STRUCTURE AND EXPRESSION OF INTEGRATED HEPATITIS-B VIRUS GENES IN AN HBS-ANTIGEN PRODUCING HUMAN CELL-LINE (HUGK-14)

A human continuous cell line (huGK-14) within a lineage of passaged cu ltures was investigated in the mode of integration and expression of h epatitis B virus (HBV) genes. HBV DNA was integrated in eight differen t sites of the cellular DNA, in each of which HBV genome was rearrange d, fragmented, and/or partly deleted. Complete HBV genome that may lea d to production of infectious virus particles was not detected in the cells nor in the culture medium. Clones of cDNA containing a complete coding frame for small HBs antigen protein (type adr) were obtained fr om mRNA of the cells. The cells were stable over the period of six mon ths of cultivation and more than 60 population doublings in the mode o f HBV integration and HBs mRNA expression. These results provide subst antial evidence for the absence of an ability for the integrated DNA t o create an infectious product in the cell; for the stable production of HBs mRNA from the cells, and suggest the usefulness of this cell li ne as a substrate for HBV vaccine production.