【正文】 cing novel phage particles that have a variety of potential uses. Foreign proteins can usually be displayed on more than one phage coat protein and in varying amounts. Generally, the smaller the foreign protein or peptide the more copies can be displayed, although this also depends on the phage used, the coat protein and the antigen displayed. phage display Examples of some methods that have been used to fuse foreign proteins/peptides to the surface of bacteriophage. Antibody Phage Display V H V L C L C H1 C H2 C H3 Hinge (Fab’)2 Fab Fc Antibody IgG structure V H V L C L C H1 C H2 C H3 Antibody IgG structure V H V L C L C H1 C H2 C H3 Fv Fv V H V L scFv V H V L Single Chain Fragment variable 非展示系統(tǒng)（ Screening) 展示系統(tǒng) (Panning) The applied use of bacteriophages ?phage therapy (use as antibacterial agents) ?phage display ?phagedelivered vaccine Phages have been used as potential vaccine delivery vehicles in two different ways: by directly vaccinating with phages carrying vaccine antigens on their surface or by using the phage particle to deliver a DNA vaccine expression cassette that has been incorporated into the phage genome. Phage vaccination the basic procedure and principles behind bacteriophage DNA vaccination A variety of delivery routes, including intramuscular, intradermal and orally have been successfully used to deliver phage DNA vaccines. Example of typical immune responses seen after immunisation with a phage DNA vaccine Averaged immune responses in 4 rabbits after three phage vaccinations. After three vaccinations with λHBsAg, average antibody responses were greater than those produced by one vaccination with protein. Stability of λ gt11 phage after storage for 24 h in SM buffer at different pH values, stored at ambient temperature. The applied use of bacteriophages ?phage therapy (use as antibacterial agents) ?phage display ?phagedelivered vaccine ?delivery vehicles for gene therapy Phages for targeted genedelivery Phages have also been proposed as potential therapeutic gene delivery vectors . The phage coat protects the DNA from degradation after injection, and the ability to display foreign molecules on the phage coat also enables targeting of specific cell types, a prerequisite for effective gene therapy. The applied use of bacteriophages ?phage therapy (use as antibacterial agents) ?phage display ?phagedelivered vaccine ?delivery vehicles for gene therapy ? Phages as vectors in geic engineering and biotechnology designs Bacteriophage vector Two examples: 1. λ phage ? λ replacement vector 2. M13 phage ? M13 phage vector ? Cloning in M13 ? Hybrid plasmidM13 vectors cos cos Long (left) arm short (right) arm Exogenous DNA (~2023 kb) λ phage vector in cloning cos cos Long (left) arm short (right) arm Exogenous DNA (~2023 kb) The applied use of bacteriophages ?phage therapy (use as antibacterial agents) ?delivery vehicles for gene therapy ?phage display ?phagedelivered vaccine ?Phages as vectors in geic engineering and biotechnology designs ?Typing of bacteria Phage typing 噬菌體與宿主菌的關(guān)系具有高度特異性，即一種噬菌體只能裂解一種和它相應(yīng)的細(xì)菌，故可用于未知細(xì)菌的鑒定和分型。例如用傷寒沙門菌Vi噬菌體可將有 Vi抗原的傷寒沙門菌分為 96個(gè)噬菌體型。這對流行病學(xué)調(diào)查、追查傳染源等具有重要意義。 Phage typing is based on specific bacteriophage lysing bacteria. The end