PRADIMICIN-S, A NEW PRADIMICIN ANALOG .1. TAXONOMY, FERMENTATION AND BIOLOGICAL-ACTIVITIES

A directed search for antibiotics active in a syncytium formation inhi bition assay using a co-culture of HeLa-T4 cells expressing CD4 antige n and BSC-1 cells expressing gp-120 led to the isolation of pradimicin S, a new member of the pradimicin family. The producing strain (AA085 1) was characterized as a new species of Actinomadura for which the na me Actinomadura spinosa sp. nov. is proposed. Production of pradimicin S by strain AA0851 was significantly improved by addition of ferrous sulfate (0. 1 approximately 0.4%) to the production medium. Pradimicin S showed potent activity against human immunodeficiency virus (HIV) L AV(BRU) strain in a CPE assay, and moderate activity against influenza virus type A. The antibiotic was active against a wide variety of fun gi and yeasts in vitro and demonstrated in vivo efficacy against a sys temic Candida albicans infection in mice.