Platelet counts and histology analysis of major organs of mice after being challenged with Stx-2 or rmVWF. Platelet counts in TG and KO before (pre) and 24 (d1) and 72 (d3) hours after being challenged with Stx-2 at the dose of 50 pg/g (A) and 250 pg/g body weight (C), or with rmVWF at the dose of 5 μg/g body weight (E). ANOVA was used to determine the statistical significance of the differences among various groups. **P < .01. (B,D,F) Percentages of mice in A, C, and E having a 30% reduction of platelet counts from the baseline. (G-H) Representative images of hematoxylin and eosin staining demonstrating the occlusive thrombi in the brain, heart, lung, kidneys, and liver obtained from KO mice that died after being challenged by high doses of Stx-2 and rmVWF. The digital images were taken under light microscope with magnification ×200.