The three-dimensional structure of Mimivirus

Area of Science:

• Virology
• Structural Biology
• Microbiology

Background:

• Mimivirus is the largest known virus and the type species of the Mimiviridae family.
• Understanding its structure is key to comprehending its biological functions and interactions.

Purpose of the Study:

• To elucidate the detailed three-dimensional structure of the Mimivirus virion.
• To characterize the unique features of Mimivirus relevant to its infectivity.

Main Methods:

• Cryo-electron microscopy (cryo-EM) was employed to determine the overall virion structure.
• Atomic force microscopy (AFM) provided high-resolution surface details.
• Integrated structural analysis combined data from both techniques.

Main Results:

• The 0.75-microm diameter Mimivirus virion features an outer layer of dense fibers.
• Beneath the fibers lies an icosahedral capsid enclosing an internal membrane sac.
• A distinctive starfish-like structure at a fivefold vertex, crucial for host infection, was resolved in greater detail.

Conclusions:

• The detailed structure of Mimivirus reveals a complex organization facilitating its biological role.
• The identified structural components, particularly the starfish-like vertex, are critical for Mimivirus pathogenesis.
• Further structural studies will advance our understanding of giant viruses.