title: A Comparison of Antiserum and Protein A as Secondary Reagents to Assess Toxoplasma gondii Antibody Titers in Cats and Spotted Hyenas.
abstract: Toxoplasma gondii is a protozoal parasite with worldwide distribution that is able to infect a wide variety of mammals and birds. Our main goal was to screen for T. gondii antibody titers in a previously untested species, the spotted hyena ( Crocuta crocuta); however, this goal first required us to investigate serological procedures that could be suitable for hyenas. Cats are the closest domestic relations of hyenas, so T. gondii antibody titers were first compared in 26 feral cats with specific or nonspecific fluorophore-labeled secondary reagents, i.e., anti-cat IgG or protein A. Substitution of anti-cat IgG with protein A caused a statistically significant drop in titer measurements in cats (P = 0.01) with a reduction of the geometric mean titer equivalent to 1 doubling-dilution. The same procedures were then applied to captive spotted hyenas. Titers measured in 9 of 10 hyenas were identical whether anti-cat IgG or protein A was used as the secondary reagent: 5 had titers <1:16, 2 had titers of 1:16, and 2 had titers of 1:32. One hyena had maximum titers of 1:64 or 1:32 when anti-cat IgG or protein A was used, respectively. The use of protein A as the secondary reagent in serologic assays can be applied to a range of mammalian species and seems unlikely to affect test specificity; however, the use of protein A may reduce test sensitivity, as suggested in the present study using cats. Despite a control program, some exposure to T. gondii had occurred in the Zoo's spotted hyenas.
authors.forename: L F
authors.initials: LF
authors.lastname: Wait
authors.affiliation: University of Adelaide, School of Biological Sciences, Adelaide SA, 5005, Australia;
authors.forename: A
authors.initials: A
authors.lastname: Srour
authors.affiliation: Zoos SA, Frome Road, Adelaide, SA, 5000, Australia. Correspondence should be sent to: milton.mcallister@adelaide.edu.au.
authors.forename: I G
authors.initials: IG
authors.lastname: Smith
authors.affiliation: University of Adelaide, School of Biological Sciences, Adelaide SA, 5005, Australia;
authors.forename: P
authors.initials: P
authors.lastname: Cassey
authors.forename: S K
authors.initials: SK
authors.lastname: Sims
authors.forename: M M
authors.initials: MM
authors.lastname: McAllister
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D002371:Cat Diseases / Q000276:immunology / Q000469:parasitology*; D002415:Cats; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D019084:Fluorescent Antibody Technique, Indirect / Q000662:veterinary; D058507:Host Specificity; D045968:Hyaenidae / Q000469:parasitology*; D007106:Immune Sera; D007074:Immunoglobulin G; D012680:Sensitivity and Specificity; D013205:Staphylococcal Protein A; D014122:Toxoplasma / Q000276:immunology*; D014124:Toxoplasmosis, Animal / Q000276:immunology / Q000469:parasitology*
chemical_list: D000913:Antibodies, Protozoan; D007106:Immune Sera; D007074:Immunoglobulin G; D013205:Staphylococcal Protein A