title: [Avidity of specific IgG antibodies as markers of recent primary infection caused by Toxoplasma gondii].
abstract: 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.
authors.affiliation: Laboratório Fleury de Análises Clínicas, São Paulo, Brasil.
authors.forename: M E
authors.initials: ME
authors.lastname: Camargo
authors.forename: S M
authors.initials: SM
authors.lastname: da Silva
authors.forename: P G
authors.initials: PG
authors.lastname: Leser
authors.forename: C H
authors.initials: CH
authors.lastname: Granato
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000915:Antibody Affinity / Q000276:immunology*; D015415:Biomarkers; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007075:Immunoglobulin M / Q000097:blood; D014122:Toxoplasma / Q000276:immunology; D014123:Toxoplasmosis / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D015415:Biomarkers; D007074:Immunoglobulin G; D007075:Immunoglobulin M
vernacular_title: Avidez de anticorpos IgG específicos como marcadores de infecção primária recente pelo Toxoplasma Gondii.