Serum antibody response to the gH/gL/pUL128–131 five-protein complex of human cytomegalovirus (HCMV) in primary and reactivated HCMV infections

BackgroundRecently, a new human cytomegalovirus (HCMV) glycoprotein complex has been identified and potentially proposed as a vaccine.ObjectiveThe aim of this study was to determine whether the HCMV gH/gL/pUL128–pUL130–pUL131 (gH/gL/pUL128–131) 5-protein (pentameric) complex (which has been recently found to be indispensable for the infection of endothelial and epithelial cells) is able to elicit a consistent antibody response in both primary and reactivated HCMV infections.Study designThe antibody response was determined by both indirect immunofluorescence (IFA) and ELISA, using fixed (IFA) or lysed (ELISA) epithelial (ARPE-19) cells infected with one or more adenoviral vectors, each carrying one HCMV gene and, in parallel, with a control adenovirus vector.ResultsThe specificity of results was determined by the reactivity of human neutralizing mAbs recognizing two, three, or four proteins of the complex. In 14 cases of primary infection, an IgG antibody seroconversion to the UL128–131 gene products was consistently detected within 2–4 weeks after onset of infection, while antibodies persisted for at least 12 months. The IgG antibody response to UL128–131 gene products was generally superior to the response to gH and appeared to follow the neutralizing antibody response (as determined in epithelial cells). In reactivated infections, the antibody response showed a trend reminiscent of a booster response. IgG antibodies were detected in HCMV-seropositive healthy adult controls, but not in HCMV-seronegative individuals.ConclusionsThe IgG antibody response to the pentameric complex could be a major target for the evaluation of the antibody response to a pentamer-based vaccine.