Structure-function analysis of soluble forms of herpes simplex virus glycoprotein D

Area of Science:

• Virology
• Molecular Biology
• Structural Biology

Background:

• Herpes simplex virus (HSV) Glycoprotein D (gD) is crucial for viral entry into host cells.
• Truncated gD forms can bind cells and inhibit viral plaque formation.
• Previous studies identified four key regions (I-IV) in gD essential for HSV entry.

Purpose of the Study:

• To investigate the structural and functional roles of specific regions in HSV Glycoprotein D (gD).
• To analyze truncated wild-type and mutant gD proteins from HSV-1 and HSV-2.
• To determine the correlation between gD structure, cell binding, and viral infectivity.

Main Methods:

• Overexpression of truncated wild-type and mutant gD proteins using baculovirus vectors.
• Structural analysis via enzyme-linked immunosorbent assay (ELISA) and circular dichroism (CD).
• Functional assays to assess cell binding, viral penetration, plaque formation, and cell-to-cell spread.

Main Results:

• Wild-type gD-1 and gD-2 showed similar antigenicity and stability but differed in secondary structure.
• Mutants in regions I and II exhibited greater structural and stability alterations than those in regions III and IV.
• All mutant proteins bound cells, but only the region I mutant failed to inhibit HSV plaque formation and spread, indicating region I's necessity for infection initiation.

Conclusions:

• HSV Glycoprotein D possesses distinct structural elements involved in different stages of the viral infection cycle.
• Region I of gD is essential for initiating HSV infection, while other regions contribute to binding and inhibition.
• The region IV mutant showed enhanced inhibition of HSV infection, suggesting complex functional roles within gD.