Hepatitis B virus small surface protein (HBsAg-S)

The Hepatitis B virus small surface protein (HBsAg-S) is the most abundant component of the viral envelope and plays a critical role in the viral life cycle, including the assembly and secretion of infectious virions known as Dane particles (UniProt: P03141). Beyond its structural role, HBsAg-S is produced and secreted in massive excess as non-infectious subviral particles that serve as immunological decoys, exhausting the host's T-cell and B-cell responses to facilitate chronic infection (PubMed: 29033825). It is the primary antigen used in prophylactic vaccines to induce protective neutralizing antibodies that prevent viral entry into hepatocytes (WHO). In the context of chronic hepatitis B (CHB), HBsAg-S is a major therapeutic target; achieving a 'functional cure' is clinically defined by the sustained loss of HBsAg from the blood (NIH). Modern therapeutic strategies include antisense oligonucleotides like Bepirovirsen and siRNA like JNJ-3989 to silence HBsAg production, as well as nucleic acid polymers like REP 2139 that block its release, aiming to alleviate immune suppression and allow the host to clear the virus (ClinicalTrials.gov).

Other names

Small surface antigenHepatitis B surface antigen SS proteinHBsAgHBV S proteinMajor surface protein

Induction of neutralizing antibodies (vaccines), inhibition of viral protein synthesis via RNA interference or antisense oligonucleotides, and inhibition of antigen release to restore host immune response.