Scientists discover 30,000 types of viruses hidden in microbes

A group of researchers led by ecologist Christopher Bellas from the University of Innsbruck came across a surprising discovery while investigating a new group of microorganisms in the waters of Lake Gossenköllesee in Austria’s Tyrolean Alps: About 30,000 unknown virus species “hidden” in the DNA of the analyzed microbes.

In a new study published April 10 in the Proceedings of the National Academy of Sciences, researchers explain that this “large-scale invasion” occurred in the single-celled eukaryotic genomes of protists. this group does not fit into plant, animal or fungal categories and is found in a wide variety of life forms found in a variety of terrestrial environments.

“We were shocked by the amount of virus we found in this analysis,” Bellas told ScienceAlert. According to the lead author of the study, “in some cases up to 10% of a microbe’s DNA was made up of latent viruses”. The good news is that these microorganisms don’t seem to cause disease in their hosts, but instead look like virophages, a class that infects their pathogenic “colleagues.”

Why do viruses invade the genomes of microbes?

Bellas admits that the study does not provide a plausible explanation for the presence of so many viruses in the genomes of microbes. “Our strongest hypothesis is that they protect the cell from infection by dangerous viruses.”speculates. The study notes that viral integrations found in most protist genomes work like prophages in bacterial genomes, genetic elements that kill the host cell exposed to threats.

Anyway, classified or unclassified as biological assets, viruses certainly insert themselves into the lives of other beings. And when this occurs in a reproductive cell (which transmits genetic information to addicts), it results in endogenous viral elements (EVEs), which are DNA sequences integrated into the host organism’s genome.

While scientists have discovered EVEs in animals, plants and fungi, the new study shows they are also found in single-celled eukaryotic organisms (protists). The research also shows that EVEs are not just genomic fossils, as supposed. Many of them look like functional viruses, which “suggests that multiple strings of these items may be part of a host antivirus system.”