Reliability of low-avidity IgG and of IgA in the diagnosis of primary infection by rubella virus with adaptation of a commercial test Gutiérrez Fernández, José Rodríguez, M. J. Ory, F. De Piédrola Angulo, Gonzalo Maroto Vela, María del Carmen Rubella virus Avidity IgG The detection of IgA and low-avidity IgG and antibodies in serum is a potentially useful marker of recent infection by a microorganism. We studied the reliability of IgG avidity and presence of IgA for the diagnosis of recent acute infection by rubella virus. Low-avidity IgG (Avy-EIA test) was determined with a modified commercial test using 8 molar urea (indirect ELISA, DiaSorin, Italy) and IgA was determined with a homemade indirect ELISA test. Twenty-five patients with recent primary infection by rubella virus (group I) and 50 healthy subjects (group II) were studied. In group I low-avidity IgG varied between 100 and 0% (67.3+/-21.8%); IgA was present in 24 patients (96%). In group II low-avidity IgG varied from 50.4 to 0% (19.8+/-16.9%). IgA was present in 2 subjects (4%). The sensitivity of the Avi-EIA and the IgA test was 92 and 96%, respectively; specificity was 100 and 96%, respectively. We conclude that both low-avidity IgG and IgA tests are helpful and reliable for the diagnosis of recent primary infection. 2024-03-18T13:17:31Z 2024-03-18T13:17:31Z 1999 info:eu-repo/semantics/article Gutiérrez J, Rodríguez MJ, De Ory F, Piédrola G, Maroto MC. Reliability of low-avidity IgG and of IgA in the diagnosis of primary infection by rubella virus with adaptation of a commercial test. J Clin Lab Anal. 1999;13(1):1-4. https://hdl.handle.net/10481/90086 10.1002/(SICI)1098-2825(1999)13:1<1::AID-JCLA1>3.0.CO;2-Z eng http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess Attribution-NonCommercial-NoDerivatives 4.0 Internacional Wiley