Optimization of DNA immunization against human cytomegalovirus.

The immune responses of mice injected with plasmids VR-gB and VR-gBΔtm expressing the full-length membrane-anchored, or secreted forms of human cytomegalovirus (HCMV)-glycoprotein B (gB), respectively, and VR-pp65 expressing the HCMV-phosphoprotein 65 (pp65) were analyzed. Pretreatment of mice with the local anesthetic bupivacaine did not enhance antibody production, and IFN-α co-expressed with the immunizing plasmids induced a moderate increase in the antibody response. However, antibody response was higher in mice inoculated at three sites in the musculus quadriceps than in mice inoculated at one site with the same dose and in the same muscle. pVR-gBΔtm induced significantly higher antibody titers than the construct expressing the membrane-anchored form of gB, and priming with pVR-gBΔtm followed by boosting with the gB subunit resulted in high-titer antibody responses. Immunization with VR-pp65 induced dose-dependent CTL responses in about 50% of the mice at a dose of 50 μg. Co-expression of IFN-α did not affect the number of responding mice. These findings might be important for optimization of humoral and cellular immune responses to HCMV after DNA vaccination.