Figure 3: Anti-LysGH15 serum did not neutralize the activity of LysGH15 in vitro.

(A) The influence of anti-LysGH15 serum on the lytic activity of LysGH15. LysGH15 was pre-incubated with serum (dilution 1:500) from immunized mice for 10 min or 1 h, and this mixture or LysGH15 alone or control buffer was added to cultures of the MRSA strain (YB57). CFU numbers were counted at different time points as indicated. (n = 3 per group per experiment). *P < 0.05 compared with the buffer control. The data are representative of 3 experiments. (B) The influence of anti-LysGH15 serum on the binding activity of C54S-LysGH15. YB57 cells were dyed with Hoechst No. 33342 fluorescent dye, and then C54S-LysGH15 or buffer was pre-incubated with serum (dilution 1:500) prior to the addition to YB57. TRITC-conjugated goat anti-mouse IgG was used. The images were acquired using laser scanning confocal microscopy (LSCM) as described in the Methods section. 1. Localization at 405 nm (blue fluorescence, emitted from Hoechst No. 33342 fluorescent dye). 2. Localization at 543 nm (red fluorescence, emitted from TRITC-conjugated Goat-anti-mouse IgG). 3. Image of an ordinary ray (normal light). 4. Overlay of the pictures shown in 1, 2, and 3.