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

Patrícia Regina Barboza Araújo, Antonio Walter Ferreira
2008 Revista da Sociedade Brasileira de Medicina Tropical  
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
more » ... 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.
doi:10.1590/s0037-86822008000200002 pmid:18545833 fatcat:m6q56rborvhb3ojktu74zpry7a