The bacteria were quantified in the trachea and the nasal tissue and mRNA levels of mouse β-defensin-3 (mBD-3) were assessed after 24 h. Infection with the wild-type bacterial strain resulted in lower mBD-3 mRNA levels in the trachea than in mice infected with the type III-deficient strain.
Mouse beta-defensin genes could be expressed in trachea and lung tissues before IAV infection, but expression of Mbd-2 and Mbd-3 was increased significantly after IAV infection.