Evaluation of a recombinant multiepitope peptide for serodiagnosis of Toxoplasma gondii infection

Abstract

Detection 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.

Fig 1

Construction of recombinant epitope plasmid. (A) The single-stranded DNA oligonucleotides (lanes 1 and 2) were annealed to the double-stranded DNA oligonucleotides (lane 3). Lane M, DNA molecular marker. (B) The double-stranded DNA oligonucleotides were cloned into NcoI- and XhoI-digested pET-32c and characterized by EcoRI digestion.

Fig 2

Purification and identification of recombinant epitope peptides. (A) SDS-PAGE analysis of purified recombinant epitope peptides. (B) Western immunoblot analysis of recombinant epitope peptides with a pool of T. gondii-positive human sera.

Fig 3

Construction, purification, and identification of the multiepitope peptide (MEP). (A) Diagram of the MEP open reading frame (ORF). (B) SDS-PAGE analysis of the purified recombinant MEP and Tag (thioredoxin). (C) Western immunoblot analysis of recombinant MEP and Tag with T. gondii (Tg)-positive and -negative human sera.