Immunochemical evaluation of two Toxoplasma gondii GRA8 sequences to detect acute toxoplasmosis infection.

In this work, two Toxoplasma gondii GRA8 protein sequences were tested by indirect ELISA and measurement of avidity to differentiate between acute and chronic toxoplasmosis infection. Using the antigen called GRA8B, 79.7% sensitivity and 84.1% specificity was achieved detecting IgG concentrations and a 71.2% sensitivity and a 68.3% specificity detecting IgA concentrations. This study is the first to report IgA detection with GRA8 by ELISA to differentiate stages of infection. Unfortunately the indirect ELISA to detect IgM was not effective in distinguishing stages. Also, this work is the first to report that the GRA8 protein can aid the differentiation between acute and chronic phase infection by measuring IgG antibody avidity, a technique in which we obtained 85.71% and 100% of sensitivity and specificity, respectively. Finally, in silico tools were used to explain the differences in our immunochemistry results.