Efficient delivery of antibody into living cells using a novel HVJ envelope vector system

Introduction of antibodies which retain their function into cells using a simple and easy method would be very useful for study of the intracellular events in living cells. In this study, we developed a new method for intracellular delivery of antibody. It includes a combination of a novel IgG-capturing protein and hemagglutinating virus of Japan envelope (HVJ-E), an inactivated Sendai virus particle which can deliver a variety of molecules into mammalian cells via membrane-fusing activity. The IgG-capturing protein, which was molecularly designed to have two functions, was prepared as a fusion protein (ZZ–NP) of ZZ-dimer derived from an immunoglobulin-binding domain of protein A and nucleocapsid protein (NP), a part of the structural protein of HVJ. ZZ–NP was efficiently incorporated into the HVJ-E particle by treatment with detergent, and enhanced the incorporation of IgG. Moreover, fluorescence immunostaining revealed that the incorporated antibody was very efficiently introduced into living cells while retaining its function, i.e. anti-NPC (nuclear pore complex) monoclonal antibody was selectively located around cell nuclei. These findings suggest that this method is useful for intracellular delivery of antibody and for analysis of biological function of sub-cellular molecules in living cells.