FIG. 5.

Fluorescent confocal microscopy of BMMs infected (100 bacteria per cell) with S. agalactiae NEM316 (A and C) or the sodA mutant, NEM1640 (B and D). F-actin was stained with β-phalloidin (green). Bacteria were labeled with anti-S. agalactiae antibodies (red). F-actin sheets associated with bacteria are indicated by the overlapping of green and red light (orange-yellow). After 30 min of infection, characteristic chains are observed and the bacterial uptake is similar for both strains (A and B). Images reconstructed from confocal xz sections show that bacterial phagocytosis for both strains is associated with actin polymerization (A' and B'). After 3 h of infection, bacterial clusters are observed with the wild-type strain (C) whereas only bacterial degradation products are labeled in the mutant (D). Images reconstructed from confocal xz sections demonstrate the intracellular localization of bacteria (C'). Magnification, ×130.