Creative Biolabs provides high-quality service in phage display antibody library construction and screening. In order to select an antibody against a predefined epitope or a cell surface antigen (Ag) not available in purified form, we have developed a guided selection strategy. Most importantly, we can use whole living cells as a direct source of target Ag.
Although advanced biochemistry and biotechnological approaches permit the availability of a large variety of proteins in purified and/or recombinant form, such proteins often do not maintain the correct conformation and are easily disrupted by biochemical manipulation. Thus, to retain the physiological status of the protein as much as possible, the use of whole living cells as a direct source of target Ag is desirable.Selection of Abs against unpuriﬁed cell surface markers by panning on whole cells is also desirable.However, panning on whole cells has been proven difficult because of the enormous number of different Ags and the low abundance of them on the cell surface.Creative Biolabs has developed this guided selection strategy to effectively solve this problem by using one of the variable chains of an available mouse mAb directed against the target Ag to drive the selection of a human Ab of corresponding specificity. This strategy also provides a great idea for isolating human mAbs against Ags present on human tumor cells.The principle of guided selection is as follows (Fig. 1).
Fig. 1 The principle of guided selection (Jespers et al.1994).
In this strategy, the murine heavy chain encoding phagemid will be used to infect the bacteria bearing the plasmid with recombinant phages fused with the human light chains to produce a murine-human hybrid Fab Library.The hybrid Fab library will be screened against the soluble antigen or on cell monolayers, followed by ELISA selection to obtain the human heavy chains. The fully human Fab library will be constructed with the obtained human heavy chains and then used for library screening.
Creative Biolabs’ scientists have extensive experience in phage display library screening based on guided selection strategy. The combination of shufﬂing of variable region genes and selection on cells provides a powerful tool for isolating human mAbs with the potential clinical application. Using this strategy, we can effectively isolate human mAb against a cell-associated Ag not available in puriﬁed form.
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