After infection with GPU993-S (Figure 6A), three out of six mice in the control group and four out of six treated with anti-Stx-1 IgY (200 mg/kg) died, whereas none of the six mice treated with any dose of anti-Stx-2 IgY (50, 100 and 200 mg/kg) died. This evidence concerns the gene STX1A and infection.