Journal of Pure and Applied MicrobiologyVol. 3 No. 2

In vitro and in vivo Influenza Virus Inhibitory Effects of a Bacterial Protease Inhibitor

Julia Serkedjieva* and Iskra Ivanova┬╣

Institute of Microbiology, Bulgarian Academy of Sciences, 26, Academician Georgy Bonchev St., 1113 Sofia, 1Department of Microbiology, Sofia University, Sofia, Bulgaria.

Received on 12 June 2009 and accepted on 22 July 2009



The fermentation product, produced by Streptomyces sp. 225b (SS 225) selectively inhibited the reproduction of influenza virus A/chicken/Germany/34, strain Rostock (H7N1) in MDCK cells shown by the reduction of viral hemagglutinin (HA) expression on the surface of infected cells, virus-induced cytopathogenic effect, the production of HA and infectious virus. The inhibitory effect was dose-dependent and affected viral penetration and some intracellular stages of viral replication. No inactivating effect of the extracellular virus was found. Using representative strains of influenza virus it was shown that the inhibitory effect was strain-specific; most sensitive to inhibition were A/Rostock and A/PR8/34 (H1N1). In addition the preparation protected mice from mortality in the experimental A/Aichi/2/68 (H3N2) (A/Aichi) influenza virus infection; the mean survival time was prolonged the lung infectious virus titres and the lung consolidation were reduced in comparison with virus control. SS 225 belongs to the group of serine proteinase inhibitors. It has been subjected to purification by ion exchange chromatography, gel filtration and HPLC analysis. It was a hydrophobic and a termostable protein, had a molecular mass of 11.1 kDa and a high content of hydrophobic amino acids.

Keywords : Influenza virus, Viral inhibition, Protease inhibitor, Streptomyces.