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Memórias do Instituto Oswaldo Cruz
Fundação Oswaldo Cruz, Fiocruz
ISSN: 1678-8060
EISSN: 1678-8060
Vol. 107, No. 3, 2012, pp. 342-347
Bioline Code: oc12049
Full paper language: English
Document type: Research Article
Document available free of charge

Memórias do Instituto Oswaldo Cruz, Vol. 107, No. 3, 2012, pp. 342-347

 en Early diagnosis of congenital toxoplasmosis in newborn infants using IgG subclasses against two Toxoplasma gondii check for this species in other resources recombinant proteins
e Silva, Carlos Henryque de Souza; de Andrade, Gláucia Queiroz; Januário, José Nélio; Carneiro, Ana Carolina de Aguiar Vasconcelos; Carneiro, Mariangela; Vasconcelos-Santos, Daniel Vitor & Vitor, Ricardo Wagner de Almeida

Abstract

The aim of this work was to evaluate the utility of ELISA-based testing of total IgG (IgGt) antibodies and its subclasses (IgG1, IgG2, IgG3 and IgG4) against soluble (STAg) and recombinant (rSAG1 and rMIC3) antigens of Toxoplasma gondii check for this species in other resources for diagnosing congenital toxoplasmosis. Sera from 217 newborns initially testing positive for specific IgM in filter paper dried blood spots were tested for specific IgM and IgG by ELFA-VIDAS®. Congenital toxoplasmosis was confirmed in 175 and ruled out in 42 infants. The validity of the ELISA tests was determined using the persistence of IgG antibodies (ELFA-VIDAS® kit) at the end of 12 months, which is considered the reference test for the diagnosis of congenital toxoplasmosis. The frequency of positivity with IgGt against STAg, rSAG1 and rMIC3 was found in 97.2%, 96.3% and 80.2%, respectively, of the newborns with confirmed congenital toxoplasmosis. IgG1 reacted with all three antigens, while IgG3 and IgG4 reacted preferentially with rMIC3. Higher mean values of reactivity (sample optical density/cut-off) were found for all subclasses when using rMIC3. All of the antigens showed high sensitivity and low specificity in detecting anti-T. gondii IgGt and IgG1 and low sensitivity and high specificity in detecting IgG3 and IgG4. In conclusion, the combined detection of IgG antibody subclasses against recombinant toxoplasmic antigens may be useful for the early diagnosis of congenital toxoplasmosis.

Keywords
congenital toxoplasmosis - ELISA - recombinant proteins - IgG subclasses

 
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