Protein disulfide isomerase of Toxoplasma gondii is targeted by mucosal IgA antibodies in humans.

Mass spectrometric analysis identified a 49 kDa antigen from Toxoplasma gondii as protein disulfide isomerase (PDI). This antigen is generally recognized by IgA in tears of healthy humans. We determined the complete open reading frame and expressed PDI recombinantly. Recombinant PDI was recognized by IgA in human tears known to contain antibodies specific for the 49 kDa antigen. High expression level and similarity to other protozoan PDIs suggest that T. gondii PDI might be a suitable target for recently described anti-protozoan drugs. PDI-specific antibodies clearly constitute part of the mucosal antibody repertoire possibly involved in defence against parasites.