In a groundbreaking study, researchers from the Weizmann Institute of Science have used single-cell RNA sequencing to map the intricate relationships between giant viruses, known as ‘giruses,’ and the single-celled marine organisms they infect, including various species of algae. The findings, published in Nature Microbiology, shed new light on the impact these colossal viruses can have on our planet’s ecosystems, from algal blooms to oxygen production and carbon fixation.
The Rise of the ‘Giruses’
Giant viruses, or “giruses,” have long fascinated researchers. The viruses are virtually unknown to science and contain more than 100 times the amount of genetic material found in some RNA viruses.
In the beginning, they were even believed to be bacteria, which cast doubt on the classification of them as viruses. Yet over the past two decades, research has begun to show that these giant viruses can have a major impact on life on the planet, especially in our oceans.
Private: ACTIVAQUA: Huge viruses from the oceans infect several single-celled algal species that are main performers in about half of our planet’s O2 output and also about 50 % of your worldwide carbon dealing. They write, ‘Rapid collapse of algal blooms due to viral infection can have considerable impacts on vast marine, atmospheric and terrestrial ecosystems…
Visualizing Relationships Between the Virus and Its Host
To answer this, researchers at the Weizmann Institute took a trip to the Norwegian fjords and seeded an algal bloom in massive bags. Using a cutting-edge method called single-cell RNA sequencing in the laboratory, they analyzed these cells.
This novel approach enabled the researchers to determine both the species of algae and whether it was infected with a Mimivirus, as well as which one. Before this study, no database included all the giant viruses identified in algae so far but thanks to a new collaboration with an expert on the evolution of viruses such a database is now being developed.
A detailed look at the RNA allowed them to pick out 972 infected cells, revealing new giant virus-host pairings as well (22). One such discovery was that the Imitervirales-07 virus infects algae cells of the Katablepharidaceae family, a connection never previously reported.
So All Life On Earth Is Screwed: Giant Viruses Have A Devastating Effect On Ecosystems
The researchers identified not only the virus-host relationships but also that there was a clear temporal link between the arrival of the viruses in samples and the population recession of host algae shortly after. That highlights what a substantial effect giant viruses may have on the ecosystems of our planet.
In the ocean, tens of thousands of square kilometers are covered by algal blooms that have an essential function in oxygen production and carbon fixation. When bathtub rings of the blooms collapse after becoming infected by a virus, it can have consequences for marine, atmospheric, and terrestrial ecosystems.
The researchers think their new approach can also be used to detect interactions between algae viruses, and other pathogens, elsewhere in the world including extreme climate environments such as the poles and Alpine lakes. This knowledge will also be fundamental to enabling us to defend against ancient pathogens, some of which may not have been in the environment for hundreds of thousands if not millions of years, so they are released once again from permafrost melting or ice-cap loss due to climate change.
