Although heterotypic secondary infection with dengue virus (DENV) is associated with severe disease, the majority of secondary infections are mild or asymptomatic. The mechanisms of antibody-mediated protection are poorly understood. In 2010, 108 DENV3-positive cases were enrolled in a pediatric hospital-based study in Managua, Nicaragua, with 61 primary and 47 secondary infections. We analyzed...

Background: The diagnostic methods which are used for acute ocular toxoplasmosis are very important; if the treatment is delayed, it sometimes leads to loss of vision. Fewstudies have been performed to evaluate serological tests used in the diagnosis of acute ocular toxoplasmosis. Objective: To evaluate the immunoglobulin (Ig) M, G and IgG avidity tests for dia...

OBJECTIVE To evaluate avidity of IgG anti-beta 2-glycoprotein I antibodies (anti-beta2-GPI) in patients with antiphospholipid syndrome (APS) and systemic lupus erythematosus (SLE) in relation to thrombosis, and to demonstrate a possible affinity maturation of IgG anti-beta 2-GPI during the disease course. METHODS 64 sera from 32 patients (18 with primary or secondary APS, 14 with SLE without ...

The aim of this study was to discriminate between primary and secondary vaccine failure in children with mumps using IgG avidity testing. Thirty-nine serum samples from children with mumps, confirmed by specific IgM, were studied. The patients were grouped according to their immunization status. The secondary immune response was defined by IgG with an avidity index >32%. A secondary response in...

Toxocariasis is a zoonotic disease in that IgM titers can remain high for long periods making difficult to determine the stage of the disease. The aim of this study is to investigate the applicability of indirect ELISA, associated with urea, to discriminate between the acute and chronic toxocariasis. IgG avidity was evaluated in 25 BALB/c mice experimentally infected with 1000 Toxocara canis eg...

The goal of this study was to investigate the importance of IgG avidity testing in newborns (NBs) diagnosed with early congenital toxoplasmosis. We collected samples from 88 puerperae infected by Toxoplasma gondii (T. gondii) and their NBs (48 acutely-infected puerperae (AIP) and 40 chronically-infected puerperae (CIP)), from two public maternity hospitals in Goiania city, Goias, Brazil, from 2...

Since its introduction in 1999, West Nile virus (WNV) infections have spread rapidly across the North American continent. Diagnosis of acute WNV infection by detection of WNV-specific immunoglobulin M (IgM) is complicated by the persistence of detectable IgM for more than 1 year in some patients. IgG antibody avidity testing was assessed as a supplemental assay in the diagnosis of current infec...

Abstract The kinetics of immunoglobulin G (IgG) avidity maturation during severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection obtained from 217 participants the Ischgl cohort, Austria, was studied 0.5–1.5 months (baseline) and 7–8 (follow-up) after infection. IgG assay, using a modified enzyme-linked immunosorbent assay (ELISA) 5.5 M urea, revealed that old age does not dimin...