Sequential recognition of antigenic markers of Toxoplasma gondii tachyzoite by pooled sera of mice with experimental toxoplasmosis.

Accurate diagnosis of maternal toxoplasmosis can enhance the success of medical treatment and prevent congenital transmission. The current diagnostic methods have many limits, and they poorly differentiate between recent and latent infections. The present work was conducted to record the sequential recognition of antigenic markers of both Toxoplasma tachyzoites whole extract and glycosylinositolphospholipids (GIPLs)-enriched fraction by specific IgG and IgM, respectively, by immunoblotting analysis of the antigens against daily pooled serum samples from mice with experimentally induced recent and latent toxoplasmosis. IgG avidity immunoblotting was tested by using a wash with 6 M urea solution as antigen-antibody disrupting agent. Band of 10 kDa reacted exclusively with low-avidity IgG in pooled sera of mice with recent infection. Band of 39 kDa was a good marker for the infection; reacting with both low-avidity IgG in recent infection and with high-avidity IgG in latent one. Bands of 15, 23, 30, 60, 66, and 97 kDa reacted with variable avidity in both phases of infection. Two antigenic bands were detected by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the GIPLs-enriched fraction of tachyzoite, the 14- and 30-kDa band. The 14-kDa band was recognized by IgM in pooled serum samples of recently infected mice only, while the 30-kDa band was recognized by serum samples of both recent and latent phases of infections. The study highlights the value of avidity immunoblotting assay to discriminate between recent and latent experimental toxoplasmosis. Further study must be carried on human to evaluate the values of the used technique.