File:Viruses-04-02973-g007.webp

English: Assembly and budding of arenaviruses. (A) Ultrathin sections of LASV-infected Vero cells. The left image shows an electron microscopic picture of LASV budding from the surface of infected cells. Discrete area of membrane thickening and membrane curvature at the left indicates an early stage of virus budding, while the particle shown at the right almost fully assembled. Bar, 100nm. The electron microscopic image shown on the right demonstrates Z protein-specific immuno-gold labeling (10nm gold particles) at LASV budding sites at the plasma membrane. Bar, 50nm. (B) Model for arenavirus assembly and budding. Z protein (blue) is the key regulator of virus assembly. Through interaction with GP (red), NP (light and dark green) and L (orange), the Z protein mediates the incorporation of viral RNP complexes into GP-spike containing particles, leading the release of infectious virions from the plasma membrane of infected cells. Viral late domains encoded by Z facilitate interaction with Tsg101 and Nedd4, thereby presumably recruiting other components of the cellular ESCRT machinery. The AAA-ATPase Vps4 is required for efficient budding of arenavirus virions.