Sialidase activity of oncogenic cells transformed by herpes simplex virus

Sialidase in normal nononcogenic hamster embryo fibroblasts was not active toward added disialo- and trisialoganglioside, but all transformed lines of hamster embryo fibroblasts studied had sialidase active toward added ganglioside substrate. The levels of exogenous sialidase activity suggested a parallel trend in the amount of this activity and the degree of oncogenicity of the transformed cells. Exogenous sialidase activity in a weakly oncogenic cell line was found to increase after passage of the cells into hamsters and isolation and cell culture of the resulting tumors which gave rise to a cell line of relatively high oncogenicity.