Oral Presentation Annual Meetings of the Endocrine Society of Australia and Society for Reproductive Biology and Australia and New Zealand Bone and Mineral Society 2016

Immunisation with aldehyde-adducted sperm proteins reduces sperm-egg binding in the mouse (#163)

Sally Hall 1 , Zamira Gibb 1 , John Aitken 1
  1. Priority Research Centre for Reproductive Science, University of Newcastle, Callaghan, NSW, Australia

The dissemination of a lifelong, species-specific immunocontraceptive for domestic and feral animal control is currently hindered by an inability to provoke an immune response to such a degree that long lasting immunity persists. One mechanism that may be able to achieve this is by exposing the immune system to sperm proteins which have been covalently modified by electrophilic aldehydes, such as acrolein (ACR) and 4-hydroxynonenal (4HNE). In this study, mouse sperm were treated with 50 µM ACR or 4HNE for 3 h at 37 ºC and protein was extracted for immunisation. Mice were immunised with 10-20 µg protein lysate with equal volumes of Freund’s adjuvant or Alhydrogel. Boosters were delivered three weeks later. Blood serum, testes and live spermatozoa were collected from mice following euthanasia. Immunohistochemistry on testis sections revealed antibodies against epididymal sperm proteins. Immunocytochemistry revealed fluorescence on spermatozoa from ACR and 4HNE groups, localised to the head and midpiece. Similarly, immunobead analysis showed a significant increase in the percentage of sperm positively bound compared to the control (ACR: 50.66 ± 1.33%, 4HNE: 54.66 ± 6.83% vs CONT: 27.00 ± 2.88%, P < 0.01). The impact of aldehyde-adduction to sperm proteins prior to immunisation was also reflected by a significant decrease in zona binding compared to the control (ACR: 8.33 ± 0.05%, 4HNE: 10.24 ± 3.73% vs CONT: 100.00 ± 2.42%, P < 0.01). Finally, immunoblotting was performed using naïve serum from mice, and serum from mice immunised with aldehyde-adducted sperm lysate. Blots probed with ACR serum revealed two prominent bands at ~100 kDa and 60 kDa, that were not evident when probed with naïve serum. Similarly, blots probed with 4HNE serum revealed a prominent band at ~100 kDa. These findings may assist in the development of a permanent fertility control method for domestic and feral animals.