Hepatitis B surface antigen peptide–Major Histocompatibility Complex (HBsAg-MHC)

The Hepatitis B surface antigen (HBsAg) peptide–Major Histocompatibility Complex (MHC) is a molecular assembly found on the surface of hepatocytes infected with the Hepatitis B virus (HBV). It consists of short peptide fragments derived from the HBsAg protein loaded onto MHC Class I molecules, most commonly the HLA-A*02:01 allele in therapeutic contexts (PMID: 34253547). This complex serves as a critical signal for the adaptive immune system, specifically allowing CD8+ cytotoxic T lymphocytes to recognize and eliminate virally infected cells or HBV-integrated tumor cells (PMID: 31110077). In chronic HBV infection, the endogenous T-cell response is often exhausted or insufficient, making this complex a primary target for novel immunotherapies such as TCR-engineered T cells (TCR-T) and TCR-like antibodies (NCT05417932). By targeting this specific peptide-MHC assembly, these therapies aim to achieve precise clearance of the viral reservoir and treat HBV-related hepatocellular carcinoma while minimizing damage to healthy, non-infected tissues. Current clinical candidates like SCG101 utilize high-affinity T-cell receptors to bind this complex and trigger a potent anti-viral and anti-tumor response (SCG Cell Therapy, 2023).

Other names

HBsAg-HLA complexHBV surface antigen peptide-MHCHBsAg-HLA-A*02:01 complexHBsAg-pMHCHepatitis B surface antigen-HLA-A2 complex

Targeted T-cell mediated cytotoxicity via recognition of viral peptides presented on MHC Class I molecules by engineered T-cell receptors (TCR) or TCR-like antibodies.