Bacterial proteins Bacterial self - antigens Homologous Human proteins Functions inspermatogenesis/male fertility
  RNLRKKLD SPNR microtubule - associated RNA - binding protein localizes
DNA response regulator protein     to the manchette in developing spermatids;
      normal spermatogenesis and sperm function
  KDGQEA TOPAZ1 Abundantly expressed in gonads during germ cell
      meiosis;involved in germ cell development and gametogenesis
  QARVKNEE SA Involved in fertilization and P36 like sperm antigen
      is involved in male infertility
Laminin binding protein KAFKK MAPO2 Helps in the induction of apoptosis of cells with
      O6 - methylguanine lesion
Hyaluronate lyase EERNL TPAP cytoplasmic poly(A) polymerase expressed in round
      spermatids; role in spermiogenesis
  VATKPL TPABP mRNA stability and translation initiation in testis
Streptococcal peptides showing resemblance with at least 5 contiguous amino acids of human peptides without any gaps and mismatcheswere considered as self - peptides. Three self - peptides with amino acid sequence RNLRKKLD, KDGQEA and QARVKNEE representing human proteins namely Spermatid perinuclear RNA binding protein (SPNR), Testis - and ovary - specific PAZ domain - containing protein (TOPAZ1) and Sperm antigen protein (SA) were obtained from DNA binding response regulator protein. One self - peptide was obtained from Laminin binding protein with amino acid sequence KAFKK which represents human Motile sperm domain containing protein (MAPO2). Finally, two self - peptides EERNL and VATKPL representing human Testis - specific poly(A) polymerase protein (TPAP) and Testis - specific poly(A) binding protein (TPABP)were obtained from Hyaluronate lyase protein, respectively. Each of these self - peptides serves to play a major role in spermatogenesis and male fertility function. Out of six putative self - peptides only three peptides of functional importance can be selected for the preparation of immunocontraception/vaccine construct namely RNLRKKLD (SPNR protein), QARVKNEE (Sperm antigen) and KAFKK (MAPO2). These self - peptides only affect the sperm functions and not the spermatogenesis mechanism. Thus, they can be targeted for a temporary period and can be reversed anytime.
Table 4: Streptococcal self - antigens homologous with human proteins showing functional importance in male fertility.