HSV-529

**HSV-529** is a replication-defective live vaccine candidate based on herpes simplex virus 2 (HSV-2), with deletions in the UL5 (helicase-primase complex) and UL29 (DNA-binding protein) genes, preventing viral replication while allowing cellular infection to stimulate broad immune responses. Developed by **Sanofi Pasteur** under a clinical trial agreement with the National Institute of Allergy and Infectious Diseases (NIAID), it is designed as a prophylactic and potentially therapeutic vaccine against **HSV-2** infection, which affects approximately 400 million people worldwide and increases HIV acquisition risk. In a phase 1 trial (NCT01915212), it demonstrated safety with mostly mild injection-site reactions (e.g., tenderness in 87% of recipients), elicited significant neutralizing antibodies (6.1-fold GMT increase in seronegative adults), HSV-2 glycoprotein D (gD) antibodies, antibody-dependent cellular cytotoxicity (ADCC), and modest CD4+ (27-46%) and CD8+ (8-18%) T-cell responses persisting up to 6 months post-dosing, outperforming gD2 subunit vaccines in immunogenicity.

Other names

HSV 2 Formulation 1-Sanofi Pasteur, a Sanofi Company-genital herpes