FIG. 6.

Localization of the AdiS protein on the streptococcal surface by IEM. S. suis strains I9481/1 (A and B) and 10 (C and D) and its isogenic capsule-deficient mutant, 10ΔEF (E and F), were grown under noninducing conditions (at 32C°) until early logarithmic growth, and then one-half of each of the cultures was shifted to a higher temperature (42°C). Noninduced and temperature-induced cultures were then fixed and subjected to IEM by using a specific antiserum against SAGP from S. pyogenes and gold particles (10 nm) coupled to protein A. Several gold particles, indicative of the presence of the AdiS protein, homologues to SAGP, are clearly visible at the surfaces of all streptococcal cells grown at 42°C (B, D, and F) but are absent in those grown at 32°C (A, C, and E), irrespective of the strain used, including the nonencapsulated mutant. Scale bars, 0.25 μm.