[Evaluation of the second fraction of excreted/secreted antigens from toxoplasma gondii by ion exchange chromatography for serodiagnosis of toxoplasmosis in rat]

ABSTRACT

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 4x106 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