A novel bead-based assay to detect specific antibody responses against Toxoplasma gondii and Trichinella spiralis simultaneously in sera of experimentally infected swine

A novel, bead-based flow cytometric assay was developed for simultaneous determination of antibody responses against Toxoplasma gondii and Trichinella spiralis in pig serum. This high throughput screening assay could be an alternative for well known indirect tests like ELISA. One of the advantages of a bead-based assay over ELISA is the possibility to determine multiple specific antibody responses per single sample run facilitated by a series of antigens coupled to identifiable bead-levels. Furthermore, inclusion of a non-coupled bead-level in the same run facilitates the determination of, and correction for non-specific binding. The performance of this bead-based assay was compared to one T. spiralis and three T. gondii ELISAs. For this

This new bead-based test, which detects T. gondii and T. spiralis antibodies simultaneously within each sample, can replace two indirect tests for the determination of respective antibodies separately, while performing equally well or better.

Results indicated that the areas under the curve of the bead-based assay were 0.911 and 0.885 for T. gondii and T. spiralis, respectively, while that of the T. gondii ELISAs ranged between 0.837 and 0.930 and the T. spiralis ELISA was 0.879. Bead-based T. gondii assay had a sensitivity of 86% and specificity of 96%, while the ELISAs ranged between 64-84% and 93-99%, respectively. The bead-based T. spiralis assay had a sensitivity of 68% and specificity of 100% while the ELISA scored 72% and 95%, respectively. Marginal homogeneity was found between the T. gondii bead-based test and one of the T. gondii ELISAs. Moreover, in this test combination and between T. spiralis bead-based assay and respective ELISA, an excellent inter-rater agreement was found. When results of samples before expected seroconversion were removed from evaluation, notably higher test specifications were found. Conclusions: This new bead-based test, which detects T. gondii and T. spiralis antibodies simultaneously within each sample, can replace two indirect tests for the determination of respective antibodies separately, while performing equally well or better.