A Rapid Diagnostic Test for Toxoplasmosis using Recombinant Antigenic N-terminal Half of SAG1 Linked with Intrinsically Unstructured Domain of GRA2 Protein

Abstract

Toxoplasma gondii is an apicomplexan parasite with a broad host range of most warm-blooded mammals including humans, of which one-thirds of the human population has been infected worldwide which can cause congenital defects, abortion, and neonatal complications. Here, we developed a rapid diagnostic test (RDT) for T. gondii infection. Antigenic N-terminal half of the major surface antigen (SAG1) was linked with intrinsically unstructured domain (IUD) of dense granule protein 2 (GRA2). The recombinant GST-GRA2-SAG1A protein was successfully expressed and purified as 51 kDa of molecular weight. Furthermore, antigenicity and solubility of the rGST-GRA2-SAG1A protein were significantly increased. The overall specificity and sensitivity of GST-GRA2-SAG1A loaded RDT (TgRDT) were estimated as 100% and 97.1% by comparing with ELISA result which uses T. gondii whole cell lysates as the antigen. The TgRDT tested with Uganda people sera for field trial and showed 31.9% of seroprevalence against T. gondii antibody. The TgRDT is proved to be a kit for rapid and easy to use with high accuracy, which would be a suitable serodiagnostic tool for toxoplasmosis.

High Expression of Water-Soluble Recombinant Antigenic Domains ofToxoplasma gondii Secretory Organelles

“…They have relatively lower molecular weight to enrich the number of antigens in a restricted condition of smaller diagnostic product with maintaining higher sensitivity. It is once again proven that IUD domain enhances the plasticity and solubility of proteins in the present study [10,26]. Therefore, based on the analysis of bioinformatics approaches, 4 recombinant antigens were cloned and promising candidates to develop serological diagnosis kits, for example ELISA or rapid diagnostic test (RDT).…”

High Seroprevalence of Toxoplasmosis Detected by RDT among the Residents of Seokmo-do (Island) in Ganghwa-Gun, Incheon City, Korea

“…However, most of them are expensive and time-consuming, and recently RDT using recombinant proteins as antigens has been developed to address these problems [18]. …”

“…Our previous study has determined the overall specificity and sensitivity of RDT to be 100% and 97.1%, respectively [18]. RDT uses rSAG1A-GRA2 antigen.…”

“…IgG/IgM RDT mounted with recombinant fragment of major surface antigen (SAG1A), GST-linker-SAG1A [12,18], were applied to the sera mentioned above. Briefly, 10 μl of serum was applied to the RDT sample hole and eluted with RDT buffer a few seconds later.…”

Digested disorder, Quarterly intrinsic disorder digest (October-November-December, 2013)

“…Using the unstructured region of Toxoplasma gondii GRA2 as a linker between GST and T. gondii SAG1A, Song et al 78 developed a new diagnostic kit for toxoplasmosis. The authors speculate that this disordered linker not only increased antigenicity, but also increased solubility as well as capture radius of SAG1A.…”