The fusion loops and membrane proximal region of Epstein-Barr virus glycoprotein B (gB) can function in the context of herpes simplex virus 1 gB when substituted individually but not in combination.

Among the herpesvirus glycoprotein B (gB) fusion proteins, the hydrophobic content of fusion loops and membrane proximal regions (MPRs) are inversely correlated with each other. We examined the functional importance of the hydrophobicity of these regions by replacing them in herpes simplex virus type 1 gB with corresponding regions from Epstein-Barr virus gB. We show that fusion activity is dependent on the structural context in which the specific loops and MPR sequences exist, rather than a simple hydrophobic relationship.