The Toxoplasma MAGI peptides induce sex-based humoral immune response in mice and distinguish active from chronic human infection

To distinguish active from inactive/chronic infection in Toxoplasma gondii-seropositive individuals, we have developed an enzyme-linked immunosorbent assay (ELISA) using specific peptides derived from Toxoplasma matrix antigen MAGI. We used this assay to measure matrix specific antibodies and pilot studies with infected mice established the validity of two peptides. The immune response against MAGI occurs in about 12 days postinfection and displays a sex difference later on in mouse model, with males producing higher antibody titers than females. Serum samples from 22 patients with clinical toxoplasmosis and from 26 patients with serological evidence of past exposure to Toxoplasma (more than one year infection history) were analyzed. Both MAGI peptides detected antibodies significant frequently and robustly from active stage than from the chronic stage of toxoplasmosis. The results indicate that both MAGI peptides may be used as a tool to differentiate active from inactive infection. It also may be considered in the design of potential vaccines in humans. (C) 2012 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.