In order to fully examine the advantages of the Gyros immunoassay platform compared with ELISA, MedImmune carried out a direct comparison between the two methodologies. The initial step in the process was to establish the assay conditions for the Gyrolab xP workstation, including creation of reagents and establishing basic conditions, optimizing conditions for maximum sensitivity, establishing positive and negative controls, and assay qualification.
Whereas, endpoint assays such as ELISA provide a number from which to back calculate a standard curve, the Gyrolab Evaluator software module calculates results from a standard curve, while the Gyrolab Viewer module provides a qualitative visual of binding for each individual column or data point, providing support when selecting the best antibody pair.
Using the Gyrolab platform, assay conditions were established in just one week, and the first assay comparison confirmed a much greater dynamic range than ELISA (Figure 2). Accuracy and precision were assessed and %CV was found to be within acceptable limits across the entire concentration range.
A head-to-head comparison with ELISA using 38 in-process samples was run, and a detailed comparison of the specific HCP assay showed exactly where the significant improvements were achieved with the nanoliter-scale platform.
Whereas just one day of testing, and two hours of analyst time was needed for the Gyrolab process, the ELISA method required eight days, and 50 hours of analyst time.
An advantage was also seen in the increased dynamic range of 4 logs, compared to 2 logs for ELISA, a significant parameter when looking to reduce the number of assay repeats. The sample-prep process was also simplified as all samples could be diluted 1:2, rather than necessitating various dilutions based on each process step as in an ELISA assay.