ABSTRACT
This chapter is devoted to the RNA phage non-VLP applications and begins with the exciting story how the RNA phages paved the way for the antisense-based gene therapy by the generation of the mRNA-interfering complementary RNA immune system. the major attention is focused on the tethering and imaging applications, which are based on the ability of the RNA phage coat to recognize the corresponding operator stem-loop. This feature led to the development of the pioneering tethering methodology that allowed identification, isolation, and purification of the desired RNA-protein complexes of various origin, when mRNAs were tagged with the operator sequence and were then highly specifically recognized by the RNA phage coat fused to different functional probes. The tethering technique allowed affinity purification of such desired RNA-protein complexes. When the RNA phage coat was fused to fluorescent probes, the revolutionary imaging technology arose. This technique enabled imaging of the processing, export, localization, translation, and degradation of operator-tagged mRNAs in live cells and live animals. The tethering/imaging methodology exploited mostly the coat protein-operator composition from the phages MS2 and PP7, including simultaneous MS2 and PP7 two-color labeling. The tethering technique is applied now to the further development of the highly productive CRISPR-Cas9 technology.
