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VECTORS

Vectors

Vectors are invaluable tools for introducing foreign genetic material into cells for the propagation of the DNA molecules themselves or for production of phage virions. Genetically engineered vectors share common features such as an origin of replication, convenient cloning sites, and a selectable marker. Years prior to pioneering phage display technology. Dr. George P. Smith developed bacteriophage cloning vectors. Since then, two different types of vectors are utilized for phage display of peptides and antibodies, namely the bacteriophage vectors and phagemids.

Cell Origins carries bacteriophag e and phagemid vectors based on the original vectors created by Dr. George Smith. Many of our vectors include built-in tagging options to streamline your phage display selections and screening procedures.

Bacteriophage Vectors

Filamentous bacteriophage vectors carry a modified version of the complete phage genome. Apart from the wild-type genes, these vectors typically contain an antibiotic selection gene and a hybrid gene encoding a recombinant fusion of the foreign peptide or antibody with the coat protein. By expressing both the wild type and hybrid genes, the display of the foreign polypeptide is intentionally limited, which can be advantageous as it encourages the selection of high-affinity peptide sequences. While bacteriophage vectors are generally unsuitable for displaying antibodies or antibody fragments due to their larger size that hampers E. coli infection and complicates transformation, they have been successfully utilized in peptide phage display. Notably, bacteriophage vectors possess the required genes for phage particle replication in their own genome, eliminating the need for helper phages during propagation.

Product Name	Cat. Number
Fd-tet	COV0001
F3TR1	COV0002
fUSE5	COV0003
f88-4	COV0004

Phagemid Vectors

Phagemids are plasmid-based vectors that possess both phage and bacterial origins of replication, along with an antibiotic selection gene. Typically, a phagemid vector encodes a coat protein (either pIII or pVIII) fused with a foreign DNA sequence. This fusion enables the display of full-length antibodies, antibody fragments, nanobodies, or peptides. Phagemids can replicate in E. coli without the need for helper phages. However, for phage clone production, helper phages are vital as they contain essential genes required for phage particle assembly and release. A significant advantage of phagemids is their compact vector DNA, facilitating easy transformation in E. coli . The efficiency of E. coli transformation directly influences the diversity of the phage display library, making it a crucial factor when selecting a suitable vector for phage display. Furthermore, the small size of phagemid vectors enables convenient manipulation using recombinant DNA technology. Unlike bacteriophage vectors, phagemids excel at displaying large proteins such as full-length antibodies and antibody fragments, as their propagation in E. coli relies on a separate helper phage.