Coumermycin inhibition of murine retrovirus replication in cultured cells

The effect of coumermycin A1 activity on the infection and replication of murine type C retroviruses was studied in vitro. The infectivity of five prototype ecotropic retroviruses was reduced by 50 to 94%, with viral titres decreased up to seven-fold. These values were substantiated by progeny production studies. Similar results were obtained with five strains of xenotropic retroviruses. Delayed inhibition of growth kinetics in mouse SC-1 cells was observed with 7.5 and 10 mg/l of coumermycin A1. This effect was markedly reduced after three cycles of freezing and thawing of the drug. Changes in the absorption spectra of coumermycin A1 were observed after eight cycles of freezing and thawing.