EJMS

Abstract

Toxoplasmosis is a worldwide endemic disease. Diagnosis is routinely assessed by serological means and they sometimes are unsatisfactory. This study aimed to evaluate Toxoplasma purified concanavalin A (Con A) glycoprotein fraction as a diagnostic antigen in diagnosis of toxoplasmosis by direct and indirect immunodiagnostic methods. Two types of Toxoplasma antigens were prepared and used in this work, crude Toxoplasma tachyzoites antigen (CTT) and purified Con A reactive antigen and were analysed by SDA-PAGE. The study included 91 serum samples and divided into 3 groups, group I: 46 samples were positive toxoplasmosis, group II: 25 samples were positive other parasitic infections, and group III: 20 samples were negative for any of parasitic infection. Anti-Toxoplasma IgG and IgM were detected in sera of different groups using both antigens by indirect enzyme linked immunosorbent assay (ELISA) with evaluation of sensitivity, specificity and diagnostic efficacy of each. Also Anti-Toxoplasma IgG were detected using both antigens by immunobloting. Polyclonal antibodies against Toxoplasma ConA reactive antigen were purified from hyperimmunized rabbits’ sera and used for detection of circulating Toxoplasma antigens using sandwich ELISA with evaluation of sensitivity, specificity and diagnostic efficacy. The results showed that the fractionation of CTT revealed several bands ranged from 110 to 12 KDa with major five bands, while purified Toxoplasma Con A reactive antigen gave 3 major bands of 95, 28 and 12 Kda. The sensitivity of ELISA in detection of anti-Toxoplasma IgG antibodies using CTT and purified Toxoplasma reactive antigens was 93% and 95% respectively and specificity was 56% and 92% respectively with diagnostic accuracy of 78.7% and 94.0% respectively in comparison with group II and was 93, 80 and 88.5% respectively for CTT and was 95, 95, and 95.0% respectively for Toxoplasma Con A reactive fraction in comparison with group III. The sensitivity of ELISA in detection of anti-Toxoplasma IgM antibodies using both antigens was 75% and 91.6% respectively and specificity was 92% and 96% respectively with diagnostic accuracy of 86%and 94.5% respectively in comparison with group II and was 75%. 90% and 84% respectively for CTT and was 92%, 100%, and 97% respectively for Toxoplasma Con A reactive fraction in comparison with group III. The sensitivity, specificity and diagnostic accuracy of sandwich ELISA in detection of circulating Toxoplasma antigens were 92% 95% and 94.5%. It was concluded that the immunoblotting is easy to perform and might be useful as an additional serological assay for routine diagnosis of T. gondii infection. Also, Toxoplasma purified ConA glycoprotein antigenic fraction could be considered as an effective antigen can be used in diagnosis of human toxoplasmosis.