Isolation and characterization of toxoplasma exo-antigens from in vitro culture in MRC5 and Vero cells

Exo-antigens from the supernatant medium of in vitro cultures of Toxoplasmsa gondii on Vero and MRC5 cells have been characterized by different immunological techniques: enzyme-linked immunosorbent assay (ELISA), counter immunoelectrophoresis (CIE), twodimensional immunoelectrophoresis (2-DIEP) and gel electrophoresis of derivated ELISA (GEDELISA). These exo-antigens are similar in molecular sizes, thermostability and of proteic nature with glucidic components. Their enzymatic properties and precipitation arcs differ. The exo-antigens, produced on Vero cells (monkey kidney cells), seem to be more antigenic than those produced on MRC5 cells (human foetal lung cells). The formaldehyde treatment stabilizes the exo-antigens, in spite of eliminating certain epitopes, and increases their migration rate; it has practically no effect on their enzymatic or antigenic activities. The pI of the formolated exo-antigens produced on MRC5 cells are mainly under 5.06.