Polyoma virus mutants as probes of variety among mouse embryonal carcinoma cell lines

Embryonal carcinoma (EC) cells are resistant to infection with polyoma virus and become permissive when allowed to differentiate. Polyoma host-range (PyEC) mutants have been selected on two embryonal carcinoma cell lines, PCC4 and F9, which differ in their differentiation potential, both in vitro and in vivo. Since PyEC mutants selected on one line failed to develop, or developed only poorly on the other, we used these two classes of mutants as probes towards several EC lines which differed in their origin and differentiation properties. From their susceptibility to either mutant, and from the effect of temperature upon the efficiency of infection, we inferred a classification of these teratocarcinoma cell lines, which is an agreement with a previous one based upon metabolic coupling. We also discussed results indicating that different EC cell lines might present steps in the process of cell determination at the embryonic level.