Herpevac

Herpevac (also known as Simplirix or gD2-AS04) is a recombinant protein subunit vaccine developed by GSK for the prevention of genital herpes. The vaccine consists of a truncated version of the Herpes Simplex Virus type 2 (HSV-2) glycoprotein D (gD2) formulated with the AS04 adjuvant system, which combines aluminum hydroxide (alum) and 3-O-desacyl-4'-monophosphoryl lipid A (MPL). The mechanism of action involves inducing high titers of neutralizing antibodies against gD2 to prevent viral entry into host cells, while the AS04 adjuvant enhances the immune response by activating Toll-like receptor 4 (TLR4). Despite showing promising results in early trials—specifically providing protection against HSV-1 and HSV-2 in women who were seronegative for both viruses—a large-scale Phase 3 trial completed in 2010 failed to demonstrate overall efficacy in preventing HSV-2 infection or disease. Consequently, GSK discontinued the development of this specific formulation for genital herpes.

Brand names

Simplirix

Other names

Herpes Simplex Virus Type 2 Glycoprotein D Vaccineglycoprotein D2 + alum + monophosphoryl lipid A