Use of LPS Extracts to Validate Phage Oligopeptide That Binds All <i>Salmonella enterica</i> Serovars

Abstract

Phage Display technology provides a mechanism for us to make bio-recognition elements on biosensors for detection of Salmonella enterica serovars. In the procedure, the filamentous M13 bacteriophage is used for acquiring peptides that have a high affinity for the target recognition. Our approach in this study was to develop peptide structures in the pIII region of this thread-shaped virus. A phage pIII library was used to perform biopanning for the phage clones to bind the target Salmonella serovars. The clones were bound, washed, eluted and amplified four times. Then, the phage peptides were sequenced tested for specificity using ELISA procedures . In this project to make a biosensor for all relevant Salmonella enterica serovars, we used common LPS salmonellae antigens as targets in the biopanning procedure. This enabled us to have a phage probe specific for all serovars of Salmonella enterica excluding the typhoid organisms. The final phage was then immobilized onto an electromagnetic platform to complete the biosensor, which gives us the real-time ability to measure resonance changes that indicate mass loading. The mass loading is an indication of binding to the target cells. Our current data with an ELISA procedure show the phage probe’s high affinity for salmonellae, very low cross-reactivity with Escherichia coli , Shigella , and no cross-reactivity to Staphylococcus aureus and Listeria monocytogenes. The biosensor with the phage showed that the capture ability for Salmonella serovars is thirty times higher than the control sensor. This biosensor is a candidate for detection of Salmonella in food and other settings.