G103

G103 is an investigational **trivalent recombinant protein-subunit therapeutic vaccine** for recurrent genital herpes caused by herpes simplex virus type 2. It contains recombinant HSV-2 glycoprotein D2, truncated UL19, and full-length UL25, formulated with the glucopyranosyl lipid A stable-emulsion adjuvant system, a synthetic Toll-like receptor 4 agonist intended to enhance dendritic-cell activation, HSV-2-specific T-cell responses, and antibody responses. The candidate originated at Immune Design and was developed with Sanofi; it entered the HSV15 Phase I/IIa study, but the study and HSV0148 project were terminated before the planned Phase II efficacy portion was conducted. ([sciencedirect.com](https://www.sciencedirect.com/science/article/abs/pii/S0264410X25011181))