Conway, David J.; Atkins, Neil S.; Lillywhite, Jane E.; Bailey, J. W.; Robinson, Ralph, D.; Lindo, John F.; Bundy, Donald A. P.; Bianco, Albert E.
Author Affiliation, Ana.
Life Sciences (Botany and Zoology)
Immunodiagnosis of Strongyloides stercoralis infection: A method for increasing the specificity of the indirect ELISA.
Transactions of the Royal Society of Tropical Medicine and Hygiene
Date of Publication
Indirect enzyme-linked immunosorbent assay (ELISA) allows sensitive detection of serum immunoglobulin (Ig) G against a soluble extract of Strongyloides stercoralis infective larvae. In this study, 40/40 (100%) human strongyloidiasis sera had high levels of anti-S. stercoralis IgG, but 30/40 (75%) filariasis sera, and 12/40 (30%) necatoriasis sera also had higher levels than control sera from UK residents. In attempts to increase the assay specificity by absorption of cross-reactive IgG, the effectiveness of pre-incubation of sera with extracts of different parasitic nematodes was investigated. One hour of incubation with 20 µg/ml aqueous extract of Onchocerca gutturosa absorbed cross-reactive IgG in most filariasis and necatoriasis sera, reducing the proportion with IgG levels above the positivity threshold by more than one-half. Preliminary results suggest that absorption with extracts of other filarial nematodes is equally effective, and that some of the cross-reactive IgG is directed against phosphorylcholine. Cross-reactive IgG in most necatoriasis sera was effectively absorbed with 20 µg/ml extract of Necator americanus. Cross-reactive IgG was not effectively adsorbed with an extract of Ascaris lumbricoides. Absorption of cross-reactive IgG is an effective means of increasing the specificity of the indirect ELISA, for use in the immunodiagnosis and immuno-epidemiology of S. stercoralis infection....