Detection of Stx1 and Stx2 neutralizing antibodies (nAb) in sera from two calves vaccinated with rStx1
. Results from the Vero cell neutralization assay (VNA). Dashed line indicates the detection limit. Calves were vaccinated on days 0 and 21 of the trial. A titre of 30 was attributed to all those samples that gave negative test results in the highest concentration tested.