ABI and Olink to push protein detection sensitivity

PLA is a sensitive assay that can detect proteins, their modifications and their interactions in both purified samples and within cells and tissues to give researchers a greater understanding of how gene and protein expression data are linked as well as providing unique insights into cell signalling processes. The exclusive license and collaboration agreement between the two firms will enable researchers to conduct protein expression studies using regents and instruments used for genotyping and gene expression analysis. As part of the co-development agreement, Applied Biosystems will develop products for in vitro​ applications using its quantitative TaqMan reagents. Traditional methods of protein analysis, such as Western blots, require relatively large amounts of sample and to measure relative changes in protein expression levels. The new technique uses two oligonucleotide-labelled antibodies that bind to different epitopes of a target protein before PCR (polymerase chain reaction) techniques join the two ends of the oligonucleotide strand providing a template for amplification and fluorescent probe detection. "In essence it's a dual-recognition immunoassay that uses an oligonucleotide reporter system that can be amplified and detected using PCR,"​ said Björn Ekström, CEO of Olink in an interview. "The great advantage with using DNA as a reporter system is that even one molecule can be amplified and detected quite easily, and this pushes the sensitivity of an immunoassay to where you can see single molecule events." ​ The PLA technology can also be used to detect proteins in fixed cells and tissue sections, enabling immunohistochemistry applications by using fluorescence microscopes, enabling the localisation of biological markers in different parts of tissues, cell types and sub-cellular structures. This technique can not only be used to study gene expression levels, but also protein-protein interactions. "The PLA can also be used to detect the protein-protein interactions that occur during cell-signalling interactions, and by having antibodies that recognise the two different proteins you can quantify the occurrence of the binding events,"​ said Ekström. He continued by stressing that the system can be very easily multiplexed and that the company would soon be publishing results showing how the technology could be used to detect up to eight different proteins at once - something that is particularly important when using valuable biological samples stored in biobanks to look for biomarkers.