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Effect of two rifamycin derivatives on the Rous sarcoma virus transformation system.

Replication of RNA tumour viruses appears to involve a DNA intermediate (provirus), as was postulated by Temin (1964) and is suggested notably by the discovery of virus-associated RNA-dependent DNA polymerase able to transcribe virus RNA into DNA (Baltimore, 1970; Duesberg & Canaani, 1970; Green et al. 1970; Mizutani & Temin, 1970; Spiegelman et al. 1970) and the recent finding, in RSV-transformed cells, of infectious DNA able to prime virus production in permissive cells (Hill & Hillova, 1971, 1972; Montagnier & Vigier, 1972).
New rifamycin derivatives have now been synthesized which are powerful inhibitors of the RNA-dependent DNA polymerase of murine sarcoma virus (MSV) (Gurgo, Ray & Green, 1972). Especially active are the 3-oxime derivatives such as AF/05 and AF/013 which also have been shown to inhibit DNA-dependent RNA polymerase by preventing initiation of the RNA chains (Butterworth, Cox & Chesterton, 1971; Meilhac, Tysper & Chambon, 1972).