NAB815 is a specific inhibitor of Stx2a (Kd= 0.01 μM)/TLR4 interactions. It inhibits the interaction between neutrophils and Stx2a with an IC50 of 0.057 μg/mL. NAB815 also prevents the formation of extracellular vesicles (EV) containing Stx2 from leukocytes and platelets, reducing its toxicity in cells (Vero cells) and in animal models (CD-1 mice). Additionally, NAB815 decreases the bacterial load in the kidneys, urine, and bladder of mice infected with Escherichia coli. It is applicable for research in hemolytic uremic syndrome (HUS).

NAB815, at a concentration of 1 nM for 4 hours, can inhibit the formation of leukocyte/platelet aggregates induced by Stx2a. When used at concentrations of 0.01-0.1 μg/mL for 4 hours, it shows a slight effect on human leukocyte viability but none on erythrocytes. Additionally, it suppresses the formation of pathological endothelial vesicles (EVs) derived from platelets and leukocytes containing Stx2a, and reduces the recruitment of complement factors in EVs induced by Stx2. At 0.01 μg/mL, NAB815 protects Vero cells from the toxicity caused by EVs triggered by Stx2a.

NAB815, when administered intravenously at a concentration of 0.01 μg/mL in a volume of 100 μL once, provides protection to CD-1 mice against free Stx2a. Additionally, a single intravenous dose of NAB815 (0.01 μg/mL, 300 μL) shields humanized EVs CD-1 mice from EV-associated Stx2a. Furthermore, NAB815 at 0.5-2 mg/L, injected subcutaneously at 0.2 mL twice daily for three consecutive days, reduces the bacterial load in the kidneys, urine, and bladder of female OF-1 mice with E. coli infections.