INHIBITION BY CYTOSINE ARABINOSIDE OF REPLICATION OF MURINE LEUKEMIA AND SARCOMA VIRUSES IN MOUSE EMBRYO CULTURES

Cytosine arabinoside is a potent inhibitor of DNA synthesis in mammalian cells in tissue culture but allows RNA synthesis to proceed. When added to mouse embryo cultures cytosine arabinoside prevented the replication of the Rauscher and Moloney murine leukemia viruses. These viruses were assayed in vitro by the leukemia virus helper assay. After an initial 7‐h exposure of Rauscher‐virus‐infected mouse embryo cells to either 10−5 M or 10−4 M cytosine arabinoside a maximum yield of only 10% of virus compared to control infected cultures was obtained after 48 h of incubation. In a similar experiment with the Moloney leukemia virus only 25–40% of virus was present in cytosine arabinoside‐treated infected cultures at day 7 of incubation when compared to controls. Cytosine arabinoside inhibits the replication of both competent and defective isolates of murine sarcoma virus in mouse embryo cultures. Under similar conditions cytosine arabinoside did not interfere with the growth of vesicular stomatitis virus in mouse embryo cultures. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company