DNA purified from naked intranuclear particles of human liver infected with hepatitis B virus

Abstract

DANE et al.¹ observed a particle 42 nm in diameter with a double shell and an inner core resembling a viral nucleoid in the sera of some patients with hepatitis B antigenemia. They postulated that this particle was the complete hepatitis B virion. Almeida et al.² showed that an internal core particle, 27 nm in diameter, could be released by treating the 42 nm Dane particle with Tween-80 (polysorbate) and that this core particle contained an antigen different from hepatitis B antigen (HBAg). Almeida³ suggested that these core particles were identical to naked particles, also 27 nm in diameter, observed by electron microscopy in the nuclei of hepatocytes of human livers infected with hepatitis B virus (HBV)^4,5. Cores isolated from Dane particles in human sera⁶ seem to be similar in morphology to the 27 nm naked particles visualised in homogenates of HBV-infected human livers⁷. We recently reported methods for isolation and purification of concentrated preparations of naked intranuclear particles of hepatocytes of HBV infected liver⁸. The ultraviolet absorption spectrum of these particles suspended in 0.05 M Tris-HCl, 40 mM KCl, 0.1% β-mercaptoethanol (BME), 10 mM MgCl₂, pH 7.5 buffer showed a peak at 264 nm and a shoulder at 280 nm indicating the presence of both nucleic acid and protein⁸. We now report the isolation of double-stranded DNA from these particles and describe the spectral properties of the isolated DNA.