The first study on the usefulness of recombinant tetravalent chimeric proteins containing fragments of SAG2, GRA1, ROP1 and AMA1 antigens in the detection of specific anti-Toxoplasma gondii antibodies in mouse and human sera

PLoS One. 2019 Jun 6;14(6):e0217866. doi: 10.1371/journal.pone.0217866. eCollection 2019.

Abstract

This study presents an evaluation of four tetravalent recombinant chimeric proteins containing fragments of the Toxoplasma gondii antigens, SAG2, GRA1, ROP1 and AMA1, as potential replacements of a the soluble, whole-cell tachyzoite lysate (TLA) used in serological assays. Recombinant chimeric proteins (SAG2-GRA1-ROP1-AMA1N, AMA1N-SAG2-GRA1-ROP1, AMA1C-SAG2-GRA1-ROP1, and AMA1-SAG2-GRA1-ROP1) obtained by genetic engineering were tested for their reactivity with specific IgM and IgG antibodies from sera of experimentally infected mice and humans with T. gondii infection using an enzyme-linked immunosorbent assay (ELISA). In total 192 serum samples from patients with acquired T. gondii infection and 137 sera from seronegative individuals were examined. The reactivity of chimeric antigens with antibodies generated during T. gondii invasion was measured and compared to the results obtained in assays based on whole-cell Toxoplasma antigen. Chimeric proteins proved effective in differentiation between T. gondii-infected and uninfected individuals (100% sensitivity and specificity in the IgG ELISAs) which shows their potential usefulness as a replacements for TLA in standardized commercial tests for the serodiagnosis of toxoplasmosis. In addition, the chimeric proteins were tested for use in avidity determination. Obtained results were comparable to those of the corresponding commercial assays, suggesting the utility of these proteins for avidity assessment. Furthermore, this study demonstrated that the AMA1-SAG2-GRA1-ROP1 chimeric protein has the potential to distinguish specific antibodies from serum samples of individuals with the early and chronic phase of T. gondii infection.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Protozoan / immunology*
  • Antigens, Protozoan / immunology*
  • Enzyme-Linked Immunosorbent Assay / methods
  • Humans
  • Immunoglobulin G / immunology
  • Immunoglobulin M / immunology
  • Mice
  • Protozoan Proteins / immunology*
  • Recombinant Fusion Proteins / immunology*
  • Sensitivity and Specificity
  • Serologic Tests / methods
  • Toxoplasma / immunology*
  • Toxoplasmosis / immunology*

Substances

  • Antibodies, Protozoan
  • Antigens, Protozoan
  • Immunoglobulin G
  • Immunoglobulin M
  • Protozoan Proteins
  • Recombinant Fusion Proteins

Grants and funding

This work was financed by the National Science Centre (Poland), granted under the project No. UMO-2015/17/B/NZ6/03480 for the years 2016-2019, to LH-G. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.