gondiiIgG test results. == Materials and methods Destruxin B == == Sample collection == The laboratory of Parasitology-Mycology at the University Hospital of Nice, France (Nice laboratory) is a member of the National Reference Centre for toxoplasmosis (Reims, France). due to reactivity against GRA8 for the majority of the sera and GRA7 to a lesser extent. The hypothesis of past contact with parasites genetically CT96 close toT. gondiisuch asHammondia hammondiorNeospora caninumseems promising and should be assessed further. Keywords:Toxoplasma gondii, IgG, False-positive, Serology, Architect, Toxoplasmosis == Abstract == Contexte: La primo-infection Toxoplasma gondiichez la femme enceinte peut avoir de graves consquences pour le ftus. Un rsultat IgG faussement positif pendant la grossesse peut mener un diagnostic erron dinfection ancienne et stopper les mesures prventives. Nous avons collect 189 srums prsentant un rsultat Destruxin B ArchitectToxo IgG (Abbott Laboratories) positif ainsi quun rsultat IgG ngatif par au moins deux autres tests srologiques, dans le but de trouver une explication aux rsultats IgG suspects faux positifs. Nous avons utilis limmunoblotrecomLine Toxoplasma IgG(Mikrogen Diagnostik) pour chercher certaines ractivits antigniques spcifiques des srums et limmunoblot LDBio Toxo II IgG(LDBio Diagnostics) comme test de confirmation.Rsultats: Les bandes GRA8 et/ou GRA7 taient positives pour 148 (78,3 %) chantillons. GRA8 tait la bande la plus frquente, apparaissant dans 133 (70,4 %) profils alors que GRA7 tait prsente pour 49 (25,9 %) chantillons. Sur les 81 chantillons tests en LDBio, 23 (28,4 %) se sont rvls positifs. Sur les 58 (71,6 %) tests LDBiongatifs (rels faux positifs IgG Architect), 23 (39,6 %) chantillons nont montr ni bande GRA8 ni bande p30 enrecomLineet leur fausse positivit reste donc inexplique puisque Abbott utilise ces deux antignes recombinants dans son test.Conclusions: La fausse positivit IgG ArchitectpourT. gondiisemble tre due une ractivit envers la protine GRA8 pour la majorit des srums et envers GRA7 dans une moindre mesure. Lhypothse dun contact pass avec des parasites gntiquement proches deT. gondiicommeHammondia hammondiouNeospora caninumsemble prometteuse et devrait tre approfondie. == Introduction == Toxoplasmosis is a parasitic disease due toToxoplasma gondii, an obligate intracellular protozoan with a worldwide distribution. The life cycle of the parasite involves sexual reproduction in definitive hosts from the Felidae family, and a broad range of intermediate hosts including mammals and birds [18,26,30,41,46,47]. Human infection occurs mainly by ingestion Destruxin B ofT. gondiioocysts present on raw and unwashed vegetables, and through consumption of raw or undercooked meat containing cysts of the parasite [6,22,48]. AlthoughT. gondiiprimary infection is usually asymptomatic in the healthy population, it can be life-threatening for others, like immunocompromised patients. In these hosts, acute infection or reactivation of a past infection can lead to severe and possibly lethal diseases (cerebral, pulmonary, or disseminated toxoplasmosis) [25,27,40]. In particular, primary infection in pregnant women and reactivation in immunocompromised pregnant women can be the cause of congenital toxoplasmosis with the risk of serious outcomes for the foetus, mainly retinitis pigmentosa, hydrocephaly, or even deathin utero[4,24,44]. Destruxin B In some countries, the health authorities have set up a prenatal screening program forT. gondii[33,34,43]. In France, pregnant women are tested in the early weeks of pregnancy for the presence of specific IgG and IgM againstT. gondii. The presence ofT. gondiiIgG at a stable level without IgM is in favour of a past infection. These women are considered to be immunised againstT. gondiiand follow-up is no longer performed. In seronegative pregnant women, monthly screening will be performed to allow early diagnosis and treatment of an acute infection in order to prevent transplacental transmission of the parasite to the foetus [43]. This highlights the importance of an accurate and reliable test for the detection of specific IgG, given that a false-positive result can lead to a misdiagnosis of past infection, and to stopping surveillance and preventive measures in a pregnant woman. Currently, many serological tests are.