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. 2022:29:52.
doi: 10.1051/parasite/2022050. Epub 2022 Nov 9.

Serological diagnosis of toxoplasmosis: evaluation of the commercial test recomLine Toxoplasma IgG immunoblot (Mikrogen) based on recombinant antigens

Vincent Jean-Pierre  1 , Julien Miozzo  1 , Hélène Fricker-Hidalgo  1 , Cécile Garnaud  2 , Marie Gladys Robert  1 , Hervé Pelloux  1 , Marie-Pierre Brenier-Pinchart  1
Affiliations

Serological diagnosis of toxoplasmosis: evaluation of the commercial test recomLine Toxoplasma IgG immunoblot (Mikrogen) based on recombinant antigens

Vincent Jean-Pierre et al. Parasite. 2022.

Abstract
in English, French

Background: IgG detection to determine immune status to Toxoplasma gondii infection and seroconversion mainly relies on ELISA techniques and, if necessary, on a confirmatory test, Western blot. This study evaluated the performance of the recomLine Toxoplasma IgG immunoblot (IB-recomLine) (Mikrogen) as a confirmatory test on a large number of sera. A total of 171 sera were selected (113 patients) and had previously been analyzed by two ELISA tests, ARCHITECT (Abbott) and VIDAS (bioMérieux) ± LDBIO-Toxo II IgG Western blot (WB-LDBIO) (LDBio). The sera were classified into three groups: group 1 included 50 sera without difficulty in interpreting the IgG results (patients with documented past infection or uninfected); group 2 included 47 sera with difficulty in interpreting the ELISA results; and group 3 included 74 sequential sera from 25 pregnant women with seroconversion.

Results: In group 1, overall IgG agreements were 94% and 90% with ARCHITECT and VIDAS, respectively. In group 2, low agreement was observed between IB-recomLine and WB-LDBIO, with eight false-positive and 13 false-negative results. In group 3, 4/13 seroconversions were detected earlier with IB-recomLine compared to other tests.

Conclusions: IB-recomLine allowed for earlier diagnosis of toxoplasmic seroconversion compared to both ELISA tests and WB-LDBIO but led to insufficient performance to confirm the immune status when ELISA results were discordant or equivocal.

Title: Diagnostic sérologique de la toxoplasmose : évaluation du test commercial recomLine Toxoplasma IgG immunoblot (Mikrogen) basé sur des antigènes recombinants.

Abstract: Contexte : La détection des IgG pour déterminer le statut immunitaire vis-à-vis de l’infection à Toxoplasma gondii et de la séroconversion repose principalement sur les techniques ELISA et, si nécessaire, sur un test de confirmation, le Western blot. Cette étude a évalué les performances de l’immunoblot recomLine Toxoplasma IgG (IB-recomLine) (Mikrogen) en tant que test de confirmation sur un grand nombre de sérums. Un total de 171 sérums ont été sélectionnés (113 patients) et ont été préalablement analysés par deux tests ELISA, ARCHITECT (Abbott) et VIDAS (bioMérieux) ± LDBIO-Toxo II IgG Western blot (WB-LDBIO) (LDBio). Les sérums ont été classés en trois groupes : le groupe 1 comprenait 50 sérums sans difficulté d’interprétation des résultats IgG (patients avec antécédents d’infection documentée ou non infectés); le groupe 2 comprenait 47 sérums avec des difficultés d’interprétation des résultats ELISA; le groupe 3 comprenait 74 sérums séquentiels de 25 femmes enceintes séroconverties. Résultats : Dans le groupe 1, les concordances globales des IgG étaient respectivement de 94 % et 90 % avec ARCHITECT et VIDAS. Dans le groupe 2, une faible concordance a été observée entre IB-recomLine et WB-LDBIO, avec huit faux positifs et 13 faux négatifs. Dans le groupe 3, 4/13 séroconversions ont été détectées plus tôt avec IB-recomLine par rapport aux autres tests. Conclusions : IB-recomLine a permis un diagnostic plus précoce de la séroconversion toxoplasmique par rapport aux tests ELISA et WB-LDBIO, mais a conduit à des performances insuffisantes pour confirmer le statut immunitaire lorsque les résultats ELISA étaient discordants ou équivoques.

Keywords: Immunoblot; Seroconversion; Serology; Toxoplasmosis; Western blot.

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Figures

Figure 1
Figure 1
Classification of sera into three groups and IgG detection techniques performed on each category of sera.
Figure 2
Figure 2
Example of a false-negative result with IB-recomLine compared to WB-LDBIO. The number of points reported by positive bands with IB-recomLine is specified in parentheses behind each antigen.
Figure 3
Figure 3
Example of toxoplasmic seroconversion with IgG detected earlier with IB-recomLine compared to WB-LDBIO. In this sequence of three sera belonging to the same patient: serum 1 corresponded to “day 0”, serum 2 to “day 9”, and serum 3 to “day 11”. The number of points reported by positive bands with IB-recomLine is specified in parentheses. Neg = negative result; pos = positive result.
See this image and copyright information in PMC

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