Rabbit antibodies to some sequences of human chorionic gonadotropin and their use for immunoassay of the hormone.

Three synthetic peptides corresponding to amino acid sequences of two human chorionic gonadotropin (hCG) subunits were conjugated to thyroglobulin and used for immunization of rabbits. The highest antibody concentration was found in antisera from rabbits immunized with the peptide corresponding to 122-145 sequence of the hormone beta-subunit. Specificity of antisera and immunoaffinity purified rabbit antibodies were studied. Antibody anti-122-145-beta hCG with antibody anti-beta hCG conjugated to peroxidase were suitable for sensitive and specific enzyme immunoassay of hCG and beta hCG. Good correlation was noted between assay of the hormone in sera of patients with trophoblastic diseases or in urine of pregnant women by ELISA with the rabbit antibody pair and by commercial kit or by ELISA with two monoclonal antibodies.