Serological reactivity against cyst and tachyzoite antigens of Toxoplasma gondii determined by FAST-ELISA

Abstract

Aims-To obtain quantitative data on the human serological response to Toxoplasma gondii tachyzoite and bradyzoite antigens. Methods-Serum samples from 30 patients who had positive antibody titres against T gondii and from 14 who were seronegative, together with sequential serum samples from four infected individuals, were screened by FAST-ELISA. Results-Serum samples from the 30 seropositive patients showed high IgG and IgM titres against the T gondii tachyzoite antigen but very low responses to cyst antigen. This result was borne out in sequential serum samples from patients with toxoplasmosis. Conclusion-Antibody recognition of the cystic stage of T gondii is low, implying that either this stage is poorly immunogenic or that the antigen load is low.