Disclosed is an expression system for expressing a herpesvirus glycoprotein complex. The expression system may include a vector inserted with two or more nucleic acid sequences that encode two or more subunits of a herpesvirus glycoprotein complex linked by one or more linking sequences such that the subunits are co-expressed simultaneously and self-processed to assemble into a glycoprotein complex. Also disclosed are vaccine compositions comprising the expression system or the vector and methods of preventing or treating herpesvirus infections using the vaccine compositions.
