Characteristics of ICH virus-induced hamster tumor cells serially propagated, in vitro, (referred HT-7 cells) were described. The predominant cell seen in the population of the HT -7 cells at the early passage levels, was the epithelial. However, these cells were replaced, following several passages, by fibroblastic cells. They propagated well in vitro and showed a lack of contact inhibition. Subcultivation of the HT-7 cells was accomplished by growing the cells in the medium with a low calcium content, 0.1 mM. All attempts to isolate infectious virus from the HT-7 cells by using supernatant fluids, lysed cells, and viable cells to inoculate dog kidney cells and Vero cells were negative. The HT-7 cells continuously possessed a virus-specific tumor antigen and their oncogenic potency toward hamsters
