Our findings raise concerns on the interpretation of studies (Muza-Moons et al., 2003; Miyake et al., 2005; Tomson et al., 2005; Gill et al., 2007) with these modified infection protocols using mutants that exhibit lag periods in disrupting epithelial barrier function such as tir (this study) and espG/orf3 mutants (Matsuzawa et al., 2005; Tomson et al., 2005; P. Dean et al., unpublished). The gene discussed is ASZ1; the disease is infection.