The infection-stage-related IgG response to Toxoplasma gondii studied by immunoblotting

The technique of SDS-polyacrylamide gel electrophoresis and immunoblotting was used to study the evolution of the IgG antibody response to Toxoplasma gondii antigens in sequential sera of acutely infected patients. The results show that the IgG immunoblot pattern can be a useful marker for the stage of T. gondii infection. A 35-kD antigen elicited the first IgG response soon after exposure. During the course of infection additional bands appeared consecutively, following a constant sequence, to evolve to a late-stage-specific pattern with about 13-15 major bands. This pattern, which was reached at least 4 months after infection, was also found in the immunoblots of 28 patients with a chronic (latent) T. gondii infection.