Hepatitis B virus surface antigen, small (HBsAg (S))

Hepatitis B virus surface antigen, small (HBsAg or S-HBsAg), is a glycosylated integral membrane protein that forms the outer envelope of hepatitis B virus (HBV). It is essential for viral entry into host hepatocytes, virion assembly, and immune evasion, as it is produced in large excess as non-infectious subviral particles to act as a decoy for the immune system. HBsAg is used as the principal diagnostic marker for HBV infection, and recombinant S-HBsAg forms the basis of current prophylactic hepatitis B vaccines[1][2][3][5][6]. HBsAg also plays a role in modulating host immune responses and is implicated in the pathogenesis of both acute and chronic HBV infection, as well as related liver diseases such as cirrhosis and hepatocellular carcinoma[3][5].

Other names

HBsAgAustralia antigenHepatitis B surface antigenSmall Hepatitis B surface antigenS-HBsAg

Neutralization by vaccine-induced antibodies (prevention of infection); Blocking viral attachment/entry via antibody binding; Passive immunization (HBIG).