Immunochemical study of equine chorionic gonadotropin (eCG/PMSG): antigenic determinants on alpha- and beta-subunits.

This research explores the antigenic determinants on alpha- and beta-subunits of equine Chorionic Gonadotropin (eCG/PMSG) using monoclonal antibodies. The study particularly examines the behaviours of three antibodies ECG01, E10, and D7. It explores their inability to bind to reduced and alkylated hormones and instead recognize discontinuous epitopes. Furthermore, the potential correlations of the antibodies’ reactivity towards different animals’ hormones like human CG and ovine, porcine, equine, and bovine LH and FSH were also considered.

Antigenic Determinants on Alpha- and Beta-subunits

• The research revolves around immunochemical mapping of equine Chorionic Gonadotropin using three monoclonal antibodies.
• These antibodies, named ECG01, E10, and D7, are raised against the native hormone.
• The antibodies fail to bind with reduced, alkylated hormones, indicating that they recognize discontinuous rather than continuous epitopes.

Examination of Monoclonal Antibodies

• The reactivity of the monoclonal antibodies was assessed towards different hormones including human CG, and LH and FSH from ovine, porcine, equine, and bovine.
• The antigenic determinant recognized by ECG01 is primarily found on the alpha-subunit of equine gonadotropins and of human CG and LH.
• The epitopes recognized by E10 and D7 monoclonal antibodies are closely similar and are predominantly present on the beta-subunit of eCG.
• These epitopes are also found in LH from all the tested species, except human LH, as well as on porcine and equine FSHs.

Antibody Binding Specifics

• ECG01 mAb appears to preferentially bind to residues around position 70.
• The region around disulfide bridges Cys-88-Cys-90 might be associated with the epitopes recognized by D7 and E10 mAbs.
• ECG01 mAb is observed not to bind with eCG simultaneously with either D7 or E10 mAbs.
• Additionally, simultaneous binding of D7 and E10 mAbs on eCG could not be achieved, suggesting closely located epitopes on the hormone’s surface.
• The ECG01 mAb has been found inhibiting eCG binding to LH and FSH receptors, suggesting that its antigenic site is closely related to hormone-receptor interaction sites.