hepatitis B surface antigen + adjuvant 2

This vaccine is a **combination of hepatitis B surface antigen (HBsAg) and a novel adjuvant**. The HBsAg component contains envelope proteins derived from hepatitis B virus (L, M, and S proteins, typically expressed in recombinant systems such as CHO or yeast cells). The adjuvant component, referred to as "adjuvant 2," is not precisely specified here, but available studies highlight alternatives to classical alum, such as **L-pampo** (a lipopeptide and synthetic dsRNA acting as TLR2/TLR3 agonists)[1] or **PEG–PAEEP** (a polyphosphoester-based amphiphilic polymer)[2]. These adjuvants are designed to **enhance both the magnitude and quality of immune responses** compared to alum, promoting higher antibody titers and a Th1-skewed isotype profile. The combination is mainly developed to achieve effective immunogenicity against hepatitis B infection, often with a reduced number of doses and/or improved efficacy in populations with lower response rates to traditional alum-adjuvanted vaccines[1][2].