Antiequine chorionic gonadotropin (eCG) antibodies generated in goats treated with eCG for the induction of ovulation modulate the luteinizing hormone and follicle-stimulating hormone bioactivities of eCG differently.
In dairy goats, treatments associating a progestogen and the equine chorionic gonadotropin (eCG) are the easiest way to induce and synchronize estrus and ovulation and to permit artificial insemination (AI) and/or out of season breeding. From the first treatment, the injection of eCG induces, in some females, the production of anti-eCG antibodies (Abs) that will interfere with the effectiveness of subsequent treatments. These anti-eCG Abs delay the preovulatory LH surge and the ovulation time, leading to poor fertility of the treated females. In this study, by in vitro bioassays, we show that anti-eCG Abs can positively or negatively modulate the LH and/or FSH bioactivities of eCG. Moreover, the modulation level of eCG bioactivity does not depend on the anti-eCG Ab affinity for eCG, as shown by surface plasmon resonance technology. The specificity of anti-eCG Abs tested by competitive ELISA highlighted the importance of a glycan environment in the recognition mechanism, especially the sialic acids specific to eCG. The different effects of anti-eCG Abs on eCG bioactivities could be explained by two hypotheses. First, steric hindrance preventing the interaction of eCG with its receptors would explain the inhibitory effect of some anti-eCG Abs; second, a conformational change in eCG by anti-eCG Abs could induce inhibition or potentiation of eCG bioactivities. It is significant that these modulations of eCG bioactivities by anti-eCG Abs impact mainly on the FSH bioactivity of eCG, which is essential for ovarian stimulation and subsequent fertility after treatment and AI, and to a lesser extent on LH bioactivity.
Hervé
Virginie
V
Unité Mixte de Recherche 6073, Institut National de la Recherche Agronomique/Centre National de la Recherche Scientifique/Université de Tours, Station de Physiologie de la Reproduction des Mammifères Domestiques, Nouzilly, France.
Roy
François
F
Bertin
Jean
J
Guillou
Florian
F
Maurel
Marie-Christine
MC
D000818:Animals; D000918:Antibody Specificity; D006063:Chorionic Gonadotropin / Q000276:immunology*; D003429:Cross Reactions; D005260:Female; D005298:Fertility / Q000276:immunology; D005640:Follicle Stimulating Hormone / Q000378:metabolism*; D006041:Goats; D007074:Immunoglobulin G / Q000097:blood; D007315:Insemination, Artificial / Q000662:veterinary; D007986:Luteinizing Hormone / Q000378:metabolism*; D010060:Ovulation / Q000276:immunology*; D011962:Receptors, FSH / Q000378:metabolism; D011974:Receptors, LH / Q000378:metabolism
D006063:Chorionic Gonadotropin; D007074:Immunoglobulin G; D011962:Receptors, FSH; D011974:Receptors, LH; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone