Protective immunity to ricin toxin conferred by antibodies against the toxin's binding subunit (RTB)

► We have produced and characterized a collection of RTB-specific murine monoclonal antibodies (mAbs). ► We have demonstrated that two RTB-specific mAbs are capable of protecting mice against ricin challenge. ► We have identified for the first time the epitopes on RTB recognized by nonneutralizing antibodies. ► The results of this study provide for the first time an immunologic basis for RTB-based vaccine and therapeutic design.