Evaluation of a Recombinant Multiepitope Peptide for Serodiagnosis of Toxoplasma gondii Infection

Abstract

bDetection of Toxoplasma gondii infection with sensitive and specific methods is a key step in the prevention and treatment of toxoplasmosis. Among the available diagnostic tests, serology is commonly used. Although serological tests give satisfactory results, the production of reliable reagents remains laborious and expensive. There is therefore a real need to acquire specific and effective recombinant antigens for the serodiagnosis of T. gondii infection. In this study, a multiepitope peptide was designed and successfully expressed in Escherichia coli, and then IgG and IgM enzyme-linked immunosorbent assays (ELISAs) were developed and evaluated. Our results showed that the new multiepitope antigen is one of the most promising recombinant antigens which could be used in routine screening of human toxoplasmosis.

Effective Diagnostic Marker for Serodiagnosis of Toxoplasma gondii Infection: New Developments and Perspectives

“…However, producing specific and standard antigens is a real challenge. Currently, most commercial serological kits use crude Toxoplasma antigens prepared through mouse passages or cell culture systems [29,30]. The soluble native antigen of T. gondii parasite has been applied as a diagnostic marker in various seroepidemiological studies [4], a researcher used crude native antigen of type I and II, for example [1].…”

“…The epitope is classified into two categories based on their primary structure: linear (continuous) epitope if the amino acids sequences in the epitope are continuous or conformational (discontinuous) epitope which composed from discontinuous sections of amino acid [46]. Attempts to achieve high sensitive and specific diagnostic assay usually assume that replacing the native antigen in all current diagnostic kits by standard and reliable reagents can significantly increase the assay performance [30]. In recent years, it has been demonstrated that the use of peptide-based antigen can meet the demand to standardize the serodiagostic test of toxoplasmosis and increase the sensitivity and specificity of these assays.…”

“…The applied antigen composition in the serodiagnostic test will be known precisely, the ability to apply more than one identified epitope, easily standardization of the assays, application of only antigen epitope will reduce the biohazard problems in using live pathogens [30]. Nowadays, the use of a diagnostic marker that contains a high density of antibody binding site increases the chances of antibody detection in serum samples and provides the potential to acquire inexpensive diagnostic methods with a high degree of specificity and sensitivity.…”

“…Therefore, a great possibility to improve diagnostic tests performance exists if multiepitope peptide is applied [48]. Application of multiepitopes antigen in diagnostic tests has been conducted successfully in several studies, employing multiepitope peptide in hepatitis C [49], influenza virus [50], leishmaniasis [51] [52], Trypanosoma cruzi [53], leptospirosis, and Mycobacterium tuberculosis [54,55] as well as T. gondii infection [30]. In all these studies, multiepitope proteins were proposed to enhance the test sensitivity.…”

“…The result indicates high immunoreactivity as well as the capability of the peptide to improve the toxoplasmosis serodiagnostic tests [56]. The newly synthesized immunodominant epitopes of T. gondii antigens (SAG1, SAG2, SAG3, GRA5, GRA6, and P35) appear to be the most promising diagnostic reagents can be applied in routine toxoplasmosis screening The demonstrated multiepitope peptides can successfully replace the recombinant antigens for differentiating the recently acquired infection from the previous infection; thus, it can serve as an effective tool for human serodiagnosis [30].…”