bImmunotherapeutic herpes simplex virus 2 (HSV-2) vaccine efficacy depends upon the promotion of antigen-specific immune responses that inhibit reactivation or reactivated virus, thus controlling both recurrent lesions and viral shedding. In the present study, a candidate subunit vaccine, GEN-003/MM-2, was evaluated for its ability to induce a broad-spectrum immune response in mice and therapeutic efficacy in HSV-2-infected guinea pigs. GEN-003 is comprised of HSV-2 glycoprotein D2 (gD2⌬TMR 340-363 ) and a truncated form of infected cell polypeptide 4 (ICP4 383-766 ), formulated with Matrix M-2 (MM-2) adjuvant (GEN-003/MM-2). In addition to eliciting humoral immune responses, CD4؉ and CD8 ؉ T cells characterized by the secretion of multiple cytokines and cytolytic antigen-specific T cell responses that were able to be recalled at least 44 days after the last immunization were induced in immunized mice. Furthermore, vaccination with either GEN-003 or GEN-003/MM-2 led to significant reductions in both the prevalence and severity of lesions in HSV-2-infected guinea pigs compared to those of phosphate-buffered saline (PBS) control-vaccinated animals. While vaccination with MM-2 adjuvant alone decreased recurrent disease symptoms compared to the PBS control group, the difference was not statistically significant. Importantly, the frequency of recurrent viral shedding was considerably reduced in GEN-003/MM-2-vaccinated animals but not in GEN-003-or MM-2-vaccinated animals. These findings suggest a possible role for immunotherapeutic GEN-003/MM-2 vaccination as a viable alternative to chronic antiviral drugs in the treatment and control of genital herpes disease. H erpes simplex virus 2 (HSV-2) is one of the most prevalent sexually transmitted diseases, having infected more than 500 million people worldwide, with an estimated 23 million new infections occurring annually (1). HSV-2 infects epithelial cells of the genital mucosa during primary infection, followed by the establishment of latency in neuronal dorsal root ganglia via retrograde transport along nerve axons. Throughout latency, virus can reactivate, causing genital lesions and/or asymptomatic shedding of virus. Although suppressive antiviral therapy has shown promise in reducing both symptomatic recurrent lesions and overall viral shedding, subclinical HSV reactivation persists, likely contributing significantly to the observed continued transmission (2). The development of an efficacious immunotherapeutic vaccine targeting HSV-2 likely represents the best strategy for preventing both lesion outbreaks and the continued spread of virus.Despite considerable effort, all vaccine candidates to date have failed to meet their defined endpoints in clinical trials. The majority of clinical trials to date have focused on prophylactic subunit vaccines, largely using the HSV-2 surface glycoproteins as immunogens. The viral envelope glycoproteins gD and gB are the dominant targets for neutralizing antibody production (3, 4), making them logical candidates for vaccine devel...