title: Parasite distribution and associated immune response during the acute phase of Toxoplasma gondii infection in sheep.
abstract: BACKGROUND
  In many countries, Toxoplasma gondii (T. gondii) is a major cause of reproductive disorders and abortions in the sheep industry, and therefore responsible for important financial and economic losses. In addition, undercooked infected lamb is an important risk factor for human toxoplasmosis. In the present study, the initial phase of the infection was investigated: the parasite's entry site, the subsequent distribution of the parasite and the host-immune response.
  
  
  RESULTS
  Parasite DNA was already detected in the cranial small intestinal mucosa the first days after oral infection with T. gondii tissue cysts. Simultaneously, high IFN-gamma and IL-12 responses were induced mainly in the mesenteric lymph nodes. The emergence of IgG1 (at 8dpi), and IgG2 (at 11 dpi) was accompanied by a decrease or even disappearance of the IFN-gamma and IL-12 response in the Peyers' patches (PP), PBMC's and popliteal LN's. Meanwhile the parasite DNA could be recovered from most mucosal and systemic tissues to become undetectable in the small intestine, popliteal LN, PBMC and spleen 3 weeks pi.
  
  
  CONCLUSIONS
  Our results indicate that parasites enter the cranial small intestine the first days after infection and that after an increase the first two weeks after infection, the parasite DNA levels in the intestine drop below the detection limit three weeks after infection. This coincides with an increase in parastic-specific serum IgG1 and IgG2 and a decrease of the antigen-specific IFN-gamma response in PP, PBMC and popliteal LN. We suggest a role for IFN-gamma and IL-12 in controlling the infection.
authors.affiliation: Laboratory of Immunology, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium. Delfien.verhelst@ugent.be.
authors.forename: Delfien
authors.initials: D
authors.lastname: Verhelst
authors.affiliation: National Reference Laboratory for Toxoplasmosis, Operational Direction Communicable and Infectious Diseases, Scientific Institute of Public Health, Brussels, Belgium. Stephane.Decraeye@wiv-isp.be.
authors.forename: Stéphane
authors.initials: S
authors.lastname: De Craeye
authors.affiliation: Moredun Research Institute, Pentlands Science Park, Bush Loan, Midlothian, Penicuik, EH26 0PZ, Scotland, UK. Gary.Entrican@moredun.ac.uk.
authors.forename: Gary
authors.initials: G
authors.lastname: Entrican
authors.affiliation: Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium. pdorny@itg.be.|Laboratory of Parasitology, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium. pdorny@itg.be.
authors.forename: Pierre
authors.initials: P
authors.lastname: Dorny
authors.affiliation: Laboratory of Immunology, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium. Eric.Cox@ugent.be.
authors.forename: Eric
authors.initials: E
authors.lastname: Cox
mesh_terms: D000210:Acute-Phase Reaction / Q000276:immunology / Q000469:parasitology / Q000662:veterinary; D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology; D000953:Antigens, Protozoan / Q000276:immunology; D016207:Cytokines / Q000097:blood; D020895:Enterocytes / Q000469:parasitology; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D019084:Fluorescent Antibody Technique, Indirect / Q000662:veterinary; D007422:Intestines / Q000469:parasitology; D008198:Lymph Nodes / Q000469:parasitology; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary; D012756:Sheep / Q000469:parasitology; D012757:Sheep Diseases / Q000276:immunology / Q000469:parasitology*; D013154:Spleen / Q000469:parasitology; D014122:Toxoplasma / Q000276:immunology; D014124:Toxoplasmosis, Animal / Q000276:immunology* / Q000469:parasitology
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D016207:Cytokines