title: SPRASA, a novel sperm protein involved in immune-mediated infertility.
abstract: BACKGROUND
  Antisperm antibodies (ASA) may be an important cause of infertility, but current tests for the detection of ASA have poor prognostic value. Identification of the sperm proteins that ASA bind to may aid the development of more useful diagnostic tests.
  
  
  METHODS
  One- and two-dimensional PAGE and western blotting analyses, as well as amino acid sequencing, were used to identify a novel sperm protein reactive with ASA (SPRASA) from infertile men. An antiserum reactive with SPRASA was produced by immunizing a rabbit with SPRASA excised from two-dimensional gels. This antiserum was used to demonstrate the localization of SPRASA on the sperm.
  
  
  RESULTS
  Amino acid sequences derived from SPRASA matched those of a theoretical protein, XP-085564. This protein is derived from the C-type lysozyme/alpha-lactalbumin gene family. Immunohisto chemistry indicates that SPRASA is localized to the acrosome. Western blot analysis revealed that 50 unselected individuals did not have antibodies that reacted with SPRASA.
  
  
  CONCLUSIONS
  Only ASA from infertile men react with SPRASA, suggesting that this novel protein may be important in the processes of fertility. The identification of SPRASA as the antigen for infertility-associated ASA raises the possibility of developing first, antigen-specific tests for ASA, and secondly, more targeted treatment for immune-mediated infertility.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Auckland, Auckland, New Zealand.
authors.forename: W W C
authors.initials: WW
authors.lastname: Chiu
authors.forename: E K L
authors.initials: EK
authors.lastname: Erikson
authors.forename: C A
authors.initials: CA
authors.lastname: Sole
authors.forename: A N
authors.initials: AN
authors.lastname: Shelling
authors.forename: L W
authors.initials: LW
authors.lastname: Chamley
mesh_terms: D000177:Acrosome / Q000737:chemistry; D000595:Amino Acid Sequence; D001323:Autoantibodies / Q000097:blood; D001324:Autoantigens / Q000032:analysis / Q000737:chemistry / Q000276:immunology; D015153:Blotting, Western; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007150:Immunohistochemistry; D007248:Infertility, Male / Q000276:immunology*; D007519:Isoantigens / Q000032:analysis / Q000737:chemistry / Q000276:immunology*; D007768:Lactalbumin / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D009113:Muramidase / Q000235:genetics; D010449:Peptide Mapping; D029589:Seminal Plasma Proteins / Q000032:analysis / Q000737:chemistry / Q000276:immunology*; D017385:Sequence Homology; D013094:Spermatozoa / Q000737:chemistry* / Q000276:immunology
chemical_list: D001323:Autoantibodies; D001324:Autoantigens; D007519:Isoantigens; C490560:SPACA3 protein, human; D029589:Seminal Plasma Proteins; D007768:Lactalbumin; D009113:Muramidase