221. SPRASA, a sperm protein with a post-fertilization function?
A. Wagner A , A. Shelling A and L. Chamley AObstetrics and Gynaecology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
Reproduction, Fertility and Development 17(9) 85-85 https://doi.org/10.1071/SRB05Abs221
Submitted: 26 July 2005 Accepted: 26 July 2005 Published: 5 September 2005
Abstract
Objectives: SPRASA is a highly conserved sperm protein that is localised to the inner acrosome membrane, and shows high homology to the alpha-lactalbumin/C-type lysozyme family.1,2 We have previously shown that SPRASA is the antigen for antisperm antibodies in some infertile patients.1 To date, the function of SPRASA is unknown but in vitro, antibodies reactive with SPRASA inhibit sperm-oocyte binding in a zona-free hamster oocyte binding assay2. Based on this preliminary data, we postulated that SPRASA plays an integral role in fertilization, and that binding of antibodies to SPRASA may inhibit its function leading to infertility. In this study we investigated the effect of inhibiting bovine SPRASA, in vitro, on fertilization and embryonic development. Methods: Viable, motile sperm was prepared from frozen-thawed bovine sperm by swim up. Bovine oocytes were obtained from slaughter-house killed animals and matured in vitro. Three different treatments were investigated. (1) Sperm were incubated for an hour with a SPRASA-reactive antiserum, washed and used to fertilize 100 oocytes in insemination droplets. (2) One hundred in vitro matured oocytes were incubated for an hour with the SPRASA-reactive antiserum, washed, and fertilized with untreated swim-up sperm in insemination droplets. (3) Sperm and oocytes (n = 100) were coincubated with the SPRASA-reactive antiserum in insemination droplets. Controls consisted of similar numbers of sperm and/or oocytes incubated with an irrelevant antiserum. Results: There was a significant reduction in the number of embryos that reached morula (P = 0.03) or blastocyst (P = 0.01) when oocytes were pre-treated with the SPRASA antiserum (treatment 2) or when sperm and oocytes were co-incubated with the antiserum (P = 0.05 morula; P = 0.01 blastocyst; treatment 3). However, there was no significant difference in the rates of embryos reaching earlier developmental stages in any of the treatment groups. Conclusion: These data suggest that SPRASA may be expressed by oocytes and/or preimplantation embryos.
(1) Chiu WW, Erikson EK, Sole CA, Shelling AN, Chamley LW. (2004). SPRASA, a novel sperm protein involved in immune-mediated infertility. Human Reproduction 19(2), 243–249.
(2) Mandal A, Klotz KL, Shetty J, Jayes FL, Wolkowicz MJ, Bolling LC, Coonrod SA, Black MB, Diekman AB, Haystead TA, Flickinger CJ, Herr JC. (2003). SLLP1, a unique, intra-acrosomal, non-bacteriolytic, c lysozyme-like protein of human spermatozoa. Biology of Reproduction 68(5), 1525–1537.
