The present invention relates to a genetically engineered P30 antigen and a combination or mixture of antigens (e.g., the genetically engineered P30 antigen and P35) that may be used in the detection of IgM and/or IgG antibodies to Toxoplasma gondii. Furthermore, the present invention also relates to methods of using this genetically engineered P30 antigen and combination of antigens, antibodies raised against this genetically engineered P30 antigen and combination of antigens, as well as kits and vaccines containing the genetically engineered P30 antigen and antigens present in the combination.