Spatially and Multivalent Matched Neutralizing Aptamer-Based DNA Nanostructure Alleviates Shiga Toxin Type 2 Infection

Shiga toxin type 2 (Stx2) is a risk factor for acute bloody diarrhea and hemolytic uremic syndrome, which has posed a major threat to global public health. Currently, there is a lack of effective strategies to combat Stx2 infection. Herein, according to the structural characteristics and infection mechanism of Stx2, we have designed a structure mediated by self-assembling DNA tetrahedral nanoframes (TDN), which can orderly assemble three neutral aptamers (TDN-S) to prevent Stx2 from entering cells and inhibit Stx2 infection. The neutralizing aptamers SA, SB, and SC can respectively bind to the three sites (sites 1, 2, and 3) on the Stx2 B subunit, which coincidentally occupy the binding sites of Stx2 and Gb3 receptor. Benefiting from the simultaneous capture of three active sites, spatial matching, and the steric hindrance effect, TDN-S exhibits excellent neutralization efficiency against Stx2. The inhibition ability of Stx2 infection in vitro was evaluated by cell viability, intracellular fluorescence imaging, and ROS levels, and the inhibition rate was as high as 80.44%. The TDN-S significantly reduces the damage to the liver, kidneys, and intestines and the inflammatory response in vivo. Overall, the neutralization strategy with multimodal interaction provides a new way to alleviate the Stx2 toxicity and serves as a model for other wide-range toxin-like inhibitions.