FIG. 3.

Inhibition of C. sakazakii ATCC 29544 (WT) invasion of Caco-2 cells by pretreatment with purified proteins. (A) C. sakazakii recombinant OmpA and OmpX were overexpressed in E. coli TOP10 and isolated using metal affinity resin. The purified proteins were resolved by SDS-PAGE. Lane 1, size marker proteins; lane 2, recombinant OmpA; lane 3, recombinant OmpX. (B) Various concentrations (0.5, 25, and 50 μg) of purified outer membrane proteins were added to confluent monolayers of Caco-2 cells and incubated for 1 h at 37°C, followed by PBS washing and a gentamicin protection assay with C. sakazakii ATCC 29544 or the ompA deletion mutant. The experiments were performed at least three times in triplicate and are expressed as means plus SD. Statistical differences are indicated by lowercase letters at P values of <0.05.