TWiV 1345: Rocky Mountain Virology High

0:00This Week in Virology, the podcast about viruses, the kind that make you sick.

0:10Hello, CSU.

0:15All right, that's great. From Microbe TV, this is TWIV, This Week in Virology, a special episode recorded on June 15th, 2026. I'm Vincent Racaniello, and you're listening to the podcast all about viruses. Today, I'm in Fort Collins, Colorado. I'm on the campus of Colorado State University. I'm here for a research symposium tomorrow where I'll be giving a keynote lecture. But since I'm here, I thought I would grab a few virologists here. There are lots of virologists here on campus. I go some places that are not so many virologists, but other places like this, it's great. So let me tell you who's here with me, and we're going to chat about their research.

1:07Well, they're all from CSU, so I don't have to tell you where they're from. On my right, Angela Bosco-Lough, thank you for joining me. Thank you. Lough, is that right? Lough, you had her. Lough? Okay, Lough. Next, Rebecca Kading. Welcome. Thanks. So Rebecca was on TWIM 121 at ASM Biodefense. It was a long time ago because TWIM is up to 375 now. So ancient. And you know, that is an interesting TWIM. I'm not going to say why. It was very interesting. But the guy on it, remember? Yes. Okay. Telling my lab about that this morning. Yeah, so that broadcast still exists. You can look at it. Okay. 121.

1:51I was flying back from Chicago. I got a call from ABC News. They wanted to use clips from that episode. Anyway, and then finally on the right, Mark Stenglein. Welcome. Thank you very much. Thank you all for joining me. You were on TWIV 196. Yeah, that was in 2012. So I calculated that that means I get to come back on in 2040. Well, maybe I won't be around. I don't know. Yeah, so that was when you were a postdoc. That's right. And we talked about snakes. That's right. A virus of snakes. Okay, so let's start with your histories. I want to know as far back as you can remember. Yesterday. Were you from yesterday?

2:32Yes. Good job. Just tell us where you're from and what kind of education you got and how you got here. Sure. So I'm a Colorado native. I was born and bred here. And I've been at CSU for an embarrassingly long amount of time. I came here in 2002 to do my undergrad and got really hooked into the world of West Nile since that was really very prescient in 2002 in Fort Collins. I'm a horse person. Apologies. And I was very nervous about having a horse in an area where we had this new disease that nobody really knew anything about. And that completely derailed my original plans, which was to be a horse veterinarian.

3:09And instead, I got hooked into the research side of things, started working on vaccine technology with the infamous Dr. Richard Bowen, who is still here at CSU. And I've never left. So I did my PhD here, graduated with that degree in 2010, and then did a postdoc at the CDC right across the street in the Arbovirology Disease Branch. I spent a few years over there working, unsurprisingly, on arboviruses in West Nile. And then I went to vet school because I'm crazy and just had to do that later in life. My memory wasn't so good. Maybe not the best choice. And then finished vet school and stayed here at CSU.

3:43So I'm pretty boring. So when you were an undergrad, you were a bio major, I guess? Microbio, yeah. So why did you want to do science? Was there something in your life that made you interested in that? I wanted to be a horse vet. I don't know why. Yeah, that was it. And then I realized that there was so much more fun stuff out there and really got hooked into the virology when I started to discover how much bigger of a deal it is to think about things from a more broad perspective than just focus on one individual animal, and that really hooked me into the world of science. So, you know, us in New York, we hosted the first West Nile outbreak.

4:16Yeah, it's your fault. I know. That's right. Yeah, you're welcome. My former colleague, Dixon DesPommiers, who was on TWIV from the beginning, was probably on your episode, he passed away last year, but he wrote a book called West Nile's Story. It's a little paperback. just in the early days, like what was going on. And he's not a virologist. He's a parasitologist, but he decided he wanted to do that. And our first episode of TWIV was West Nile virus because I got him. Circles back. And we just talked about it for a really long time. Rebecca, tell us your story. Oh, boy. It's been a secure disroute.

4:59Young Rebecca would have no idea that this is where I would be sitting. And today I was going to be a ballerina when I was little. And so this is a very different career path, but been a very rewarding one. I did my undergrad at the University of Delaware, and I was interested in wildlife conservation. At the time, Delaware didn't have that as its own major, and so I had to major in entomology in order to take the bird and mammal classes. And so I sat in the entomology classes, and I was like, I don't want to study bugs. And then I ended up really liking it. worked for a couple summers at the state of Delaware Mosquito Control Program, and then started to connect the dots for One Health at that time before that became a term.

5:40But, you know, I got to be up in the helicopter and, you know, out on the salt marshes and learn about mosquitoes. And there was, this was before West Nile, but there was Eastern equine encephalitis virus surveillance happening in St. Louis encephalitis. So I started to learn about disease ecology. And so then, you know, really became fascinated with this. So then I went and did my master's at the University of Arkansas with Max Meisch and studied rice field mosquitoes and then PhD at Johns Hopkins and then started to integrate more of the diseases and worked on malaria for my PhD. And then I've been out here since 2007.

6:14I did a postdoc at the CDC right across the street and then happy to be here for the last 10 years at CSU. Are you from Delaware originally? From Delaware originally, yep. Okay, East Coaster. Yep. And why did you get interested in science? Do you remember? I've always liked nature and the outdoors, and even, you know, pre-college, I would always like to go on hikes and interested in birds, and so it's kind of gravitated me toward the sciences there, yeah. A lot of people say that, you know, they like the outdoors and that got them into science. Really interesting. Okay, Mark, what's your story?

6:49Yeah, so I grew up in Minnesota and also like we have several Minnesotans among the faculty here. Like young Rebecca, young Mark didn't know what I wanted to do when I grew up. And so I went to college and I was good at math. So I was a math major in college. And then I still didn't know what I wanted to do. But I ended up with a job at an engineering company where I worked for seven years doing computer programming for this company that built test facilities for jet engines. And so that was kind of cool, but I realized I wanted to get into science because that seemed cooler. So I went to grad school at the University of Minnesota and did work on antiviral enzymes called Apobex with Reuben Harris.

7:32And then when I was kind of timed to be a postdoc, I ended up going to UCSF and worked with Joe DiRisi, which was what I was doing when I was last on TWIV, doing metagenomics to try to discover new viruses. and that led me to get a job here and I've been here since 2014. Science is cool, isn't it? It is cool. Science is fun. And that's why we do these podcasts to tell people about it because nowadays, you know, science is having some problems, as you know, and so we have to tell people how cool it is. So we usually discuss papers on our programs and we always do the wow factor. Isn't this so cool, right?

8:13We have to keep doing that. So when Mark came on to TWIV, we used to, well, normally we record online. And so he was about to come online. And then he said, Mark, he said, Joe wants to come, Joe DiRisi, his boss, because he heard that he was going to be on this podcast. And the famous Joe DiRisi, who doesn't have time for anyone, suddenly wanted to be on this podcast. So I thought that was good for us. All right. Let's talk about your science. And so, Angela, first, maybe you could give us an overview of what the interests of your work are. Yeah, so it started definitely with arboviruses, and so I've always been a virologist at heart.

8:55But I really got a lot more into kind of the overarching theme of animal viruses after I went to vet school. And so now I spend a lot of my time kind of bridging the gap between arboviruses, studying things like St. Louis encephalitis and West Nile in their natural reservoir host, which is primarily birds. And then when the tides change and a new pathogen emerges, such as SARS-CoV-2, we'll kind of switch focus to that for a little while. My lab did a ton of work on host competence, different species susceptibility. And right now it's all about the high pathavian influenza virus. So I spend most of my time studying that, doing a lot of kind of transmission studies, mostly between species and within species of mammals and birds, and trying to kind of figure out some of the ways in which you can potentially intervene and interrogate those processes to hopefully at some point break the cycle.

9:44Okay. So I've looked at a couple of your papers, and I've written them down here, so I want to ask you about them, okay? Sure. Hope I can remember them. Well, yeah. I mean, if you don't remember, you could just say. So the first one, susceptibility of wild and domestic songbirds to Usutu virus. So what is Usutu virus? Great question. I had to look it up when we started this project. It's a close relative, actually, of West Nile and St. Louis, but primarily circulates in Europe and mostly in songbirds. So like the European blackbirds and some birds that are very similar to our version of the American robin.

10:21This is a virus that doesn't cause a lot of disease in people, but can. But is one of those kind of more worried about it from a perspective of if it emerges in the U.S., what could it do to our songbird population? Could it actually interfere with maybe equines or humans here as well? So that particular paper was looking at American species of songbirds for susceptibility to determine if they had the same pathogenesis as these European birds. And it turns out some species do, and some species are a little bit different. So in our American robins, it wipes them out, which was a scary thought. It kills them.

10:54So the European songbirds, it kills them as well? It does, yeah. And how is it spread among birds? Mosquitoes, yeah. And these are mosquitoes that just bite birds or do they bite other things? They will bite other things, but a lot of the species that primarily spread it tend to preferentially feed on birds. And I heard this a while ago. I don't know if it's true, but before they die, do they lose their ability to sing? That's a great question. I should have asked them, but I forgot. That's what I heard. But, of course, if you're about to die, you're not going to sing. Maybe they'll croak, I suppose.

11:28So you wanted to know if American songbirds would be susceptible. So this is a European isolate virus, I presume. Correct. And are they? Are you American songbirds? Very much so. So what is an American songbird? I don't even know that. Oh, good question. So the two that we studied were house finches and American robins and also house sparrows. And again, a little bit different between species. So in house sparrows, we didn't see a lot of disease, but in finches and robins, quite a significant amount of disease. I walked into my hotel room before and I heard birds singing. Probably not. And I said, this is not real.

12:01And there's a thing next to the bed that plays birds. How do I shut this thing off? Did you figure it out? Yeah, it took a while. There's a lot of buttons on it. So how do you inoculate the bird? That's what I was going to, yeah. Well, for this particular site, we just did a subcutaneous inoculation with a needle. mosquitoes would have been the best way to do that. We were looking for kind of a basic study. But the sub-Q is kind of like a mosquito bite. Exactly. Okay. So the songbirds you tested, the virus reproduces in all of them, and they all, what was the end point, death? It was, unfortunately, death or euthanasia in our case in Robins and Finches.

12:42How sparrows survived and became biremic, but didn't end up having any sort of clinical disease that we could say. Yay sparrows. I know. They're just the little guys that keep ticking. And so how long did this take to kill the birds? It was only four or five days for the robins, which was really sad. I think a little bit longer for finches. And it took us about two years to catch four robins. So it was quite the study. So these are all wild-cut birds? They were, yes. So the implication is if the virus came to the U.S., then these birds would be susceptible, right? Our thought is that it could be susceptible.

13:19We also wanted to look and see would they potentially be protected if they had immunity to West Nile or St. Louis encephalitis, which there's pretty good evidence that at least in the birds that didn't succumb to infection like the sparrows, there's some good cross protection. Robins, we didn't actually have enough birds to test that. And robins, as most people who are familiar with West Nile know that they're good amplifying species. They don't usually succumb to infection, at least not to that level. So I'm not sure if they would be able to overcome Usudo. It was pretty devastating in them. Do we have the mosquitoes here that would transmit it among them?

13:52Potentially. I think most Culex species would be potentially able to transmit. But I don't think, at least I haven't seen any recent literature about which exact species would be able to carry it here in the U.S. And so birds are the reservoir host, right? There's no other mammal involved. Not that I'm aware of. Okay. Usutu virus. All right. Next one. Rabbit hemorrhagic disease virus, infection of snowshoe hares. I just wanted it because I like snowshoe hairs. Me too. It's a great name and it's a great animal. So what is that? So rabbit hemorrhagic disease is a logovirus that only infects rabbits and causes really significant disease in what we would call kind of European rabbits or basically domestic species.

14:35And the history on that, if you're unfamiliar, is it was intentionally introduced as a form of biological control in Australia and New Zealand, where domestic rabbits that were loose and had very few predators were kind of ravaging the landscape. Those were rabbits that had been imported from Europe, right? For hunting. Yep. Okay. So they quickly did what rabbits do best and became very prolific. And then when this was introduced originally, it really wiped out about 80 % of the population. And then there's always few rabbits that are refractory. So over time, their population's replenished. And then the second variant came out, this RHDV2, which unfortunately impacts not just the domestic species, but also wild rabbits.

15:17So the original virus really didn't impact wild rabbits, which are cottontails and hares primarily in this country, among others. So RHDV2 shows up, unsurprisingly, because when you mess with viruses and, you know, they do their own thing, and had a pretty big impact when it showed up in the United States and wiped out quite a few of our native wildlife species, not full species, but individuals within populations. And then, of course, people who breed rabbits were terrified because it's about 100 % mortality. So our goal was to try to look at some of these kind of keystone species and see how badly are their populations going to be impacted?

15:52How susceptible are they? And interestingly enough, these hares were kind of refractory. So we see 100 % mortality in the domestic rabbits, about 50 % in cottontails, and we actually had no mortality in the hares. They get a little sick and then they recover. and potentially have lifelong immunity. So it was a really cool study to have some actually promising results about a species that, and at this point, I think we're now six years in, and I don't think we've had any massive die-offs in any of our native species. So good news on that front. How did the virus get into the U.S. from, where did it come from, Australia, New Zealand?

16:27This one actually probably came from Europe. I think France was maybe the epicenter of the RHTV2 outbreak when it actually crossed into the European continent. And then from there, I'm not sure how it got here. We had introductions, almost separate introductions at the same time across two different parts of the U.S. So yeah, who knows? Is it a DNA virus or an RNA virus? It's an RNA virus. So the thing that's interesting about using viruses is biocontrol. You know, Australia tried myxoma virus for the same thing, and it didn't work. Right. Because you always have a certain fraction of rabbits that are resistant.

17:02And then they multiply very quickly, and that's it. So they keep trying. And it doesn't work. I would say stop. Just leave them alone, right? Find better ways. Why are they called snowshoe hares? Because they turn brilliant white in the wintertime, and they have these lovely long paddle-like feet so they can hop across the snow and stay on the surface. All right, next one. Are you ready? I'm ready. This is like Jeopardy. It is. I know. I have to make sure I remember talking about that. So far, you've been winning. Yeah, you remember. Remember, exploring roots of infection of severe fever with thrombocytopenia virus in animals.

17:37I remember that emerged a number of years ago. So tell us about that virus. Yeah, so I'm just going to call it SFTS because that's much easier than saying that five times fast. So this is another kind of emerging pathogen of interest. It's currently not in the United States, but circulates primarily in parts of Asia. So it showed up, I think, first in China and now is endemic in parts of Japan, China, and I think Korea, if I'm not mistaken. It's a banyovirus, so something that you'll hear more about. Not my first virus study, so I'm a little bit shady on some of the details. But virus that can cause a lot of disease, particularly in people.

18:13Almost certainly it's tick transmitted. And our goal was to try to figure out, are there a reservoir host species? And if so, is this primarily going to be a virus that's factored by ticks? Or are there other routes potentially of exposure? Human cases have happened in close contact with infected cats as well as in close contact with hospitalized human patients. So it's not only tick transmitted. It could also have either an aerosol component or a close contact droplet component of some sort. So we've done a few studies where we infected different species, and cats, weirdly, are pretty susceptible.

18:45But this study was done in mice, and all we were trying to do was determine are there different routes in which you can inoculate and still produce disease. And in these poor little immunocompromised mice, pretty much everything causes mortality. So definitely not just ticks. Can have other routes of transmission in addition to the true vector. So that's interesting because you figure a tick-borne virus, that's the way it's going to go through the blood, right? But this may be a respiratory component. So people who are infected do shed virus in respiratory secretions. Yeah, at least in droplets for sure.

19:18So what is thrombocytopenia? Because people are not going to know, right? Yeah, so it's a decrease in platelet count. So essentially, you can't really clot. And that can lead to pretty severe, in some patients, it leads to pretty severe anemia. And patients that succumb ultimately usually develop not disseminated intravascular coagulation problems. So I was in Kansas a few months ago, and they're very proud that they have the site of bourbon virus, which I think is a similar tick-borne disease, right? Yep. Which farmers can get because they're always getting bitten by ticks. So there are a few, I think there are some other isolates from the U.S.

19:54that cause a similar disease, right? Yeah, Heartland would be the other example. That's the other one. Is that also in Kansas, the Heartland? I think it's right in Missouri, but I'm fairly sure there's been a Kansas isolate or two. Heartland. Okay. Now SARS-CoV-2 in wildlife. So there's an intraspecific SARS-CoV-2 Delta transmission among red foxes and striped skunks. So what's going on there? Yeah. So fortunately now, not a lot, thank goodness. But early in the pandemic, I think it was pretty obvious that there were some wildlife components and a lot of folks found like deer-to-deer transmissions.

20:32So we looked at other species that were susceptible and then looked to see if they could also provide an ongoing transmission chain within that species to see if that was going to be a source of long-term viral endemicity. And we found that certainly with red fox in particular, for whatever reason, they were fairly susceptible to infection without disease and could, in fact, transmit to each other with direct contact. We didn't really see true aerosol transmissions. If they didn't actually get a chance to bump noses, then we didn't see transmission between the species. And kind of same thing for skunks.

21:06So transmission can occur, but probably is driven more by that close contact than by anything else, at least in those species. So that's a new transmission term, bump noses. Yes. That's how we do it. So animals do that? Well, some do more than others. Like a fox would bump noses with a, what is it, a skunk? Well, hopefully not with a skunk. I feel like that would end badly. But that's how they would transmit, by close contact. Yeah, and we were mostly looking at within the same species, so certainly they will have interactions like that. And these are foxes that you had captured and brought into the lab, right?

21:40These were actually animals that were farmed, So we were able to purchase instead of trap. So quite a few wild animals are infected with SARS-CoV-2, right? Correct. So is it still out there? Are people looking? Do you know? I think people are still looking. I feel like it's possibly still out there. I see a hand in the back. So people are still looking. I think the answer to... Is it still out there? We haven't found any SARS-CoV-2 specifically in the animals we've looked at it in, but we have found other coronaviruses. There you go. When you're at a virology place, you know, with a lot of virologists, you can answer your question.

22:15So you think this is, I remember mink were identified early on in mink farms in Europe, right? And they actually transmitted it back to humans. Right. So are we worried about this ongoing? I would say I'm much more worried about the people sitting next to me than the mink. I think human to human transmission is definitely the most common. And at this point, with Omicron being the most dominant variant and whatever is now on the landscape, it feels to me like people are going to be our own worst enemy for SARS-CoV-2 indefinitely. Does Omicron go into wild animals? Weirdly, when we looked at this in direct experimental inoculations, we get significantly lower levels of shedding with Omicron.

22:53And in some species, none at all. So it definitely seems to have made that kind of leap towards humans and is a bit more human adapted in these later variants. All right. You also are interested in West Nile virus. We heard that at the beginning. Here's one. Cross protection between West Nile virus and emerging flaviviruses in wild birds. Excellent. So what's that about? So we did this study. You caught birds, right? Yeah. So these are wild-caught birds primarily with some folks in the audience, I'm sure. Who caught the birds here? They're not here. Yeah, I know, right? Usually that's my job is to catch the birds.

23:27I'm not as good at it as I used to be. How do you catch a bird, by the way? I just grab it out of you. No. I'm not that gullible. We use misnets. A net, okay. So we would trap primarily sparrows, but we've also done this work in blackbirds and robins, and years ago in crows, and then do inoculations. Oh, you were counting crows. Absolutely. That was a good reference to the ban. And then we would do kind of these, what we call heterologous challenge. So we'll start with one flavivirus, West Nile or St. Louis encephalitis or Japanese encephalitis, and then inoculate with the reciprocal and see if they have cross-protection.

24:04Did they? So depending on the species and depending on the virus, yes. And typically we see with West Nile as the primary infection confers a lot of immunity to the other flaviviruses, but sometimes that's a little bit inhibited when you go the reverse. And we are noticing recently, and I don't even have the data for this 100 % finished yet, But some of these newer isolates of St. Louis encephalitis actually may be able to escape some of the immunity from West Nile. So there's a bit of viral evolution that's happening kind of in real time right now that might change how we predict some of these exposures.

24:42So all these viruses are arboviruses, right? And they all infect various mammals in the woods. In the woods, yes. You want to know what's out there? Yes? Yeah. And birds in particular. And birds. Yeah. Okay. Right, and so this has implications for being protected against a different flavie when you're infected with one, basically. So we saw the same thing with enteroviruses. If you immunize a mouse with polio, it would become resistant to, like, rhinoviruses and other enteroviruses. It's kind of interesting because you have to be careful when you do serological surveys because you can be fooled by the cross-reactivity.

25:20Exactly. So if you did a survey for West Nile virus, you know, maybe these people were infected with something else. It's definitely a concern. You have to be careful. All right. I have one more for you. Let's talk about H5N1. So you look, here's your paper, susceptibility and viral shedding of peridomestic wildlife infected with clade 2.3.4.4b. You know what that is. Yeah. Highly path. So by the way, Dixon always, whenever we talked about West Nile, he would always say a murder of crows. Yes. Because it does kill crows, right? It does. And that's what you call a murder. You guys know a murder is a bunch.

25:57I think it's just two or more crows. I think so. Yeah. There's a joke about that. You know, why did the crows go to jail? Because they got together. Murder of crows. It's not my, I'll stick with my day job. So what did you find in peridomestic? This is wildlife that lives around people, right? Correct. Yeah. That was another favorite Dixon word, peridomestic. It's a great word. It is. It makes you sound much smarter than you. So what are examples of peridomestic animals? So we think about like rodents, house mice, deer mice, skunks, raccoons, anything that kind of comes in and gets in your trash or in your house that you'd prefer it didn't and cause problems.

26:42Okay. But also animals that are really well adapted to living near human establishments. So you look for H5N1 in these animals, what'd you find? Correct. That almost everything gets H5N1, unfortunately. So you infected them, right? Correct. You captured them and then you just grabbed them, right? Same thing, yeah. Especially the skunks, I'm very good at scrubbing. And all of them can be infected? As of now, I'm not sure I've actually tested a mammal or bird species that was refractory to H5N1. So it's pretty devastating. In some species, like skunks, it's very lethal. Other species will end up having a little bit of viral shedding.

27:21We did this in possums, for example. They'll shed virus very minimally but don't seem to be clinically affected. Cottontail rabbits, same thing. But for whatever reason, animals like cats, skunks, foxes, coyotes, all those kind of more carnivorous species seem really adversely affected. So a cat could eat a bird, a dead bird that's infected and would get sick. Yeah, potentially. And experimentally that does happen. Sparrows and robins, your other story. Can they be infected? Yes, unfortunately. So if people have a bird feeder, first of all, should they not have bird feeders anymore? I wouldn't go that far, but I would be cautious about it.

27:58And certainly those of us who have cats probably should try to keep our cats from eating birds if you possibly can. Good luck. Right, I know. Good luck with that. So if you find dead birds around your feeder, what should you do? I would definitely put gloves on if at all possible and make sure to put that dead bird someplace where a cat can't get to it. Okay. Maybe bury it, right? Bury it, I put it directly in the trash can. You know, there's stories of people walking along the beach, like on Long Island. My colleague, Daniel Griffin, he says, they find lots of dead shorebirds. Right. And maybe it's H5N1.

28:30I wouldn't doubt it for a second. So how worried are you about H5N1? I'm pretty worried. On a scale of 1 to 10? I'd say about a 7. I don't want to be a panic button about it, but the way it's moving through different species and the way there's new genotypes emerging that have some really scary characteristics, like increased mammalian to mammalian transmission, makes me think we just need to keep this one really forefront. I mean, this one's interesting because it's in so many mammals, right? Right. And before it wasn't. Especially not. Although humans so far seem to be spared, right? I know.

29:03Keep your fingers crossed. So far. The dairy cows, I think, were a pretty big warning that that's really never happened before. Yeah, we just talked about a study on the last TWIV. They actually put dairy cows in a BSL-3, and they infected them. And then they milked them, and they took the milking equipment and put it on another cow, and it didn't transmit it. That's crazy. So how does it transmit among cows? Nobody knows. I know. It's a mystery. Do they bump noses? No, cows bump some noses. They do. But I don't think there's very much respiratory. Most of it is in the milk. You know what levels are in milk?

29:3810 to the 11th. That's crazy. Or 12th, PFU per mil. I thought polio was the best. That's incredible. So what are you doing that's exciting right now? Right now, we're looking at a lot of different routes of transmission between different species for flu. And these are kind of, they seem a little bit intricate, but we'll take, for example, chickens and we'll expose them to, in a roundabout way things like skunks or cats and trying to see if we have interspecific and intraspecific transmission between chicken to chicken, cat to cat, and then between all those species. And trying to look really and see if there's ways in which you could, one, interrupt that cycle, but also make better predictions about how it's happening.

30:23And what we've found is that while there is aerosol component to flu, this is another one that takes a lot of direct contact. And I think on the mammal side, ingestion is really important. eating the virus. Yeah. If we put a cat and a chicken in the same room and the chicken is infected, it doesn't infect the cat. But if the cat then eats infected chicken meat, they do get infected. So it's a matter of there's ways to probably help prevent that. And I think not feeding raw cat food is the number one. So, you know, this highly pathogenic H5N1 emerged in the 90s in China. And early on, they were feeding zoo animals, dead birds, and they were transmitting it to them without knowing it because they didn't know about it at the time.

31:08Okay, that's it for you. Good job, Angela. I'll come back. I'll come back to you. But Rebecca, Rebecca, tell us your overall interests in the lab. So our DLF studies the ecology and transmission of mosquito-borne and bat-borne viruses. And so we have a couple of main research pillars going on. We're working on mosquito-borne viruses, most specifically Raffelli fever viruses. We've developed a niche for ourselves. You guys both work on, you collaborate, I think. In fact, both three of you collaborate, right? In fact, I heard this is a collaborative place, right? Highly collaborative. Is this true?

31:46Absolutely. Yeah. Cool. You know, many places don't do that. Everybody's on their own. No, it's one of the great things about being here. So, yeah, so we've been working a lot on Rafale fever. And then another big section of the lab is focused on bat-associated viruses. And we've had a field project in Uganda for many years that we've been working on viral ecology in bats in eastern Uganda. Have you gone? Many times, yes. Is it cool? Very fortunate. It's a beautiful and wonderful place to work. But now you probably wouldn't want to go, right? today's not the best day to go there no for many reasons right okay so i looked at some of your papers and some of them are reviews interestingly so we'll talk about that the first one is like a meta-analysis socio and socioeconomic benefits associated with bats i think this is cool because most people probably think bats are bad right yeah yeah and that bats get a bad rap why do they Why do they get a bat?

32:44They're scary. They're fly. I mean, there's superstitions about bats. Aren't they really vampires? There are vampire bats, yes. But this was the brainchild of a student over in Uganda that I'm on his Ph.D. committee. And he's very interested in the human-bat interactions from the infectious disease perspective, but also from the conservation perspective. And there's a lot of habitat change in Uganda, a lot of pressures on the bats. And, you know, the messaging is, you know, one of one health and, you know, how do you protect the bats and protect human health? And so he designed a study to ask people and understand, you know, what their impressions of bats were and what the benefits that they viewed of bats.

33:29Do they use bats for bat guano? What religious purposes are they? What medicinal purposes? Lots of different cultural things that came up in conversation that people, yes, do value bats, even though there is some superstition. So then the next step would then be to take that information and how do you design conservation measures that are around these things that people view bats that are important. So why are bats good? Why are bats good? There's so many reasons. So many reasons. They pollinate plants. There's some plants that are completely dependent upon bats. They disperse seeds and help forest regeneration.

34:10Their guano can be used as fertilizer. They consume crop pests, and there's economic estimates of them saving agricultural industry billions of dollars every year in the United States. And so they're very important species to the ecosystem. Is there anything bad about them? I would say no, but we have to let bats be. And if they have viruses, just leave them alone. Then they're fine. Some people would be happy if you got rid of all the bats. No. Would that be bad? No, yes, that would absolutely be bad. What would happen if we could just grab them all like you do? What would happen? Complete ecological collapse.

34:55Really? Yeah. Yeah. There's so many systems that are dependent upon bats and, you know, to remove them would be devastating. You know, Curtis Subtle says the same thing about viruses. If you remove all the viruses on the planet, you would have ecological collapse. So I was at an aquatic virus meeting and I asked another guy and he said, oh, Earth would recover. Because Earth is pretty resilient, right, to all the things we do to it. So maybe it would if you took all the bats away too. But I understand they're very useful. That's a really cool study. But I think many people have a bad view of bats, mostly because they're a little creepy, right?

35:35Yeah. And they fly. It's a rodent with wings, right? Well, no. No, but... Right, I understand. But that's the way people look at it. And you know what people do when they have a bat in their house? They freak out, right? Yes. So for all those reasons. So I think this is really important to tell people that you should leave bats alone. Yeah. Yeah. Okay. Another one. Intrinsic factors driving mosquito vector competence and viral evolution. So this is interesting for our listeners. What is mosquito competence? Yeah. So vector competence is, you know, if we were to think about, you know, take mosquito under completely controlled conditions in the laboratory, feed it a virus, can it transmit?

36:21So just the ability to, well, in our case, a test tube. But if it were a natural system, upon biting, could it excrete virus in the saliva? So all of the things that would happen inside of the mosquito, not considering the environmental influences, that could also impact things out in the field. So vector competence, one thing that we study here that would get some assessment of risk of vector-borne transmission. So why is it important to know the competence of a mosquito species? If and when there are viral introductions and invasions, which mosquito species are important to focus on for control and mitigation of that event, which mosquito species are responsible for transmission in the field.

37:08So is competence all about how much virus is made in an infected mosquito? Yeah. That, so you can look at, you know, the, you know, percentage that could transmit or, you know, the amount there, if some of them are able to transmit earlier than others, or, you know, there's a number of different, you know, things along the timeline that you can use to measure, you know, which vectors may be more important than others. So how do you measure it in the lab? In the lab? So we have, you know, provide the mosquitoes with an artificial blood meal that's spiked with virus, and then we feed that to the mosquitoes and then wait, you know, usually seven, 14 days, different time points, and then dissect the mosquitoes.

37:49So it's very gruesome for a mosquito's perspective. You pull off the legs and wings and you collect saliva. You force the proboscis into a tube that has immersion oil and make it salivate and it's got no legs and wings in there. So it's, you know, and then, but you look in, you know, then you can look at different compartments and have different metrics of transmission. So if the carcass is infected, then it's an infection. If the legs and wings are infected, that means the virus got out of the midgut and disseminated. So it's a disseminated infection. And if the saliva is positive, then it's a transmission event.

38:21So you can break down, you know, have those very standardized ways to look at it and compare that across virus strains and mosquito species. So is there any one mosquito that's great in competence for many viruses? There's a lot. One that we have here, Culex tarsalis is an important vector of viruses we have here, West Nile and St. Louis, but it's also very competent for Riff Valley fever, which we don't have here, but that's something important to know. Yes, in case the virus ever came, right? That would be important. So what controls competence? So you can measure it, and that's great, but what controls it?

39:00There's a lot. And so, you know, the first, there's physical barriers that the virus has to get through. So, you know, it has to infect the mid-gut epithelial cells. It has to get out into the body cavity. So there's mid-gut infection and escape. There's salivary gland infection and escape. But then along those ways, there's, you know, different immune factors that are impacting it, where the mosquito, the RNA interference responses that are, you know, the mid-gut that are trying to control that virus infection. There's microbiome. There's endogenous viruses. There's lots of different things happening within the mosquito as its own little ecosystem that the virus has to overcome in order to be transmitted.

39:39So not every mosquito is the same. So if you capture wild mosquitoes, do you find viruses in them, or is it very rare to do that? Yeah, we find viruses in them. Some could be pathogenic and some that are just there, viruses of those mosquitoes. In fact, the next paper addresses that. But before I get to that, if you could make mosquitoes not competent, let's say you're working on competence for many years and you figure out how to get rid of it, and then you can release mosquitoes and repopulate the world with non-competent mosquitoes, right? It sounds bad. There are very smart people working on that.

40:23What would happen? Would it be bad? Because we said if you took all the bats away. Well, first, let's answer this. If you took all the mosquitoes away, would that be bad? Yeah, my kids just asked me that the other day. And what did you tell them? I mean, mosquitoes are a food source out there for animals. They're probably like potato chips. Are there nutritious food sources out there for bats to eat than mosquitoes? But they're out there. So they're serving a function. Okay. So bats probably eat mosquitoes, right? They do. And birds do, right, as well? Okay. So let's go back to my original idea.

41:00If you could get rid of competence for viruses, would that be okay or would that be a problem? Do you need to transmit viruses? It would be bad for the viruses, but I mean. It would be okay, you think? Yeah. Because, you know, we can replace mosquito populations, right? People are working on that? Yeah. I just thought of it right now. Really, I did. That's what I love about these podcasts is that as people are talking, all kinds of questions pop into my head. The only thing you need to do is listen. listen people don't listen a lot these days okay and so listening is the key to everything because if you listen you'll get engaged right okay so now the next one which follows up on this modernizing the toolkit for arthropod blood meal identification so this is a title that if a lay person saw it they would say why are you doing this right so why is this important yeah so that mosquito blood meal identification, you know, something that I got into in graduate school, and it's always been very, I mean, interesting.

42:07You catch a mosquito in the field. It's got a little big fat, you know, abdomen. It's got a blood meal. What is it? Well, we could use DNA techniques to figure out what that is. But that puts some ecological context to what we might learn in the laboratory. So that, you know, provides an interaction. So if we say, oh, I remember where that trap was, that mosquito fed on a raccoon or that mosquito fed on a great horn now? Like, well, now we know that this mosquito species comes in contact and feeds on this particular animal. And so putting the pieces together for, you know, virus transmission, you know, we learn in the lab about vector competence.

42:41We know, Ken, is it physically possible for the mosquito to transmit the virus? But then we consider what's going on out in the field with, you know, what the reservoir is and all the great work that Angela has been doing. And, you know, are the mosquitoes actually biting the animals that are amplifying the virus and perpetuating that cycle. And so that adds some really important information to studies to be able to identify those connections between mosquitoes and the amplifying host. So do mosquitoes in general tend to bite the same species? Are they diversification? It varies. It varies. Even by place and time, too.

43:18So Culex tarsalis, our big vector out here, predominantly ornithophilic, feeds a lot on birds, but it also bites mammals. And that changes over the course of the summer. It shifts its feeding behavior in time. It also shifts its feeding behavior in space. If we capture Kelex tarsalis in a very natural area, it's going to have fed on a lot of different things. But we've trapped these Kelex tarsalis on feedlots and they feed on cattle. And so this is a bird feeding mosquito that will feed on anything that's in front of it. So they're opportunists. They're opportunistic. They don't shop at the same supermarket.

43:52That's right. That's pretty cool. I didn't know that. So what does the modernization refer to in the title? So it's just, you know, that review is just looking at all the different technologies that have come out in the past, you know, 10 or 15 years that people are using. And what are the pros and cons of different ones and, you know, what we've learned is advanced and what's worked best for going after that question. Are they mainly nucleic acid-based? Yeah. Have you done this in your lab? Yeah, it's a fun thing to incorporate, and it adds neat information to studies. And so you basically sequence the DNA that you get out of the blood, and since we've had sequences of many species, you can easily identify what's in there, right?

44:38Yep, yep. Are there often multiple species in the blood? Yeah, we can pick that up. But it usually has to be a case where maybe the mosquito started to feed on one animal and then got brushed off and went straight to another one. So those both blood meals are pretty fresh. But it's possible to pick up more than one. And so let me just get my biology right. So female mosquitoes take blood, not male mosquitoes, right? Correct. And they do so so they can make eggs. And they do it just once in their lifetime? They don't live long enough or do they live longer? No, they take many blood meals in their lifetime, and that depends on species, too.

45:18Aedes aegypti is going to be feeding most days, taking smaller blood meals and use that for energy, too. Other mosquitoes, they may have to digest that blood meal and lay eggs, and then they'll go look for another blood meal. Oh, so Aedes bites every day? Aegypti will, yeah, every day, every other day, frequently. That's why it's a good transmitter of viruses, I guess, right? Yes, it is. Because we'll pick up and then where others who don't bite very often are not going to transmit very efficiently, right? Less efficiently after waiting, you know, five to seven days before they would be ready to take another blood meal.

45:52Then that's, you know, a more significant amount of time. So that brings me back to West Nile. You don't work on West Nile, do you? I have before. Well, I'm going to ask you. So it's my understanding that every human infection is a new spillover essentially from a mosquito because humans don't transmit. Is that right? Why is that? Why don't humans transmit? It's a great question. Does anybody know the answer to that? Well, I always assumed it was because the viremia is not enough that if a mosquito bit them, they would get enough. Correct. But does that sound good? Yeah. That's what I tell everybody.

46:22That's what I tell everybody. But now you have the experts here. Does it sound okay? Yeah. Okay. All right. Let's see. Can bats serve as reservoirs for orboviruses? So bats are bitten by mosquitoes. They are. We've gotten mosquito blood meals from bats. Wow. Yep. And I guess this happens when they're sleeping, more or less, right? Yeah. And those results were from a study in Uganda, and they were fruit bats. And so I'm picturing, envisioning the fruit bats hanging in mango trees or whatever they were doing and feeding at dusk, and mosquitoes are biting them because they're there and they're susceptible, too.

47:01Wow. I mean, these bats are so cool, yet they get bitten like everybody else, right? Yep. But that raised the question of, can bats be reservoirs for arboviruses too? And maybe. And so it's been an interesting line of investigation. So to find out, you collect mosquitoes and you just look at where the blood meal came from and you find occasionally from bats, right? We have found that, yep. Can you collect the mosquitoes in the vicinity of where bats roost? Yep. Yep. Yep. So one of the, you know, interesting, you know, kind of circumstantial pieces of evidence in putting this together in Uganda.

47:38So we had, you know, blood meals from Keleks profuscus mosquitoes. They're from fruit bats. And we have fruit bats, you know, that we sampled blood from in areas and they were seropositive for Babonky virus. And so then Babonky virus. It's related to synbis virus. Babonky. Babonky. Great. And so then testing the mosquitoes, you know, it's mosquito pools of Kelex profuscus, also positive for Babonky virus. And so, you know, the bats are seroconverting, mosquitoes are positive, mosquitoes are feeding on the bats. And so the last thing we would need to do is do some experimental infection to see if that could happen.

48:14But that's kind of, you know, yeah, it seemed like, you know, mosquitoes are circulating Babonky virus among fruit bats in Uganda. How important that is to the ecology of Babonky virus? I don't know, but it was happening. Are any coronaviruses arboviruses? Are they transmitted by mosquitoes, in other words? No. No, not that we know of. No, they're gastrointestinal viruses, if not. Okay. So bats are bitten by mosquitoes. They do have... But are they reservoirs? That's the question. Do they serve as reservoirs where mosquitoes can pick up a virus and go somewhere else? Yeah, I think that's still a question out there.

48:57And if they can, how important is it? Yeah. So has anyone just gone into a bat colony and sampled and looked systematically to see if they're infected with arboviruses? Well, yeah. Yes. And you'll find them. We pick up a lot of flavivirus antibodies, and this gets back to the cross-reactivity. At the end of the day, a lot of times we can just say flavivirus. Okay. But, you know, there have been antibodies against West Nile and yellow fever that we've picked up and, you know, it's out there circulating. Okay. I have a little note here. So you've also worked on Rift Valley fever. And Mark also has worked on it.

49:41I'm going to ask you about it too. But what things are you doing now that we haven't talked about that's not published? uh right now well we're um or you know recently published too i can say that so we're we're um you know involved in collaboration with ipc our health institute in tanzania um so we have some field field work with rift as well um and so looking at viral ecology with a number of different partners um and so recently published paper at robert sumay is the first author i'm looking at epidemiology of rift. And it's, I think, you know, there's, there seems to be more and more evidence coming out, you know, our historical understanding of rift, valley fever is these big, big epizootics every 10 to 15 years with the El Nino climate cycles on in East Africa.

50:29But, you know, it seems like from, you know, the data that are coming out that there's also these pockets of endemicity where it's just always there. And it's circulating and you have, you know, pretty high degree of seroprevalence in people and animals and, you know, the mosquitoes that we tested were not what we were considering to be primary vectors. And they were being collected during the dry season. So nothing to do with rainfall. And they were positive for the virus. And so there's some interesting aspects of the ecology of rift, I think, that deserve a lot more attention outside of responding to outbreaks and just trying to understand longitudinally what's going on.

51:06Okay. All right, Mark, tell us your overall interest in the lab. Yeah. So the last time we talked, it was about snake viruses. And when I first got to CSU, my lab started working on snake viruses. But we found ourselves in this building, in this group of labs called the Center for Vector-Borne Infectious Diseases. And it's a lot of people here work on lots of different arboviruses and mosquito-transmitted viruses. So now my lab has sort of switched to working more on insect viruses and not so much on snake viruses. But that brings up my question. I was going to ask you, but I forgot. So do mosquitoes bite snakes?

51:45Sure, yeah. Really? Yeah. Reptiles, no problem? Yeah. But not fish, right?

51:53Because the fish are underwater. Maybe the flying fish when they're jumping out of the water. Is there anything not bitten by a mosquito? Yeah, I guess fish. Whales, right? Yeah, whales. Maniches, we can go on. Okay. So, yeah. So now we're working mostly on insect-infecting viruses. And we really have, I'd say, a couple main projects. One is much more basic. And that's on a virus that naturally infects the model organism, Versophila melanogaster. And so that is a really kind of remarkably successful natural virus of those fruit flies. So if you, this summer, if you have fruit flies in your kitchen buzzing around the bananas or maybe around the peaches here in Colorado, those fruit flies are almost certainly infected by this virus that we're studying.

52:46So it's a really nice project that combines the ability to sample these flies in the wild with all the abilities of all the different tools that are available for a model organism like Drosophila monogaster. So that's one project. And then the other project is working on buniviruses, and that is really about virus evolution. That's a project that we're collaborating closely with Greg Ebel's lab, also here in the building. And that's really about bunyavirus evolution. And really the questions there are, one, we're trying to understand if two viruses that were previously separated were able to meet in an infected host, in a co-infected host, would they be able to reassort?

53:33And reassortment is this process where viruses exchange genome segments to generate new viruses. When you're talking about influenza viruses, you have H5N1 or H1N1. Those genotypes referred to by H5 and H1, those are reassorting genotypes relative to each other. So it's like shuffling of genes, shuffling of viral genes. So that project's really about reassortment, and we're trying to understand what are the rules that determine whether viruses can reassort or not. It's also about this sort of other evolutionary question, which is, you know, when you're shuffling genes, you're combining genes that haven't had a chance to evolve to work together.

54:10So how do viruses solve the problem of having these incompatible genes? How do they end up making functional combinations from genes that hadn't previously evolved to work together? So you're not doing snakes anymore? Yeah, not so much. A little bit. There's a little bit of interaction still with that community, but not so much. Okay. So you wrote a really interesting commentary not too long ago, The Case for Studying New Viruses of New Hosts. Yeah. And I think people should hear about that. So tell us what that is. Yeah. I mean, I said earlier that I think science is cool, and I think it's cool.

54:49I also think it's fun. I think that's one of the main reasons to do science and be a scientist is because it's pretty interesting and it's honestly fun. and so I'm personally motivated. We're in a department and science as a whole, especially NIH-funded science, is really a lot of the times people rationalize their research in terms of the importance to human health and the importance to the economy, but for me, honestly, a personal motivation is really just like curiosity and doing fun things. So that's sort of where that that commentary came from. Just this idea that it's fun to go out and explore new things.

55:28And the other part about it is beyond it just being fun is that you can really learn a lot of really useful things. In fact, a lot of the most transformative advances in science are totally serendipitous and were unpredictable before they happened. CRISPR is a good example. It's like being used to correct genetic problems in people, and it's being used as a therapy. But that was totally unpredictable from the early CRISPR papers. It was just some weird bacterial thing that people noticed in, you know, these weird repeated sequences that people noticed in bacterial genomes. And the first papers were not published in really high-profile journals, but it ended up being really important and is probably going to be really important going forward.

56:12So that commentary is just sort of reviewing all of the different advances that have been made in infectious disease research that were just based on kind of studying random viruses and the way that made us better able to respond to pandemics. So for instance, the mRNA vaccine technology, a lot of that was driven by research that was not really high profile at the time, but really set the stage for being able to respond more effectively when the pandemic did happen. So that was the point I was trying to make in that article. So this issue of serendipity, right, we all know it's really important, but most people don't get this.

56:53They want focused research. They want you to cure cancer or diabetes or some other, right, make a vaccine. But as you just said, the way you get there is by letting scientists do what they want. But depending on who's in charge in this country, it's not so appreciated. So what can we do? Yeah. I mean, I think one thing we can do, I don't, you know, one thing we can do as scientists and as like the funders of science in this country is fund a broad range of research on a lot of different topics and not just research that is on paper translational research with some like supposed immediate benefit because honestly a lot of the translational research is great but i don't think it's necessarily even more likely to lead to like important advances than just pure science curiosity-based research um so i think you just have to fund a broad range of research um i mean this whole issue of serendipity it it reminds me of some a story from when i was hanging out with my my wife's family once on the fourth of july it's about to be the fourth of july um And we were at her family's lake cabin in rural Minnesota, and they were doing like a homemade firework show.

58:08And it was a little bit sketchy, to be honest. And so we're sitting around. It's like late at night, right by the lake. They're shooting up fireworks. And a firework misfires. And it like comes down and the shells start like landing in amongst the lawn chairs where everybody's sitting. and everybody gets up and like scatters because they were running away from these fireworks that are like exploding and my wife and her sister stayed there they sat in their chair and they I said later I was like why didn't you run away and they're like we're just as likely to get hit if we run away as if we stay here and I swear there's a connection um I feel like that's what research is like like you don't know those fireworks exploding or like the next big discovery you don't know where they're going to go off you might as well just you know running to try to chase things is not going to get you somewhere.

58:58I feel like that could be a strange analogy. I understand. So there was a story in the news recently. This guy at Harvard just had his grant taken away and they said, your research is of no interest to the American people. And it's like, how do you know? How can anyone predict what is of interest until you do it? Right? So this is the problem that people don't understand this need to just let good scientists wander. So anyway, that's why I wanted to bring this up. So the other issue that is embodied in this studying new viruses, we have used, in virology, we have depended on model systems, right?

59:38You have a polio or a smallpox or a flu. Sometimes they are medically relevant, but not always. But not every virus you discover can be a model system because you need to develop cell cultures and animals and so forth. So you end up doing a lot of cataloging, right? Yeah. And I think that it's an issue with discovery of virus sequences by metagenomics. And so my lab has done a lot of metagenomics where you discover a new virus sequence. But I think you wrote a commentary back in 2016 called Moving Beyond Metagenomics or something like that. And And it made the point, and it's a point I completely agree with.

1:00:19It sort of shaped how I think about my lab is finding virus sequences is one thing, but you really need to do the next step and do experiments. So that Drosophila project is sort of an example of how I'm trying to do that. Do you think that we should know everything that's out there? Like find all the virus sequences? Yeah. Sure. I mean, you do learn things by finding new virus sequences, And it's really easy and getting easier and even less expensive to find more virus sequences. And if you go outside, if you go in the courtyard and sample any plant or any insect, you're going to find, you know, five new viruses.

1:00:56So I think that there's value in doing that and there's value in doing more focused follow-up studies of some of them. So what fraction of all the viruses out there do you think we know? Gosh, it's got to be less than 1%. Really? Yeah. I mean, that's just, I'm making that up, but that's, there's, I mean, there's, other people have done the math and there's, I mean, there's, there's at least one, you know, there's, there's, you, you can estimate it by saying how many viruses per species and how many species there are. So it's like the number of species on earth, which is a really big number times, say 20 viruses per species, which is probably not, not, it's probably even more than that.

1:01:35I mean, I think it's important not just for humans, but animals as well, to know what's out there and what might be a threat, right? I don't know if you saw this recent story out of China. There's a shrimp virus that started infecting people. Huge host jumper. I've never seen something, but people handling shrimp, crustaceans, somehow they get the virus in there and it causes a human infection. So that's why you need to know these things to be prepared, right? Okay, another paper I'd like to talk about, Rapid Evolution of SARS-CoV-2 in Domestic Cats. Yeah, so that's a project that really is from Sue Vandewood's lab.

1:02:13She's the dean of our college, and her lab has a long history of working on cat viruses. So I was on the committee of one of her students, Laura Boucher, who did a really good job studying SARS-CoV-2. So this is another story of SARS-CoV-2. SARS-CoV-2 infection in other animals. And so this was in cats. And so really just like trying to understand what happens to the virus after it jumps into new species, which is a really interesting kind of basic virus evolution question. And so using domestic cats as a system to study that. So do cats naturally get infected from their owners, for example? Yeah, they do.

1:02:52Do they get sick? I don't know, Angela. You might know better. Rarely. Rarely get sick? They can, but not usually. Okay. And do they transmit it to other animals? Rarely. They can, but it usually doesn't go much farther than cat, maybe to other cats. Maybe they're not shedding very much. They don't shed as much, and they don't shed for very long. And especially with newer variants, they shed less than people. Okay. But what this study found is that when the virus enters a new host, it diversifies and changes, which is what you would expect, right? And so maybe those changes are adapting it to the animal and maybe preventing it from going back to where it came from.

1:03:29These are the interesting questions that come from that kind of thing. Do you think that, I asked you the same question, but I'll ask you, do you think these infections of animals with SARS-CoV-2 are threats for future human spillback? Yeah, it's a good question. I suppose there's this possibility that the virus could evolve in a way that changed its properties, changed its phenotype, and then were it to reinfect humans, that could be problematic. But I think, like Angela said, from a pure numbers standpoint, I think the probably biggest likelihood of getting infected is from another human. Yeah, right.

1:04:03Because even deer don't seem to give it back to people. And a lot of deer are infected. Okay, that brings us to Rift Valley. So I resisted asking you about Rift because I want to ask you. But you can chime in. Okay. Especially if he says something wrong, right? Rift Valley fever virus. So safety of a Rift Valley human vaccine candidate in mosquitoes. Oh, this is very interesting. So first, tell us what Rift Valley fever virus is. Yeah. So first of all, I'll say Rebecca is far more of a Rift Valley fever virus expert than I am. Well, she's here. Yeah. And so Rift Valley fever virus is a virus that, you know, mosquito transmitted, causes big problems in other parts of the world.

1:04:46Not here yet. And so there's a vaccine under development. What does it infect? So it infects cattle, it infects humans. Yeah, small remnants in cattle are mainly amplifying. So it's agriculturally important. It's very important agriculturally. And when it infects people, is it bad? It can be, yeah. I mean, it would cause febrile illness, but then it can progress into very severe hepatitis disease, central nervous system involvement, and hemorrhagic fever. And how is it? It's mosquito transmitted because that's in the title of your paper. Okay. Okay, so now we know what it is, and we have a vaccine candidate.

1:05:23Yeah, so this is an interesting vaccine candidate. It's an attenuated virus where they've deleted two genes out of the virus. And this is a bunyovirus, three-segmented RNA virus that doesn't have that many genes. It has like five or six genes. And they've deleted two of the genes to create this vaccine. And I believe it's from Brian Byrd at UC Davis, the originator of this virus. vaccine candidate. And it's being evaluated for efficacy and safety. And so this project, and I should say deletion of those genes, it does not diminish the ability of the virus to replicate. So these are like these sort of accessory genes that do something else.

1:06:08But not that the virus still from a basic replication standpoint is fine. And so the purpose of this study, which was mostly run out of Rebecca's lab, was to make sure that if a human got vaccinated with this vaccine, the virus was attenuated, but it'd be replicating the human. If a mosquito bit that human, would then the mosquito be able to transmit infection to another animal? And it turns out that the answer is basically no. if there's really very diminished ability for the mosquitoes to transmit it because the virus is weakened. And one of the reasons is probably because these genes were deleted that are important for replication of mosquitoes.

1:06:51So normally in RIFT, do mosquitoes bring it from human to human? It's possible. I think people can develop viremias high enough to infect mosquitoes. But mostly it's from a non-human animal to a human. I think that would be hard to determine in the field. I think mosquitoes would probably start it with animals, but then people can also become infected by handling infected animals, so then you don't really know the origin of infection at a certain point. So in this paper, how did you assess what you just told? How did you assess whether this would be transmissible to some other animal, the vaccine particularly?

1:07:32So this was through experiments like Rebecca was describing, where you can blood feed mosquitoes experimentally and then assess whether they have virus in their saliva, which is a very good proxy for whether they'd be able to transmit it in a subsequent blood feeding event. I presume you did some genomics on this, right? Yeah, that was my role. That is really the mosquito rift person. And what did you look at in terms of genomics? So we were just looking at the, you know, validating the sequence of it, making sure that the vaccine didn't revert, for instance. Okay. Because you delete these genes, make sure that there was no reversion of that deletion, which would be bad.

1:08:14You don't want it to revert. Or it could reassort with another bunyovirus in whatever host. But this is a human-specific vaccine, right? Yeah. That's the idea, to protect people against disease. So the idea would be mosquito could take this and bite an animal somewhere that has a bunyovirus. it would reassort and now make regular or worse Rift Valley fever virus, right? Well, I mean, the argument is if a wild-type strain reassorts with the vaccine strain, it's going to attenuate the wild-type strain. But yeah, this was an interesting project, too, from the regulatory standpoint. Just because the vaccine is derived from an arthropod-borne virus, it qualifies under the genetically modified organism licensure rules.

1:09:01And so we had to demonstrate that it's safe from release into the environment as a vaccine strain. Oh, that's interesting. So yellow fever vaccine never had to undergo that, right? Because it was developed so long ago. Maybe so, yeah. Are there any other vaccines for arboviruses? We had to do similar safety studies for the Ebola vaccine because it's derived from vesicular somatitis virus with Ebola virus glycoprotein. And so we had to put that in mosquitoes and make sure it wasn't transmitted. So I guess if you had a West Nile vaccine for people, you would do the same thing. Yeah. You would have to.

1:09:38Yeah. Okay. So Mark, what else is going on that you'd like to talk about? Yeah. So a project that I haven't talked about was a spinoff of this Drosophila project. And that was, we've, this is now a preprint, but it's been in review for the, this has been the hardest paper to publish that I've ever experienced. It's been in review in various forms since 2024. And that is a project of a former PhD student, Lexi Keene, who's now doing a postdoc in the UK. And that was sequencing RNA from entomological museum specimens that were up to 100 years old. So there's this idea, if you've worked in a molecular biology lab, you've probably been trained to be really careful about RNA, that RNA is very unstable and it's, you know, you need to wear all the gloves all the time and use special reagents.

1:10:30And so there's this idea that RNA is very short-lived, because it is, in fact, short-lived in cells. But there's been a lot of...there's been a decent amount of published evidence that RNA might actually survive well in, like, dried biological samples. So this was a project where Lexi went back and got...so, insect museum specimens from, you know, as far back as the 1890s. and has showed that RNA survived really quite well in those specimens. And sequenced the RNA. It's all, I mean, it survived. It's very fragmented. Like, it's like little tiny, you know, 30 base fragments of RNA. But it's there, and you can make a sequencing library from it.

1:11:10And you can recover host RNA. You can recover virus RNA. You can assemble the virus genomes. So we're, you know, we were reconstructing virus genomes from infections that happened 100 years ago. which is kind of cool. That's sort of right when some of the specimens she sampled were Drosophila melanogaster because we're interested in Drosophila viruses. So as she's sampling Drosophila from the time period, the early 1900s, when Drosophila genetics was emerging as a field and when people were figuring out what viruses were and how they worked. So it's been a pretty cool project. So you could see, were some of the insects Drosophila in these museums?

1:11:50Yeah, we specifically requested Drosophila specimens. And you can see some of the same viruses that are around today. That's right, yeah. What are some of these viruses that infect Drosophila? So the one we're working on, the main one, is called Galbit virus. It's a double-stranded RNA virus, vertically transmitted. So it's an inherited virus, which is an interesting idea for viruses to be inherited from your parents. It infects the flies throughout their lives. And they're fine. Yeah, apparently. Although we see an interesting phenomenon where in lab populations, they lose infection over time.

1:12:22So there's clearly some kind of fitness cost that we don't understand. Yet 75 % of flies in nature are infected. So there's something we don't understand about the fitness costs. You know, in yeast, many viruses are also inherited. They don't have capsids even. Does this Drosophila virus have a capsid? It does have a capsid. We recently generated some cool EM images of the capsid. So it's a capsid, but they're basically cytoplasmic capsids. They're sort of pretty good evidence they don't actually even do cell-to-cell extracellular transmission like you would normally think of a virus. Do they replicate, and then as the cells divide, they're partitioned?

1:12:59Yep. So related viruses in plants, like if a plant is infected, you can graph that plant onto like a root stock, and the root stock never gets infected. Got it. It's all by cell division during mitosis and meiosis. this. Okay, I have one more question for all of you. So we'll start with you, Angela. If you hadn't been a scientist, what would you have done? Oh, good question. I'm currently cycling between two things that I would have done if I'd have been smarter. One of them is I just love being out in nature, but also love like landscape. And so I probably would have gone into some sort of horticulture field.

1:13:35And if I was a better musician, that was my first love. But you know, that's not a great way to make a living or make yourself happy. So that was it. What instrument did you play? I'm a singer. You're a singer. Okay. So you maybe would be a singer and be famous. Yeah. Oh, yeah. Sure. Okay. That's cool. I like that one. Rebecca, you already answered this, but maybe you'll give a different answer. What would you have done? I mean, the track I was on was performing arts and ballet. So how long did you do ballet? Up until I was 19. I took a gap year. Well, I went to performing arts high school my senior year, and then I took a year and danced in Philadelphia.

1:14:18And that's a whole saga. Why didn't you do it? It was too hard? You didn't think you'd be good at it? It just wasn't panning out to be what I was hoping it was going to be. Plus, you can't go past 40 probably, right? Right, right. So, yeah, it was a lot of life-changing decisions at that juncture. But I'm also a violinist, so we should form a band. I know. I was just thinking it. Then we will be famous, so give us a few years. Do you still sing? I do. Okay. You guys should do that. I know. It's on our list. So every year I have a bona fide ballerina in my virology class at Columbia, right, New York City.

1:14:54We have a couple of ballet corps, and they're people who are actual dancers. I had a dancer from the New York City Ballet who, and I said once, why are you, she actually got the highest grade in the course. It's amazing. Why are you taking virology? She said, I want to be a doctor. I said, why? She said, well, I've been injured my whole career, and now I know so much about injuries that I want to be a doctor. And she was, you know, she said, I can't dance forever, and I want to do something else. But they were all very smart, very interesting. Thank you. Mark, what would you have done? Yeah, I mean, I guess I sort of did have a previous career as a computer programmer, so that always seems like it could be a good option.

1:15:36But honestly, the job that always seems really appealing to me is driving a riding lawnmower and having a really big field where I just like all day just back and forth. And maybe I could listen to a twib or other podcasts. Yes, but that just seemed really like, I think I would like that. Isn't that science, basically? Yes, yeah, Hershey Heaven. Well, that's what Einstein said. He said, I don't like scientists who take a piece of wood, find the thinnest part, and drive a lot of nails through it. He didn't like that. All right, that's very interesting. I used to cut my parents' lawn, and I used to ride on that.

1:16:19It wasn't very interesting. It wasn't? No, because I had to do it for them. That was the problem. All right. That's a special episode of TWIV. You can find the show notes at microbe.tv slash TWIV. If you have any questions or comments, you can send them to TWIV at microbe.tv. And if you enjoy these programs, we don't do ads on our programs. We depend on your support. If you like them, we'd love to have your support. You can go to microbe.tv slash contribute. Microbe TV is a 501c3 nonprofit. So in the U.S., your donations are federal U.S. tax deductible. My guests today from Colorado State University, from biomedical sciences, Angela Bosco-Loth.

1:17:06Thank you so much for joining me today. From microbiology, immunology, and pathology at CSU, Rebecca Kading. Thank you so much. Thank you. And from microbiology, immunology, and pathology, Mark Stenglein, thank you so much for joining me. I'm Vincent Racaniello. You can find me at microbe.tv. I'd like to thank the American Society for Virology and the American Society for Microbiology for their support of TWIV, Ronald Jenkes for the music, and Jolene Ramsey for the timestamps. You've been listening to This Week in Virology. Thanks for joining us. We'll be back next week. another twiv is viral.