title: RASA, a recombinant single-chain variable fragment (scFv) antibody directed against the human sperm surface: implications for novel contraceptives.
abstract: BACKGROUND
  A recombinant single-chain variable fragment (scFv) antibody was engineered to a tissue-specific carbohydrate epitope located on human sperm agglutination antigen-1 (SAGA-1), a sperm glycoform of CD52.
  
  
  RESULTS
  cDNAs encoding the variable regions of the S19 [IgG(1)kappa] monoclonal antibody (mAb) were identified, linked, and cloned into the pCANTAB 5E vector. The recombinant anti-sperm antibody (RASA) was expressed in E. coli HB2151 cells as a 29 kDa monomer and, remarkably, also formed multimers of approximately 60 and 90 kDa. RASA reacted with the endogenous SAGA-1 antigen by Western blot analysis, labelled the entire human sperm surface by indirect immunofluorescence, and aggregated human spermatozoa in a tangled (head-to-head, head-to-tail, tail-to-tail) pattern of agglutination, as was also observed with the native S19 mAb.
  
  
  CONCLUSIONS
  These results demonstrate that active recombinant antibodies can be produced to a tissue-specific carbohydrate epitope on the human sperm surface, thereby opening opportunities for novel contraceptive agents.
authors.affiliation: Department of Cell Biology, Center for Recombinant Gamete Contraceptive Vaccinogens, University of Virginia Health System, Charlottesville, Virginia 22908, USA.
authors.forename: E J
authors.initials: EJ
authors.lastname: Norton
authors.forename: A B
authors.initials: AB
authors.lastname: Diekman
authors.forename: V A
authors.initials: VA
authors.lastname: Westbrook
authors.forename: C J
authors.initials: CJ
authors.lastname: Flickinger
authors.forename: J C
authors.initials: JC
authors.lastname: Herr
mesh_terms: D000595:Amino Acid Sequence / Q000235:genetics; D000954:Antigens, Surface / Q000276:immunology; D001483:Base Sequence / Q000235:genetics; D001698:Biomedical Engineering; D002449:Cell Aggregation; D002462:Cell Membrane / Q000276:immunology; D003270:Contraceptive Agents; D000939:Epitopes; D019084:Fluorescent Antibody Technique, Indirect; D006023:Glycoproteins / Q000276:immunology; D006801:Humans; D007135:Immunoglobulin Variable Region / Q000235:genetics / Q000276:immunology*; D008297:Male; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D011994:Recombinant Proteins; D057127:Single-Chain Antibodies; D013094:Spermatozoa / Q000276:immunology* / Q000502:physiology; D020729:p120 GTPase Activating Protein
chemical_list: D000954:Antigens, Surface; D003270:Contraceptive Agents; D000939:Epitopes; D006023:Glycoproteins; D007135:Immunoglobulin Variable Region; C557248:RASA1 protein, human; D011994:Recombinant Proteins; C120760:SAGA-1 protein, human; D057127:Single-Chain Antibodies; D020729:p120 GTPase Activating Protein