Specificity of polyclonal oligopeptide antisera targeting glycoprotein hormones from the Japanese Eel (Anguilla japonica).

Glycoprotein hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), and thyroid-stimulating hormone (TSH), play essential roles in the reproductive endocrinology of teleosts. However, research on these hormones in non-model species such as the Japanese eel (Anguilla japonica) has been constrained by the lack of specific immunological detection tools. Recombinant A. japonica FSH, LH, and TSH were expressed using a Bombyx mori-based silkworm-baculovirus system. Polyclonal antibodies were then generated using two distinct immunogen strategies: (i) chimeric constructs fusing β-subunits with a murine α-subunit, and (ii) synthetic peptides representing unique, non-conserved β-subunit epitopes. Both approaches induced antibody responses, but only peptide-based immunogens yielded polyclonal antisera with high specificity and sensitivity. These antibodies distinguished homologous glycoprotein hormones without cross-reactivity and retained target selectivity in mixtures simulating physiological serum conditions. Peptide-derived antibodies provide a robust and precise tool for the immunological discrimination of FSH, LH, and TSH in A. japonica. This strategy establishes a scalable framework for species-specific hormone assay development and offers translational potential for endocrine monitoring, reproductive management, and diagnostic applications in aquaculture biotechnology.