Phage Libraries for Generation of Single Chain Fv Antibodies for Intracellular Immunization

Antibodies are heterodimers that specifically bind to a target molecule (anti-gen). Their ability to interfere with antigen function or synthesis make them useful tools for the in situ analysis of intracellular molecules. Antibodies can be directly introduced into the cell or they can be expressed from their genes in a specific cellular compartment where they will bind their target. The introduction of antibodies intracellularly was first successfully achieved by micro injection (in the cytoplasm or in the nucleus)1 or more recently, by electroporation.2 The specific (but transient) effects that were obtained by these methods opened the way to a large number of applications. Expression was also obtained by injection of poly A+ mRNA purified from a hybridoma secreting an antibody of interest in xenopus oocytes.3 For example, an anti-golgi protein antibody mRNA was able to inhibit the intracellular trafficking of a viral protein.4 These experiments showed clearly that a specific antibody/antigen interaction was possible in eukaryotic cells.