Viruses have been assumed to be toxic to almost every living thing, but recent research suggests otherwise. In fact, they may really be somewhat beneficial and even appetizing!
Scientists have discovered that certain animals have evolved to ingest specific viruses for sustenance and energy. The study was published in the journal Proceedings of the National Academy of Sciences.
Research Findings
In a report by Interesting Engineering, University of Nebraska researchers John DeLong and colleagues have shown that a type of Halteria may consume many infectious chloroviruses. Species of Halteria are tiny ciliates found in freshwater settings worldwide.
The research group has also proven for the first time that an organism may develop physiologically and even reproduce when fed only a virus-only diet, known as virovory.
James Van Etten of Nebraska University first discovered Chloroviruses. They are pathogens that infect microalgae.
Eventually, the invading chloroviruses will cause their single-celled hosts to burst like balloons, releasing carbon and other vital components for life into the surrounding seas.
Associate professor of biological sciences at the University of Nebraska, DeLong, says that is basically locking carbon down in this type of microbial soup layer, preventing grazers from transmitting energy up the food chain.
However, if ciliates feed on viruses for supper, virovory may counter the carbon recycling that viruses are infamous for spreading.
DeLong argues that virovory is responsible for carbon's ability to go up the food chain, which viruses normally prevent.
The Virovory Concept
DeLong says ciliates in a small pond eat 10 trillion viruses every day.
Multiplying the number of viruses, ciliates, and water yields a significant amount of energy transmission up the food chain, he said.
"If this is happening at the scale we think it could be, it should completely change our view on global carbon cycling," DeLong added.
DeLong recognized how chloroviruses created food webs. Biologist Van Etten, and virologist David Dunigan showed in 2016 that chloroviruses could only reach algae coated in Paramecia when small crustaceans eat the Paramecia and eject the algae.
Even without infection, the existence of viruses and bacteria in water made it inevitable that the former would end up in the latter.
Therefore, this only says that everyone and everything was "constantly ingesting viruses." Because it is in the sea, it felt inevitable.
However, virovory had never been established. Potential impacts on bacteria, food webs, or ecosystems were not discussed.
Experimentation Phase
To test the concept, DeLong drove to a nearby pond and sampled water. He gathered every variety of microbe he could in water drops in his lab. He added chlorovirus.
DeLong would go through the drops after 24 hours for any evidence that a species was enjoying the chlorovirus, considering it more like a snack than a danger. It was in Halteria.
Chloroviruses dropped 100-fold in two days. Halteria, which just ate the virus, grew 15 times faster. Halteria without chlorovirus grew slowly.
Before introducing the virus to the ciliates, scientists dyed some green chlorovirus DNA to ensure it was consumed. Its vacuole, a ciliate's stomach, quickly became green.
Ciliates ate the virus, and the illness was their source of sustenance.
DeLong and his colleagues have found other ciliates that, like Halteria, thrive on viruses. Virovory is more common than expected.
