Suppression of behavioural and physiological oestrus in the mare by vaccination against GnRH

Abstract

Objective To examine the immunogenicity of an equine immunocontraceptive vaccine and its efficacy in controlling hormone-related behaviour.Design A total of 24 mares at two sites in Australia were vaccinated with an immunocontraceptive vaccine comprising gonadotrophin releasing hormone (GnRH) conjugated to a carrier protein in immunostimulating complex as an adjuvant. Twelve animals at each site received a placebo of adjuvant alone and served as controls for seasonal oestrus, hormonal and behaviour patterns. Animals were observed for injection site reactions, ovarian and follicular activity, and serum levels of antibody, 17 β -oestradiol and progesterone in the weeks following vaccination. Mares were also examined for oestrous behaviour by teasing with a stallion.Results All mares responded to vaccination. Two weeks following the second vaccination there was a peak in antibody response to GnRH that declined gradually over the following weeks. Commensurate with the elevated anti-GnRH antibody there was a marked effect on ovarian activity with a reduction in 17 β -oestradiol and progesterone levels in the 24 vaccinated mares. There was also a reduction of oestrus-related behaviour as determined by a teaser stallion. This effect lasted a minimum of 3 months and correlated with the initial level of antibody response. ConclusionFollowing a conventional two-dose immunisation regime this commercially available equine immunocontraceptive vaccine was effective at inhibiting oestrous behaviour for at least 3 months. This vaccine has a high level of safety since there were no significant local reactions nor were there any adverse systemic responses to vaccination.

Vaccination against gonadotropin-releasing factor (GnRF) with Bopriva significantly decreases testicular development, serum testosterone levels and physical activity in pubertal bulls

“…As it has been shown in many investigations published during the last years [3][4][5][6][7][8][9][10]17,20,[29][30][31][32][33][34] vaccination against GnRF was able to induce an increase in anti-GnRF antibody titer.…”

“…The suppression of reproductive function using an anti-GnRF vaccine has been demonstrated in numerous studies in cattle [3][4][5][6][7][8][9][10][11][12][13], sheep [10,[14][15][16][17][18][19][20][21], pig [22][23][24][25][26][27][28], horse [29][30][31][32][33][34] and in wild animals [35][36][37][38][39].…”

EFFECTS OF A GONADOTROPIN-RELEASING HORMONE VACCINE ON OVARIAN CYCLICITY AND UTERINE MORPHOLOGY OF AN ASIAN ELEPHANT (ELEPHAS MAXIMUS)

“…24,28 Cessation of cycling through GnRH vaccination would be expected to decrease the likelihood of negative outcomes with these pathologic conditions, and the likelihood of significant negative adverse effects is considered low. 11,16,18,20,26,39 Many factors can influence the immune response to GnRH vaccination, including individual genetic and immune status variation, patient age, vaccine dose, species variation in regard to optimal adjuvants, and the conjugant and specific design used in the manufacture of the vaccine. 17,19,20,40,41,48,54 Preliminary evaluation of a GnRH vaccine for control of aggression and musth behavior in bull elephants has shown some degree of variation in the response of individuals, and this phenomenon has been noted in a variety of other species.…”

“…Immunization against GnRH has been used successfully to suppress ovarian function in a number of domestic, laboratory, wildlife, and livestock species. 3,10,18,22,23,30,31,36,42,49,55 The primary structure of the decapeptide GnRH is largely conserved in mammals, but by itself is not immunogenic. 23,46 The vaccine in this study was developed by using a recombinant ovalbuminGnRH fusion protein, marketed under the trade name Repro-BLOCt (Amplicon Vaccine, LLC, Pullman, Washington 99163, USA).…”

Managing a mare for breeding and sport

“…A new commercially available vaccine (Equity TM , Pfizer Animal Health, Australia), with a modified adjuvant and carrier protein has been designed specifically for use in the horse. A recent study from Australia (Elhay et al 2007) documents the effect of this vaccine on 24 mares (12 treated, 12 control) using a conventional two-dose immunization regime: All mares responded to vaccination with Equity TM with an effect that lasted for a minimum of 3 months and correlated with the initial level of antibody response. This vaccine has a high level of safety since there were no significant local reactions nor were there any adverse systemic responses to vaccination.…”