A modified splenomegaly assay system employing the Rauscher murine leukemia virus provides a precise and workable experimental model that is suitable for the screening and evaluation of potential antiviral agents in vivo. The antitumor antibiotic streptonigrin and the closely related streptonigrin methyl ester and isopropylidine azastreptonigrin have been found to possess significant antiviral activity. Virus-infected mice treated with appropriate levels of these agents have yielded spleens weighing as little as 15% of those found in infected nontreated controls. Additional evidence of antiviral activity was found in the demonstration that long term treatment with suitable levels of these agents is able to markedly prolong survival time of mice infected with the Rauscher virus. The data obtained with streptonigrin and its derivatives illustrate the magnitude and reproducibility of the effects that can be obtained with an active antiviral agent in terms of both splenomegaly and survival time extension.

1

This study was supported by Contract PH 43-64-50 from the Cancer Chemotherapy National Service Center, National Cancer Institute, NIH, United States Department of Health, Education and Welfare.

2

Presented in part at the Proceedings of the American Association for Cancer Research on April 8, 1965, Philadelphia, Pennsylvania.

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