Content area
Full Text
1.
Introduction
In 1985, George Smith was the first to employ a phage display system (1). He expressed, by inserting exogenous DNA into phage gene III, various foreign peptides on the capsid of the filamentous bacteriophage f1. Peptides and proteins of interest were obtained from a library of random insert genes in a phage display vector by ≥1 rounds of selection, thus facilitating the analysis of associations between genotype and phenotype (1). The common principle of all phage display systems is that exogenous peptide-coding sequences are inserted into a phage capsid protein gene, which allows the expression of foreign proteins or peptides fused to the capsid protein of the phage particle (2–4). Exogenous peptides or proteins of interest are subsequently selected from a large library of phage particles by techniques such as affinity elutriation (5,6). Phage display systems are an efficient and rapid tool in the investigation of protein sequences and have also been particularly important in proteomics.
Numerous bacteriophage species have been employed in phage display systems, including f1, fd, T4, M13 and T7, of which the latter two examples are considered to be efficient display vectors. The most commonly employed phage display system is M13 as it contains nonessential regions that allow exogenous gene insertions. Exogenous peptides, retaining their normal function, are expressed in the M13 coat proteins (7,8) and the phage retains the ability to accumulate at high concentrations in hosts. Although a few of peptide repertoires successfully expressed in a cDNA library of filamentous phage (9,10), M13 phage display is associated with limitations in the construction of the cDNA library. The formation of fusion proteins consisting of the coat proteins and the expressed peptides, and the secretion of phage into the periplasm, are also potential problems in M13 phage display. However, these problems associated with M13 phage display may be avoided by using the T7 phage display system.
Rapid development in the research of pathogenic microorganisms and proteomics has been achieved through use of the T7 phage display system. Various virus vaccines, such as those against influenza virus and hepatitis B virus, require frequent development, and the methods of diagnosis and treatment of infectious diseases also require continuous improvement. By using a T7 phage display library, one study identified the mechanism...