Humoral responses and immune protection in mice immunized with irradiated T. gondii tachyzoites and challenged with three genetically distinct strains of T. gondii

► Efficient oral immunization by irradiated tachyzoites was seen in experimental toxoplasmosis. ► Protection to disease and infection could be obtained with different strains challenge. ► Bone marrow cells produced mostly high avidity antibodies than spleen cells. ► IgG avidity and its producing cells are good markers of effective immunity and its memory.