Streptovirudins -- new antibiotics with antiviral activity. The antiviral spectrum and inhibition of Newcastle disease virus in cell cultures.

Streptovirudins are new antibiotics isolated as a mixture of several structurally related compounds from fermentations of Streptomyces griseoflavus (Krainsky) Waksman et Henrici var. thuringensis JA 10124. They possess antiviral activity against RNA and DNA viruses cultivated in chick embryo cells, namely Sindbis, fowl plague, Newcastle disease (NDV), pseudorabies, vaccinia and sheep abortion viruses. The naturally formed streptovirudin complex, in concentrations of 20-2.5 mug/ml inhibited the viral cytopathic effect and caused 100 percent plaque reduction. Mengo, Coxsackie B1-B5, ECHO 30 and 33, and polio (wild and attenuated types 1, 2, and 3) viruses grown in FL cells were not sensitive in the agar-diffusion plaque-inhibition test. The antibiotics failed to show a direct virucidal effect on the NDV virion itself or to influence virus adsorption and penetration processes. Addition of streptovirudin complex during a one-step growth cycle of NDV from 0-4 hours after virus adsorption resulted in complete suppression of virus yield. The antibiotic complex consists of two main groups: I - A1, B1, C1, D1, E1 and II - A2, B2, C2, D2, E2, each of which possess antiviral activity.