Plasmid DNA-expressed secreted and nonsecreted forms of herpes simplex virus glycoprotein D2 induce different types of immune responses

Herpes simplex viruses (HSVs) are significant pathogens and major targets o f vaccine development. Several attempts have been made to develop prophylac tic and therapeutic vaccines for HSV types 1 and 2. Although these vaccines elicit strong humoral responses, the overall impact on pathology has been disappointing. An effective vaccine for HSV must induce both humoral and ce llular immune responses. DNA vaccines are ideal candidates for HSV vaccines because they induce both types of immune responses. This study showed that the type of immune response generated by immunization with DNA vaccines is modulated by expression of various forms of an antigen, each with a differ ent cellular localization. Expression of cell-associated forms of HSV-2 gly coprotein D (gD) induces primarily a Th1 response, whereas expression of se creted go results in a Th2 response. Immunization with plasmids expressing different forms of the antigen may increase the efficacy of a vaccine.