Genetically engineering of T7 bacteriophage for detection and treatment of cancers

Abstract

Phage display is a powerful tool to identify peptide ligands that exhibit a high affinity and specificity to a variety of targets, including small molecules, proteins, whole cells and tissues, and even inorganic materials. Facile genetic manipulation of phage provides unique opportunities to construct a peptide platform for opti-mizing molecular recognition, assembly, and functions of biological molecules. Genetically engineering of T7 bacteriophage is useful for diverse application in nanotechnology, biomedicine, and drug discovery. T7 phage has an icosahedral shape with a diameter of about 55 nm, displaying 415 peptides on 10B major coat protein. The size and shape of T7 phages and its multivalency are very desirable for intracellular delivery applications for imaging and cancer therapy. Here, the T7 phage has developed as a functional nanocarrier for diagnostic and therapeutic applica-tion which is genetically programmed to assemble gold nanoparticles (AuNPs) for tumor-targeted imaging and photothermal therapy. To assemble AuNPs on the surface of T7 phage, a Au-binding peptide was dis-played to each 10B capsid protein along with a PC3 cell surface binding peptide in a tandem arrangement. The engineered T7 phage allowed cell targeting and imaging with precisely controlled AuNPs binding and expression of cell target motif through one-step genetic engineering, showing cancer therapeutic effect by photothermal therapy. In addition, T7 phage library system has been constructed for identifying diverse target ligands. Since the success of biopanning depends on the diversity of library, T7 phage display system may increase the possibility of identifying affinity peptides for target molecules due to the decreased sequence bias compared to M13 phage libraries. The generated T7 phage library was verified by biopanning for identifying streptavidin binding peptides. It is expected that the genetically engineering of T7 phages, which in tandem display two different motifs having distinct characteristics, can be a promising and powerful platform for theranostic application. Furthermore, the engineering of T7 phage is promising that it can be extensively used in biomedical field, provided that availability of various formats of phage display and improvement in the library construction.