Enzyme immunoassay: binding of Salmonella antigens to activated microtiter plates

A heat extract prepared from radiolabeled Salmonella cells was used to determine if covalent binding to activated surface of polystyrene plates would improve antigen retention thus contributing to increase sensitivity in an enzyme immunoassay for Salmonella antigen. The effect of treatment with ethylchloroformate on the retention of antigens passively absorbed to polyvinylchloride and polystyrene plates was also investigated. Chemically modified plates retained more radiolabeled antigens after washing than did untreated plates in which the antigens had been physically adsorbed. However, improvement of assay sensitivity depended on the type of plate used for covalent binding of antigen. N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP), was found to be potentially useful for mediation of covalent binding of antigens to activated plates.