Enhancement of infectivity of encephalomyocarditis virus RNA by amphotericin B methyl ester.

The methyl ester of amphotericin B (AmBME), a macrolide polyene antibiotic, enhanced the infectivity of encephalomyocarditis (EMC) virus RNA for L929 cells. AmBME alone (100 microgram/ml) resulted in increases in EMC virus RNA infectivity of 10- to 100-fold. Addition of DEAE dextran at concentrations (5 microgram/ml), which alone slightly suppressed EMC virus RNA infectivity, further augmented the effects of AmBME (augmentation in infectivity up to 750-fold). AmBME did not inhibit RNase, did not enhance EMC virus infectivity and increased infectivity of EMC virus RNA which was already cell-associated. The polyenes are probably acting by increasing intracellular penetration of polyribonucleotides.