Herpes Simplex Virus 1 Envelope Cholesterol Facilitates Membrane Fusion

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Herpes simplex virus 1 (HSV-1) entry into host cells is a complex process involving viral proteins and host cell interactions.
• The role of viral envelope cholesterol in HSV-1 entry and infectivity remains incompletely understood.

Purpose of the Study:

• To investigate the impact of cholesterol depletion on HSV-1 entry, infectivity, and the function of viral fusion proteins.
• To determine the specific role of HSV-1 envelope cholesterol in the viral entry mechanism.

Main Methods:

• Treatment of HSV-1 with methyl beta-cyclodextrin (MβCD) to reduce envelope cholesterol.
• Assessment of viral entry and infectivity in various cell types.
• Analysis of viral protein composition and ultrastructure using electron microscopy.
• Measurement of virion fusion activity and stability.

Main Results:

• MβCD treatment significantly reduced HSV-1 envelope cholesterol, inhibiting viral entry and infectivity.
• Cholesterol depletion did not alter viral protein composition or virion ultrastructure.
• Removal of cholesterol markedly reduced virion fusion activity, indicating its critical role in membrane fusion.
• MβCD treatment did not affect viral attachment or endocytic uptake.
• Cholesterol removal compromised virion stability.

Conclusions:

• HSV-1 envelope cholesterol is essential for viral entry and infectivity, primarily due to its role in facilitating membrane fusion.
• Cholesterol is a critical component for the fusion step of HSV-1 entry, independent of viral attachment and endocytosis.