Effect of Rifampicin and Two of its Derivatives on Cells Infected with Moloney Sarcoma Virus

It is shown that rifampicin, and especially the related antibiotic 2′,6′-dimethylN(4′)-benzylN(4′)-[desmethyl]rifampicin (DMB-rifampicin) can inhibit focus formation by Moloney sarcoma virus on BALB/3T3 tissue cultures. At 10 μ g/ml DMB-rifampicin totally inhibits focus formation while reducing virus replication by at least a factor of fifty and cell proliferation by only a factor of three. These observations, taken together with those of others, suggest a role for an RNA-dependent DNA polymerase and the gene for its synthesis both in normal cell processes and in the transformation process.