Ebola virus glycoprotein needs an additional trigger, beyond proteolytic priming for membrane fusion

Area of Science:

• Virology
• Molecular Biology
• Structural Biology

Background:

• Ebolavirus causes severe hemorrhagic fever with high lethality.
• The viral glycoprotein (GP(1,2)) mediates host cell attachment, entry, and fusion.
• GP(1,2) undergoes sequential cleavage events crucial for viral infection.

Purpose of the Study:

• To investigate the functional consequences of GP(1,2) cleavage by endosomal cathepsins.
• To determine if enzymatic priming and low pH trigger conformational changes necessary for fusion.

Main Methods:

• Antibody binding assays.
• Hydrogen-Deuterium Exchange Mass Spectrometry (DXMS).
• Enzyme-linked immunosorbent assay (ELISA).

Main Results:

• Enzymatic priming of GP(1,2) is essential for fusion but does not induce conformational changes.
• Low endosomal pH does not trigger GP1-GP2 dissociation or fusion.
• The ebolavirus GP(1,2) ectodomain remains in a prefusion conformation after cleavage and glycan cap removal.

Conclusions:

• Ebolavirus GP(1,2) requires an additional, unidentified endosomal trigger for conformational changes and membrane fusion.
• Understanding this trigger is key to elucidating ebolavirus infection mechanisms.