Stx2, the most common Stx type produced by EHEC strains isolated from HUS patients (Mellmann et al., 2008), is released from the bacteria in two forms: as a free soluble protein and in association with outer membrane vesicles (OMVs) secreted by EHEC (Kolling and Matthews, 1999; Yokoyama et al., 2000; Kunsmann et al., 2015; Bielaszewska et al., 2017). Here, STX2 is linked to hemolytic-uremic syndrome.