COMPARISON OF DIFFERENT ANTIBODY-CONJUGATE DERIVATIVES FOR THE DEVELOPMENT OF A SENSITIVE AND SPECIFIC PROGESTERONE ASSAY

Antibodies raised against progesterone with hormone-carrier protein br idges placed at four different carbon positions were used to compare t he sensitivity and specificity of homologous and heterologous enzyme-h ormone conjugates. All heterologous assays were at least twice as sens itive as the corresponding homologous assays. The best results were ob tained by using antibodies against 7alpha-carboxyethyl-thioether-proge sterone with 6beta-hemisuccinate-progesterone conjugate (or hemimaleat e). The sensitivity with human sera was 0.25 ng ml-1 and, the highest crossreaction 10% with 5beta-pregnane-3,20-dione, and reproducibility, recovery and accuracy were satisfactory. The correlation coefficient with radioimmunoassay in 103 human sera tested was r = 0.915. The assa y was successfully applied for the diagnosis of pregnancy in dairy cat tle.