Herpes Simplex Virus 1 Can Enter Dynamin 1 and 2 Double-Knockout Fibroblasts

Area of Science:

• Cell Biology
• Virology
• Molecular Biology

Background:

• Dynamin GTPases are essential for endocytic vesicle fission.
• Viruses, including herpes simplex virus 1 (HSV-1), can exploit cellular machinery for entry.
• HSV-1 entry into cells is known to involve both direct fusion and endocytic pathways.

Purpose of the Study:

• To investigate the role of dynamin in efficient HSV-1 entry into fibroblasts.
• To determine if HSV-1 can utilize alternative entry pathways in the absence of dynamin.
• To elucidate the specific mechanisms of HSV-1 internalization influenced by dynamin.

Main Methods:

• Utilized conditional dynamin 1 and dynamin 2 double-knockout (DKO) fibroblasts.
• Infected control and DKO cells with HSV-1 and Semliki Forest virus.
• Employed the dynamin inhibitor dynasore.
• Performed electron microscopy on infected cells.
• Assessed viral entry at low temperatures to block endocytosis.

Main Results:

• HSV-1 entered both control and DKO fibroblasts with comparable efficiencies.
• Semliki Forest virus entry was efficient in DKO cells, indicating functional alternative pathways.
• Dynasore treatment inhibited HSV-1 entry in control cells but not in DKO cells.
• Electron microscopy revealed entry via plasma membrane fusion and endocytosis in both cell types.
• HSV-1 entry occurred even at low temperatures, suggesting dynamin-independent, non-endocytic pathways contribute.

Conclusions:

• HSV-1 entry is dependent on dynamin in normal cells but can occur independently in dynamin-deficient cells.
• The adaptability of HSV-1 allows it to utilize alternative cellular pathways for entry.
• Dynamin-independent entry mechanisms, including plasma membrane fusion, are significant for HSV-1 internalization.