Evaluation of the Second Fraction of Excreted /Secreted Antigens from Toxoplasma gondii by Ion Exchange Chromatography for Serodiagnosis of Toxoplasmosis in Rat

Background and According to the previous studies, Toxoplasma gondii excreted / secreted antigens (E/SA) appear to be suitable marker for serodiagnosis of toxoplasmosis. Most of the previous studies used whole E/SA. The present study, was carried out to evaluate the ELISA method using E/SA components from Toxoplasma gondii for the diagnosis of toxoplasmosis. Components obtained by incubation of tachiziotes at RPMI-1640 culture medium were purified by Ion exchange chromatogeraphy and fractions were analyzed by native-PAGE electrophoresis. Forty noninfected rats were injected as IP with 4×106 Toxoplasma tachyzoites and their serum samples were collected at 8, 15, 22 and 60 days after infection then were tested by dye-test. Based on these results the sera of 15 and 60 days were selected and tested by ELISA using E/SA. Second fraction of chromatography was selected as antigens. The cut-off point of ELISA with 99% confidence was found to be 0.41. Optical density of all sera samples of 15 and 3 of 60 days after infection and 2 negative sera were over the test cut-off. Therefore sensitivity and specificity of the method were determined to be 100% and 91% respectively. These results indicated that the second fraction of Ion exchange chromatography of Toxoplasma E/SA under these conditions may be useful tool for the serediagnosis and differentiation of acute and chronic phases of toxoplasmosis.