Arenavirus is a virus that belongs in a viral family known as Arenaviridae. The name arenavirus derives from the appearance of the spherical virus particles when cut into thin sections and viewed using the transmission electron microscope. The interior of the particles is grainy or sandy in appearance, due to the presence of ribosomes that have been acquired from the host cell. The Latin designation "arena" means "sandy."

Arenaviruses contain ribonucleic acid (RNA) as their genetic material. The viral genome consists of two strands of RNA, which are designated the L and S RNA. The ribosomes of the host that are typically present inside the virus particle are used in the manufacture of the components that will be assembled to produce the new virus particles. Little is known about the actual replication of new viral components or about the assembly of these components to produce the new virus...