Isolation of Virus‐producing Transformants from Human Gastric Cancer Cell Line, HGC‐27, Infected with Human T‐cell Leukemia Virus Type I

A human anaplastic gastric cancer cell line, HGC‐27, showed marked degeneration with formation of multinucleated syncytia and cell detachment of nearly all cells which began 24 hr after and reached a maximum 2 to 3 days after co‐cultivation with X‐irradiated MT‐2 cells, HTLV‐I producing human cord leukocytes. Less severe degeneration without formation of syncytia was also observed in the cultures inoculated with cell‐free MT‐2 culture media. Morphologically altered cells began to proliferate and formed piled up colonies in some of the cultures co‐cultivated with X‐irradiated MT‐2 cells after a long culture period. The two clones designated HGC/MT2 (Cl‐1) and HGC/MT2 (Cl‐2) were separated by cell cloning. HGC/MT2 (Cl‐1) and HGC/MT2 (Cl‐2) cells were positive for HTLV‐I gag proteins (p19 and p24) and pX gene products, p40^x, as demonstrated by immunohistochemistry and immunoblotting analysis, contained HTLV‐I provirus DNA, and consistently produced type C virus particles.