Quantification of fungal antigens in soil with a monoclonal antibody-based ELISA: analysis and reduction of soil-specific bias

Wilfred Otten, Christopher A. Gilligan, C. R. Thornton

Research output: Contribution to journalArticle

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Abstract

This paper describes methods to improve the use of immunoassays for quantification of soilborne fungal antigens. Calibration curves, prepared by diluting known quantities of an antigen into soil extracts and into soil, were described by a four-parameter logistic curve from which two principal criteria, the lower detection limit and the horizontal locational parameter, were used to summarize the sensitivity and bias of an immuno-assay. We identify two sources of bias, retention of the antigen in soil due to bonding and interference of soluble soil components in plate-trapped—antigen, enzyme-linked immunosorbent assays. Using a monoclonal antibody that recognizes a putative catechol oxidase secreted by hyphae of Rhizoctonia solani, we show that bias due to retention of the antigen in soil is substantially greater than bias due to interference. Three soils were compared: a sand, a clay, and a loam. The degree of retention varied with soil type, with more than a 1,000-fold reduction in sensitivity in the clay soil. Addition of CuSO4 to the extraction solution and optimizing the volume of extractant reduced the bias and increased the sensitivity of the assay for all three soils. Possible mechanisms for the effect due to Cu2+ and the implications for the design and use of calibration curves for assays involving quantification of fungal antigens in soil are discussed.
Original languageEnglish
Pages (from-to)730-736
Number of pages7
JournalPhytopathology
Volume87
Issue number7
DOIs
StatePublished - Jul 1997

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soil
antigens
fungal antigens
assays
monoclonal antibodies
calibration
enzyme-linked immunosorbent assay
copper sulfate
Thanatephorus cucumeris
immunoassays
catechol oxidase
clay soils
hyphae
soil types
detection limit
clay
sand
extracts
methodology

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Otten, Wilfred; Gilligan, Christopher A.; Thornton, C. R. / Quantification of fungal antigens in soil with a monoclonal antibody-based ELISA : analysis and reduction of soil-specific bias.

In: Phytopathology, Vol. 87, No. 7, 07.1997, p. 730-736.

Research output: Contribution to journalArticle

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abstract = "This paper describes methods to improve the use of immunoassays for quantification of soilborne fungal antigens. Calibration curves, prepared by diluting known quantities of an antigen into soil extracts and into soil, were described by a four-parameter logistic curve from which two principal criteria, the lower detection limit and the horizontal locational parameter, were used to summarize the sensitivity and bias of an immuno-assay. We identify two sources of bias, retention of the antigen in soil due to bonding and interference of soluble soil components in plate-trapped—antigen, enzyme-linked immunosorbent assays. Using a monoclonal antibody that recognizes a putative catechol oxidase secreted by hyphae of Rhizoctonia solani, we show that bias due to retention of the antigen in soil is substantially greater than bias due to interference. Three soils were compared: a sand, a clay, and a loam. The degree of retention varied with soil type, with more than a 1,000-fold reduction in sensitivity in the clay soil. Addition of CuSO4 to the extraction solution and optimizing the volume of extractant reduced the bias and increased the sensitivity of the assay for all three soils. Possible mechanisms for the effect due to Cu2+ and the implications for the design and use of calibration curves for assays involving quantification of fungal antigens in soil are discussed.",
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Quantification of fungal antigens in soil with a monoclonal antibody-based ELISA : analysis and reduction of soil-specific bias. / Otten, Wilfred; Gilligan, Christopher A.; Thornton, C. R.

In: Phytopathology, Vol. 87, No. 7, 07.1997, p. 730-736.

Research output: Contribution to journalArticle

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