title: Human endogenous retrovirus-R (ERV 3) env-like antigens expressed in baboon testes and epididymides.
abstract: BACKGROUND
  A substantial component of the vertebrate genome comprise of retrovirus-related sequences named as endogenous retroviruses (ERVs). The role of these ERV-related sequences in the biological processes of the host species is still unknown. However, they have been associated with tumourigenesis, autoimmune diseases and placental morphogenesis in primates.
  
  
  OBJECTIVE
  To determine the expression of ERVs in male baboon reproductive tissues.
  
  
  METHODS
  The testes and other reproductive tissues from sexually immature and mature male olive baboons (Papio anubis) were investigated for the expression of endogenous retrovirus-related particles. Immunohistochemical staining was performed using antibodies raised against human immunodeficiency virus (HIV)-1/2, simian immunodeficiency virus (SIV) and human ERVs. Biochemical properties were determined by western blot, and reverse transcriptase (RTase) activity in epididymal spermatozoa, ejaculate spermatozoa and seminal fluid was evaluated.
  
  
  METHODS
  Institute of Primate Research, Nairobi, Kenya.
  
  
  RESULTS
  ERV3 env-like antigens were detected on spermatogenic cells in mature baboon testes and on epididymal spermatozoa. Similarly, antigens cross-reactive with antibodies to HIV structural and envelope glycoproteins were expressed in mature and juvenile baboon testes. In addition, reverse transcriptase activity was detected in ejaculate spermatozoa, seminal fluid and epididymal spermatozoa.
  
  
  CONCLUSIONS
  These results indicate that retroviral-related genes were expressed in normal male baboon testes and spermatozoa, similar to humans. The functions of these ERVs in vertebrates remains unclear.
authors.affiliation: Reproductive Biology Division, Institute of Primate Research, PO Box 24481, Karen, Nairobi, Kenya.
authors.forename: J M
authors.initials: JM
authors.lastname: Mwenda
authors.forename: M W
authors.initials: MW
authors.lastname: Sichangi
authors.forename: D
authors.initials: D
authors.lastname: Oduor-Okello
authors.forename: E O
authors.initials: EO
authors.lastname: Wango
authors.forename: D K
authors.initials: DK
authors.lastname: Langat
mesh_terms: D000818:Animals; D000957:Antigens, Viral, Tumor / Q000378:metabolism*; D004195:Disease Models, Animal; D020077:Endogenous Retroviruses / Q000276:immunology*; D004822:Epididymis / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D010215:Papio; D012194:RNA-Directed DNA Polymerase / Q000378:metabolism; D013737:Testis / Q000378:metabolism* / Q000473:pathology
chemical_list: D000957:Antigens, Viral, Tumor; D012194:RNA-Directed DNA Polymerase