Hepatitis B core protein (HBc or HBcAg)

The **Hepatitis B core protein** (commonly called *HBc* or *HBcAg*) is the major structural protein forming the icosahedral nucleocapsid of HBV, composed of 240 subunits that enclose the viral DNA[2][4]. It is a helical protein with five alpha-helices, organized into N- and C-terminal domains connected by a hinge; the N-terminal domain (residues 1–140) controls capsid assembly, while the C-terminal domain (residues 141–183) is involved in RNA/DNA binding and genome maturation[1][5]. HBc not only provides physical protection for the viral genome but also regulates genome packaging, reverse transcription, and nuclear release during the HBV lifecycle[1]. It interacts with host proteins and is subject to phosphorylation and other modifications, contributing to viral persistence and pathogenesis[1][5]. HBcAg is also an immunodominant antigen recognized strongly by the host immune system, making it a focal point for vaccine and antiviral drug development[6]. Drugs targeting this protein, such as core protein allosteric modulators, disrupt capsid assembly or stability, offering a novel therapeutic approach in HBV infection[5]. HBcAg is commonly used as a biomarker for active HBV replication and disease progression[4][6]. Therapeutic targeting requires caution due to potential immune-related safety challenges and resistance development[5][6].

Other names

Hepatitis B core antigenHBcAgHBcCore protein

Disrupts capsid assembly/stabilization; Inhibits viral replication by altering genome packaging and maturation