Negative-strand RNA viruses constitute the phylum Negarnaviricota, in the kingdom Orthornavirae and realm Riboviria.

Within the phylum, there are two major branches that form two subphyla: Haploviricotina, whose members are mostly non-segmented and which encode an RdRp that synthesizes caps on mRNA, and Polyploviricotina, whose members are segmented and which encode an RdRp that snatches caps from host mRNAs.

The subphylum Haploviricotina takes the first part of its name, Haplo, from Ancient Greek ἁπλός, meaning simple, and 'viricotina is the suffix used for virus subphyla.

The subphylum Polyploviricotina follows the same pattern, Polyplo being taken from Ancient Greek πολύπλοκος, meaning complex.

As new nucleotide sequences are synthesized by RdRp, capsid proteins are assembled and encapsidate the newly replicated viral RNA.

[10][7][13] Some −ssRNA viruses are ambisense, meaning that both the negative genomic strand and positive antigenome separately encode different proteins.

All ambisense viruses contain a hairpin loop structure to stop transcription after the protein's mRNA has been transcribed.

[2] Excluding the family Aspiviridae, −ssRNA viruses contain an outer viral envelope, a type of a lipid membrane that surrounds the capsid.

Arthropods frequently live together in large groups, which allows for viruses to be transmitted easily.

Over time, this has led to arthropod −ssRNA viruses gaining a high level of diversity.

[5] Negarnaviricota belongs to the kingdom Orthornavirae, which encompasses all RNA viruses that encode RdRp, and the realm Riboviria, which includes Orthornavirae as well as all viruses that encode reverse transcriptase in the kingdom Pararnavirae.

[26][27] Many diseases caused by −ssRNA viruses have been known throughout history, including hantavirus infection, measles, and rabies.

[28][29][30] In modern history, some such as Ebola and influenza have caused deadly disease outbreaks.