title: Antibody responses measured by various serologic tests in pigs orally inoculated with low numbers of Toxoplasma gondii oocysts.
abstract: OBJECTIVE
  To follow antibody responses measured by various serologic tests in pigs orally inoculated with low (< or = 10 oocysts) numbers of Toxoplasma gondii oocysts.
  
  
  METHODS
  24, 2- to 3-month-old pigs.
  
  
  METHODS
  Pigs (n = 42) were inoculated orally with 10 (14 pigs) or 1 (28 pigs) infective oocysts, and 6 pigs served as uninoculated controls. Blood (serum) samples were obtained at 1- to 3-week intervals until euthanasia. At necropsy, the brain, heart, and tongue of pigs were bioassayed in mice and cats for isolation of T gondii. Modified agglutination test (MAT), using whole, fixed tachyzoites and mercaptoethanol; latex agglutination test (LAT); indirect hemagglutination test (IHAT); Sabin-Feldman dye test (DT); and ELISA were used to evaluate serologic responses to T gondii.
  
  
  RESULTS
  T gondii was isolated from tissues of 13 of 14 pigs each fed 10 oocysts, 17 of 28 pigs each fed 1 oocyst, and 0 of 6 control pigs. 29 of 30 T gondii-infected pigs developed antibodies when measured by MAT, DT, and ELISA; the 1 seronegative-infected pig had been fed 10 oocysts and was euthanatized 69 days after inoculation. LAT detected antibodies in 26 of 30 T gondii-infected pigs. IHAT detected antibodies in 11 T gondii-infected pigs.
  
  
  CONCLUSIONS
  MAT, DT, and ELISA were more sensitive serologic assays than LAT and IHAT for detecting antibodies induced by low numbers of T gondii in pigs.
authors.affiliation: USDA, Agricultural Research Service, Beltsville, MD 20705-2350, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Dubey
authors.forename: C D
authors.initials: CD
authors.lastname: Andrews
authors.forename: P
authors.initials: P
authors.lastname: Lind
authors.forename: O C
authors.initials: OC
authors.lastname: Kwok
authors.forename: P
authors.initials: P
authors.lastname: Thulliez
authors.forename: J K
authors.initials: JK
authors.lastname: Lunney
mesh_terms: D000372:Agglutination Tests; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000917:Antibody Formation; D001921:Brain / Q000469:parasitology*; D002415:Cats; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006321:Heart / Q000469:parasitology*; D008297:Male; D051379:Mice; D013552:Swine; D013997:Time Factors; D014059:Tongue / Q000469:parasitology; D014122:Toxoplasma / Q000302:isolation & purification*; D014124:Toxoplasmosis, Animal / Q000175:diagnosis / Q000276:immunology* / Q000469:parasitology
chemical_list: D000913:Antibodies, Protozoan