Fig. 3
The fold difference in the serum survival of Cjr−-RS218 compared to that of Cjr+-RS218 and the deposition of C1q and properdin on the strains. (a) The fold difference in the serum survival (the survival rate of Cjr−-RS218/the survival rate of Cjr+-RS218) after 3 h of incubation in 40% sera, which were NHS and NHS with the classical, alternative, or lectin pathway inhibited. The horizontal dashed line represents 1-fold (the survival of the two strains is similar). The serum survival of Cjr−-RS218 was approximately 24.8-, 1.1-, 1.5-, and 22.9-fold greater than that of Cjr+-RS218 in NHS or NHS in which the classical, alternative, or lectin pathway was inhibited, respectively. (b) The fold difference in survival in 40% HI-NHS and 40%-modified HI-NHS, in which the classical, alternative, or lectin pathway was inhibited. Cjr−-RS218 and Cjr+-RS218 showed similar serum survival in these sera. For (a) and (b), the results are shown as the mean ± standard deviation, and the data are representative of three independent experiments performed in triplicate. Classical− NHS, C1q-depleted NHS in which the CP is blocked; Alternative− NHS, factor B-depleted NHS in which the AP is blocked; Lectin− NHS, mannose-treated NHS in which the LP is blocked; Classical− HI-NHS, heat-inactivated C1q-depleted NHS; Alternative− HI-NHS, heat-inactivated factor B-depleted NHS; Lectin− HI-NHS, heat-inactivated mannose-treated NHS. (c) The levels of C1q deposition after incubation in 40% NHS. (d) Flow cytometry histogram of C1q deposition on the bacteria after 3 h of incubation in NHS. (e) The levels of properdin deposition after incubation in 40% NHS. (f) Flow cytometry histogram of properdin deposition on the bacteria after 3 h of incubation in NHS. For (c) and (e), the data are presented with GMFI. The results are shown as the means ± standard deviations, and the data are derived from three independent experiments. The HI-NHS control groups were bacteria incubated in HI-NHS, while the unstaining control groups were the bacteria without fluorescence staining. *, P value < 0.05; **, P value < 0.01; ***, P value < 0.001