Toxoplasma gondii antigen recognition by serum immunoglobulins M, G, and A of queens and their neonatally infected kittens.

Objective: To evaluate antigen recognition patterns of serum IgM, IgG, and IgA from queens and their kittens as a method of diagnosing neonatal toxoplasmosis.
Animals: 5 pregnant queens were inoculated orally with Toxoplasma gondii tissue cysts during gestation (18 to 44 days). On various days after parturition (0 to 97), serum was obtained from queens and kittens (n = 19).
Procedure: Tissues from most kittens were assessed for T gondii infection by bioassay in mice. Serum samples were evaluated by IgM, IgG, and IgA western blot immunoassays for the presence of T gondii antibodies. Antigens recognized by kitten serum samples, but not by the corresponding queen serum sample, were considered to indicate neonatal infection with T gondii.
Results: Using the results of western blot immunoassay, 8 of 19 kittens (age, 2 to 97 days) were determined to be infected with T gondii. Western blot immunoassay results correlated well with bioassay results, identifying 7 of 8 bioassay-positive kittens. Western blot immuno-assay additionally identified 1 kitten as infected, but tissues from the kitten had not been bioassayed. In each of the 5 kittens that developed clinical signs of toxoplasmosis, the diagnosis of neonatal toxoplasmosis was supported by results of the western blot immunoassays.
Conclusion and Clinical Relevance: Comparison of queen and kitten T gondii antigen recognition patterns of IgM, IgG, and IgA can be used for antemortem diagnosis of neonatal toxoplasmosis.