Heterologous structure of coating antigen on sensitivity of ELISA for sulfamethazine: evidence from molecular similarity analysis

Six structurally similar sulfonamide haptens have been linked to ovalbumin by diazo-method used as coating antigen. An enzyme-linked immunosorbent assay (ELISA) was developed to investigate heterologous structure of coating haptens on sensitivity of ELISA for sulfamethazine. The sensitivities of ELISA, expressed as IC50 values, ranged from 94 to 877 ng mL- 1 when six coating antigens were employed. The results suggested that the structural heterology of coating hapten had significant effect on ELISA sensitivity. In order to evaluate the relationship between the degree of hapten heterology and ELISA sensitivity, we used molecular similarity methods to qualitatively represent the degree of coating hapten heterology. The Molecular Access System (MACCS) structural keys and the Tanimoto similarity coefficient were used to calculate and compare the degree of coating hapten's similarity, and the authors found that the sensitivity of ELISA was not in direct proportion with degree of coating hapten heterology in the case of study.