Virology: How PARP14 Regulates Virus Infection (ft. Dr. Tony Fehr)

Maria Losito: Welcome to the first episode of Interview with a Biologist. I am your host, Maria Losito, and I’m joined today by Dr. Tony Fehr, who is an associate professor of Molecular Biosciences from the University of Kansas. How are you doing today, Tony?

Tony Fehr: Great, Maria, very happy to be here with you today.

Maria Losito: Thank you. All right. In general, what are your research interests?

Tony Fehr: Yes, so, I'm a lifelong virologist, I have been studying viruses since I was an undergraduate in college at the University of Nebraska, and over time, that has evolved into me mostly studying viral genes and how do viruses utilize their genetic material to replicate themselves inside of a host cell and also cause disease --and mostly using animal models.

 My current research interests are largely in coronaviruses, as you are well aware of, and this unique intersection between the host's innate immune response and these viral proteins and viral genes that are out there, trying to stop those host's antiviral defenses. We often call this host pathogen conflict, where the host is trying to stop a virus in its tracks.

But the viruses are like, ‘You know, I'm not going to let you do that. So, I'm going to develop my own genes that can directly counter those responses.’ And so that's where the area of virology is that we are really interested in.

Maria Losito: So, you are a professor here at KU, what classes do you teach?

Tony Fehr: Yeah, so, as a virologist, I teach all about virology. So actually, I have both undergraduate and graduate courses dedicated to virology.

Maria Losito: And then is there a specific thing about any of those classes that you would like to tell us about?

Tony Fehr: I love viruses, we learn a lot about them. These classes are packed with a lot of information, they're very hard, but I'll point out, at least for the undergraduate class, I work with Dr. David Davido, who is also a molecular virologist here at KU. So, you get expertise in multiple different areas of virology when you take this class.

You are also getting information from the experts. In addition to what we teach, we actually bring in a lot of guest lectures to enhance the experience of the students. So, David will bring in clinical virologists. So, the students get a little bit of clinical virology. I bring in some of the people working at KDHE, and this year I'm actually bringing in a guest speaker from NBAF, or the National Bio and AgroDefense Facility, to talk about vaccine development and vaccine regulations that they deal with over there. These other opportunities give students a little bit of an idea of what they might want to do in the future if they want to do something related to virology.

So, I think that's kind of one of the unique aspects of this class, but we cover a lot of different things. I have guest lectures that talk about plant virology. We will bring in speakers from across the country to talk about their area of virology. So, I think it's a very interactive class and you just learn a lot about viruses.

Maria Losito: It's awesome that you're able to give our students such a wide range of guest lectures and people to look up to and realize that there are so many more jobs out there than they realize.

Tony Fehr:

Yeah, it is really cool, and also, we try to bring a lot of research-based ideas into the class, too. It's not just memorizing facts, which is still a large part of it, because you got to learn all the little intricate details, but we try to bring in aspects of our research, even throughout the class.

Maria Losito: So, you recently published a paper, called “PARP14 is an Interferon Induced Host Factor that Promotes IFN Production and Affects the Replication of Multiple Viruses” in a very broad way, what kind of scientific topics does that research touch on?

Tony Fehr: Yeah, so, this will come back to my research interests, talking about the host's response to viruses as well as viruses’ ability to counter those responses. My lab, I would say about 5 or 6 years ago, was really the first to identify a connection between this host response called ATP rib oscillation -- I know, that’s a lot, right? But I'll break it down into cellular modification.

 So, our host cells start modifying our proteins or genes immediately once we detect virus and that will trigger an antiviral response that can try to kill the virus. In this manuscript really identified a new host human protein that is able to restrict virus replication.

So that was really the first time anybody had shown that this protein could do this. And so that was really exciting. In addition, it not only restricted the virus, but it also enhanced what's called our innate immune response, and that's kind of tricky, but it's also called the interferon response,  and I actually almost laughed when you said ‘IFN’ because I probably should have written it out as interferon -and these are literally molecules that interfere. That's why they are called interferons with virus replication. 

PARP14, we found is one of the proteins within the host cell, that really amplifies the interferon response. In a broad way, we have really just identified a novel host factor that really helps us drive these antiviral responses.

Maria Losito: With that bit of starting point under our belt, can you go a little bit deeper into this recent publication of yours?

Tony Fehr: I think that there's not a whole lot deeper I can go, I think I can state that our innate immune response can be great for us. It's good for responding to viruses, but as many of us also have lots of inflammatory diseases, a lot of autoimmunity diseases that are often triggered by overreactions or over stimulation of these antiviral responses, and so, I think going forward, what I'm really excited about is the idea that PARP14 could be a target for not just virus infections, but also for inflammatory diseases, autoimmunity. Diabetes is often an inflammatory disease.

Actually, I have started working with an investigator over KUMC, named Hubert Tse, who does diabetes and autoimmune research and we're very interested in starting to parse out -does PARP14 play a role in those types of diseases? -and really broaden the depth of what our research is doing.

Maria Losito: As you mentioned, the majority of your research relates to coronavirus. What caused you to expand into looking into these other viruses? I know for this paper, you expanded to herpes simplex virus 1(HSV1).

Tony Fehr: Because we could. It was it was more of, we had these results in the coronavirus system, and again, I worked with David Davido for many years. He's an HSV1 researcher. We found out that a lot of the tools we were using to study PARP14 aren't restricted to just using them in coronavirus infection, we can infect a lot of the cells.

The type of reagents we had to study PARP14 could be utilized for multiple different viruses. We had them in our freezers. So, we decided, let's see what happens. We weren't expecting to see robust differences with these other viruses, we were kind of expecting the -I guess our null hypothesis, as we call it in the science world, would be that PARP14 may have had an effect on coronaviruses, but probably won't have an effect on these other viruses.

But we decided to test them and what we found was that PARP14, in fact, did affect the replication of these viruses and in unique ways. We found that PARP14 could repress HSV1 replication - so, it was an inhibitor of HSV1. Whereas with VSV, Vesicular Stomatitis Virus, -which by the way, is related to rabies virus- it causes significant disease in cattle and other livestock across the country.

But with VSV, we found that PARP14 was actually enhancing its replication. Which was completely unexpected and where we ended the paper. That is about what we found out and we thought, ‘Okay, well, this makes it really interesting.’

Maria Losito: It’s interesting that the viruses had such different responses to PARP14, that it nullified some, and enhanced the other. Do you think that you would consider going down further into that rabbit hole and discovering what causes that?

Tony Fehr:  Yeah, absolutely. I think that’s a great point. Of course, the research does not stop where this paper is at, understanding the mechanisms and how PARP14 restricts these viruses is still up in the air. We still don't know those fine details of how this happens, and we are invested in in finding that out.

We just got new funding, to address how PARP14 affects coronavirus infection -we just got a $1.5 million grant to study that over the next five years. And with David Davido’s group, we just got about a $400,000 grant to study its role on HSV1 over the next two years.

Maria Losito: Congratulations, that’s huge.

Tony Fehr: We are excited to keep pushing and working on and uncovering more about PARP14 and its role in the antiviral response.

Maria Losito: I'm excited to talk to you again about this in a few years and see how things have changed.

In general, why is it important that we research antiviral responses and host pathogen conflicts? What kind of impact could that have down the line for people?

Tony Fehr: Viruses are everywhere and they really impact a lot of different diseases. As I mentioned earlier, diabetes, there's connections to different types of viruses with that disease. There are connections to autoimmunity and overactive antiviral responses. Flu is ravaging our country right now. Covid was one of the most impactful viruses of the 21st century and possibly even in the 20th century. Viruses aren't going away.

Constantly developing new treatments is important. From a more immune focused aspect, there's a lot of different immune disorders out there, asthma, allergies, diabetes, and even dermatitis -those are all inflammatory diseases, we need to know more about the inflammatory responses. Why are those going awry? How can we combat those? I think we will have a lot of positive health outcomes in the next 40 to 50 years, if we really dive into these different scenarios.

Maria Losito: In a way, your research is groundwork for further medical discoveries and pharmaceuticals.

Tony Fehr: Absolutely. You know, we do basic research, although we do have an antiviral development program in my lab, targeting some of the coronavirus genes, but yes, the cool thing that we are working on in PARP14 is they are highly druggable, right? They have really nice pockets -there are inhibitors actually out there for these compounds.

So, in theory it wouldn't take terribly long to transfer these targets into potential therapies. Now, will they certainly be able to do that? We don't know yet. We are still a long way from really nailing down whether this is a really good target, or if something we learn about the pathways that it’s involved in a better target.

A lot of basic research needs to happen before we really know what to go after, but the PARPs are druggable targets. Actually, there are a number of cancer drugs that target other PARP enzymes, and there's a body of research that says that we can target these proteins- these human proteins- to better health outcomes.

That makes this area of research really exciting, and it’s something I've been really excited about throughout my career. Once I got into this area of PARPs, in ADP Ribosylation, it really fascinates me, and I think it's something that will drive our lab for years to come.

Maria Losito: It's always great to have so much out there that you can continue to study and find out more about.

Tony Fehr:  Yeah, this field really didn't take off until about ten years ago, 2014 or 2015. There were some major discoveries that really just started driving this field forward, and now we're seeing papers on PARPs and ADP Ribosylation, a lot more than we were ,10 or 15 years ago, when I started this field.

So, to say, I have seen the field start from almost its infancy to where we are today, and we're still a long way from understanding this response- the PARPS and host response, as well as some of the other responses that are out there. There is a long way to go, but I think that is a very fruitful area of research.

Maria Losito: What methods did you utilize to find your results?

Tony Fehr:

That's a great question, Maria. So, in molecular virology, we use straight knockouts. We take cells in a culture dish, and we will infect them with our coronavirus. Then these cells are going to have a knockout of PARP14 -so, we are going to get rid of PARP14 and then look at what happens, to better understand what PARP14 is really responsible for.

We also have the PARP14 inhibitors that other groups have developed. So, we have inhibitors of PARP14, that were able to really tell us what PARP14 is doing as well, we combined using knockouts of PARP14 in cells with inhibitors to define what PARP14 was doing in the context of the coronavirus infection or the herpes virus infection.

[Our methods are] a lot of cell culture, combined with virus infection- viruses that we created, or David Davido had- and measuring outputs of these host responses. We measure those outputs by measuring the number of viruses that's produced or measuring the amount of interferon that is produced from the host cell, and that can be done through a variety of different methods as well.

Maria Losito:  We've talked a lot about host response, what is it that your lab is doing in regard to coronavirus?

Tony Fehr:

This whole line of research started when we started studying this coronavirus protein called Mac1. This is the coronavirus protein that directly counters this PARP response. It does so by ripping the ATP ribose off of these targets.

So, we add this modification to cells where the main protein from coronaviruses rips it off, we were able to find early on that if the coronaviruses don't have this this gene, we can we could use mutations to get rid of the activity of this gene, and in that case the host wins, the PARPs win. If the coronaviruses have the Mac1, the virus wins. So, we see that without Mac1, the virus replicates poorly, especially in mice.

[Mac1] does not cause disease. Knowing that prompted us to start developing inhibitors for this Mac1 protein and in a separate publication, we released earlier this year, we had evaluated a number of Mac1 inhibitors, that we found inhibit coronavirus replication.

To understand Mac1, we do a lot of mutations. This is actually where we have undergraduate students working in the lab. [They work] on this protein, trying to define what parts of Mac1 actually dictate this function. Then we continually make new and better inhibitors.

I'm excited to get a new batch of potential inhibitors from one of my collaborators in the next few weeks. We’re in a constant state of testing that next batch of Mac1 inhibitors and seeing if we can continually make them better to the point where maybe they could be used therapeutically, or at least used for research purposes, down the line. This has really been my pet project for a long time, studying this Mac1 protein. Only recently have we gotten into the host response part of it. I've been really studying this protein in depth for a long time, and it’s one of my favorites.

One of my favorite things we do in the lab is to dissect the biochemistry of this Mac1 protein and how it really counters these host responses. That's the really exciting part of the lab, developing inhibitors and understanding the biochemistry of this protein. I often that we are a virology lab that does some biochemistry! There are a lot of biochemistry labs that study virus proteins and I'm a virology lab that studies a little bit of biochemistry. It's really fun. We get to work on the virus side, but also do some in-vitro biochemistry on how this protein functions. 

Maria Losito: Thank you for joining us today, Dr. Fehr, I really appreciate it, and thank you for giving us a deeper look into your research!

Tony Fehr: Absolutely. Thank you very much, Maria. And again, we're really interested in viruses and if you're interested as a student here at KU, please sign up for our classes. I think you would really enjoy learning more about the virus world.

Maria Losito:

Thank you for listening to Interview with a Biologist. You can check out the show notes for more information about Doctor Fehr's work, as well as a link to the research paper discussed in this episode. A full transcript of this episode is available at Biology.ku.edu.

Further Reading: Fehr lab research from the University of Kansas suppresses coronavirus by targeting Mac1