FIG 3.

Influence of TLR2 agonist Pam3CSK4 on pathology of hamsters with leptospirosis. (A) Effect of Pam3CSK4 on leptospiral growth. A total 10⁶ leptospires in 0.5 ml of EMJH medium supplemented with or without 100 μg of Pam3CSK4 were cultured at 29°C. Growth was analyzed for 4 days by using a Petroff-Hausser chamber and a dark-field microscope. Each data point exhibits the means from triplicates ± standard deviations for three independent experiments. P values of <0.05 were considered significant (*, P < 0.05). (B) Survival curves of hamsters in the infected control group (n = 6) and the group coinjected with leptospires and Pam3CSK4 (n = 6). Hamsters were injected with leptospires or coinjected with leptospires and Pam3CSK4. *, P < 0.05 versus untreated controls as determined by a by Kaplan-Meier log rank test. (C) Histopathology scores for kidneys, livers, and lungs of hamsters. The data represent the mean histopathology scores for the two groups of hamsters. Statistical analysis of the results for infected controls (n = 6) and the group coinjected with leptospires and Pam3CSK4 (n = 6) was performed by using the Wilcoxon rank sum test. *, P < 0.05. (D) Histopathology of kidneys (a and b), livers (c and d), and lungs (e and f) of hamsters in the infected control group (a, c, and e) and the group coinjected with leptospires and Pam3CSK4 (b, d, and f). Magnification, ×200. Samples were collected over a 21-day experimental period, and representative photographs are presented. (E) Leptospiral burdens in the kidneys, livers, and lungs of hamsters in the infected control group (n = 6) and the group coinjected with leptospires and Pam3CSK4 (n = 6) as determined by qPCR. Samples were collected over a 21-day experimental period. The results are presented as numbers of genome equivalents per microgram of tissue DNA, and the differences were compared by one-way ANOVA. *, P < 0.05. (F) Survival curves of hamsters treated with Pam3CSK4 6 h after infection with leptospires (n = 8) and untreated controls (n = 8). Hamsters were injected with leptospires. Six hours later, Pam3CSK4 (100 μg) was intraperitoneally injected into hamsters. *, P < 0.05 versus untreated controls as determined by a Kaplan-Meier log rank test.