protective element. So, the other side of adaptive immunity are T cells. T cells are cells that when--let's say a macrophage, so macrophages go around gobbling things up. Their whole job is to gobble things up, right? And then the other side of it is, whatever they've taken in, they're going to present pieces of that on the outside. Okay? So, what the T cell does is it comes along, and the T cell will recognize very specific antigens, okay, that that's the things that are decorating the outside of the macrophage. So, the T cell comes and says, I know that one. And when it interacts with the macrophage through a number of receptors, including that little bit of protein antigen that was presented, that activates the T cell. Okay? So, when the T cell becomes activated, it releases things that then activate your macrophage that has the organism in it to kill it.

>> Oh, uh‑huh.

>> Okay? So, that's how that‑‑it's a little bit more complicated than antibodies, but that's, that's how T cells work. So, that's called cellular immunity. So, even with viruses, cellular immunity is also pretty important. So, like, with influenza, CD8 cells are really important. I'm trying to think of my laundry list of viruses. I mean, you have that component there too. For Francisella, that cellular immunity that's engendered by T cells is really the dominant immune response that you need, you know, and we just, we're not quite sure exactly how that works or when it fails, like why, why don't you go to develop a long‑term immune response? Because normally that's what happens.

>> Normally like the T cells remember that?

>> Yep, that's right.

>> And they store it in your body's memory?

>> Yep. So, your T cell, so you have naive T cells. But as soon as they've had that interaction where they recognize what was being produced by the macrophage, that sends signals to that cell to transition first to what's called an effector cell. It has an effect. Right? If it gets the right signals, eventually it will, a small population of those, so they'll multiply and divide. That's one of the signals that it gets. And a special population of those will transition to what's called a memory cell. Okay? And those memory cells are really important because the next time you get exposed to that pathogen, you already have a little group of expanded memory cells. You're not starting all over with that, you know, one naive T cell floating around waiting to find something that's being presented. Instead, you have this collection of cells that is ready to respond. And with Francisella, we never get there. So, we get that effector cell, but they're not really long‑lived. And so eventually they die off. And so we never get to the memory part. And we don't know why. We don't know why we don't have memory. So, the significance of that is like, for example, if you look at populations of people that were vaccinated for smallpox, okay, and this was work that was done by a number of labs, including I think Rafael does it at Emory, and they went back, you know, to people that had been vaccinated 60 years ago, and were able to evaluate their cellular immune response directed against things like smallpox. And they still have memory populations around. That's a long‑‑it's decades. We can't even get it a year. It's like, so, that's a pretty interesting phenomenon. And so if we can figure out why it's manipulating the T cell that way, then we can design a better vaccine. Right? One that's effective, more effective than what's been done in the past.

>> Yeah, it seems really weird.

>> It is very weird. See, you've become indoctrinated now in determining like it's weird. We're like, yeah, it's weird, it's very weird.

>> Yeah, that will probably be in the title of this podcast somewhere.

>> It's just weird.

>> Yep, it's just weird. Cool. And how big is your team of people in the lab?

>> So, currently, I have, well, I have three postdocs and two staff scientists. Or not staff scientists. Excuse me. Two microbiologists. So, permanent FTE. And then every once in a while, I have a post‑baccalaureate fellow or summer intern. So, we hover around six people-ish. And that's, that's, it's kind of balanced between full‑time employees and fellows.

>> How often are you recruiting? As some of those people probably cycle through.

>> Yeah, yeah, I mean, a little bit of it depends on sort of where they are in their career. You know, some people postdoc for a couple of years, and some people postdoc for five years. So, everybody is offset a little bit. So, it's hard to tell when positions will be open. And you never know. A lot of it, as we talked about, as far as timing, right? So, yeah, it's unpredictable.

>> Right. If someone really wants to work with you, there might be a spot open every year, two years?

>> You never know.

>> Yeah.

>> Always ask. You never know what's going to happen. So, yeah, I mean, it's not, it's not on a predictable basis where I can say, oh, yes, every year I'm looking to fill a spot. But, you know, it's like, there's always opportunity. And so, you know, I've had people contact me that were just starting their job search, and I may not have had anything open. And then, you know, got back in touch with me later. I'm like, oh, yeah, I have a slot that, you know, is about to come open in a couple of months, you know, if you're interested. And so, I mean, oftentimes, that's how it works in science. It can be a little unpredictable. It just depends on where people are in their careers as well, and what opportunities they have to move forward. And so‑‑

>> Yeah.

>> Yeah.

>> What kind of things are you looking‑‑do you look for in people who would want to contribute to your research?

>> So, they, I mean, I hate to use sort of like general terms like hard‑working and nice person, because everybody says that.

>> There's only so many things you can say.

>> Yeah, well, and some of‑‑well, I mean, because it's true, all right? I mean, science is, science is not for wimps. It's hard. There is a lot of doing things over and over again. And, you know, your hypothesis was wrong, or, you know, it's like, it can be pretty intense. I like to look for people that are thoughtful scientists. So, you don't just go in and I'm just going to do this experiment, that are really thinking about what they're doing and why they're setting it up, in part so because we work in a containment environment, you don't want to waste time in there. But also invested in the process. I mean, this is my, one of my favorite things. So, if it's not that person's, one of their favorite things, that can be hard, because you have to have a lot of passion and a lot of drive and a lot of patience. And so if that's not, if science really isn't that way for you, that may be not a good match. So, I look for people that are excited about what they're doing, that they want to be here every day. And it's not all work either. I mean, I think, as with any successful lab. You have to sort of craft those personalities. And that's something a little intangible. And I can't say, oh, you have to be this kind of person. It just depends on how you fit with the people in the lab, you know? And if the personalities are all working well together and they're not all the same--I have a very diverse group of people, but when they work together, that also makes it a lot of fun too. So, you know, I mean, you have to have that balance there, I think. I think, in a general sense, that’s probably what I'm looking for. I'm not necessarily looking for people that are, oh, I'm an immunologist, or I've worked on Francisella, or this or that. I mean, one of the postdocs I have had not worked on infectious disease and is really more of a biochemist. But it's working out great.

>> Yeah, it fits into a certain‑‑

>> It fits. I had a need and he had a desire to work on an infectious organism, and sometimes we don't talk each other's language, but it's okay. I just tell him, keep saying the words to me. I will understand them eventually. But that's a great example of, in that, in that, again, it was a, I think the personalities fit well together where it's just great. So, you never, you never know, you never know. Some of it depends on what's going on.

>> Cool. Are there one or two recent papers that were published out of your lab, in case someone's looking for, like, what's the most up‑to‑date stuff that you're doing?

>> Yeah, so, we will have a number of papers that we're submitting in the next month or so.

>> Oh, cool.

>> So, be on the lookout for really new stuff. But if I had to pick two of our recent publications that I think are the most significant, well, maybe three. One is the paper describing the ability of Francisella capsule to manipulate host cell metabolism. So, that came out in the Journal of Immunology in 2015, 2016. I'd have to look up the specific reference. If you search Francisella capsule metabolism, it will pop up.

>> Okay.

>> And then another paper that we had, looking at adaptive immunity, this came out two years ago, what was significant about that was that it showed that if we manipulate the cellular response in a very specific way, that we can actually improve existing vaccines. And I won't go into all the details, but it had to do with how well the T cell recognized the antigen. So, we were able to manipulate that in a way that was non‑specific to Francisella and improve the existing vaccine. That was also in JI, I believe. So‑‑

>> And that kind of shows the broader implications of studying this one weird organism?

>> It could for sure, yeah, for sure. And then if I had to pick one more, several years ago now, the papers describing the activity of the lipids. So, we did it. And we're now, we're now identifying what the specific lipids were. But in those two manuscripts, it was just demonstrating that you could have these lipids which appear to be inert, but in stimulated response, were quite potent at impairing inflammation in the in vitro environment, so in a dish, and then also in vivo in an animal. So, and those were in Clinical and Vaccine Immunology and I think also again the Journal of Immunology.

>> Got a good memory. I guess when a paper publishes, that's kind of a big moment.

>> We remember it, we document it with ice cream cake in my lab, because we don't get papers published every day. So, everyone gets ice cream cake.

>> Yeah, so, if you want, if you want ice cream cake‑‑

>> You've got to publish.

>> You've got to follow up. If you want to work here.

>> That's right. That's right.

>> Cool. And so for the next, the next few years, or next 10 years, however makes sense to answer it, what are things that you're looking, that you want to explore further, or any particular goals you might have for your research?

>> So, we have pretty heavily invested in looking at how this organism interacts with the metabolism of the host cell. I think there are a number of labs that are starting to explore that because of work that was done, you know, really, some really beautiful work that had been done over the last 10 years by a very small group of investigators that are sort of exploding now into the general science field. And part, too, we just have better tools. I think understanding that interaction will unlock a lot of the mysteries that we have about Francisella. It will also be extremely applicable to many, many other infectious diseases. And so, in addition to really investing time and energy in that for Francisella and tularemia, we're building a platform and we're establishing the tools to be able to continue to look at with other infectious diseases. So, in a collaborative way, because that's what RML is – RML is infectious disease – we may be able to help some of our colleagues address if they have similar questions. And so that's really, in a very broad sense, what we're going after. And I think it will, you know, again, I think it will open up the idea for novel therapeutics, better vaccine design, along with also helping our neighbors.

>> Roughly, how many collaborative projects do you have going on with other researchers here?

>> Just a couple. So, you know, we've worked with Sonja's group. And then I collaborate, I've just started a collaboration with an investigator out in Bethesda who works on mycobacterium, because we're trying to answer similar questions. She's very interested in how this mycobacterium manipulates mitochondria and metabolism and things like that. So, and, you know, sometimes collaborations aren't necessarily big, or, you know, well‑defined, so, you know, I work with another investigator at Washington State University because we're filling an immunological gap that he doesn't necessarily have in his lab. So, while I wouldn't say it's, you know, we collaborate extensively, but when an opportunity presents itself, we're happy to help.

>> If I even can say it correctly, Francisella tularemia.

>> Tularensis.

>> Tularensis.

>> You've got it.

>> Sorry.

>> Well, there's tularemia. That's where it gets its‑‑

>> Yeah, Francisella tularensis, what kind of a bacteria is this? I know I should have asked this a long time ago.

>> That's okay.

>> But I'm just curious. Like, where does it fit within the world of bacteria?

>> So, it's considered a gram‑negative facultative intracellular pathogen. It's, ooh, I don't want to get this wrong.

>> You can grab your textbook if you want.

>> I think it's in the family or genus of Enterobacteriaceae. But it's a, yeah, for general purposes, gram‑negative facultative intracellular pathogen. And what that means is that--gram‑negative, has an LPS.

>> I don't know what you just said.

>> Yeah, so, that's why I'm just like, if they're looking at it clinically, that's what they‑‑they look for gram‑positive versus gram‑negative bacterium.

>> Is that like a polysaccharide?

>> That's right.

>> Oh, I did, I kind of know what you said.

>> See, you knew. You just didn't know you knew. And then the fact that it's a facultative intracellular pathogen, what that means is that it's not wholly dependent on replicating in a host cell, which means‑‑

>> It can float around?

>> Yeah, you can‑‑in the environment, in nature, it’s almost always associated with a host cell. But we can grow it in broth, we can grow it in agar, things like, things like that. So, that would probably be the best way to characterize it.

>> Well, thank you, Katie. I appreciate everything.

>> Yep, you're welcome.

>> It's great to learn more about this weird bug.

>> Well, we're, as you can tell, we're happy to talk about it any time. Any time. Thank you for coming out to RML.