SCNN1B and cystic fibrosis: To test if introducing a wild-type copy of the mexEFoprN operon would also reduce the virulence of the CF isolate Pa LESB58, Scnn1b-Tg mice were infected with Pa LESB58 pME6032 (vector control) or Pa LESB58 pME6032::mexEFoprN (restored strain).