Chemotaxis is required for antral colonization at time points after 14 h postinoculation (PI). Female FVB/N mice were infected with the SS1 wild type (black bars) or the isogenic Che− mutant (gray bars) for 14 h, 36 h, or 1 week. At each time point, stomachs were removed, and divided into the corpus (A), the C-A transition zone (B), and the antrum (C) and plated to determine H. pylori colonies. Error bars indicate standard error of the mean. n = 8 or 9 for 14 and 36 h, derived from two independent infections. n = 7 for 1 week, derived from one independent infection. *, P < 0.05; **, P < 0.01 (Student's t test). Data were also used for the doubling-time calculations in Table 1 and shown in Fig. 3.