This disclosure provides modified cytomegalovirus (CMV) gL proteins and complexes comprising gL proteins, in particular pentameric complexes comprising gH, gL, pUL128, pUL130, pUL131. The disclosure also provides methods of purifying pentameric complexes and reducing contaminating dimeric complexes consisting of gH and gL. Also provided are uses of pentameric complexes in immunogenic compositions and vaccines.