A novel neutralizing monoclonal antibody against both ricin toxin A and ricin toxin B, and application of a rapid sandwich enzyme-linked immunosorbent assay.

Two strains of neutralizing monoclonal antibodies (MAbs) anti-ricin, both B chain and A chain, named 3D74 and 4C13, were generated efficiently. The two antibodies recognized different epitopes located in a separated toxin structure domain characterized by enzyme-linked immunosorbent assay (ELISA) and Western blotting. 3D74 recognized space conformation epitope, whereas 4C13 recognized linearity epitope of ricin. 4C13 possessed a novel neutralizing ability; the safe period for intraperitoneal injection of 100 microg of antibody was 30 min after intraperitoneal injection of 2 microg of ricin (10 times LD50). Using 3D74 and 4C13 as pair-matching antibodies, we established sandwich ELISA and rapid ELISA for detection of ricin. The detection sensitivities were 31.3 and 156 pg/ml, respectively. Rapid sandwich ELISA was sufficiently sensitive and was performed easily for ricin detection without any special instruments.