Rapid and Sensitive Detection of the Interaction of Human Papillomavirus Virus-Like Particles with Yeast Whole Cell RNA Using Biolayer Interferometry

RNA is a potential contaminant encountered in the production of recombinant yeast products such as proteins and virus-like particles (VLPs) and can be a particular concern when RNA associates with the product of interest. In this study a method to monitor and quantify the interaction of RNA with yeast-expressed human papillomavirus (HPV) VLPs using biolayer interferometry (BLI) is developed. Both biosensors with immobilized VLPs as well as biosensors with immobilized RNA are tested. Two types of recombinantly expressed HPV VLPs are used, Type 18 and Type 11. The data show that yeast whole cell RNA associates with Type 18 but not with Type 11 (maximum binding signal of 0.20 +/- 0.02 nm on immobilized VLP probes for Type 18 vs. 0.03 +/- 0.01 nm for Type 11). Additionally, the results show that a higher ionic strength weakens the affinity by both decreasing the association rate and increasing the dissociation rate, resulting in the dissociation constant increasing from 0.48 x 10(-9) to 2.1 x 10(-9) M, with phosphate ions having a greater effect on the reduction of association compared to chloride ions.