Enhancement of protective humoral immune responses against Herpes simplex virus-2 in DNA-immunized guinea-pigs using protein boosting

Genital Herpes is a common sexually transmitted disease that is caused mostly by Herpes simplex virus type 2 (HSV-2). Its prevalence has increased in developing countries in spite of the availability of valuable antiviral drug therapy. Considering the importance of HSV-2 infections, effective vaccines remain the most likely hope for controlling the spread of HSV diseases. In the present study, the complete HSV-2 glycoprotein D gene was isolated and cloned into different plasmid vectors to construct a DNA vaccine and prepare recombinant subunit vaccines using a baculovirus expression system. The vaccines were tested alone or in combination to evaluate their ability to induce protective immunity in guinea-pigs against genital HSV infections. Immunization elicited humoral responses as measured by neutralization tests and enzyme-linked immunosorbent assay, and immunized animals had less severe genital skin disease as well as reduced replication of the challenging virus in the genital tract during experimental infection. Our results further demonstrate that DNA priming-protein boosting induced a neutralizing antibody titer higher than that obtained with DNA-DNA vaccination. The massive increase of antibody titer following DNA priming-protein boosting might be attributed to a recall of B cell memory.