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New approaches with different types of circulating cathodic antigen for the diagnosis of patients with low Schistosoma mansoni load.

Grenfell R, Harn DA, Tundup S, Da'dara A, Siqueira L, Coelho PM - PLoS Negl Trop Dis (2013)

Bottom Line: In our previous investigations, the use of crude antigens led to false-positive results.Recently, focus has been given to highly purified Schistosoma mansoni antigens, especially to circulating antigens.Interestingly, the "crude antigen" worked as a good marker for control of cure after praziquantel treatment.

View Article: PubMed Central - PubMed

Affiliation: Schistosomiasis Laboratory, Rene Rachou Research Center, Oswaldo Cruz Foundation (Fiocruz), Belo Horizonte, Minas Gerais, Brazil.

ABSTRACT

Background: Schistosomiasis mansoni is a debilitating and sometimes fatal disease. Accurate diagnosis plays a key role in patient management and infection control. However, currently available parasitological methods are laborious and lack sensitivity. The selection of target antigen candidates has turned out to be a promising tool for the development of more sensitive diagnostic methods. In our previous investigations, the use of crude antigens led to false-positive results. Recently, focus has been given to highly purified Schistosoma mansoni antigens, especially to circulating antigens.

Method: Thus, our main goal was to test different types of circulating cathodic antigen glycoprotein (CCA), as "crude antigen," the protein chain of recombinant CCA and two individual peptides. These schistosome proteins/peptides were tested in a new diagnostic method employing immunomagnetic separation based on the improvement of antigen-antibody binding.

Principal findings: Use of recombinant CCA as a diagnostic antigen allowed us to develop a diagnostic assay with high sensitivity and specificity with no false-negative results. Interestingly, the "crude antigen" worked as a good marker for control of cure after praziquantel treatment.

Conclusions/significance: Our new diagnostic method was superior to enzyme-linked immunosorbent assay in diagnosing low endemicity patients.

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Related in: MedlinePlus

Individual analysis of 102 serum samples by the IMS protocols.Each OD value is representative for the mean of four absorbance values. Cut-off values are represented by bars. In (a) IMS-crude Ag (cut-off = 0.20); (b) IMS-CCAr (cut-off = 0.06); (c) IMS-CCApep1 (cut-off = 0.16); and (d) IMS-CCApep2 (cut-off = 0.13). Artwork created by Prism 5.0 software.
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pntd-0002054-g004: Individual analysis of 102 serum samples by the IMS protocols.Each OD value is representative for the mean of four absorbance values. Cut-off values are represented by bars. In (a) IMS-crude Ag (cut-off = 0.20); (b) IMS-CCAr (cut-off = 0.06); (c) IMS-CCApep1 (cut-off = 0.16); and (d) IMS-CCApep2 (cut-off = 0.13). Artwork created by Prism 5.0 software.

Mentions: IMS-crude Ag presented a sensitivity of 90% and a specificity of 92% for a cut-off value of 0.197, which showed that the “crude antigen” might be considered a good marker for schistosome infection with five missing positive patients and four missing negative individuals. Moreover, IMS using CCAr showed an excellent result providing a sensitivity of 100% and specificity of 96% for a cut-off of 0.063, where only two negative individuals presented false-positive results. Finally, IMS using CCA peptides showed similar effectiveness with the same sensitivity (80%) and a specificity of 90% and 92%, respectively for cut-off values of 0.164 and 0.133. When analyzing false-positive and false-negative results, we could see that the use of these 20 amino acids peptides decreased the diagnostic effectiveness with 10 false-negative results for both peptides, five for IMS-CCApep1, and four for IMS-CCApep2. The positivity ratios achieved by each IMS method were 91% (93/102), 98% (100/102), 85% (87/102) and 86% (88/102), for IMS-crude Ag, IMS-CCAr, IMS-CCApep1 and IMS-CCApep2, respectively. The positivity ratio achieved by IMS-CCAr was significantly higher than the other three IMS assays (χ2 = 0.74, p<0.05). Figure 4 shows the individual OD for each positive and negative patient as determined by each IMS protocol.


New approaches with different types of circulating cathodic antigen for the diagnosis of patients with low Schistosoma mansoni load.

Grenfell R, Harn DA, Tundup S, Da'dara A, Siqueira L, Coelho PM - PLoS Negl Trop Dis (2013)

Individual analysis of 102 serum samples by the IMS protocols.Each OD value is representative for the mean of four absorbance values. Cut-off values are represented by bars. In (a) IMS-crude Ag (cut-off = 0.20); (b) IMS-CCAr (cut-off = 0.06); (c) IMS-CCApep1 (cut-off = 0.16); and (d) IMS-CCApep2 (cut-off = 0.13). Artwork created by Prism 5.0 software.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585039&req=5

pntd-0002054-g004: Individual analysis of 102 serum samples by the IMS protocols.Each OD value is representative for the mean of four absorbance values. Cut-off values are represented by bars. In (a) IMS-crude Ag (cut-off = 0.20); (b) IMS-CCAr (cut-off = 0.06); (c) IMS-CCApep1 (cut-off = 0.16); and (d) IMS-CCApep2 (cut-off = 0.13). Artwork created by Prism 5.0 software.
Mentions: IMS-crude Ag presented a sensitivity of 90% and a specificity of 92% for a cut-off value of 0.197, which showed that the “crude antigen” might be considered a good marker for schistosome infection with five missing positive patients and four missing negative individuals. Moreover, IMS using CCAr showed an excellent result providing a sensitivity of 100% and specificity of 96% for a cut-off of 0.063, where only two negative individuals presented false-positive results. Finally, IMS using CCA peptides showed similar effectiveness with the same sensitivity (80%) and a specificity of 90% and 92%, respectively for cut-off values of 0.164 and 0.133. When analyzing false-positive and false-negative results, we could see that the use of these 20 amino acids peptides decreased the diagnostic effectiveness with 10 false-negative results for both peptides, five for IMS-CCApep1, and four for IMS-CCApep2. The positivity ratios achieved by each IMS method were 91% (93/102), 98% (100/102), 85% (87/102) and 86% (88/102), for IMS-crude Ag, IMS-CCAr, IMS-CCApep1 and IMS-CCApep2, respectively. The positivity ratio achieved by IMS-CCAr was significantly higher than the other three IMS assays (χ2 = 0.74, p<0.05). Figure 4 shows the individual OD for each positive and negative patient as determined by each IMS protocol.

Bottom Line: In our previous investigations, the use of crude antigens led to false-positive results.Recently, focus has been given to highly purified Schistosoma mansoni antigens, especially to circulating antigens.Interestingly, the "crude antigen" worked as a good marker for control of cure after praziquantel treatment.

View Article: PubMed Central - PubMed

Affiliation: Schistosomiasis Laboratory, Rene Rachou Research Center, Oswaldo Cruz Foundation (Fiocruz), Belo Horizonte, Minas Gerais, Brazil.

ABSTRACT

Background: Schistosomiasis mansoni is a debilitating and sometimes fatal disease. Accurate diagnosis plays a key role in patient management and infection control. However, currently available parasitological methods are laborious and lack sensitivity. The selection of target antigen candidates has turned out to be a promising tool for the development of more sensitive diagnostic methods. In our previous investigations, the use of crude antigens led to false-positive results. Recently, focus has been given to highly purified Schistosoma mansoni antigens, especially to circulating antigens.

Method: Thus, our main goal was to test different types of circulating cathodic antigen glycoprotein (CCA), as "crude antigen," the protein chain of recombinant CCA and two individual peptides. These schistosome proteins/peptides were tested in a new diagnostic method employing immunomagnetic separation based on the improvement of antigen-antibody binding.

Principal findings: Use of recombinant CCA as a diagnostic antigen allowed us to develop a diagnostic assay with high sensitivity and specificity with no false-negative results. Interestingly, the "crude antigen" worked as a good marker for control of cure after praziquantel treatment.

Conclusions/significance: Our new diagnostic method was superior to enzyme-linked immunosorbent assay in diagnosing low endemicity patients.

Show MeSH
Related in: MedlinePlus