Vaccination experiment analyzing the attenuation of MT4 at day 30 p.v. For vaccination, C57BL/6 mice were treated with PBS (n = 10; grey solid circles), MT5 (5x107CFU; n = 10; black solid circle) and MT4 (5x107 CFU; n = 10; open circle). (A) Fecal shedding as analyzed by plating. PBS-controls: below detection limit (stripped line); (B) Colonization by the vaccine strains (MT5, n = 5 and MT4, n = 5) in cecal content, mLN, spleen and liver; (C) Cecal pathology at day 30 p.v.. n.s., not significant; *, statistically significant (p < 0.05).