Validation Parameters for Quantitating Specific Proteins Using ELISA or LC-MS/MS: Survey Results

TLDR: The need remains for a harmonized set of protocols for protein quantitation in testing of GMOs, particularly for LC-MS/MS, and current practices for assay linearity, accuracy, and precision are surveyed.

Abstract: Genetically modified organisms (GMOs) express one or more exogenous genes inserted through genetic engineering resulting in the production of novel protein(s). Agencies responsible for deregulating GMOs require that levels of the newly expressed protein(s) be characterized. Ideally, the quantitation methods used will be validated according to Good Laboratory Practices (GLPs) that are accepted by these global regulatory agencies. Targeted protein quantitation may be performed using enzyme-linked immunosorbent assays (ELISAs) with commercial kits or specially produced and validated antibodies. Proteins may also be quantitated by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Although some scientific guidance exists for validation of ELISA, the need remains for a harmonized set of protocols for protein quantitation in testing of GMOs, particularly for LC-MS/MS. We surveyed various industry experts to determine current practices for assay linearity, accuracy, and precision; assay specificity; detection limits; and methods to assess analyte stability for both ELISA and LC-MS/MS. We compared the survey results with assay criteria suggested in the literature and governmental guidance documents.