Abstract: The present invention relates to a glycoconjugate immunoreactive with Toxoplasma gondii antibodies, (monoclonal) antibodies against these glycoconjugates, and cell lines capable of producing monoclonal antibodies. The invention is further concerned with immunochemical reagents and methods for the detection of T. gondii or antibodies directed agains T. gondii. Furthermore the invention relates to a therapeutic reagent for the inhibition of replication of T. gondii parasites and a method for the production of a live attenuated T. gondii vaccine. It has now been found, and in contrast with earlier publications in this art, that several glycoconjugates are immunoreactive with Toxoplasma gondii specific antibodies comprising a glycan core structure having general formula (I) wherein R1=Hydrogen, —PO 3 —CH 2 —CH 2 —NH 2 (ethanolamine-phosphate), or —PO 3 —CH 2 —CH 2 —NH—X, wherein X=a T.