Immunogenicity of recombinant maltose-binding protein (MBP)-gonadotropin releasing hormone I (GnRH-I)

A recombinant fusion protein, maltose-binding protein (MBP)--gonadotropin releasing hormone I (GnRH-I), was produced by cloning a gene fragment encoding a tandem repeated GnRH-I hexamer peptide (GnRH-I6) into the pMAL-c4x vector which was subsequently expressed in E. coli TB1. MBP-GnRH-I6 was affinity purified. MBP-GnRH-I6 was verified by SDS-PAGE and Western blot and immunogenicity tested in boars. Injection of the recombinant fusion protein into boars yielded a high-titer antibody specific for GnRH-I. This was followed by serum testosterone and the degeneration of spermatogenesis. These results showed that MBP-GnRH-I6 acted as a strong immunogen and could be a candidate for an immune antifertility vaccine.