Direct repeat-mediated deletion of a type IV pilin gene results in major virulence attenuation of Francisella tularensis. - Forslund AL; Kuoppa K; Svensson K; Salomonsson E; Johansson A; Byström M; Oyston PC; Michell SL; Titball RW; Noppa L; Frithz-Lindsten E; Forsman M; et al. (Molecular microbiology, 2006)