WES: An Alternative to ELISA

By Glenn Petrie, Ph.D.
Senior Scientific Advisor
ABC Laboratories
www.abclabs.com

Analysis of protein expression in biological tissues presents numerous challenges. The protein of interest is present in an extremely complex matrix, containing hundreds if not thousands of other proteins, and is typically at very low concentrations. The analysis must be sensitive, precise and most importantly specific. Several methods including Western blot and LC/MS/MS have been utilized, but ELISA is currently the method of choice. The method is specific and sensitive, particularly with the use of electrochemiluminescence detection. However, regardless of the particular format, ELISAs are complicated, labor intensive and time consuming. Coating, blocking, binding and multiple washings present many opportunities for variability resulting in typical CVs of 15-25%.

An alternative to ELISA is an automated Western analysis. ABC Labs has recently acquired the Protein Simple® Wes™ system. This instrument utilizes an automated, quantitative capillary electrophoresis-based Western technique using an antibody against the target protein. Standards, samples and reagents are prepared and loaded into the Wes plate. The plate and a capillary cartridge are loaded into the instrument and the run is started. All subsequent steps are automated. Protein concentrations are extrapolated from a standard curve prepared using the reference standard and a linear fit is used for regression.

Experience in our lab has shown the instrument to be accurate, precise and easy to use. Standard curves were linear with an R² of 0.997 and an LOD of < 1.0 pg/µl.  Analyses of a protein extracted from biological tissue have yielded excellent results: interday/interanalyst CVs averaged <15% with accuracy ranging from 100-104%. Based on our experiences, ABC Laboratories is actively pursuing the replacement of some ELISA methods by those utilizing the WES system.

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