Purification of naked intranuclear particles from human liver infected by hepatitis B virus

The isolation and purification of the naked intranuclear particles of a human liver infected with hepatitis B virus is described. The particles had a diameter of 27-28 nm, were hexagonal, and showed the presence of capsomeres and spikes with lengths of 7-10 nm projecting from the surfaces. The particles formed cubic arrays with center-to-center distances of 40-42 nm. The overall particle symmetry was icosahedral. The ultraviolet absorption spectrum of the particles showed a peak at 264 nm with a shoulder at 280 nm. Endogenous DNA polymerase activity was not detected in fractions containing particles. DNA polymerase activity was present when activated DNA or d(A-T)(n) was used as exogenous template.