Thursday, June 12, 2008

Avidity of IgG antibodies against excreted/secreted antigens of Toxoplasma

Rev Soc Bras Med Trop. 2008 Apr;41(2):142-147

Avidity of IgG antibodies against excreted/secreted antigens of Toxoplasma gondii: immunological marker for acute recent toxoplasmosis

Araújo PR, Ferreira AW.

IInstitute of Tropical Medicine, Faculty of Medicine, University of São Paulo, São Paulo, SP.

Detection of anti-toxoplasma IgM antibodies has frequently been used as a serological marker for diagnosing recently acquired toxoplasmosis. However, the persistence of these antibodies in some patients has complicated the interpretation of serological results when toxoplasmosis is suspected. The purpose of the present study was to evaluate the avidity of IgG antibodies against excreted/secreted antigens of Toxoplasma gondii by means of immunoblot, to establish a profile for acute recent infection in a single serum sample and confirm the presence of residual IgM antibodies obtained in automated assays. When we evaluated the avidity of IgG antibodies against excreted/secreted antigens of Toxoplasma gondii by means of immunoblot, we observed phase-specific reactivity, i.e. cases of acute recent toxoplasmosis presented low avidity and cases of non-acute recent toxoplasmosis presented high avidity towards the 30kDa protein fraction, which probably corresponds to the SAG-1 surface antigen. Our results suggest that the avidity of IgG antibodies against excreted/secreted antigens of Toxoplasma gondii is an important immunological marker for distinguishing between recent infections and for determining the presence of residual IgM antibodies obtained from automated assays.

PMID: 18545833 [PubMed - as supplied by publisher]

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