Usefulness of GRA6 derived synthetic polymorphic peptides in Toxoplasma serotyping of worldwide human samples by an immunoenzymatic assay

Clin Vaccine Immunol. 2008 Jul 30. [Epub ahead of print]

Usefulness of GRA6 derived synthetic polymorphic peptides in Toxoplasma gondii serotyping of worldwide human samples by an immunoenzymatic assay

Sousa S, Ajzenberg D, Vilanova M, Costa J, Dardé ML.

Center of Parasite Immunology and Biology, INSA, Rua de S. Luis 16, 4000-509 Porto, Portugal; Instituto de Ciências Biomédicas de Abel Salazar, Largo do Professor Abel Salazar 2, 4099-003, Porto, Portugal; Laboratory for Veterinary Research, LNIV-INRB, I.P. Rua dos Lagidos, Lugar da Madalena, 4485-655 Vairão VCD, Portugal; Université de Limoges, EA 3174-NETEC, and National Reference Center and Biological resource Center for Toxoplasmosis, CHU Dupuytren, 2, av Martin Luther King, 87042 Limoges Cedex, France.

Serotyping is a simple typing method that consists in an immunoenzymatic assay (ELISA) using synthetic polymorphic peptides derived from Toxoplasma gondii antigens. We developed a new ELISA assay based on GRA6 C-terminal polymorphic peptides. Serum samples from 41 human infections due to 23 archetypal (type I, II or III) and 18 non-archetypal strains were selected in order to validate this approach. For 20 out of the 23 archetypal infections, there was a clear correlation between microsatellite genotype and GRA6 serotyping. All infections due to non-archetypal strains were misclassified as archetypal strain infections. The GRA6 C-terminal peptides from these strains were analysed to explain this misclassification. A second group of 455 patients with acute and chronic toxoplasmosis due to unknown genotypes from different European, African and Latin American countries were included in this study, and the strain type predicted by this method. The results suggest that serotyping is a promising method for typing strains, although limitations exist for African and South American strains as a consequence of higher peptide polymorphism. Other peptides from different markers must be studied in order to discriminate archetypal from non-archetypal strains.

PMID: 18667636 [PubMed - as supplied by publisher]