Patterns of single- and double-stranded hepatitis B virus DNA and viral antigen accumulation in infected liver cells.

Liver sections from five patients with persistent hepatitis B virus (HBV) infection and active cirrhosis were shown to contain intracellular HBV DNA by in situ hybridization using cloned 3H-labelled HBV DNA probes. Two classes of infected cells, with different distributions throughout the liver, were distinguished: (i) cells containing a low copy number of double-stranded HBV nucleotide sequences, confined to the cell nucleus and thought to represent HBV DNA, and (ii) cells containing large amounts (estimated to be greater than 10 or 15 genome copies per cell) of HBV DNA, much of it in a single-stranded form and largely confined to the cell cytoplasm; these single-stranded regions represented widely separated regions of the HBV genome, in contrast to the structure of the DNA in mature virions. It is likely that these latter cells may be supporting viral DNA synthesis. Cells with large amounts of cytoplasmic HBV DNA invariably contained hepatitis B surface antigen (HBsAg) and in addition contained either no detectable hepatitis B core antigen (HBcAg), or cytoplasmic HBcAg or nuclear HBcAg in that order of frequency. Cytoplasmic HBcAg was highly predictive of the presence of large amounts of cytoplasmic HBV DNA in the same cell, while either nuclear HBcAg, or cytoplasmic HBsAg, were often seen both in cells with and without such levels of DNA. These patterns, relating HBV DNA and antigen content in naturally occurring asynchronous infection in a heterogeneous cell population, should provide a background to further studies of the virus replication cycle with a defined experimental system, when such a system becomes available.