Hepatitis B core-related antigen (HBcrAg) (HBcrAg)

Hepatitis B core-related antigen (HBcrAg) is a serum biomarker composed of three proteins from the hepatitis B virus (HBV) precore/core gene: hepatitis B e antigen (HBeAg), hepatitis B core antigen (HBcAg) forming the viral nucleocapsid, and a 22-kDa precore protein (p22cr) in empty particles, all sharing a 149-amino-acid sequence. It serves as a noninvasive surrogate for intrahepatic covalently closed circular DNA (cccDNA) levels and transcriptional activity, correlating with serum HBV DNA, HBsAg, and viral replication even when HBV DNA is undetectable during nucleos(t)ide analogue therapy. HBcrAg remains detectable in HBsAg-negative or HBV DNA-suppressed chronic hepatitis B (CHB) cases, aiding differentiation of active CHB from inactive carriers. Elevated HBcrAg predicts risks like HBeAg seroconversion, HBV reactivation, post-transplant reinfection, and hepatocellular carcinoma (HCC) progression or recurrence in CHB and liver cirrhosis patients. Guidelines in Japan, Asia, and Europe recommend HBcrAg for CHB monitoring, with high-sensitivity assays like iTACT-HBcrAg enhancing its utility for low-level detection. No direct therapeutic drugs target HBcrAg, but it guides antiviral management and outcomes.

Other names

Hepatitis B core antigen (HBcAg)Hepatitis B e antigen (HBeAg)22-kDa precore protein (p22cr)