SEC-HPLC of InvaplexNAT and InvaplexAR. A TSK-Gel G5000PWXL column was calibrated as described in Materials and Methods. Retention times of blue dextran (BD; 2 MDa), thyroglobulin (T; 669 kDa), and ovalbumin (O; 43 kDa) are indicated. The UV (215-nm) traces of S. flexneri 2a InvaplexAR (17.5 µg, red line) and S. flexneri 2a InvaplexNAT (70 µg, blue dashed line) are shown. The higher total protein load for InvaplexNAT was necessary to reveal the high-molecular-mass complex (HMMC) peak (run time of approximately 16.8 min) in the InvaplexNAT sample. mAu, milliabsorbance units.