Cell "metatranscriptome" mining builds an understanding of the viral "universe."

A team of researchers from NLM and collaborating academic research institutions have discovered new RNA bacteriophages, a virus that attacks bacteria, advancing the understanding
of viral evolution.
The findings were published in
the journal Cell.

Viruses are thought to be the most abundant and diverse biological entity on Earth, and researchers know only about
them.
The advent of metatranscriptomics — the sequencing of total RNA in samples from specific environments — is helping researchers discover important features
of Earth's RNA virions.
In this study, the researchers identified multiple novel viruses that provide insights
into the diversity, host range, and evolution of RNA viruses.

The researchers mined more than 5,150 different variable transcriptomes from an existing knowledge base and found 2.
5 million RNA virus-derived sequences
.
This expansion corresponds to a fivefold increase
in known RNA viral diversity.
According to the study authors, many of the viruses discovered are truly new viruses that are only distantly related to previously known viruses
.
The two most unusual groups of viruses form potential new doors, while the others are divided into many new classes and orders
.

"The most notable findings were a dramatic increase in the number and diversity of viruses that infect bacteria, which make up a much
larger proportion of RNA viruses than we previously thought," the authors said.
According to the study authors, the collection of a large number of new RNA viral genomes provides insight into the evolution of RNA viruses and should be a major resource for
RNA virology.

Editor's note: Metatranscriptomics is the study of the transcriptome of all microorganisms in the natural environment, including the transcriptome information
of cultureable and non-culturable microorganisms.

Expansion of the global RNA virome reveals diverse clades of bacteriophages