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Clinical and Diagnostic Laboratory Immunology, July 2000, p. 607-611, Vol. 7, No. 4
Mécanismes Moléculaires de la
Pathogénèse des Sporozoaires, Institut Pasteur de Lille,
IBL, 59019 Lille Cedex,1 and Service de
Biologie Clinique, Département
d'Hématologie-Immunologie-Cytogénétique, Centre
Hospitalier de Valenciennes, 59322 Valenciennes
Cedex,2 France
Received 22 November 1999/Returned for modification 29 February
2000/Accepted 5 May 2000
The potential of the dense granule antigens GRA1 and GRA6 of
Toxoplasma gondii to be used as diagnosis reagents in a
recombinant form was evaluated. Both proteins were expressed in
Escherichia coli as glutathione-S-transferase
(GST) fusions. The GST-GRA1 fusion comprises the entire GRA1 sequence
devoid of its N-terminal signal peptide. Separate expression of the two
N- and C-terminal hydrophilic regions of GRA6 showed that only the
N-terminal hydrophilic part of the protein was recognized by a pool of
positive human sera in an immunoblot. One hundred T. gondii-positive and 98 negative human sera were tested in two
separate immunoglobulin G (IgG)-direct enzyme-linked immunosorbent
assays (ELISAs) using either GST-GRA1 or GST-GRA6-Nt recombinant
protein. Whereas the sensitivity of the GST-GRA1 IgG ELISA was low
(68%), the GST-GRA6-Nt IgG ELISA reached a sensitivity of 96%. The
reactivity to GRA6-Nt was shown to be high even with human sera of low
IgG titers. In addition, comparison of the optical density values for
each serum revealed that GRA1 may complement GRA6-Nt to reach an
overall sensitivity of 98%. Therefore, the GST-GRA6-Nt ELISA could be
used together with another antigen like GRA1 for the development of a
recombinant antigen-based test for serodiagnosis of toxoplasmosis.
1071-412X/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Enzyme-Linked Immunosorbent Assays Using the
Recombinant Dense Granule Antigens GRA6 and GRA1 of Toxoplasma
gondii for Detection of Immunoglobulin G Antibodies


*
Corresponding author. Mailing address: Institut Pasteur
de Lille, 1, rue du Pr. A. Calmette, 59019 Lille, France. Phone:
(33) 3.20.87.11.64. Fax: (33) 3.20.87.11.58. E-mail:
marie-france.cesbron{at}ibl.fr.
Present address: Molecular Parasitology, Université Libre de
Bruxelles, Rhode Saint Genèse, Belgium.
Present address: Hôpital St Antoine, 59000 Lille, France.
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