title: Rubella-specific IgG1 avidity: a comparison of methods.
abstract: Two methods of determining the avidity of specific IgG1 were compared with sera from different categories of rubella infection. Both methods were based on an antiglobulin enzyme-linked immunosorbent assay. In one method the absorbances were compared with and without diethylamine (DEA) in the serum diluent over a range of serum dilutions and the difference between the dilution curves measured (DEA-shift). In the other, the absorbances at a single serum dilution were compared with and without urea in the wash fluid used after the antigen/serum incubation (avidity index). Various concentrations of DEA were also assessed in the avidity-index method, as this method is simpler to perform. The DEA-shift method was shown to be more sensitive for diagnosing recent primary rubella or immunization by demonstrating specific IgG1 of low avidity. The avidity-index method, however, was more specific when sera from cases of reinfection or non-specific rubella IgM reactivity were tested. 35 mM DEA was found to be the optimal concentration of DEA when DEA was substituted for urea in the avidity index method.
authors.affiliation: Department of Virology, Royal Preston Hospital, U.K.
authors.forename: H I
authors.initials: HI
authors.lastname: Thomas
authors.forename: P
authors.initials: P
authors.lastname: Morgan-Capner
mesh_terms: D000907:Antibodies, Bacterial / Q000032:analysis*; D000915:Antibody Affinity; D000918:Antibody Specificity; D004048:Diethylamines; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007106:Immune Sera; D007074:Immunoglobulin G / Q000032:analysis*; D012409:Rubella / Q000382:microbiology*; D012411:Rubella Vaccine; D012412:Rubella virus / Q000276:immunology*; D012680:Sensitivity and Specificity
chemical_list: D000907:Antibodies, Bacterial; D004048:Diethylamines; D007106:Immune Sera; D007074:Immunoglobulin G; D012411:Rubella Vaccine; C034281:diethylamine