69 Michelle Flenniken – Bee viruses (in English)

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Speaker 1: From the Oregon State University Extension Service, this is Pollination, a podcast that tells the stories of researchers, land managers, and concerned citizens making bold strides to improve the health of pollinators. I'm your host, Dr. Adoni Melopoulos, assistant professor in pollinator health in the Department of Horticulture. In past episodes of Pollination, we've talked about some of the factors that contribute to poor pollinator health. We've had a number of episodes, for example, that have focused on how to create pollinator habitats and how to reduce the exposure of pollinators to pesticides. But in this episode, we're going to come to another really important factor, and that is the diseases that pollinators face.

And one set of diseases that's particularly curious, and I thought this was a great occasion to reach out to Michelle Flanagan, who's one of the world's experts on honeybee viruses. Dr. Flanagan is an assistant professor in the plant sciences department at Montana State University. She is the co-director of the Pollinator Health Center at MSU. You remember on episode 60, we had Dr. Bob Curtis also from the Pollinator Health Center. In this episode, Dr. Flanagan is going to peel back the very crazy and strange mysteries of viruses and their association with bees. This is a great episode to learn one of the cutting edges in pollinator health bees and viruses. I hope you enjoy the episode.

I am really excited. I'm on the other side of the Rockies. I'm actually in Calgary today, and I'm joined on the same side of the Rockies with Dr. Michelle Flanagan. Welcome to Pollination. Thank you. I'm excited to be here. Well, I'm excited as well, because I've been, you know, I noticed that we are heading into flu season, and I know I hate the flu. And I know people may be surprised that insects also suffer from viruses.

And I thought this was a great opportunity to get you on the show. So to begin with, how do honeybees even get infected with viruses? They don't sneeze or anything like how does a virus get into a bee?

Speaker 2: So honeybees are infected with viruses, just like you and I are. One of the ways that honeybees pick up viruses is they can pick them up from pollen or floral resources. So if an infected bee lands on a flower and then later an uninfected bee lands on that same flower, they could pick up a virus at that same time. Unlike when you and I touch a doorknob after somebody has sneezed and not properly washed their hands, we could also pick up the influenza virus on that doorknob.

Speaker 1: OK. OK, so they can pick it up on flowers. Is that the only way? Yeah.

Speaker 2: No. And then we also, virologists use this term called vertical transmission. That means that bees can get viruses from the queen bee actually through the eggs or from the front. So the viruses can be sexually transmitted, just like viruses in mammalian populations can be. And then many of us are probably familiar or I've seen bees doing this action called trophallaxis or mouth-to-mouth feeding.

Yeah. So bees can transmit viruses that way. That's a really good way. And when you think about a bee colony, it's a great place for viral infections. And they're really crowded. If you think of honey bees with over 40,000 individuals crawling all over each other, great for virus transmission. So we call that horizontal virus transmission. And bees can pick up viruses just from each other as well. Another major factor and probably the most discussed is that borough a destructor might this ectoparasitic might that parasitizes bees. It can bite bees and transmit viruses, particularly deformed wing viruses to the bees and from one bee to another. And so that's a really important way that bee viruses are what we call vectored. So that's the borough a destructor might kind of act like a tick or a mosquito, which we kind of all appreciate transmits human viruses.

Speaker 1: Oh, right. So as many listeners who've heard previous episodes know, these mites are everywhere. All the honey bee colonies have them. So I guess they're just constantly just like a mosquito vectoring around whatever virus is already in the colony.

Speaker 2: Right. That's another good reason to monitor your mites if you're a beekeeper and keep those mite levels down so that way you can reduce the chance of the virus spreading due to mite infestation. And so when a bee colony dies due to mite infestation, then those mites are going to need to find a new home so they can get on robbing bees. Robbing bees would be those that would be coming into that dead colony taking it through sources and bringing it back to the colony. But at the same time, they could take those mites from the dead or dying colony back with them. And of course, then the mites, the mites, harbor viruses.

Speaker 1: Oh, right. OK. And we had a really good show, I think, with Ellen Toppenshofer out in Oregon talking about how these mites can really move from apiary to apiary. So that's OK. All right.

So doorknobs and mosquitoes. I got it. All right.

That's really simple for me to understand. Well, I guess, you know, just building off what you said, I can totally understand when, you know when I pick up a scientific journal article, it just seems like there are always these new viruses being found. Just to maybe break it down, how do people find these viruses in the first place?

Because you can't like to see them or anything, I guess. And how many do we know about? And are we kind of at the limit or are there just going to be many, many, many more viruses to be found in honeybee colonies?

Speaker 2: Right. So virologists discover viruses in many different ways. Sometimes they investigate different sick animals and try to discover what's causing them to be sick. But more recently, there has been a new technology called high throughput sequencing.

And sequencing has enabled scientists to take any sample, whether that's from a bee or human specimen, and basically sample all the nucleic acid in the tube. And when you think about viruses, viruses are just a little tiny and you're right, they're small, so they're very difficult to see. Many of the viruses that infect bees are only 30 nanometers in diameter. And so that means about 2,000 of them could fit across the diameter of a single hair. And a lot of them look the same.

So under a transmission electron microscope, many of them just look like little soccer balls. So we use their genome or nucleic acids to identify them. We use high throughput sequencing, meaning we sequence a lot of samples and it can be done, they say it's the cost has gone down and that's true.

But it's not that cheap to do high throughput sequencing still. But that's how scientists have discovered many more bee viruses. So importantly, these are new to science or new to us, but maybe many of them are not new to bees. We've recently discovered them, but they might not be new.

Speaker 1: That's good because you know, you read about it in the newspaper or something and you think, oh, it just got discovered, but it could have been there and we've just been able to characterize. OK, that's real clear.

Speaker 2: And every time I go to a beekeeping conference, of course, they don't want to hear about yet another thing that can infect their bees. But from my perspective, it seems important to know everything that can infect them. And that way we have this great baseline to better study what are the major factors that contribute to weak or weak colonies or colony losses. Oh, that's a really good point.

Yeah. And I don't know how many we expect to find, but we'll definitely discover more. And part of that is because of the way we prepare the samples. So many bee viruses are these small little RNA viruses that I said look like little slacker balls. And when we make the sample preparation, we are kind of maybe augmenting for that type of virus. And if we would prepare our samples in a different way or even make what we call nucleic acid library in a different way, we're going to discover different types of viruses.

So most recently, many negative-sense single-stranded RNA viruses that are the particular category of the virus have been discovered where predominantly we were kind of looking for positive-sense single-stranded RNA viruses before.

Speaker 1: Oh, because of what you said, we were preparing the samples in a certain way. And so we'd find the positive ones. And now we're using some other methods and we're finding the negative ones.

Speaker 2: That can be true. Yep. It depends on the actual handling of the nucleic acid, which is probably a little bit more detailed than your listeners want to get into. And then, but that does matter.

Like how you do it. There are also DNA viruses, but only one of those has been described as box bees. And that's in part because these viruses are in general larger in size. And so depending on how you prep that original sample, you may have inadvertently gotten rid of other DNA viruses that would have been in your sample. OK.

Speaker 1: So we may find some more and it sounds pretty, it sounds like a pretty tricky art finding them.

Speaker 2: I think it could be, it could be considered tricky, but really it's all about how sequencing technologies have got cheaper. So more people are using them. We'll use them now in a variety of different bee species. Most of our work has focused on honeybees for a long time. And of course, there are thousands of different bee species from which to look at. Then we have to prepare the sample and then sequence it. And depending on how we do that might influence the category of viruses that we discover.

Speaker 1: OK. OK. All right. So technology is going to be cheaper. More people are doing it. And so I imagine we're sampling more and more bee colonies. Are we finding that there are some common viruses that a lot of US honeybee colonies have?

Speaker 2: Yeah. So there are still some major ones that had kind of been described early days with Bailey and Ball and by transmission electron microscopy and antibody-mediated techniques for you to discover the first bee viruses like black queen cell virus and deforming virus, sacroid virus, things like this, chronic deprolsus virus as well. And so those are the most common bee viruses. So I guess when you think about it, the ones that were discovered first are likely the most common and abundant, although there are others.

For example, we discovered a new virus called the Lake Sinai virus group, which was named after Lake Sinai, South Dakota, near where we gained the first sample. All right. But these viruses are very abundant and widely worldwide distributed.

Speaker 1: OK. All right. So these viruses have funny names. So Lake Sinai virus is the one that deform wing cell, the form wing virus, you said. What are these courses? I guess the one is a point of discovery. But these other ones like the black queen cell virus you mentioned. Is this what the symptomologies are like of the viruses? Yeah.

Speaker 2: So viruses can either be named after symptoms. And you're right. Black queen cell virus was first discovered because it is called this black end queen cell and the queen cell is the wax compartment that kind of looks like the shell of a peanut on the outside of a typical honeycomb pattern where the queen bee develops and they saw a blackening of that larva. So then they isolated this virus from this black end queen cell and they called it the black queen cell virus.

So that makes sense. Other viruses like chronic bee paralysis virus can often be detected because they create greasy, shiny bees that exhibit paralysis and then have this name. But then what's the unfortunate thing with these obvious names is that there are plenty of bees that test positive for the black queen cell virus and chronic bee paralysis virus, but they're not exhibiting these overt symptoms. And so then these names become kind of too bad, you know, or a bee can have deformed wing virus, but not have deformed wing.

Speaker 1: Oh, that is real. I'm glad that you clarified that because that can be confusing. So if somebody, you know, had the virus detected, they would expect to find these greasy, paralyzed bees, but it looks fine. OK, so the symptoms. Yep. OK. It's sort of like the method of discovery. People started by finding weird bees and trying to figure it out. OK. All right. Yeah.

Speaker 2: And then another thing is, is that virologists to kind of get away from that little bit of source of confusion then can name viruses after geographic landmarks like mountains or rivers and things like that. And so that's how the Lake Sinai viruses were named. And then you'll also notice that none of the viruses that we talked about so far have the hostname, but we know that honey bees are Apis malifera and that this large DNA virus that they discovered, they called Apis malifera filamentous virus. But then the problem with including the genus or species name from which the virus was discovered is that a lot of these viruses, in fact, a range of bees or a range of insects and even arachnids like arora. And so naming, putting the genus and species name from which it was discovered can also be very confusing.

Speaker 1: Well, let me get this straight. So some of these viruses that are in honey bees can be in other insects.

Speaker 2: Yeah. In particular, bees, bees, I think about many of us get kind of human-centric when we start to think about viruses and pathogens and we think that, oh, there are specific viruses that infect humans versus the ones that infect horses or dogs or cats or chimps.

But for insects and plant viruses, viruses can have a broader host range, which includes completely different insects in different genres even, as well as I mean, varroa and destructor mites are kind of far away on the tree of life, and deforming virus likely replicates in both the mites as well as the host honey bee. Wow.

Speaker 1: OK. All right. So this is really tricky. OK. Well, let's take a break I want to come back and I want to talk a little bit about how beekeepers can respond to these viruses or what it means when they have these viruses in their colonies. OK. We're back. We had a really interesting conversation during the break.

Always do. And, you know, I think I didn't quite appreciate how strange viruses are from other like other cells, other living cells. So just maybe walk us through a virus that gets into the bee and then what happens? Like, what does the virus do then? Yeah.

Speaker 2: So viruses are different than cells or other organisms in that they are obligate intracellular pathogens. At first, that sounds like a mouthful, but that means that they need a host cell to replicate.

OK. They can't do it themselves. So they have they encode genes and they encode genes that include to make their capsid, which is if you picture an M &M, which I often like to describe virus as the M &M, the hard candy shell on the outside is like the protein shell of the virus. OK. And then the chocolate center of the M&M would be all the nucleic acid or all the genomic information.

And that's what scientists like me used to detect and quantify viruses. OK. All that chocolatey center. OK. But now when we think about a virus getting into a cell, it can't replicate on its own. And so it needs to use the host machinery to replicate. It needs the host to make its protein.

Speaker 1: OK. Oh, OK. This is the difference. This is the big difference because all, you know, in my cells, they're constantly making these proteins that, you know, I live off of.

But to build another virus is going to hijack the host, the honeybee cell to make it. Yeah. OK. Gotcha.

All right. OK. A beekeeper sent this listing of viruses. I know people can do this in various places and in their colonies. How are they going to interpret this kind of, you know, I've got six different viruses. Where do they go from there?

Speaker 2: Yeah. So I think this is a really good question, one I also get a lot from local beekeepers here. So it kind of depends on where their test came from. So we know that the bee-informed partnership does provide some viral testing. Often they collect samples at the apiary level, so from several different colonies that are sent for analysis one time a year. OK. And so then the beekeeper will get back this report from just one test. And All this does is give the beekeeper, what I call a snapshot of the viruses that are present in their colony at any particular date or day of the year.

OK. And so although that's kind of interesting, it's really more important. The only studies that we're involved in are called longitudinal monitoring projects or temporal monitoring projects at the colony level, meaning we take samples from the same colony over time and then correlate that to the health of the colony. And we use colony population size as a proxy for health. So a honeybee colony with lots of bees would be considered healthier.

OK. A honeybee colony with fewer bees would be considered weak. So when beekeepers get this report back, all they're getting is a list of viruses associated with that given sample. If that given sample is from something like a whole apiary, which could have, 50 colonies or even more, then really you're just getting a complete snapshot of what viruses are present. And often we find viruses are present in bee colonies.

That's pretty common. Just like if we did a sample of samples from all the school buses around town, that as they go to school, we're going to get positive viruses for a lot of things like rhinoviruses that cause colds in humans. OK. And so I think it's more informative to take samples over time from individual colonies, because our studies and others have demonstrated kind of the dynamic nature of virus infection in individual colonies that maybe they have a certain virus this week, but three weeks later, they won't test positive for that.

Speaker 1: OK, so if you do these snapshots, I guess what might happen is you may be at the peak of that kind of dynamic cycle or you may be low down and you don't see it. So it doesn't it may not tell you much about what you said at the beginning. The ultimate measure is how many bees you have. Yeah.

Speaker 2: And so then we do see and in general, like in several studies now, there are some general trends like deforming virus levels tend to go up in the fall and that also correlates with increased levels of mite infestation in general. That's kind of a general statement that holds. A grad student in my lab, Will Glany, published a study in Plus One that really has an I like the figure because it's quantitative PCR.

So it shows. was how much of each virus is there at any given time. And then it's a colorful kind of wave of the abundance changing. And it really is a good illustration of this dynamic nature of viral infection that we were just talking about.

Speaker 1: Okay, all right. So I guess the first point is if a beekeeper gets this list back to sort of be conscious of the fact that it may be pooling a lot of colonies together and you're gonna inevitably find something. The other thing is that it may not ultimately correlate with the colony's health because it really is this, it can't sort of, you can't envision this wave that you see in the research.

Speaker 2: Yeah, and then another thing I think about, and the first thing I always say is that's completely normal. We see viruses in healthy colonies all the time. Another important outcome of our longitudinal monitoring studies has been that, depending on when you look, we did one study that showed pathogen prevalence, so the number of pathogens you tested positive for in February was greater in weak colonies than it was in strong colonies.

And that seems like such an obvious statement that people assume that's true all the time. But then if you look in those same colonies and you look in spring when the population is building up and it's a different time in the life cycle of a colony, they can test actually positive for more viruses but actually have more bees. And so more research on the dynamics and how that impacts colony health is needed spite the fact that there've been several studies done. Most of those have been at the apiary level. So then we kind of need to dial it down a little more fine-scale to really understand what's going on.

Speaker 1: Well, I guess this raises a question. I'm thinking about the first part of the segment that we did was constantly finding new viruses and new techniques and sort of building what we know as we go. And I guess the second part is that this question of being able to answer to the beekeeper, clearly these viruses are having an effect is gonna be based on really looking at this problem more than cataloging it, really kind of thinking about how it's interacting with colony health over time.

Speaker 2: Yeah, and the test that they get back, if they had them at the colony level, maybe that would help inform them about which colonies that they'd wanna get cells to graft queens from.

Like maybe you would choose the one that had less viral. So at certain times of the year for certain beekeepers, potentially especially those that breed their queens, they may be informative. Otherwise, it may not be that informative to get that snapshot test.

Speaker 1: Well, it raises this question, given what we know and I understand we're sort of just piecing together what we know, is there anything beekeepers can do to reduce damage caused by viruses?

Speaker 2: Yeah, so one of the things that I always recommend beekeepers do is be vigilant about tracking their mite levels in their colonies. So that means monitoring periodically, and monthly, and administering anti-mite treatments as needed. The Honey Bee Health Coalition has an excellent guide, which is available online and even via our MSU Pollinator Health Center resource page, that describes several anti-mite treatments, including organic options. And it's known for sure if you reduce your levels of mites, you'll reduce your levels of deformed wing virus, so at least one of the viruses. Now not all viral infections correlate with mites loads, but reducing your mites is definitely something that beekeepers can do. And then another thing beekeepers can do is kind of just bolster the health of their colony in general by providing adequate nutrition.

That could be by situating their colonies in suitable sites or providing supplemental nutrition, like protein patties, but more research is needed in this area to just make sure what the role of nutrition and pathogens, but I guess I feel confident at this stage I just like with humans, if your nutritional status is better, your immune system will be likely better to fund off pathogens.

Speaker 1: Okay, that makes a lot of sense. Maybe just to wind this up, just kind of, and it sounds like viruses seem kind of just generally weird and their effects seem kind of nebulous. So can you tell, in your mind, what are some of the most pressing research questions around viruses and honey bees? Like what do you see in the next five years being some of the big questions that need to be asked?

Speaker 2: Yeah, so I think viruses are actually very interesting, but they are weird in the sense that they need their host cell to replicate. But we can learn a lot about the host by studying this virus-host-cell interaction and that's kind of the focus of research in my lab. But I think some of the most exciting areas of bee virus research right now are investigating the extent of transmission between co-forging these species, even those from different genres, and the factors that govern those transmission events, like do colony density plays a role. Does the type or number of floral resources play a role?

Speaker 1: Just before you go on. So the idea would be viruses are going between different bee species and that transmission route is really poorly defined. We don't really understand, you put a lot of bee colonies into a place that transmits better. All that's kind of a little poorly defined at this point.

Speaker 2: Yeah, well, I guess there have been good studies, particularly those by Diana Cox-Foster and others that have demonstrated that definitely bee viruses can be transmitted between honey bees and bumble bees via pollen.

That's well appreciated. But then what are the other ecological factors that play a role? If there are certain flowers, if there are certain bee densities, does that impact the actual transmission in a kind of real-world study? And then what we're particularly focused on is what are the molecular mechanisms of the antiviral defense. And so we really drill down as both the individual bee and cellular levels and the actual proteins that are fighting off the viruses, we care about those mechanisms. And it's not only interesting from a basic science point of view, why and how bees fend off viruses, and why the bee has evolved certain antiviral defense strategies.

But we think down the long road when bee breeders like Cucoby and others are making a list of traits that they could breed better bees for certain areas of the country in addition to breeding for gentleness and honey production and all these other traits that they breed for, there may be some certain genes or gene expression levels that are correlated with fighting off viruses that they could add to that list of traits that they're already breeding for.

Speaker 1: Oh, okay. Oh, that sounds great. And that sounds like, but you really, I think what you've emphasized is to be able to get to that really wonderful outcome, you have to understand these mechanisms within the bees. Like you're gonna have to kind of really... Yeah. Okay.

Speaker 2: Yeah, and then what we've learned of, and I was a postdoc in a lab that studied fruit flies, and we know loads about the genetics of fruit flies and what those genes do. And what we do know is that bees are, I mean, of course we know and appreciate that. Bees are really different than fruit flies and mosquitoes, but of the insects that have been studied, most are known for antiviral defense and fruit flies and mosquitoes.

Speaker 1: And this is a thing. They can fight viruses. Yeah. Cool.

Speaker 2: Yeah. And so one of our particular interests is in the role of double-stranded RNA in stimulating antiviral defense. So double-stranded RNA is produced by viruses when they replicate, but it's not produced by the expression of our genes. We make single-stranded RNA. And so this double-stranded RNA becomes like a beacon of viral infection and stimulates the immune response in both honeybees and humans, actually. But the response is different. So in fruit flies and mosquitoes, there's a sequence-specific RNA interference, which is also important in honeybees. It depends on the sequence of that double-stranded RNA, but we've seen both honeybees from my lab and bumblebees from other labs that just double-stranded RNA in its own right can stimulate the antiviral defense mechanism. So really drilling down how that works and why that evolved that way are kind of really areas that I'm interested in.

Speaker 1: This is fantastic. Okay, well, let's take a break. I'm gonna come back. We've got these questions I ask all my guests. I've never asked them of a virologist, so I'm really excited to see what your answers are gonna be. Okay. We are back. The first question I have for you is, do you have a book on honeybees or viruses or anything that you wanna recommend to our listeners?

Speaker 2: Yeah, so I decided to pick a couple of books that are virus books. Most of your guests recommend great B-books. I thought it'd be different. The first book that I picked is called, Vaccinated by Paul Offit, who's a medical doctor who wrote about vaccines in general, I think it's an important time for that, and I think it's an important time for the public to be more educated about vaccines. We know that there have been, again, measles outbreaks in places like Disney World in the US due to a lack of vaccination and herd immunity. So I think this book does a really good job of summing up how important vaccines are, and one of the interesting twists from this book is that it features Dr. Maurice Hilleman, who's actually an alum of Montana State University, where I'm talking to you from right now. It was called Montana State College at the time when he graduated in 1941, but Maurice Hilleman, who came from Myles City, Montana, is credited with saving more lives than any other scientist in the 20th century. Really? He developed and improved more than 25 vaccines, including nine of the 14 recommended for children these days, like the measles, mumps, and rubella vaccine, the first anti-cancer vaccine, which is the hepatitis B vaccine, as well as vaccines for meningitis and pneumonia.

So he's an amazing individual to read about, and the way that Dr. Paul Offit writes this book, Vaccinated, is really tenable like you can, I think even non-scientists can read it, and it kinda, there's just a good book that you could, there are some take-home messages that you could use, with people in the grocery store lines, if the topic of vaccines ever came up.

Speaker 1: And they do in the grocery line. There are all the tabloids there, so it inevitably comes up.

Speaker 2: Well, or, you know, I just think of it as like, as like, moms shopping with their kids, and getting ready for school, or dads shopping with the kids, and a lot of schools require vaccines, and things like that.

So I guess I was kinda more thinking in terms of like, where families are, and you always see families of all types at the grocery store. Sick or healthy. Everybody needs to see.

Speaker 1: They do. Okay, that's really great, and I actually, 'm glad to know a little bit about the history of vaccines and virology. It's, I mean, it's, these are things that people probably, probably vaccines happened before we knew much about viruses. Probably it had, you know.

Speaker 2: It's true, yeah, and that's really amazing. I teach virology here at Montana State University, and I think that those first vaccines, against the rabies virus before we knew what a virus was, that scientists generated during their time are even more amazing than generating a vaccine right now. And I have a second book if I'm allowed.

Speaker 1: You are, go for it.

Speaker 2: Cool, so there's another book called Spillover by David Kwaman. He's also a local author. He lives in Bozeman, Montana, and often writes for National Geographic. And although I knew him from Bozeman, Montana, I met him at the American Society for Virology.

So he was really doing his due diligence and learning about viruses when he wrote this book. And I think it's particularly pertinent to be researchers because I read the road spillover kind of incorrectly a lot in papers. And so spillover by definition is known as when a pathogen spills over from a reservoir population that it may or may not be doing damage. And that reservoir host usually has a high burden of virus or a lot of virus. And then it comes into contact with a novel host. And then now it causes problems in that novel host. But remember that early in the show, I told you that insects, and viruses, infect a lot of different insect species, honeybees, bumblebees, wetbees, and all these kinds of bees, may share a lot of these viruses. And so you wouldn't define viral transmission as spillover.

Speaker 1: Right, this is a very human-centric kind of view of it because, in those systems, there are always crossing species boundaries.

Speaker 2: Yeah. Okay. Yeah, so Spillover is a good book. They use different illustrations, different kinds of Hendra and Nipah viruses, and samples of spillover events from bats, horses, people, and things like that in the book. But I think it does a nice job of illustrating what spillover is and it's kind of a fascinating read as well.

Speaker 1: Excellent. Those are really great. I'm going to pick them up. Fascinating. And they have never been recommended on the show before. Good job.

Speaker 2: That's what I figured.

Speaker 1: Well, the next question we ask our guests is if there's a go-to tool. And I know you've, in this show, you've mentioned a lot of tools real quick. Is there one tool that you...

Speaker 2: Yeah, that's what you're saying. No, no, it's okay. I think we will link to the lab in the show notes. And I know there's a series of really great videos that just came out of Montana State sort of talking about these things in more detail and giving images. But tell us a little bit about, you know, when you're doing your work, is there a tool that really is the workhorse, or do you really, really need to do the work that you do? Yeah, so if to do Honey Bee host-virus interaction work, my go-to tool would be the quantitative PCR instrument, which allows us to detect and quantify the number of viral genomes or viral RNAs that there are in any given sample. It also allows us to determine the relative amount of Honey Bee genes that are being expressed or turned on in response to virus infection. So you can use the QPCR machine to not only look at virus abundance but also host gene expression. And so we use it every day, many times a day, and I couldn't do my job without it.

Speaker 1: Describe what this thing looks like. Is it a box?

Speaker 2: Yeah, so it's like, yeah, it's interesting when you go to a lab. I think that non-lab people think of them as very different, but it is kind of this big box, maybe the size of, I'm trying to think of something, maybe the size of a microwave, that we can put in samples, and we put in 96 samples at a time, and they're in these like what we call 96 well-fate. So we can do a lot of samples at once.

And all it really is is it's not that sophisticated technologically. All it does is heat and cool the samples that in a designated regime. And that's how PCR works, is that when you heat a sample, the DNA denatures, and then you cool the sample, and a polymerase primed with a piece of DNA gets started and reads the sequence or copies it. And so, and then at every given cycle, the machine takes a picture, and the picture is of this fluorescent dye that binds into the double-stranded DNA sequences every time it's made. And so, at every cycle of this, hot temperature, medium temperature, hot temperature, medium temperature, it's gonna take a picture and identify how many photocopies of that virus are in that tube at any given time. And so, that's how we enumerate the number of viruses.

Speaker 1: Okay, and so each cycle, it should be making more and more.

Speaker 2: Yeah, it's like a photocopier. Okay, all right, okay, cool. All right, awesome. So the last question I have for you is, you're a honeybee person, we often ask people, well, I guess the first question is, the way I pose this question is, are honeybees your favorite pollinator? If they are, why? Yeah, so, honeybees are my favorite pollinator species. And in part, because they're the first ones that I really became scientifically interested in, while I was a postdoc at UCSF, working with Ro Landino and collaborating with Joe Rodriguez in California, that's when the honeybee colony losses were really kind of hitting the news around 2006, 2007. So, I became interested in them from a molecular biologist flash virologist perspective and realized that there was a lot of work to do on the side of honeybee viruses. And then, as I learned about them, I think they're amazing insects, eusocial, cavity-nesting bees, native to Europe, of course, but they were introduced into North America until the late 1600s. And I just think they're amazing to learn about. And I think since I'm not from an entomology background, I learned about bees and amazing interworking, so bee colonies kind of later in life.

And I'm still amazed by them. I really enjoy going to our bee yard we have about 10 bee colonies here and we collaborate with commercial beekeepers all over the US for, the same samples. And I just find it fascinating. And of course, they're important for pollinating our fruit, nuts, and vegetables. And I think that many more bee aficionados don't count honeybees as their favorite. So, I'm happy to do that.

Speaker 1: No, that's great. I love honeybees too. They are also my first bee and I've done a lot of work with them. I really love honeybees. Well, thanks so much for taking time out to fill us in on viruses. I really appreciate, your pollination. Thank you.

Bye. Thanks so much for listening. Show notes with information discussed in each episode can be found at pollinationpodcast.oregonstate.edu. We'd also love to hear from you and there are several ways to connect. For one, you can visit our website to post an episode-specific comment, suggest a future guest or topic, or ask a question that can be featured in a future video. See you next week.

Michelle Flenniken is an Assistant Professor in the Plant Sciences Department at Montana State University. She is a microbiologist investigating honey bee host–pathogen interactions and Co-Director of the Pollinator Health Center at MSU. Michelle received a B.S. in Biology from the University of Iowa, then was a Peace Corps volunteer in Ghana, before obtaining her Ph.D. in Microbiology from Montana State University. She did postdoctoral research at the University of California, San Francisco prior to becoming a faculty member at MSU.

Listen in to learn how viruses affect pollinators, how virologists study them, and which ways beekeepers can best protect their colonies from infection.

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“When you think about a bee colony, it’s a great place for viral infections. They’re really crowded, if you think of honeybees, there’s over 40,000 individuals crawling all over each other.” – Michelle Flenniken

Show Notes:

  • How pollinators can get infected by viruses
  • The difference between horizontal and vertical transmission
  • Why monitoring your mite infestations can help minimize viral transmissions
  • How virologists have been studying and finding these myriad viruses
  • What common viruses affect United States pollinators
  • How the names of the viruses are determined
  • The process of infection with viruses and pollinators
  • How beekeepers can best test their colonies for viral infections
  • What beekeepers can do to reduce the damage caused by viruses
  • What Michelle sees as some of the most exciting research in virology right now
  • The evolution of how bees fend off viruses
  • How different RNA strands are used to create defenses against viruses

“I think that many of us get human centric when we start thinking about viruses and pathogens and we think that there are specific viruses that infect humans and those that affect other animals, but for insects and plant viruses, viruses can have a broader host range which include completely different genre.” – Michelle Flenniken

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