Evaluation of Heterologous Prime-boost Vaccine Strategy Using Full-length Cytomegalovirus Glycoprotein B to Trigger BALB/c Mice Immunity

Human cytomegalovirus glycoprotein B (gB) emerges as a viable candidate for eliciting neutralizing antibodies. This research specifically focused on exploring the immune reaction prompted by the nonglycosylated variant of the gB, with a comprehensive assessment of humoral immunity in mice. The gB coding sequence was optimized and expressed in pET-15b. Additionally, pcDNA3.1(+) vectors were also used for cloning the same gB sequence as the DNA vaccine. The gB was purified using a Ni-NTA chromatographic column. SDS-PAGE and Western blotting were used to confirm protein expression and purification. Using the prime-boost strategy, 8 different BALB/c mice were injected with DNA vaccine plus gB heterologous vaccine at 3 intervals. We evaluated the interferon (IFN-γ), interleukin (IL-4), immunoglobulin (Ig) G1, IgG2a, and IgG2b using enzyme-linked immunosorbent assay. It was shown that the mice administered with DNA vaccine plus gB had higher IFN- γ and IL-4 levels compared to controls. On the other hand, the mice that received 3 doses of gB showed the highest levels of IgG1 and IgG2a. However, IgG2b was at its highest in mice administrated with DNA vaccine plus gB. The total IgG was higher in mice that received gB than in other interventions. According to the findings, the DNA vaccine enhanced total IgG in immunized mice more effectively than the gB. This could be attributed to conformational changes owing to a lack of glycan moiety. Furthermore, combining nonglycosylated gB with DNA as a heterologous vaccine strategy enhances innate immunity by increasing the IFN- γ levels.