Arenaviridae are single stranded RNA viruses. The arenaviridae S RNAs that have been characterised include conserved terminal sequences, an ambisense arrangement of the coding regions for the precursor glycoprotein (GPC) and nucleocapsid (N) proteins and an intergenic region capable of forming a base-paired "hairpin" structure. The mature glycoproteins that result are G1 and G2 and the N protein PMID:2042397.

The representative domain of this superfamily entry was characterised in lassa fever virus (LASV), a member of the family Arenaviridae, which causes severe hemorrhagic fever and is highly endemic in Western Africa.

The arenaviral nucleoprotein NP has been implicated in suppression of the host innate immune system. The NP encapsulates the viral ssRNA PMID:8599223.

This N-terminal domain folds into a novel structure with a deep cavity for binding the m7GpppN cap structure that is required for viral RNA transcription PMID:21085117. The C-terminal domain has 3'-5' exoribonuclease activity and is involved in suppressing interferon induction PMID:21085117. It forms a typical alpha/beta/alpha sandwich architecture and contains a CCHE zinc-binding site near the 3'-5' exonuclease active site.

PFAM:PF00843, INTERPRO:IPR000229,DOI:10.1073/pnas.1016404108,DOI:10.1038/nature09605