Antibody Overview | Phage Display Overview | Utility of Selected Antibodies | Glossary

Based on their unique properties, antibodies have been widely used as powerful tools in diagnostic and therapeutic applications as well as in basic biomedical research. The availability of sFv antibody phage display libraries has greatly expanded our ability to isolate antibodies against unlimited targets. As the size and genetic complexity of human sFv phage display libraries have increased in size, a greater number of high affinity antibodies that are directed against more epitopes on the target protein have been isolated. Libraries of the sizes that we have developed (12 and 15 billion members) have provided high affinity human sFvs against all targets that we have examined to date.

The whole phage display screening/selection process takes about three to four weeks to complete, with the initial identification and isolation of antibodies usually within 10-14 days and the genetic characterization of the antibodies within 1-2 additional weeks. The selected antibodies are fully human in nature, which reduces the likelihood of adverse immunological responses when used in human. As the phage antibody contains the genes that code for the antibody proteins, these genes can be recovered and are available for use in different bacterial, eukaryotic and mammalian expression systems to produce human monoclonal antibody fragments, sFv-IgG1 fusion proteins, or whole human monoclonal antibodies.

One can easily imagine use of the selected antibodies in imaging and immunotherapy. The selected antibodies can also be used as intrabodies. By definition, intrabodies are antibodies that are directed against target molecules that are inside a cell and expressed within a particular cellular compartment as directed by the intracellular localization signals genetically fused to N- or C-terminus of the antibody. Intrabodies have wide applications in dissecting target protein function, in target validation and functional genomics, as well as acting as potential therapeutic reagents. For a recent comprehensive review on intrabody technology, please see the reference by Zhu and Marasco, 2003. Dr. Marasco’s laboratory at DFCI has created a set of intrabody expression vectors over the years that can accept the sFv antibodies from phage display selection with easy Sfi I/ Not I compatible restriction sites. It is the Center’s hope that in the near future the Center will be able to help the NFCR investigators in building intrabodies for gene "knock-out" and gene therapy experiments.

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