FIG 3.

Survival of hamsters immunized with E. coli expressing LigA7-13. Hamsters in groups of 8 were immunized with E. coli expressing LigA7-13 (in red) or E. coli containing the empty vector (i.e., control-immunized group, in blue) and challenged with L. interrogans serovar Copenhageni strain Fiocruz L1-130. Hamsters were challenged with 10³ bacteria by the i.p. route in experiment 1 (A) and with 10² bacteria by the i.d. route in experiment 2 (B). Animals were observed and weighed daily for 28 days. Animals were sacrificed when they met endpoint criteria, which included a 10% decrease of the body weight, or at 28 days postinfection. None of the control-immunized animals survived. In contrast, 3 of 8 (37.5%) LigA7-13-immunized animals survived in experiment 1, and 5 of 8 (62.5%) LigA7-13-immunized animals survived in experiment 2. In both experiments, survival curves are significantly different between LigA7-13-immunized and control-immunized hamsters (experiment 1, P < 0.0001; experiment 2, P = 0.0174).