Clonal variation of the mouse cells in the endogenous C-type virus induction by 5-iodo-2'-deoxyuridine.

Using an MLg cell line originating from a single newborn ddY mouse, N-tropic C-type virus able to infect the cells or origin was induced by 5-iodo-2'-deoxyuridine (IUdR). All the clones isolated from the MLg cell line released the virus after IUdR-treatment. There was more than a 100-fold difference in the virus inducibility between the highly and lowly inducible clones. The [125I]IUdR incorporation was, however, the same for the both types of clones. When the induced virus was titrat-d in the S+L-C182 cells, the XC plaque titre was about tenfold higher than murine sarcoma virus rescue focus titre.