title: Experimental neosporosis in bulls: parasite detection in semen and blood and specific antibody and interferon-gamma responses.
abstract: OBJECTIVE
  To investigate the presence of Neospora caninum in semen and blood, and the development of specific antibody and interferon-gamma (IFN-gamma) responses in experimentally infected bulls.
  
  
  METHODS
  Eight bulls were intravenously infected with 10(8) live N. caninum tachyzoites of NC-1 isolate. The presence of N. caninum in semen and blood was assessed using a nested-PCR procedure. PCR-positive semen samples were bioassayed using a BALB/c nu/nu mouse model. Specific anti-N. caninum antibody and IFN-gamma responses were also examined. In parallel, eight seronegative bulls were studied as non-infected controls. All bulls were monitored for 26 weeks.
  
  
  RESULTS
  All eight experimentally infected bulls showed N. caninum DNA in their semen and/or blood samples at some time during the course of the study. Parasite load in semen ranged from 0.1 to 14.5 parasites/ml (mean 6.0). N. caninum could not be detected in BALB/c nu/nu mice inoculated with PCR-positive semen samples. A significant increase in mean serum specific IgM antibody response to N. caninum was detected between 10 and 28 days post-infection (p.i.). Serum specific IgG, IgG1, and IgG2 antibody levels in experimentally infected bulls were significantly different after 21, 10, and 14 days p.i. as compared to controls, respectively. Specific anti-N. caninum IgG were detected in seminal plasma from infected bulls and values obtained were different from controls after 25 days p.i. Mean specific IFN-gamma responses in experimentally infected bulls were significantly higher than controls 3 days p.i.
  
  
  CONCLUSIONS
  This is the first study to report the presence of N. caninum DNA in the semen and blood of experimentally infected bulls. Our observations indicate an intermittent presence of N. caninum in low numbers in semen and associated with chronic stage of the infection. This study is also the first to report the detection of anti-N. caninum IgG in seminal plasma of experimentally infected bulls.
authors.affiliation: Grupo SALUVET, Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid (UCM), Ciudad Universitaria s/n, E-28040 Madrid, Spain.
authors.forename: E
authors.initials: E
authors.lastname: Serrano-Martínez
authors.forename: I
authors.initials: I
authors.lastname: Ferre
authors.forename: A
authors.initials: A
authors.lastname: Martínez
authors.forename: K
authors.initials: K
authors.lastname: Osoro
authors.forename: A
authors.initials: A
authors.lastname: Mateos-Sanz
authors.forename: I
authors.initials: I
authors.lastname: Del-Pozo
authors.forename: G
authors.initials: G
authors.lastname: Aduriz
authors.forename: C
authors.initials: C
authors.lastname: Tamargo
authors.forename: C O
authors.initials: CO
authors.lastname: Hidalgo
authors.forename: L M
authors.initials: LM
authors.lastname: Ortega-Mora
mesh_terms: D000818:Animals; D000917:Antibody Formation; D002417:Cattle; D002418:Cattle Diseases / Q000097:blood / Q000469:parasitology; D003048:Coccidiosis / Q000097:blood / Q000276:immunology / Q000469:parasitology* / Q000662:veterinary; D004195:Disease Models, Animal; D005260:Female; D007371:Interferon-gamma / Q000097:blood*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D018688:Neospora / Q000276:immunology / Q000302:isolation & purification*; D018512:Parasitemia / Q000469:parasitology / Q000662:veterinary; D012661:Semen / Q000276:immunology / Q000469:parasitology*
chemical_list: D007371:Interferon-gamma