Influence of carrier protein conjugation site and terminal modification of a GnRH-I peptide sequence in the development of a highly specific anti-fertility vaccine. Part I.
OBJECTIVE
We previously immunoneutralized gonadotrophin releasing hormone (GnRH), using an analogue of GnRH (des-1 GnRH-I), conjugated to tetanus toxoid via a carbodiimide reaction. The castration effect on the reproductive system was not consistent in all the treated animals. Therefore, we examined the possibility that conjugation to the carrier protein via the N- or C-terminal could have an effect on efficacy.


METHODS
GnRH analogue sequences were synthesized consisting of an additional cysteine at either terminal and specific conjugation was carried out using a bifunctional linker agent.


RESULTS
Conjugation of the monomer through the N-terminal proved to be a highly effective means of causing immunocastration in terms of decreased gonadotrophin and testosterone concentrations and testicular size, whereas conjugation through the C-terminal proved to be ineffective. This was reflected in the ability of the antibodies to bind native GnRH, but not the levels of the anti-GnRH antibodies.


CONCLUSIONS
Immunoneutralization efficacy was attributed to the importance of preserving the GnRH C-terminal.
Ferro
Valerie A
VA
Department of Immunology, University of Strathclyde, Glasgow, UK. v.a.ferro@strath.ac.uk
Khan
Mohammad A H
MA
Earl
Elizabeth R
ER
Harvey
Michael J A
MJ
Colston
Angela
A
Stimson
William H
WH
D000595:Amino Acid Sequence; D000818:Animals; D000918:Antibody Specificity; D001284:Atrophy; D001665:Binding Sites; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D005640:Follicle Stimulating Hormone / Q000097:blood; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors* / Q000276:immunology; D006727:Hormone Antagonists / Q000737:chemistry* / Q000276:immunology / Q000494:pharmacology; D007114:Immunization; D007074:Immunoglobulin G / Q000096:biosynthesis / Q000276:immunology; D007075:Immunoglobulin M / Q000096:biosynthesis / Q000276:immunology; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry* / Q000276:immunology / Q000494:pharmacology; D009929:Organ Size / Q000187:drug effects; D010446:Peptide Fragments / Q000737:chemistry* / Q000276:immunology / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013091:Spermatogenesis / Q000187:drug effects; D013329:Structure-Activity Relationship; D013737:Testis / Q000187:drug effects / Q000473:pathology; D013739:Testosterone / Q000097:blood; D022642:Vaccines, Contraceptive / Q000737:chemistry* / Q000276:immunology / Q000494:pharmacology
C473154:HWSYGLRPGC-TT; D006727:Hormone Antagonists; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D009842:Oligopeptides; D010446:Peptide Fragments; C473153:TT-CHWSYGLRPG-NH2; D022642:Vaccines, Contraceptive; D007987:Gonadotropin-Releasing Hormone; D013739:Testosterone; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone