Abstract
Antibodies against a microcystin (MCYST) leucine-arginine variant (MCYST-LR) were demonstrated 4 weeks after immunization of rabbits with either MCYST-LR-polylysine- or MCYST-LR-ethylenediamine-modified bovine serum albumin. A radioimmunoassay (RIA), a direct competitive enzyme-linked immunosorbent assay (ELISA), and an indirect competitive ELISA were developed for characterization of the antibodies. Indirect ELISA and RIA revealed that MCYST-LR-ethylenediamine-bovine serum albumin was a better immunogen. Competitive RIA and direct ELISA revealed that the antibodies had good cross-reactivities with an MCYST-arginine-arginine variant (MCYST-RR), MCYST-LR, an MCYST-tyrosine-arginine variant (MCYST-YR), and nodularin (NODLN); but they had lower reactivities with variants MCYST-leucine-tyrosine (MCYST-LY) and MCYST-leucine-alanine (MCYST-LA). The antibodies did not cross-react with ozonolyzed MCYST-LR. The concentrations causing 50% inhibition of binding of reduced MCYST-LR to the antibodies by MCYST-RR, MCYST-LR, MCYST-YR, NODLN, MCYST-LA, and MCYST-LY in the RIA were 43, 105, 112, 503, 671, and 1,920 ng/ml, respectively. The concentrations causing 50% inhibition of binding of MCYST-LR-horseradish peroxidase to the antibodies by MCYST-RR, MCYST-LR, MCYST-YR, NODLN, MCYST-LY, and MCYST-LA in the ELISA were 1.75, 2.2, 3.4, 4.6, 50, and 114 ng/ml, respectively.