Use of SAG2A recombinant Toxoplasma gondii surface antigen as a diagnostic marker for human acute toxoplasmosis: analysis of titers and avidity of IgG and IgG1 antibodies

Béla, Samantha Ribeiro; Silva, Deise A. Oliveira; Cunha-Júnior, Jair P.; Pirovani, Carlos Priminho; Chaves-Borges, Flávia Andrade; Carvalho, Fernando R.; Oliveira, Taísa Carrijo de; Mineo, José Roberto

doi:10.1016/j.diagmicrobio.2008.05.017

Cited by 38 publications

(29 citation statements)

References 34 publications

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“…In this context, determination of IgG avidity in sera has 0165-2478/$ -see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.imlet.2011.05.006 been useful in several parasitic diseases, including toxoplasmosis [14,15], hidatidosis [16], schistosomiasis [17], toxocariasis [12] and neurocysticercosis [13].…”

Section: Introductionmentioning

confidence: 99%

IgG avidity in differential serodiagnosis of human strongyloidiasis active infection

et al. 2011

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IgG avidity assays have been developed for several parasitic diseases although there are no researches focused in strongyloidiasis diagnosis. Definitive diagnosis of strongyloidiasis is based on the presence of Strongyloides larvae in stool, but majority of cases involve low and irregular larval output. While limitations of serological assays for strongyloidiasis are well known, characteristics of persons who are misdiagnosed based on negative coproparasitological tests have been little explored. The aim of the present study was to evaluate the use of IgG avidity to detect patients with active strongyloidiasis and to characterize sources of disagreement between serology and coproparasitology. A total of 80 serum samples was analyzed, 40 from patients with Strongyloides larvae in stool (G1) and 40 from individuals with negative coproparasitology, but positive serology (G2). Serum samples were analyzed in an indirect IgG avidity ELISA using urea 6M in serial double dilutions from 1:80 to 1:2560. Avidity index (AI) was calculated to each serum dilution and analyzed as screening AI (serum dilution of 1:160) or mean AI of different serum dilutions that had a positive result. Statistical analyzes were performed by Mann-Whitney's (U) and Fisher's exact tests. At screening dilution, median of AI was 68% in G1 and 88% in G2 (P<0.0001), whereas median of mean AI in G1 was 72% and in G2 94% (P<0.0001), but there was no significant differences between both AI in each patient group. A cut off value established at AI of 75% demonstrated a significant difference between groups, with G1 sera showing AI<75% and G2 sera with AI>75% (P<0.0001). In conclusion, IgG avidity assays may distinguish active infection with Strongyloides stercoralis from suspect or serologically false positive cases.

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Section: Introductionmentioning

confidence: 99%

IgG avidity in differential serodiagnosis of human strongyloidiasis active infection

et al. 2011

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“…A previous study has shown a promising application of ICT based on recombinant T. gondii major surface antigen 2 (TgSAG2) for the detection of antibody to the infection in cats (10). A more recent report has documented limitations of TgSAG2 in the detection of antibody in early and acute stages of infection (12). Therefore, the development of a new ICT with a more sensitive and specific antigen for detecting the infection in animals and humans is required for preventive and control programs for toxoplasmosis.…”

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confidence: 99%

Development of an Immunochromatographic Assay Based on Dense Granule Protein 7 for Serological Detection of Toxoplasma gondii Infection

Terkawi

Kameyama

Rasul

et al. 2013

Clin Vaccine Immunol

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Dense granule antigen proteins derived from Toxoplasma gondii (TgGRAs) are potential antigens for the development of diagnostic tools. TgGRA7 and TgGRA14 were detected in the peritoneal fluid of T. gondii-infected mice, suggesting that TgGRAs may be highly antigenic proteins. Here, TgGRA7 and TgGRA14 were evaluated as candidates for the development of a marker for a rapid diagnostic test. The specificity and sensitivity of purified recombinant proteins of TgGRA7 and TgGRA14 were compared in an indirect enzyme-linked immunosorbent assay (iELISA) using a series of serum samples from T. gondii-experimentally infected mice and using recombinant T. gondii major surface antigen 2 (TgSAG2) as a reference control. The iELISA with TgGRA7 showed the greatest diagnostic accuracy and could detect anti-TgGRA7 antibody in acute and chronic infections. A total of 59 field samples from pigs were also examined by the iELISAs, and the results compared with those of the latex agglutination test (LAT). Among the three recombinant antigens, TgGRA7 had the highest rates of positivity, with significant concordance (88.14) and kappa value (0.76) in comparison with the results using LAT. Furthermore, an immunochromatographic test (ICT) based on recombinant TgGRA7 was developed for rapid detection of antibodies to the infection. The ICT differentiated clearly between sera from T. gondii-infected mice and uninfected or Neospora caninum-infected mice. Pig sera were examined with the ICT, and the results compared favorably with those of LAT and iELISA for TgGRA7, with kappa values of 0.66 and 0.70 to 0.79, respectively. These data suggest that the ICT based on TgGRA7 is a promising diagnostic tool for routine testing in the clinic and mass screening of samples in the field.

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“…In a previous study, the recombinant rhoptry antigen (rROP1) gave low or borderline avidity with 26 of 34 (76%) suspected acute toxoplasmosis serum samples when compared with the VIDAS IgG Toxo avidity assay (bioMérieux, Marcy l'Étoile, France). 38 In another study by Bela et al, 19 the recombinant surface antigen (rSAG2A) gave low or intermediate AIs for 60% of acute-phase serum samples and detected 70% of chronic serum samples based on an AI of >60% in an IgG avidity ELISA. Drapala et al 20 evaluated two different mixtures of recombinant proteins (rROP1 + rSAG2 and rROP1 + rGRA6) in an IgG avidity assay and compared these with the VIDAS IgG Toxo avidity assay.…”

Section: Fundingmentioning

confidence: 99%

“…15 These include surface antigens (SAG), [17][18][19][20] dense granule antigens (GRA), 17,18,20,21 microneme protein (MIC) 18 and rhoptry antigens (ROP). 20,38 Proteins encoded by AG12b and AG18 belong to none of the above-reported groups since a different approach was used in the present study.…”

Section: 37mentioning

confidence: 99%

Identification, production and assessment of twoToxoplasma gondiirecombinant proteins for use in aToxoplasmaIgG avidity assay

Teh

Amerizadeh

Osman

et al. 2016

Pathogens and Global Health

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The IgG avidity assay is an important tool in the management of suspected toxoplasmosis in pregnant women. This study aimed to produce new Toxoplasma gondii recombinant proteins and to assess their usefulness in an IgG avidity assay. Toxoplasma positive and negative serum samples were used, the former were categorized into low (LGA) and high (HGA) IgG avidity samples. Immunoblots were performed on 30 T. gondii cDNA clones to determine the reactivity and IgG avidity to the expressed proteins. Two of the clones were found to have diagnostic potential and were analyzed further; AG12b encoded T. gondii apical complex lysine methyltransferase (AKMT) protein and AG18 encoded T. gondii forkhead-associated (FHA) domain-containing protein. The Histagged recombinant proteins, rAG12b and rAG18, were expressed and tested with LGA and HGA samples using an IgG avidity western blot and ELISA. With the IgG avidity western blot, rAG12b identified 86.4% of LGA and 90.9% of HGA samples, whereas rAG18 identified 81.8% of both LGA and HGA samples. With the IgG avidity ELISA, rAG12b identified 86.4% of both LGA and HGA samples, whereas rAG18 identified 77.3% of LGA and 86.4% of HGA serum samples. This study showed that the recombinant antigens were able to differentiate low avidity and high avidity serum samples, suggesting that they are potential candidates for use in the Toxoplasma IgG avidity assay.

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Use of SAG2A recombinant Toxoplasma gondii surface antigen as a diagnostic marker for human acute toxoplasmosis: analysis of titers and avidity of IgG and IgG1 antibodies

Cited by 38 publications

References 34 publications

IgG avidity in differential serodiagnosis of human strongyloidiasis active infection

IgG avidity in differential serodiagnosis of human strongyloidiasis active infection

Development of an Immunochromatographic Assay Based on Dense Granule Protein 7 for Serological Detection of Toxoplasma gondii Infection

Identification, production and assessment of twoToxoplasma gondiirecombinant proteins for use in aToxoplasmaIgG avidity assay

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