Identification of Toxoplasma gondii in-vivo induced antigens by cDNA library immunoscreening with chronic toxoplasmosis sera

Microb Pathog. 2013 Jan:54:60-6. doi: 10.1016/j.micpath.2012.09.006. Epub 2012 Oct 5.

Abstract

Toxoplasmosis is an infection caused by the parasite Toxoplasma gondii. Chronically-infected individuals with a compromised immune system are at risk for reactivation of the disease. In-vivo induced antigen technology (IVIAT) is a promising method for the identification of antigens expressed in-vivo. The aim of the present study was to apply IVIAT to identify antigens which are expressed in-vivo during T. gondii infection using sera from individuals with chronic toxoplasmosis. Forty serum samples were pooled, pre-adsorped against three different preparations of antigens, from each in-vitro grown T. gondii and Escherichia coli XLBlue MRF', and then used to screen a T. gondii cDNA expression library. Sequencing of DNA inserts from positive clones showed eight open reading frames with high homology to T. gondii genes. Expression analysis using quantitative real-time PCR showed that SAG1-related sequence 3 (SRS3) and two hypothetical genes were up-regulated in-vivo relative to their expression levels in-vitro. These three proteins also showed high sensitivity and specificity when tested with individual serum samples. Five other proteins namely M16 domain peptidase, microneme protein, elongation factor 1-alpha, pre-mRNA-splicing factor and small nuclear ribonucleoprotein F had lower RNA expression in-vivo as compared to in-vitro. SRS3 and the two hypothetical proteins warrant further investigation into their roles in the pathogenesis of toxoplasmosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibodies, Protozoan / immunology*
  • Antigens, Protozoan / genetics
  • Antigens, Protozoan / immunology*
  • Chronic Disease
  • Escherichia coli
  • Gene Expression
  • Gene Expression Profiling
  • Gene Library
  • Humans
  • Mice
  • Open Reading Frames
  • Real-Time Polymerase Chain Reaction
  • Sequence Analysis, DNA
  • Toxoplasma / genetics
  • Toxoplasma / immunology*
  • Toxoplasmosis / immunology*

Substances

  • Antibodies, Protozoan
  • Antigens, Protozoan