Vaccination against gonadotropin-releasing hormone (GnRH) using toxin receptor-binding domain-conjugated GnRH repeats.
A method for the preparation of an immunogen containing multiple copies of a self-peptide in linear alignment was designed in order to overcome the difficulty of inducing an immune response to poorly immunogenic peptide antigens. DNA fragments encoding multiple repeats of the self-peptide were generated by a new technique, termed template-repeated polymerase chain reaction (TR-PCR), which could be subcloned into an expression vector for production of peptide repeats as an immunogen. This approach was tested by constructing fusion proteins containing the receptor-binding domain of Pseudomonas exotoxin A and multiple copies of the 10-residue sequence of the peptide hormone gonadotropin-releasing hormone (GnRH). Immunization of female rabbits with the immunogen that contained the exotoxin receptor-binding domain and 12 copies of GnRH (PEIa-GnRH12) resulted in the generation of high-titer antibodies specific for GnRH. Although at equal molar basis of the GnRH moiety, the immunogen that contained single copy of GnRH (PEIa-GnRH1) induced low-titer anti-GnRH antibodies. These observations suggest that the presence of multiple peptide repeats is a key factor in eliciting an immune response. In addition, anti-GnRH antibodies effectively neutralized GnRH activity in vivo, as demonstrated by the degeneration of the ovaries in the injected rabbits. Because anti-GnRH antibody could be functionally analogous to GnRH antagonist, which has been used to treat patients with ovarian cancer, vaccination of PEIa-GnRH12 presents a potential therapeutic application for the treatment of GnRH-sensitive ovarian cancer.
Hsu
C T
CT
Graduate Institute of Life Science, National Defense Medical Center, Academia Sinica, Taipei, Taiwan.
Ting
C Y
CY
Ting
C J
CJ
Chen
T Y
TY
Lin
C P
CP
Whang-Peng
J
J
Hwang
J
J
D036002:ADP Ribose Transferases; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000097:blood; D001427:Bacterial Toxins; D001667:Binding, Competitive; D019496:Cancer Vaccines / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005098:Exotoxins / Q000276:immunology* / Q000378:metabolism; D005260:Female; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors* / Q000276:immunology*; D010051:Ovarian Neoplasms / Q000188:drug therapy; D010053:Ovary / Q000276:immunology / Q000473:pathology; D010455:Peptides / Q000276:immunology / Q000378:metabolism; D010957:Plasmids; D017434:Protein Structure, Tertiary; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019444:Vaccines, DNA / Q000008:administration & dosage / Q000276:immunology; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A
D036002:ADP Ribose Transferases; D000907:Antibodies, Bacterial; D001427:Bacterial Toxins; D019496:Cancer Vaccines; D005098:Exotoxins; D007987:Gonadotropin-Releasing Hormone; D010455:Peptides; D011993:Recombinant Fusion Proteins; D019444:Vaccines, DNA; D037521:Virulence Factors; D000097668:Pseudomonas aeruginosa Exotoxin A