P35 and P22 Toxoplasma gondii antigens abbreviate regions to diagnose acquired toxoplasmosis during pregnancy: toward single-sample assays

Abstract

Background: P35 and P22 Toxoplasma gondii proteins are recognized by specific IgG at the early infection stage, making them ideal for acute toxoplasmosis pregnancy control. Both proteins have been studied to discriminate between acute and chronic toxoplasmosis. However, results were hardly comparable because different protein obtainment procedures led to different antigens, the referencepanels used were not optimally typified, and avidity tests were either not performed or narrowly examined. Methods: We bioinformatically predicted P35 andP22 regions with the highest density of epitopes, and expressed them in pET32/BL21DE3 alternative expression system, obtaining the soluble proteins rP35a and rP22a. We assessed their diagnostic performance using pregnant woman serum samples typified as: not infected, NI (IgG−, IgM−), typical-chronic, TC (IgM−, IgG+), presumably acute, A (IgG+, IgM+, low-avidity IgG), and recentlychronic, RC (IgG+, IgM+, high-avidity IgG).