Virus-only diet can fuel the physiological and population growth of an organism

In the calm waters of a single pond, a million virus particles can enter a single-celled organism known for its tiny hairs (cilia) in a single day.

For the past three years, John DeLonge at the University of Nebraska-Lincoln has been busy discovering secrets that are potentially game-changing. These virus particles are not only a source of infection, but also a source of nutrition.

In a Pac-Man-worthy turn, DeLonge and his colleagues Harteria -; microscopic ciliates that live in freshwater around the world; We have also shown for the first time that a virus-only diet, which we call “virus bolie,” is sufficient to promote physiological growth and even population growth in organisms.

Chloroviruses, a carrier-defining discovery by James Van Etten of Nebraska, are known to infect microscopic green algae. Eventually, the invading chlorovirus bursts the single-celled host like a balloon, releasing carbon and other life-supporting elements into the open ocean. That carbon that might have gone to predators of tiny creatures is instead siphoned off by other microbes – a stringent recycling program for miniatures, and seemingly forever.

It’s really just holding back carbon in this kind of microbial soup layer and preventing energy uptake by herbivores up the food chain.”

John DeLong, Associate Professor of Biological Sciences, University of Nebraska-Lincoln

But given that ciliates feed on the same virus for dinner, biorobory could offset the carbon recycling the virus is known to sustain. It may help and facilitate the escape of carbon from chain remnants, endowing it with the upward mobility that the virus suppresses.

“Multiplying the number of viruses, the number of ciliates, and the approximate amount of water yields this massive energy transfer (up the food chain),” DeLong estimated. A small pond ciliate could eat 10 trillion viruses in a single day. It should change.”

“No one noticed”

DeLong was already familiar with how chloroviruses entangle food webs. In 2016, ecologists he partnered with Van Etten and virologist David Dunigan showed that chloroviruses gain access to algae. Parameciumonly when eaten by small crustaceans Paramecium Drain newly exposed algae.

The discovery put DeLong in “another headspace” when it comes to thinking and researching viruses. Given the great abundance of viruses and micro-organisms in the water, he thought it was inevitable–infection aside–. The former can get caught up in the latter.

“It was clear that all things had to put the virus in their mouths all the time,” he said. It looked like

So DeLong dives into the research literature and intends to uncover any studies of virus-eating aquatic organisms and, ideally, what happens when they eat. I showed up with something. One study in the 1980s reported that unicellular protists could consume viruses, but did not delve further. Some papers from Switzerland later showed that protists appear to remove viruses from wastewater.

“That’s it,” said DeLonge.

Nothing was said about the potential impact on the microbes themselves, let alone the food webs and ecosystems they belong to. This surprised DeLonge, who knew that viruses were built on a foundation not only of carbon, but of life’s other elements. Hypothetically at least, they were nothing more than junk food.

“They’re made up of really good stuff. Nucleic acids, a lot of nitrogen and phosphorus,” he said.

“So many will eat whatever they can get their hands on. Surely someone would have learned how to eat these really good ingredients.”

As an ecologist who spends a lot of time using mathematics to explain predator-prey dynamics, DeLong wasn’t entirely sure how to investigate his hypothesis. Ultimately, he decided to keep it simple. First, we need volunteers. He drove to a nearby pond to collect water samples. Back in his lab, he has enclosed all the microbes he can manage, regardless of species, in water droplets. Finally, he added a generous amount of chlorovirus.

After 24 hours, DeLong examined the drops for signs that any species seemed to enjoy companionship with the chlorovirus. Even one species treated the virus more like a treat than a threat. Harteriahe found it.

“At first, it was just a hint that there were more,” DeLong said of ciliates. “But they were big enough that you could actually grab them with a pipette tip, place them in a clean drop, and count them.”

Chlorovirus numbers have plummeted 100-fold in just two days.population of HarteriaThey grew on average about 15 times bigger over the same period, eating nothing but the virus. Harteria On the other hand, those deprived of chlorovirus did not grow at all.

To confirm that Harteria Because they were actually consuming the virus, the researchers tagged a portion of the chlorovirus DNA with a fluorescent green dye before introducing the virus into the ciliate. Sure enough, its vacuole, the ciliate equivalent of the stomach, immediately glowed green.

Undoubtedly, the ciliate was eating the virus. And that virus was holding them up.

“I was calling my co-authors, ‘They grew up! We did it!'” DeLonge said of the findings. “I’m excited to see something so basic for the first time.”

Delong wasn’t done. His mathematical side suggests that it is possible that this particular predator-prey dynamic, even if it seemed odd, shares common ground with the more pedestrian pairings he was accustomed to study. I wondered if it was sexual.

He started by graphing chlorovirus reduction against chlorovirus growth. HarteriaThat relationship that DeLong found is generally consistent with what ecologists have observed between other microscopic hunters and their game targets.of Harteria It also converted approximately 17% of the consumed chlorovirus mass to its own new mass. Paramecium They feed on bacteria, and milli-scale crustaceans feed on algae. The rate at which ciliates prey on viruses and even the ~10,000-fold disparity in size are consistent with other aquatic case studies.

“I had the motive to decide if this was weird, or if it was appropriate,” DeLong said.

DeLong and his colleagues have since identified other ciliates such as: Harteria, the virus can thrive by eating alone. The more they discover, the more likely it is that virus research is occurring in the wild. the evolution and diversity of species within it? their resilience in the face of extinction?

Again, he chose to keep it simple. As soon as winter in Nebraska is over, DeLonge returns to the pond.

“Well,” he said.