Viruses in this kingdom share a number of characteristics which promote rapid evolution, including high rates of genetic mutation, recombination, and reassortment.

The kingdom is subdivided into five phyla that separate member viruses based on their genome type, host range, and genetic similarity.

In modern history, RdRp-encoding RNA viruses have caused numerous disease outbreaks, and they infect many economically important crops.

Because +ssRNA viruses create intermediate dsRNA forms, they have to avoid the host's immune system in order to replicate.

[6][7] Negative-strand RNA viruses have genomes that function as templates from which mRNA can be synthesized directly by RdRp.

[8] Replication is the same process but executed on the positive sense antigenome, during which RdRp ignores all transcription signals so that a complete -ssRNA genome can be synthesized.

[10] For many -ssRNA viruses, at the end of transcription, RdRp stutters on a uracil in the genome, synthesizing hundreds of adenines in a row as part of creating a polyadenylated tail for the mRNA.

To counter this, dsRNA viruses typically retain their genomes inside of viral capsid in order to evade the host's immune system.

Copy choice recombination occurs when the RdRp switches templates during synthesis without releasing the prior, newly created RNA strand, which generates a genome of mixed ancestry.

[19] The exact origin of Orthornavirae is not well established, but the viral RdRp shows a relation to the reverse transcriptase (RT) enzymes of group II introns that encode RTs and retrotransposons, the latter of which are self-replicating DNA sequences that integrate themselves into other parts of the same DNA molecule.

The five phyla are separated based on the genome types, host ranges, and genetic similarity of member viruses.

Cucumber mosaic virus infects more than 1,200 plant species and likewise causes significant crop losses.

Brome mosaic virus, while not causing significant economic losses, is found throughout much of the world and primarily infects grasses, including cereals.

As a whole, RNA viruses were discovered during a time period of major advancements in molecular biology, including the discovery of mRNA as the immediate carrier of genetic information for protein synthesis.

[33] Viruses in the kingdom that are transmitted by arthropods have been a key target in the development of vector control, which often aims to prevent viral infections.