Towards a novel vaccine against human cytomegalovirus based on a chimeric Ad5F35 adenovirus vector expressing the immunodominant antigenic domain 1 epitope.

BACKGROUND: Antibodies induced from glycoprotein B (gB) by antigenic domain (AD)-1 demonstrate broad neutralizing activity across different human cytomegalovirus (HCMV) types. This study aimed to prepare a novel HCMV vaccine using the modified adenoviral vector Ad5F35 to direct the expression of the conserved HCMV epitope AD-1 and to determine its transfer and expression in peripheral blood mononuclear cells (PBMCs). METHODS: AD-1 genes were amplified from AD169 HCMV strain and cloned into the Ad5F35 vector. Ad5F35-AD-1 virus vaccine was prepared by packaging Ad5F35-AD-1 into HEK293 cells. RT-PCR and fluorescence detection were used to detect the expression of AD-1 in HEK293 cells. PBMCs were stimulated in vitro with Ad5F35-AD-1 virus vaccine. The AD-1 expression in PBMCs was determined with immunocytochemistry and cell viability was measured to observe the possible adverse effects of AD-1 on PBMCs. RESULTS: We constructed an Ad5F35-AD-1 vector and transferred it into HEK293 cells to prepare the Ad5F35-AD-1 virus vaccine successfully. The AD-1 gene was proved to be expressed in HEK293 cells. In vitro stimulation of PBMCs with Ad5F35-AD-1 showed the highly efficient expression of AD-1 and low cytopathic activity in PBMCs. CONCLUSION: The novel vaccine Ad5F35-AD-1 is a promising candidate for clinical trials and may be of utility in prime-boost strategies for HCMV prevention and control.