Differential formation of disulfide linkages in the core antigen of extracellular and intracellular hepatitis B virus core particles.

Our understanding of the assembly of hepatitis B virus is still very limited. We present evidence to demonstrate that the HBc antigen formed oligomers through disulfide linkages in the extracellular hepatitis B virus core (HBc) particles. However, the intracellular HBV core particles did not contain disulfide-linked HBc antigens. Furthermore, the extracellular particles which had disulfide bonds were more stable than intracellular particles at pH 7.5 and 10 and in 3 M NaCl and 4 M urea. These data suggest that the formation of disulfide bonds in the HBc antigen is important for the integrity of the viral core particles.