Ultrastructural analysis of monkeypox virus replication in Vero cells

Area of Science:

• Virology
• Cell Biology
• Microscopy

Background:

• The 2022 worldwide monkeypox virus (MPXV) outbreak presented distinct clinical features.
• Understanding MPXV's biological mechanisms is crucial, yet many aspects remain uninvestigated.

Purpose of the Study:

• To investigate the ultrastructural characteristics of MPXV asynchronous infections in vitro.
• To elucidate early viral events and cellular responses during MPXV infection.

Main Methods:

• Transmission electron microscopy (TEM) was employed to examine MPXV-infected Vero cells.
• A viral strain isolated from a 2022 outbreak patient was used.

Main Results:

• TEM revealed intracellular mature virus particles adhering prior to cell entry.
• Observed reorganization of rough endoplasmic reticulum into 'mini-nuclei' structures linked to genome replication.
• Identified distinct granular and fibrillar viral factory sites, viral crescents, and varied MPXV morphotypes.
• Documented cellular alterations including cytoskeleton changes and increased multimembrane vesicles.

Conclusions:

• This study provides novel ultrastructural insights into multiple stages of the MPXV life cycle.
• The findings contribute to a deeper understanding of MPXV pathogenesis at the cellular level.