Sialic acid content in four cell strains transformed by adenoviruses and/or SV40

The sialic acid content in hamster cells primarily transformed by adenovirus was found lower than in cells transformed by papovavirus SV40. Intermediate concentrations were shown in a cell strain transformed by an adenovirus-SV40 hybrid. An adenovirus 19 - transformed cell strain derived from the NIL-2 hamster cell line, adapted to unlimited growth in vitro prior to the exposure to the adenovirus, revealed a high content of sialic acid. The concentration of sialic acid in cells transformed by DNA-viruses may depend both on the transforming virus and on the preceding history of the cell line. The tumors revealed more sialic acid than the in vitro cultures derived from the same cell strains. This finding is discussed.