Nucleus softens during herpesvirus infection.

Area of Science:

• Cell Biology
• Biophysics
• Virology

Background:

• Nuclear mechanical properties are influenced by both external forces and internal cellular modifications, including viral infections.
• Herpes simplex virus type 1 (HSV-1) infection reorganizes nuclear structures and affects nuclear functions, but its impact on nuclear mechanobiology remains unclear.

Purpose of the Study:

• To investigate how HSV-1 infection alters the mechanical properties of the cell nucleus.
• To elucidate the underlying mechanisms responsible for infection-induced changes in nuclear stiffness.

Main Methods:

• Microscopy techniques were employed to observe nuclear structural changes during HSV-1 infection.
• Computational modeling was used to simulate and analyze the impact of viral infection on nuclear mechanics and cellular forces.

Main Results:

• The cell nucleus exhibits decreased stiffness (softening) during HSV-1 infection.
• The viral replication compartment has lower biomolecular density than euchromatin. The nuclear lamina shows increased lamin proteins, more outward curvature, and reduced movement.
• Computational models suggest nuclear softening is caused by the removal of lamina-associated domains or reduced outward forces, potentially increasing nuclear envelope tension.

Conclusions:

• HSV-1 infection significantly alters nuclear mechanics, leading to a softer nucleus.
• Proposed mechanical model explains the coordination between nuclear deformation during infection and reduced nuclear stiffness.