Figure 3: Synergistic effect of mAbs to neutralize ricin in vitro. mAbs or mAb mixtures (1 : 1 ratio) at concentration of 313 ng/mL were premixed with ricin 35 ng/mL for 2 hours before exposure to Vero cells. Cell viability was assessed by Alamar blue staining. Data are means of triplets. * or ** indicate or 0.01, as compared with the single antibody control group.