title: Ovine Enzootic Abortion (OEA): a comparison of antibody responses in vaccinated and naturally-infected swiss sheep over a two year period.
abstract: BACKGROUND
  Prevention and control of ovine enzootic abortion (OEA) can be achieved by application of a live vaccine. In this study, five sheep flocks with different vaccination and infection status were serologically tested using a competitive enzyme-linked immunosorbent assay (cELISA) specific for Chlamydophila (Cp.) abortus over a two-year time period.
  
  
  RESULTS
  Sheep in Flock A with recent OEA history had high antibody values after vaccination similar to Flock C with natural Cp. abortus infections. In contrast, OEA serology negative sheep (Flock E) showed individual animal-specific immunoreactions after vaccination. Antibody levels of vaccinated ewes in Flock B ranged from negative to positive two and three years after vaccination, respectively. Positive antibody values in the negative control Flock D (without OEA or vaccination) are probably due to asymptomatic intestinal infections with Cp. abortus. Excretion of the attenuated strain of Cp. abortus used in the live vaccine through the eye was not observed in vaccinated animals of Flock E.
  
  
  CONCLUSIONS
  The findings of our study indicate that, using serology, no distinction can be made between vaccinated and naturally infected sheep. As a result, confirmation of a negative OEA status in vaccinated animals by serology cannot be determined.
authors: Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Switzerland. gerber_andrea@access.unizh.ch
authors: Andrea
authors: A
authors: Gerber
authors: Ruedi
authors: R
authors: Thoma
authors: Evangelia
authors: E
authors: Vretou
authors: Evgenia
authors: E
authors: Psarrou
authors: Carmen
authors: C
authors: Kaiser
authors: Marcus G
authors: MG
authors: Doherr
authors: Dieter R
authors: DR
authors: Zimmermann
authors: Adam
authors: A
authors: Polkinghorne
authors: Andreas
authors: A
authors: Pospischil
authors: Nicole
authors: N
authors: Borel
mesh_terms: D000034:Abortion, Veterinary / Q000453:epidemiology / Q000276:immunology / Q000382:microbiology*; D000818:Animals; D000907:Antibodies, Bacterial / Q000096:biosynthesis* / Q000097:blood; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000276:immunology*; D023501:Chlamydophila / Q000235:genetics / Q000276:immunology*; D023521:Chlamydophila Infections / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011247:Pregnancy; D012338:RNA, Ribosomal, 23S / Q000737:chemistry / Q000235:genetics; D016036:Seroepidemiologic Studies; D012756:Sheep; D012757:Sheep Diseases / Q000453:epidemiology / Q000276:immunology* / Q000382:microbiology*; D013557:Switzerland / Q000453:epidemiology; D014613:Vaccines, Attenuated / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; D004269:DNA, Bacterial; D021903:DNA, Ribosomal Spacer; D012338:RNA, Ribosomal, 23S; D014613:Vaccines, Attenuated