Can viruses be beneficial? | DW Documentary

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This citadel is located in the Berlin district of Spandau. Wildlife pathologist Gudrun Wibbelt studies infectious diseases in small animals such as squirrels and bats. Alex Greenwood is a Professor of Wildlife Diseases in the German capital. Their joint research shows that a bat colony like this one could be the incubator for the next pandemic. Almost all known diseases, especially viral diseases, come from wildlife. These viruses are millions of years old, and the animals have been around forever. What has changed is how we interact with nature. The citadel’s basement is home to tropical bats in a special enclosure. Some of the 1,400 bat species worldwide seem to be perfect virus carriers. Bats are mammals like us, and they live in large groups. Some fly about fifteen kilometers in the wild, so they can spread pathogens far. It’s inevitable that pandemics will keep occurring. All of humanity has had to deal with pandemics and will continue to do so. And the further we encroach into the habitats of wild animals, the more likely it becomes. Until now, the animals were left on their own, and we didn’t interact with them. Viruses pose a major threat to humans and other organisms. But viruses can also heal us. Throughout the course of evolution, they’ve majorly impacted life on Earth. The larger and more densely packed an animal population is, the more likely it is for dangerous virus mutations to occur. Viruses evolve to spread faster. And some are then transmitted to humans. The problem right now is, when we have a pandemic or outbreak, we focus on the human side. How can we prevent people from getting sick? How can we treat people? Rightfully so! But if we want to be proactive in preventing outbreaks, we need to understand how animals deal with pathogens. If we understand why they survive certain viruses — like rabies or SARS — and then take that functionality and apply the knowledge to humans, we’ll benefit. Some tropical bat species transmit Ebola and rabies. And many other animals, like rodents, pigs, and chickens, are perfect virus carriers too. The virus that caused COVID-19 passed through one or more unknown intermediate hosts before reaching us. And it mutated several times along the way to become dangerous to humans. Viruses are adept at surviving. How can we best describe them? Viruses are infectious, organic structures. They have no metabolism and can only reproduce in the cells of a suitable host. Unlike bacteria, viruses aren’t living organisms and they’re about one hundred times smaller. Several thousand viruses are known, but more than one hundred million probably exist. Gudrun Wibbelt is examining a bat at the Leibniz Institute for Zoo and Wildlife Research. The animal was found dead in the parking lot of a Berlin hospital. The pathologist’s research aims to identify early on which virus makes its host and potential carrier sick. And whether the virus poses a risk for humans. This is the little heart. These are the kidneys. Here’s the liver. Here you see the intestine and there’s the stomach. The intestines look too enlarged, too voluminous to me. I assume the bat probably had intestinal inflammation and perhaps died of a diarrhea-related illness. Attacks by viruses, including the coronavirus, always follow the same pattern. A virus “docks” onto a cell, releases genetic information and forces the host cells to produce new viruses. The new ones then attack other cells, also forcing them to reproduce. The infected cell dies about two days later. At the same time, our immune system attacks the virus. Gudrun Wibbelt wants to find out how the bat died and which viruses it carried. Some of them could be dangerous for us, because these animals are ideal hosts for viruses. They have a strong immune response. That means, bats can carry pathogens without getting sick themselves, making them the perfect hosts. You can be infected with a virus and later expel it without anything happening. Or you can be infected by a virus, and the immune system responds by forming antibodies, but without you getting sick. Or you might get infected by a virus and get sick. Those are the three ways. There are bats and the coronavirus — and also Ebola, for instance. The viruses manage to reproduce in the animals and get expelled again. But even a large viral load doesn’t hurt bats. In fact, they’re known as reservoir hosts, meaning they carry infections that don’t bother them. But then there are others who get sick from the virus. Bats carry a predecessor of the virus that causes COVID-19, but as far as we know, they didn’t directly infect us with SARS-CoV2. I understand that people find bats a little too dark and mysterious. It’s a bit unfortunate that they’ve been around for so long and have such an affinity for viruses. But it’s no reason to worry when you see a bat. In fact, they eat all the moths and mosquitoes that bother us and farmers. If we didn’t have bats, then we’d need a lot more pesticides for farming. Bats are useful to us in a lot of ways that people don’t realize. Still, it’s undeniable that in recent years, viruses are increasingly being transmitted from animals to humans. In 1997 there was the bird flu, in 2009 the swine flu, and the first case of COVID-19 was recorded at the end of 2019. Virologists like Alex Greenwood think there will be more such diseases in the future. We've been for a long time, more and more invading the spaces where wildlife lives and also wildlife that we normally wouldn't have contact with through the destruction of forests, conversion of land, the use of wet markets where we eat and consume wildlife. And there's no reason to think that that couldn't happen again if we are caught by the wrong pathogen at the wrong time, in the wrong place. Alex Greenwood thinks we still know too little about diseases in wildlife. Because there’s not enough funding for systematic research, it’s often by chance that scientists discover new viruses in animals. We need to invest in figuring out what are these pathogens, why are they there? Where? In what species? What are they doing there? Are they doing something good? We don't have these answers. We didn't see this pandemic coming. We didn't see the last pandemic coming. We don't know when Ebola will break out again. We don't really know what the next viral outbreak will be in people. It could happen right now, even in the middle of a pandemic. In Hamburg, just a stone’s throw away from the city’s harbor, is the Bernhard Nocht Institute for Tropical Medicine. It contains a high-security wing with a database of viruses. Lisa Östereich works in a biosafety level four laboratory, the highest security level. There are four such labs in Germany and about fifty worldwide. Here, scientists study deadly pathogens, most of which don’t have vaccines or effective therapies. We have a filter in the suit, or “pressure relief valves.” We connect a tube and then air is blown into the suit, with overpressure if necessary. The gloves are firmly attached to the suit. The boots are tightly secured too. The suit’s interior is subject to overpressure, so when we’re in the lab, air only flows outward and never in. The suit is completely airtight, so we’re protected. The institute’s collection includes one hundred different viruses. One of the latest additions to the biosafety level four laboratory is the Ebola virus. Lisa Östereich traveled to Western Africa to help diagnose potential cases in a mobile lab. Scientists here in Hamburg are constantly analyzing and cataloging new viruses. Viruses have a relatively simple structure. They’re very small and have few components. Still, we don’t really know how to prevent or modify sicknesses, or at least how to make them less severe. That’s why we have to continually re-exam viruses. Because they’re so small, they have few weak spots. And they’re so highly specialized that no two viruses are completely alike. The surfaces of many viruses exhibit appendages resembling spikes or thorns. Underneath is often an envelope around the genetic material. The genetic information lies on the DNA’s double helix or usually single-stranded RNA. There are many RNA viruses especially that can be dangerous to humans. Ebola and the Lassa virus are both examples of RNA viruses. But there’s also hemorrhagic fever viruses — meaning viruses that cause bleeding — such as Crimean-Congo hemorrhagic fever. Or the dengue virus, which you can contract traveling in Asia — that’s also an RNA virus. So is yellow fever. So there are quite a few. Coronaviruses are also RNA viruses. RNA is almost always single-stranded and more chemically susceptible than DNA, meaning errors occur more often when it’s copied. The virus mutates. But the human immune system is slow to respond, which makes vaccine development more difficult. Virologist Stephan Günther identified the SARS virus in 2003 — a close relative of the virus that causes COVID-19. The viruses we work with have a high chance of killing you if you get infected. But the viruses that are actually thriving are influenza, the Spanish flu, or COVID today — they’re highly contagious. Or there are viruses like HIV where you don’t even realize you’re infected but can be a carrier anyway. Ebola kills one out of three infected people, but the right contact restrictions work to stop the spread. By February 2021, SARS-CoV-2 had infected one hundred million people and killed two million worldwide. Never before had virologists’ work received so much attention. Lisa Östereich uses fluorescent substances that react to certain DNA sequences to identify pathogens. Viruses have simple structures and can be replicated in labs. But recreating such infectious, organic structures is difficult. Viruses generally evolve to become the “evolutionary optimum,” so to speak. Usually when you start to change something about the virus, you’ll end up worsening its properties and decreasing its chance of survival rather than improving it. Nature has already created the optimum. And if you synthesize it, the result is usually worse. The coronavirus is from nature — not from a lab. A research team from the US and the UK proved that in February 2020. Amid the pandemic, it’s become clear that global information sharing offers a chance to defeat deadly viruses. At Lake Constance in southern Germany, researchers are trying to better understand the role of viruses. Christian Voolstra and his team from the University of Konstanz regularly take water samples and study them in the lab. What impact do pathogens have on aquatic ecosystems? Christian Voolstra is investigating the interactions between viruses, bacteria and larger animals. This is lake water... This here is about 100 milliliters, or half a glass. What we know is that there are about 100 million viruses per milliliter of lake or seawater. That means there’s 100 times that here. And when you think about it, there are more viruses inside here than people on Earth. And if you now look at the lake as a whole and think about how many “100 milliliters” is in it, you get an idea of the magnitude we’re talking about. There’s no place on Earth without viruses. All ecosystems are built on them. Christian Voolstra discovered that corals for instance benefit from viruses, because they kill off dangerous bacteria. The same is true for humans. Viruses can help us by killing harmful bacteria in our digestive system, for example. I think it’s important to understand that nothing is “good” or “bad” in nature. And viruses and bacteria are everywhere. Plus, when you take the number of pathogenic viruses compared to all viruses, it’s really a very small fraction. Viruses are an integral part of nature and keep our ecosystem balanced. Only a small number of viruses are dangerous, and many help us. They’re even part of us. The human genome contains virus fragments left over from past pandemics. How viruses become embedded in our genomes and the ensuing effects is plain to see in another species. Six koalas live in the Duisburg Zoo. And just like humans, they’re accustomed now to contact restrictions. They are not allowed to meet other koalas. A pandemic threatens the survival of the entire species. Koalas and their viruses are Alex Greenwood’s specialty. He is collaborating closely with biologist Volker Grün, who coordinates breeding for all koalas in European zoos. Alex Greenwood is researching a special family of viruses: retroviruses. They infiltrate the koalas’ genes. And this “gene defect” causes diseases years later. So, we're in the middle of a pandemic right now. But koalas have been going through a pandemic for the last 50,000 years. The difference being that it's not just a pandemic where the virus infects individual to individual. It's actually gotten into their genome. So the viruses managed to invade the genome of these animals and then be spread from parents to offspring. Like other viruses, retroviruses attack cells and force them to produce more retroviruses. And that’s just the first stage of the attack. Retroviruses also embed themselves in genetic material. The same can happen in humans — they become part of us, and we can pass them on to our offspring. But not many viruses manage that. Each retrovirus in our genome conceals countless failed attempts by other viruses. And this has been happening through the animal world for millions and millions of years. And so that most animals, including humans, have maybe 10 percent of their genomes made out of retroviruses that have gone through this process. The koalas are basically the beginning of this process. And so they're facing what we must have faced millions and millions of years ago. And we're seeing in real time unfolding before our eyes in these animals. Volker Grün is worried about the koala population. After all, the animals in European zoos have not yet been infected by the koala retrovirus — but should a new animal join them from Australia, that could change fast. We had a case where animals were imported. Everything had been approved by the Australians and the nature conservation authorities. But then we tested them here in Europe and they were positive. So of course, we said stop, we’re not going to put them together with our animals, because we were of course afraid they might infect them. That would obviously ruin everything. That was the right thing to do. They should always be tested. As soon as it’s in the population, in an enclosure with multiple koalas, they can infect each other. Even if just one animal is positive. In a few years, they’ll maybe all be. And that would be bad. What if we were to mate them? They’d have an increased risk of cancer. And it’s not just the cancer itself. They’d get it relatively early on and then wouldn’t be able to reproduce. Too many animals would die before producing offspring. Maintaining the population would be impossible. The virus in the genome not only causes cancer but makes them more vulnerable to other pathogens. We can’t predict the effects of retroviruses on individual koalas. But overall, the viruses threaten the whole population. If all koalas were to become infected with the koala retrovirus, they could die out. It's as if koalas are hardcore smokers. So it doesn't mean they're going to get cancer, but you're increasing the risk. And so the koala retrovirus is like smoking 20 to 30 packs of cigarettes a day, because it's putting so much pressure — so many possible places where it can land and do something bad. We humans and our ancestors were also attacked by retroviruses over millions of years throughout our evolution. These and other viruses managed to anchor themselves in our germline and make up 47 percent of our DNA. Just 2 percent determine our bodies’ composition, while 51 percent controls how and when genes are read — or activated. Just like with the koalas, it’s not clear how retroviruses will impact humans in the long term. That’s because they take root differently in each person’s genome. And it’s difficult to distinguish the viral effects from environmental ones. For humans, the last of our retroviruses to have gone through this happened a very, very long time ago. There's evidence that our retroviruses that we have sometimes may be involved in or lead to cancer. There is there are studies that suggest that they still retain a little bit of their cancer-causing potential. So, but these are sort of these after-effects that have to do with the virus being a little bit virus-like still after all these millions of years. But it's nothing like the koala retrovirus, which is still much more virus-like and causing much more direct, acute problems, also at the individual level, than you would see in other species, including humans. There are also retroviruses in the genetic material of extinct animals, such as dinosaurs. And the role played by retroviruses is only just being researched. One pioneer of retrovirus research in humans is virologist Joachim Denner from the Free University of Berlin. I don’t think dinosaurs have been well-examined, but I’m sure they also had endogenous retroviruses. They were just a dead-end track in evolution. But they left behind a lot, of course. And we can see that behind us. Joachim Denner is researching how to cut retroviruses out from the genome. And he wants to better determine their effects. I think retroviruses are the most interesting viruses around. They’re called retroviruses because they have an enzyme that can transform the viral genome — or RNA — into DNA and then implant this DNA copy into the genome of the host cell using another enzyme. The process is called reverse transcriptase. The single-stranded RNA turns into double-stranded DNA. And only then can it slip into our genome. The foreign genes then remain, like parasites in a host. Just like the parasites being exhibited here in the Museum of Natural History in Berlin, retroviruses have diverse effects. We often only see the negative properties of parasites, bacteria, or viruses. But Joachim Denner is focused on the positive impact of the thirty different retrovirus families in our genome. I wouldn’t call them parasites, because that implies they’re harmful. They just ended up in our genomes. They basically just stay there, so for a long time we called them genetic junk, or garbage. And we now know they’re harmless. But they fulfilled important functions throughout our evolution, and they play a vital role in the placenta. An enzyme formed by a particular retrovirus enables the placenta to appear in the uterus in the first place and an embryo to develop. Animals related to us also carry this type of retrovirus in them. This endogenous retrovirus enabled more advanced mammals to develop. That means without these endogenous retroviruses, which may have been involved in the development of placental animals maybe 380 million years ago, we wouldn’t exist. How can we harness the good aspects of viruses? In Europe in early 2020, COVID-19 began spreading first in Italy. And it hit the population hard. In Rome, at the biotech company ReiThera, about 60 people are working on a COVID-19 vaccine. The vaccine utilizes non-replicating viruses as transport capsules. Marco Soriani is the Project Director at ReiThera. This is the team that was involved in the isolation of the vector. A vector is a virus shell. And the shell is used as a transport capsule for the vaccine. The challenge is to find a virus shell the human body doesn’t already know, so the immune system doesn’t attack the transport capsule. Angelo Raggioli found a potential candidate in January 2020. He was examining a gorilla’s stool. Angelo is actually the person that isolated the wildlife virus from the stool of a gorilla. It is a gorilla kept in captivity in a zoo. And then what actually Angelo did was able to get the virus by several passages and cleaning of the material. The vector comes from a species of very close to human, but not the human species. This has allowed us to actually reduce the risk of pre-existing immunity against the vector itself. The researchers removed the genetic information from the “gorilla virus” and inserted the spike protein’s DNA, found on the outer shell of the coronavirus. The coronavirus uses this protein to dock onto cells and invade them. The modified gorilla virus works as a vaccine by forcing our cells to produce the corona-spike protein. So the virus causes our bodies to create antibodies without making us sick. Then if the “real” coronavirus attacks, these antibodies stick onto the spike proteins. And the virus can no longer dock onto the cells. ReiThera can manufacture eighty to one hundred million doses per year. And the vaccine can be stored in normal refrigerators. This is actually the room in which we will produce the initial lots of our COVID-19 vaccine. I have a vial here. This is the vaccine. As you can see, it is a transparent solution. In phase two trials, the vaccine is tested on about one thousand volunteers. It appears safe so far. Gabriele Nastasi from Verona, in northern Italy, took part in the phase one trial in fall of 2020. Some of my friends think it’s great I volunteered. Others said I was crazy. They said, “Why would you do that? You have no idea what’s in the vaccine.” Gabriele Nastasi was one of ninety volunteers in the phase one trial. After being vaccinated, he had to log observations on his heath every day for a month. Starting from the day we’re vaccinated, we write down everything in a journal for a month. And every day, we check the injection spot for swelling, redness, or localized pain. Worldwide, there are more than ninety vaccine trials where testing is underway on humans. Currently, there are four different approaches to develop a vaccine against COVID-19. Viral vector vaccines such as ReiThera are made out of other existing viruses. Their advantage is they’re highly effective. But the drawback is that the vaccine doesn’t work if people are immune to the viral vector. One viral vector vaccine from the UK was already approved in the EU. Inactivated virus vaccines are a classic choice. They’re easy to develop and proven to be effective. But it’s time-consuming to produce them in large quantities. The third type is a newcomer. The RNA genetic material isolated from the coronavirus is injected into the muscles. This stimulates the immune system to produce antibodies. Millions of people are currently being vaccinated with the Pfizer-BioNTech vaccine. The fourth method is also new. It involves injecting only the coronavirus spike protein. Our immune system then forms antibodies against the virus. It’s crucial to continue developing these different approaches to keep up with the constantly changing virus. And initial findings show the ReiThera vaccine is effective. If it all works out, it would be awesome to say, I contributed to advancing this research that might really be a game-changer and take us a step closer to normal life. That would be immensely gratifying. So viruses help us fight other viral pathogens. But we can use reprogrammed viruses in completely other ways, too. Virotherapy is used to treat cancer. Here in Tübingen in southwest Germany, Ulrich Lauer is researching this medical revolution. He’s testing drugs for different types of cancer because viruses also attack cancerous cells. This has been a known fact for 50 years. In 1971, a doctor observed a sort of “miraculous healing” of a boy in Uganda. He had a tumor on his eye. But after he came down with measles, the tumor disappeared within a month. The virus had eliminated the cancer. And we also know that when cancer patients have had been infected by a virus, in rare cases the cancer can completely disappear within a few weeks. And of course, virus-induced destruction of cancer cells can occur. And the idea now is to optimize safe viral vector vaccines for destroying cancer and strengthen their immune response to cancer cells. Ulrich Lauer takes herpes viruses and reprograms them. These genetically modified viruses don’t attack healthy cells in the body anymore, but instead specifically target tumor cells. After a day or two, the growing viral load in the cancer cells causes them to burst. And when they burst, the cancer cells break into many pieces and the immune system recognizes them as foreign. Prior to that, the immune system had trouble recognizing the cancer cells and didn’t respond sufficiently, but now it has a sharpened sense and specifically targets the cancer cells. So virotherapy has two effects. First off, the viruses attack the cancer cells directly and destroy them. Secondly, the vaccination with the modified virus activates the immune system, putting it into alarm mode. At the Tübingen University Hospital, doctors are already treating patients with melanoma skin cancer using approved virotherapy. The medicine is called Imlygic and requires long-term storag at minus 80 degrees Celsius, similar to some COVID-19 vaccines. Helmut Fischer is Thomas Eigentler’s patient. Despite chemotherapy and immunotherapy, the skin cancer continued spreading on his leg. About twenty thousand people in Germany develop this aggressive type of cancer every year. Virotherapy may be a game-changer. Looking back at the side effects, what struck you? Anything serious? Not at all with the virotherapy. I felt slight discomfort, but I wasn’t nauseated and didn’t have a fever like with previous treatments. So I was determined to complete the therapy. So far, virotherapy is approved for patients like Helmut Fischer who fail to respond to more-established treatments. But that might change soon. It was a real ray of hope for me to be offered virotherapy, and it was a breakthrough, because after months of treatment, I noticed that the spots were getting paler. At the end, the doctors didn’t know where else to inject anything. And samples showed no more melanoma cells could be detected. So the virus attacked the cells and did a great job. In Tübingen, Heidelberg and at other institutes worldwide, virotherapies are being developed to help fight other types of cancer. These cost-effective vaccines could then supplement — or even replace — costly chemo- and immunotherapies. I think in the next five to ten years, besides the virotherapy currently used only for skin cancer, many more virotherapies will crop up, for every type of tumor — more or less. The next step will be to vaccinate against cancer before it even becomes visible. Then we could provide lifelong prevention by permanently strengthening the immune system and reducing the likelihood that cancer even breaks out in the first place. Back to Lake Constance, the water reservoir for southern Germany. Biologist Christian Voolstra regularly examines the lake, which is teeming with viruses. Similar to almost any body of water on Earth, the lake contains 100 million viruses per milliliter. And these viruses form the basis of life. They’re necessary for all life on Earth. But humankind has only very recently become aware of this fact. Some people are terrified by sharks, and others love them — like I do. And that’s what we would call an apex predator. It’s at the top of the food chain and keeps everything in check from there. It’s what scientists refer to as top-down control. There’s also control from the bottom, called bottom-up. And that’s what viruses do. Viruses are basically there keeping the bacteria in check. Otherwise, we’d be swimming or living in a bacterial soup. Viruses kill bacteria so that we can live. And the dead bacteria also become nourishment. Every minute, viral attacks in the water generate one hundred million tons of biomass worldwide. Throughout the planet’s oceans — the cradle of life — there wouldn’t be enough space or nutrients for advanced lifeforms without viruses. Without the constant viral attacks upon bacteria, Earth would have fewer species and less abundance. We are highly dependent on viruses doing their job so that we can do ours. Viruses remain a major threat to humans. But they’re also a part of us. We wouldn’t exist without viruses. Nor would the world as we know it.
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Channel: DW Documentary
Views: 185,094
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Keywords: Documentary, Documentaries, documentaries, DW documentary, full documentary, DW, documentary 2021, documentary, viruses, virus, SARS-CoV-2, COVID-19, coronavirus, corona, pandemic, Ebola, bacteria, evolution, pharmaceutical research
Id: kYAx2MFji1M
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Length: 42min 25sec (2545 seconds)
Published: Sat Aug 07 2021
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