Hepatitis B virus nucleocapsid protein (HBcAg (or HBV core protein; also referred to as Cp or Cp183 in the literature))

The **Hepatitis B virus nucleocapsid protein** (HBcAg, core protein) is the principal structural component forming the icosahedral capsid (nucleocapsid) of hepatitis B virus. It consists of about 183 amino acids and forms dimers that assemble into icosahedral shells, packaging the viral pre-genomic RNA and polymerase for reverse transcription into DNA. The core protein contains a C-terminal domain with arginine-rich motifs acting as a nuclear localization signal (NLS), which is essential for the nuclear import and proper intracellular trafficking of the viral genome. Dynamic post-translational modifications regulate its roles in assembly, disassembly, and interactions with host factors. The nucleocapsid protein is a validated drug target, with several capsid assembly modulators in development aiming to disrupt the HBV lifecycle by interfering with encapsidation, genome replication, or nuclear delivery. HBcAg is a key diagnostic marker in serology for infection status, and therapeutic interventions against it are crucial for curative strategies against chronic hepatitis B[1][2][4][5][7][8][9].

Other names

Hepatitis B core antigenCore proteinHBV core proteinCp183 (full-length form, 183 amino acids, common in literature)HBcAg

Disruption of capsid assembly (CAMs bind to core proteins, accelerating or misdirecting capsid formation) - Inhibition of nucleocapsid assembly and viral DNA synthesis - Destabilization of capsid structure, inhibiting packaging and nuclear import of the viral genome