Proteinase inhibitors from Streptomyces with antiviral activity

An extensive screening study for the production of proteolytic inhibitors has been carried out on 75 Streptomyces strains. It was found that 18 of the strains and/or their variants (24%) produced proteinaceous substances, which belonged to the group of typical serine protease inhibitors. 23 samples were tested for inhibitory activity on the replication of influenza virus A/Germany/34, strain Rostock (H7N1) (A/Rostock) in chicken embryonic fibroblast (CEF) cells. Eleven of the tested samples (52.2%) significantly inhibited viral growth. Further the specific inhibitory effect on the replication of influenza virus A/Aichi/2/68 (H3N2) (A/Aichi) in Madin‐Darby canine kidney (MDCK) cells and on the growth of herpes simplex virus type 1, strain DA (HSV‐1) in Madin‐Darby bovine kidney (MDBK) cells was tested. Nine samples significantly inhibited A/Aichi and four – HSV‐1. The most effective inhibitors, produced by Streptomyces sp. 225b (SS 225b) and Streptomyces chromofuscus 34‐1 (SS 34‐1) protected mice from mortality in the experimental influenza A/Aichi virus infection. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)