Reactivity profile against Stx2 by Immunoblotting (WB) in HUS patients and healthy children (controls). A) Each bar represents samples reactive to A and B subunits or only A subunit or non-reactive. * Significant differences were observed between the groups (p = 0.032). B) Representative immunoblotting strips from HUS patients (lanes 3 and 4) and control sera (lanes 5 and 6) reactive to Stx2. Immunoblotting reaction was carried out by incubating nitrocellulose membranes, containing purified Stx2 toxin subjected to 12.5% SDS-PAGE, with sera from HUS patients and healthy individuals followed by incubation with goat anti-human IgG. Lanes 1 and 2 represent positive and negative controls of the assay, respectively, purified toxin incubated with rabbit anti-Stx2 polyclonal antibody (lane 1) or pre-immune rabbit serum (lane 2), followed by peroxidase-conjugate anti-rabbit IgG. The arrows represent the A subunit (32 kDa) and B subunit (7.5 kDa) of Stx2.