[Avidity of specific IgG antibodies as markers of recent primary infection caused by Toxoplasma gondii]

Rev Inst Med Trop Sao Paulo. May-Jun 1991;33(3):213-8.
[Article in Portuguese]


For serologically characterizing a recent primary toxoplasma infection, the low avidity of IgG specific antibodies was studied. Avidity was evaluated as the decrease of IgG antibody titers in ELISA after treating plates with 6 M urea, as a dissociating solution of low avidity antigen-antibody complexes. Sixty nine serum samples were studied, presenting characteristic patterns of recent, transitional or chronic toxoplasmosis. Serological patterns were determined according to results of IgG and IgM immunofluorescence, IgM-capture, and hemagglutination tests. Twenty three serum samples from each of the referred patterns I, II and III were titrated. For chronic toxoplasmosis infections, which presented a serological pattern III, observed decrease of titers was 3% +/- 3%. For pattern I recent toxoplasmosis sera it was 34% +/- 12%, and for transition pattern II, 12% +/- 9%. Thus, a low avidity of IgG specific antibodies can be applicable for the diagnosis of a recent toxoplasmosis infection.

Publication types

  • English Abstract

MeSH terms

  • Animals
  • Antibodies, Protozoan / blood*
  • Antibody Affinity / immunology*
  • Biomarkers
  • Enzyme-Linked Immunosorbent Assay
  • Fluorescent Antibody Technique
  • Humans
  • Immunoglobulin G / blood*
  • Immunoglobulin M / blood
  • Toxoplasma / immunology
  • Toxoplasmosis / immunology*


  • Antibodies, Protozoan
  • Biomarkers
  • Immunoglobulin G
  • Immunoglobulin M