FIG 4.
Antibody response and efficacy of protective immunity induced in hamsters after immunization with the pool of recombinant proteins plus flagellin as an adjuvant. Hamsters were subcutaneously immunized twice with the pool of recombinant proteins at an interval of 15 days. One day before the second immunization (prime) and 1 day before the challenge (boost), the hamsters were bled, and the sera were analyzed by ELISA. Microtitration plates were coated with recombinant proteins and incubated with serial dilutions of serum samples collected from the immunized hamsters to measure the antigen-specific IgG responses. On the 31st day, animals were challenged by intraperitoneal inoculation of L. interrogans serovar Copenhageni strain Fiocruz L1-130. (A) Antibody responses after immunization with the pool of recombinant proteins without LigAC but with FliC. (B) Antibody responses after immunization with the pool of recombinant proteins and LigAC plus FliC. (C) Survival of the hamsters after the lethal challenge. The percentage of hamsters that survived was calculated as the number of survivors divided by the total number of animals challenged in three experiments (detailed results are in Table S5 in the supplemental material). (D) Renal colonization in animals surviving the challenge. The percentage of animals with renal colonization was calculated as the number of hamsters positive for kidney infection divided by the number of surviving hamsters in three experiments (detailed results in are Table S6). Results are expressed as the means ± SE.