Productive Infection of Mouse Cells

If this altered ganglioside metabolism is related to some viral function, is it a function involved in transformation, productive infection, or both Mouse cells are permissive for polyoma virus and are rarely transformed by it (cf. Eckhart, 1969). Upon viral infection, the cells undergo a series of discrete events which result in cell lysis and release of new virions (cf. Weil and Kara, 1970). These include the appearance of viral-specific T-antigen, induction of cellular and viral DNA synthesis which is maximum at 25-30 hr postinfection, synthesis of viral coat proteins and new virions (present at 50 hr.), and, finally, cell lysis and virus release (5-7 days after infection). Swiss 3T3 and TAL/N cells were treated with sufficient polyoma virus to ensure infection of all cells. Hematoside UDP-GalN AcA-acetylgalactosaminyl-transferase was then determined at two key times after infection (Table V). The activity of this enzyme was similar to that seen in mock-infected cells. The results indicate that the reduced aminosugar transferase activity in virally transformed cells is specifically related to some transforming function of the viruses and is not a consequence of lytic infection of the cell. 

Ganglioside Metabolism in Flat Revertant Cell Lines 

Since the altered ganglioside metabolism is found in virally transformed cell lines which have altered growth properties in culture and in 

TABLE V. A-Acetylgalactosaminyltransferase Activity in Mouse Cells Lytically Infected and Transformed by Polyoma Virus  

Time of harvest after exposure to virus (Transferase activity as percent of control) 

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