Recombinant mouse beta-defensin 2 inhibits infection by influenza A virus by blocking its entry.

Human influenza A virus (IAV) is a major cause of life-threatening respiratory tract disease worldwide. Defensins are small cationic peptides of about 2-6 kDa that are known for their broad-spectrum antimicrobial activity. Here, we focused on the anti-influenza A activity of mouse beta-defensin 2 (mBD2). The prokaryotic expression plasmid pET32a-mBD2 was constructed and introduced into Escherichia coli Rosseta gami (2) to produce recombinant mBD2 (rmBD2). Purified rmBD2 showed strong antiviral activity against IAV in vitro. The protective rate for Madin-Darby canine kidney cells was 93.86% at an rmBD2 concentration of 100 microg/ml. Further studies demonstrated that rmBD2 prevents IAV infection by inhibiting viral entry. In addition, both pretreatment and postinfection treatment with rmBD2 provided protection against lethal virus challenge with IAV in experimental mice, with protection rates of 70 and 30%, respectively. These results suggest that the mBD2 might have important effects on influenza A virus invasion.