Avidity analysis of the human immune response to a chitin binding protein of Toxoplasma gondii

A 30-33 kDa electroeluted fraction of T. gondii tachyzoites improved discri mination between acute and chronic phase sera when used instead of the whol e tachyzoite extract in an avidity-ELISA. In order to identify the componen ts of these fractions, crude tachyzoite antigen was fractionated by anionic exchange chromatography. The 30-33 kDa antigen cluster eluted in the not-b ound fraction could account for a large proportion of the antibody response against the 30-33 kDa electroeluted fraction. According to the N-terminal sequence data, this antigen fraction is composed mainly of SAG1 and another protein with high homology to chitin binding proteins from plants. (C) 200 1 Australian Society for Parasitology Inc. Published by Elsevier Science Lt d. All rights reserved.