Fig. 2.

Serum sensitivity assay of the wild-type (WT) strain V. cholerae A1552 and its outer membrane protein-deficient derivatives. a The bacterial survival percentage after incubation with untreated NHS is shown with blue columns. The red columns represent the survival percentage of bacterial strains incubated with NHS pretreated with EGTA/Mg²⁺ to inhibit the classical pathway of complement activation (colors refer to the online version only). Values represent the mean ± SD of three independent experiments. The single asterisks indicate EGTA/Mg²⁺-treated NHS versus untreated NHS (p < 0.005). The double asterisks indicate untreated NHS wild-type A1552 versus its mutant derivatives (p < 0.005). b Immunoblot of whole-cell lysates from the wild-type V. cholerae strain A1552 and its mutant derivatives. The arrow indicates immunoblot reactivity to OmpU. The molecular weight markers are shown at the left of the membrane.