Strongyloides-Specific IgE Phage cDNA Clones and Development of a Novel ELISA for Strongyloidiasis

Abstract

Strongyloidiasis, caused mainly by the nematode Strongyloides stercoralis, is prevalent worldwide and potentially fatal in immunosuppressed patients. We report on a new IgE biomarker to diagnose Strongyloides infection. Sera from two groups infected with Strongyloides served as positive samples: Group 1A, in which infection was confirmed by stool-microscopy and/or stool-polymerase chain reaction (PCR) and was seropositive by an IgG-enzyme linked immunosorbent assay (ELISA) and an IgG4 rapid test, and Group 1B in which infection was confirmed by stool-PCR but was seronegative. Negative samples (controls) comprised infections with other parasites (Group II) and healthy donors (Group III). Immunoscreenings of an S. stercoralis complementary DNA (cDNA) library were performed, and the cDNA clone with the highest diagnostic potential (clone A133) was selected for recombinant protein production and then evaluated using IgE Western blot and ELISA. The Western blot showed that the recombinant protein (rA133) was 100% reactive with Group IA (n = 10) and Group IB (n = 5), and 96% non-reactive with Groups II and III (n = 25). Subsequently, the IgE-ELISA was developed and showed 100% diagnostic sensitivity in Groups IA (n = 32) and IB (n = 11); and 99.3% specificity in Groups II and III (n = 144). In conclusion, this study has identified rA133 as a novel recombinant protein with potential diagnostic value, and that the IgE-ELISA incorporating this protein may be useful for patient diagnosis and epidemiological studies.

Design and expression of a chimeric recombinant antigen (SsIR-Ss1a) for the serodiagnosis of human strongyloidiasis: Evaluation of performance, sensitivity, and specificity

“…Sears et al reported high sensitivities and specificities (up to 99% and 100%, respectively) using a prototype recombinant Ss-NIE/Ss-IR-based ELISA [ 37 ]. Ahmad et al introduced a novel recombinant protein, rA133, for an IgE-based ELISA, achieving a sensitivity of 100% and specificity of 99.3% [ 38 ]. Additionally, De Souza et al and Rascoe et al utilized recombinant antigens in various assay formats, consistently showing high sensitivities and specificities [ 39 , 40 ].…”

The Relationship of Parasite Allergens to Allergic Diseases

“…Antistrongylastacin IgE was present in 93% of infected subjects but not in healthy or Wuchereria bancrofti-infected individuals [39]. Finally, the S. stercoralis IgE-binding recombinant protein rA133 is recognized by IgE from 100% of infected patients but not from healthy controls or individuals infected with other parasites [40].…”

Are humanized IgE reporter systems potential game changers in serological diagnosis of human parasitic infection?

“…We speculate here that used in combination with IgE reporter systems, sensitivity could be strongly enhanced. A recent IgE-based ELISA for diagnosis of Strongyloides stercoralis infection in humans based on a recombinant allergen (rA133) demonstrated very high specificity (99.3%) and sensitivity (100%), although tested serum numbers were relatively small (Ahmad et al 2021).…”