Semiquantitative Dot Blot with the GRA8 antigen to differentiate the stages of toxoplasmosis infection.

In this work we present a novel methodology to differentiate the phases of toxoplasmosis infection: the "semiquantitative Dot Blot". It is a simple technique that does not require expensive equipment, does not involve a long technique development, and can be used in a low-complexity laboratory. In this study, two recombinant sequences of Toxoplasma gondii GRA8 antigen were used, and specific IgG antibodies were detected in selected patient samples. This method makes it possible to obtain a score for each serum and define whether the patient is in the acute or chronic phase of the infection. The sensitivity and specificity results varied depending on the antigenic sequence used. With GRA8A, 62.1% and 72.7% were obtained, while with GRA8B, 82.8% and 72.1% were obtained, respectively. Although the sensitivity and specificity values were not close to 100%, they were similar to those reported with the same antigens in ELISA. Therefore, this quantitative technique would be a good alternative to ELISA.