Evaluating the Antigenic Markers of Toxoplasma gondii RH strain for Differential Diagnosis of Acute and Chronic Toxoplasmosis

Toxoplasmosis is one of the most prevalent parasitic infections common among humans and animals having two acute and chronic phases related to IgM and IgG, respectively. Immunoblotting is one of the serological methods with high sensitivity and specificity. Therefore, the present study aims to evaluate T. gondii RH strain antigen using the Western blot assay, their applications to distinguish between acute and chronic infections and their sensitivities and specificities. A sample of 0.02 ml of T. gondii RH strain antigen along with 10 tachyzoites was injected into the peritoneal cavity of 50 white lab mice (Mus Musculus) and the peritoneal fluids of infected mice were collected after 4 days. After sonication, the protein concentration was determined using the Lowry method. Then the molecular weight of fractions was determined using SDS-PAGE electrophoresis. Seventy serum samples (30 samples of acute Toxoplasmosis, 30 chronic Toxoplasmosis and 10 serum samples of healthy individuals as controls) were investigated using the Western blot assay to identify and distinguish the antigenic markers of acute and chronic phases of the disease. Five proteins of approximately 12, 28, 41, 72, and 130 KDa were often recognized by IgG antibody present in the sera from patients with chronic toxoplasmosis. Antigens of 12, 28, and 41 KDa were recognized in all patients indicating the sensitivity and specificity of 100% for the test. Furthermore, the sensitivity and specificity of the test for the antigens of 72 and 130 KDa were 50% and 100%, respectively.